CHAPTER 17

MARINE MAMMALS

THOMAS C. POULTER

Communication in all animals is received by the sense organs and includes olfactory, tactile, visual, acoustic, and thermal systems. Messages can be defined as any impact of the outside world upon an organism that does not destroy the organism but that does evoke a reaction, of whatever magnitude, from the organism. These messages may be simple, involving only one sensory organ, or complex, such as a fire, which includes olfactory, visual, thermal, and acoustic messages. We may have transspecific signals between different species for example, the call of a sea gull upon seeing a person will alert sea lions and cause them to go into the water even though the sea lions have not seen the person, but language implies the existence of at least two individuals of the same species.

The marine mammals to one degree or another receive communications in all five sensory channels, and the relative use of those channels by the different species will vary widely; the olfactory sense appears to be completely absent in the cetaceans, whereas in the sea lion it is quite highly developed and is one of the important factors by which sea lions identify their own pups from others.

The actual visual capability of some species does not necessarily correlate with their ability to interpret what they see. A California or Steller sea lion will recognize a person as such whether the person is standing still or is in motion and will even recognize different individuals with whom they are familiar. However, an elephant seal bull will pass within a few feet of a person standing motionless to charge a person in motion at a distance of twenty feet or more. Since auditory communication in marine mammals is by far the most uniform means of communication, this chapter on communication in marine mammals will deal almost exclusively with auditory communication.

Our knowledge of marine mammals is very spotty; it ranges from those which have changed the history of mankind, such as whales, fur seals, and sea otters, to others which are completely unknown to scientists. The list of marine mammals of the world assembled by Dr. Victor B. Scheffer and Dale W. Rice contains four orders: sea otters, pinnipeds, sirenians, and cetaceans. These four orders are broken down into 117 species. Of the 117 species listed by Scheffer and Rice, 83 have been studied with respect to their ability to generate some sort of underwater sounds suitable for communication and/or echolocation. Without exception, all 83 species generate underwater sounds.

One can almost certainly assume that if sounds are generated, they can be, and probably are, used for some sort of communication. Whether an animal can, and does, use the sounds it generates in a system of echolocation is more problematic. Bioacousticians have somewhat arbitrarily divided underwater signals into echolocation signals and communication signals—all sharp clicks have been called echolocation signals and all others communication signals.

There is evidence that marine mammals may have a preference for using clicks for echolocation, but that such a division is not wholly justified is shown by experiments with human blind subjects. They detect targets and make size (and to a remarkable degree shape and texture) discriminations, by using a hiss or whistle, either continuous or in short bursts, or by pronouncing words with F and S sounds in them, and some use a clicking noise with their tongues. If a human being can use such a variety of signals for echolocation, it seems obvious that many of the marine mammals’ signals would also serve well for this purpose. In most cases where clicks have not been reported in an animal’s signals, sonagrams almost invariably show that clicks actually constitute a part of many of the signals but are so well integrated that our ears do not resolve them.

Recent work shows that sharp clicks may also be used by some marine mammals as much or more for communication as for echolocation. It also appears that these clicks may have still other associations with animal behavior.

For taxonomic considerations this discussion of communication among marine mammals has been organized to follow the list of marine mammals of the world prepared by Scheffer and Rice. For convenience of reference the species under each order have been numbered consecutively; this number is preceded by the first letter of the name of the order. The illustrations are then numbered consecutively for each species; thus P-2-1 would be the first figure concerning the Steller sea lion, which is the second species listed under the pinnipeds. (See Refs. 10, 14, 15, 22, 23, 24, 44, 47, 112, 120, 121, 124, 135, 138, 142, 143.)

SEA OTTERS

SO-1, Sea Otter Enhydra lutris Linnaeus, 1758

Karl W. Kenyon reports that the most common distress call of both the adult and the young sea otter is a scream. If a pup is taken away from its mother, they will both scream. Their mild alarm signal is a high-pitched, shrill call which sounds more like a whistle. The femaleto-pup communication is a chuckling or cooing sound, and another of their signals is a hiss or cry like a young gull. When the sea otters are eating, they produce a grunting or chuckling sound.⁵⁷

PINNIPEDS

P-1, South American Sea Lion Otaria byronia Blainville, 1820

The barking in air of the South American sea lion is not unlike that of the California sea lion Zalophus, but the author has been unable to find recordings of their underwater signals.¹⁹

P-2, Steller, or Northern, Sea Lion Eumetopias jubatus Schreber, 1776

The Steller, or northern, sea lion is the most portly of the pinnipeds (Fig. P-2-1). Its vocalization and behavior are a part of the study that has been conducted over the past five years on Ano Nuevo Island and at the Biological Sonar Laboratory of Stanford Research Institute working jointly with Dr. Robert T. Orr of the California Academy of Sciences. Ano Nuevo, on which from 1000 to 1200 pups are born annually, is the largest Steller sea lion rookery outside the Arctic. This study has included the first successful raising of Stellers from very young pups (Fig. P-2-2), and six to twelve of these animals of different ages have been maintained in the laboratory for study.

The Steller sea lion is one of the more vocal pinnipeds, particularly in and about the rookery during pupping season. As in many other species the vocalizations of the males and females are quite different, but neither of them barks as does Zalophus.

The breeding Steller bulls come into the rookery area in late April or early May, two to three weeks before the arrival of the cows, to establish their sites in the rookery area for their harems. The early arrivals have ample room and may spread out without evoking serious threats from other bulls. During this early period, they may spend considerable time sitting erect, with their heads high in the air, swaying slowly from side to side while “crooning” or making a continuous slightly warbling or pulsating sound with scarcely a break for breathing. This seems to be the only condition under which this “crooning” signal is used. In addition to a great variety of growls, grunts, and snorts, the bulls use as their major type of vocalization in air a threatening growl which is their loudest and most characteristic signal. They also make a loud snort as they lunge at another animal or a person who ventures too close. If a person retreats, they will not follow through; and if the lunge is at another bull, more often than not, the lunge will stop short of actual contact.

While the bulls are establishing their areas, sharp lunges at one another are common but usually fall short of actual contact. However, once a major battle is begun it may continue, with repeated snorts and growls by both animals. They are rarely badly injured before one with numerous gashes, particularly around its chest and the forward portion of its huge neck, decides to retreat. The bulls never fight to the death, but they may sustain major injuries. Their fighting procedure is to spar for a chance to sink their teeth into their opponent and then, using their 2000 pounds and their huge muscular necks, to shake their heads sidewise until their teeth tear out through the opponent’s skin. During this shaking process, the other animal’s entire body is whipped about so much that it has no chance itself of getting a hold until that of the first one is broken. The longer teeth of the older bulls leave some ugly gashes even through the protective mane which covers most of the neck and shoulders. The vanquished animal usually retreats to the bachelor herd, but an older bull has been known to retreat only about fifty feet, where he will remain the rest of the season without acquiring a harem.

As the cows begin to appear and swim by in small groups, the bulls frequently go to the edge of the rock or into the water to entice the passing females into their harems, using a type of vocalization which they continue to employ during and after the establishment of the harems. The vocalization, which is accompanied by a rapid nodding of the head, is a repeated, low-1evel, rattling grunt signal synchronized (or nearly synchronized) with the nodding of the head. An established harem may contain from a few to as many as twenty-five cows. The bull spends most of his time within the harem vocalizing; this is usually accompanied by his scolding or head-nodding signal. This call is loudest when the cows get restless in the harem or, particularly, if two cows start to fight. If this scolding call does not stop the fight, the bull effectively stops it by moving between the two cows.

Once a bull has established himself as a harem master, he apparently becomes a permanent member of the “club”; an older bull may be allowed to occupy a spot on the edge of the rookery after he is apparently too old to acquire a harem. However, if a bachelor bull enters the rookery area, he is set upon by all of the bulls that can get at him, including any old bull without a harem. As many as five bulls have been seen biting an intruder, with others trying to reach him. They frequently do not allow him to retreat the way he entered; instead, he must run the gantlet of the other bulls and find another way out. During all of this there is much vocalization, the bulls close in snorting, those farther away growling or roaring threateningly, the cows calling to their pups, and the pups scampering to get out of the way of the oncoming bulls. After any such disturbance it takes the rookery some time to settle down; there is considerable lunging of bulls at one another as they return to their harems.

Steller cows have a higher pitched and less pulsating call, somewhat resembling that of a dairy cow. Both bulls and cows also have shortduration threatening exchanges with accompanying threatening gestures. Subadult male and female animals from a few weeks to several months of age produce a loud, continuous sound similar to a belch. The older the animals, the lower will be the pitch of the signal. The very young pups have a cry which is not unlike the bleating of sheep (but less pulsating). The Steller sea lions are very much less vocal under water than are the California sea lions; Steller underwater vocalizations more nearly resemble their in-air signals, with much less clicking than the California sea lion emits.

Totally blind animals are apt to occur in any large group of animals. The extent to which they survive and carry on a normal life throws much light upon their communications and echolocation capabilities. Figure P-2-3 shows a large Steller bull which was determined experimentally to be totally blind.¹¹⁵ He appeared to be in the best of health and during the 1965 pupping season selected and successfully defended his harem area, established a normal sized harem, and apparently functioned as effectively as a harem master as did other animals with normal sight.

The cows appear to stay with the newborn pups continually foi several days, after which they divide their time between making extended trips to sea presumably to feed and nursing the pups in the rookery. Since almost twice as many pups as cows may be present in the rookery at any one time, this would indicate that the cows spend almost half of their time at sea. From observing that pups often appear to remain unattended for a few days at a time, we believe that these feeding periods at sea may last up to a few days. When the cow returns, she frequently stops at the edge of the rookery area and makes a series of calls. Almost immediately some pup in the rookery answers, even though none of the pups nearby pay any attention to her calls. The answering pup at once starts in the direction of the cow, sometimes on the gallop and at other times making progress slowly, but in either case there is a frequent exchange of vocalization between the cow and pup. In those cases observed, the cow has remained where she originally called from and allowed the pup to come to her; as soon as the pup reached the cow, it immediately started to nurse.

With so many cows out at sea feeding, many hungry pups are left in the rookery, and they frequently try to nurse another cow. The cow rebuffs them at first with growls and snorts; and if they are persistent, she will bite at them or grab them in her teeth and toss them aside. Even this may not be a sufficient deterrent for hungry pups, who may return squawking, with mouths wide open, and shaking their heads. On several occasions a cow has been seen to grab a pup and throw it into the air with such force that it will travel ten to twenty feet, tumbling end over end before it lands on other animals or on the rocks.

In the later stages of the pupping season the harems become less and less orderly, and the bulls are less interested in stopping fights between cows. If one cow shows interest in or is aggressive toward another cow’s pup, the result may be a fight between the cows. On at least two separate occasions, fights have been observed to start between two cows near the upper edge of the rookery on Ano Neuvo Island, at a point where it is twenty feet straight down over the rock to the water. As the fight increased in tempo and the pups milled about trying to keep out of the way, one cow grabbed the pup of the other cow and threw it over the edge. This broke up the fight, and the cow whose pup had been thrown over the edge immediately set out to retrieve it. In one case the pup was killed as it hit the rocks below, but in the other case the pup landed on a two-foot-wide ledge about two-thirds of the way down, apparently unhurt.

At first there was considerable exchange of vocalization between the cow and her pup, and there appeared to be no way that the cow could reach the pup from above or below. The cow, however, worked her way head-first down the almost vertical rock wall and eventually reached the ledge where the pup had landed. She lay down on the seaward side of the pup and allowed it to nurse for about twenty minutes. Then, unable to see a way to go back up or on down, and instead of diving, the cow jumped, landing flat in some water that was not more than six inches deep. She was dazed for a moment, and then started around to come up through the rookery to the top side. A bachelor bull waiting in the water tried to prevent her from leaving there, and after considerable maneuvering she disappeared below the surface of the water and traveled underwater out through a narrow passage to open water; a few minutes later she reappeared up above the pup.

After about an hour of frequent exchanges of vocalization, the cow started down again and with equal difficulty reached the ledge; but as the pup came to her, it slipped off the ledge, bouncing two or three times, and again landed apparently unhurt. Instead of jumping down this time, the cow attempted to climb down head-first but partially slid and partially fell down, apparently with less ill effect than from her previous jump. The cow and pup then nuzzled each other for a moment before the pup began to look for a place to nurse.

Figure P-2-4 shows sonagrams of the typical steller sea lion’s vocalization.¹⁴¹⁰²׳^a

P-3, California Sea Lion, Zalophus californianus Lesson, 1828

The following discussion is based on five consecutive years’ study of the California sea lion both in the laboratory and on Ano Nuevo Island, where they have hauled out in increasing numbers since 1961, reaching their maximum about the first of September as they migrate north from their breeding grounds. The maximum in 1961 was above 3400, whereas in 1966 it was in excess of 18,000.¹⁰² This number drops to a small per cent during their breeding season in the islands farther south.

The California sea lion, the best known of the pinnipeds, is the species found most extensively in zoos and in trained-animal acts. It is one of the more abundant of the sea lions to be found in readily accessible areas, and its size makes it a good show animal. The California sea lion is also the most vocal pinniped, both in air and under water, found outside the polar regions. It was first studied for its echolocation capability by the author in 1962, when it was observed that two totally blind California sea lion bulls appeared to be in as good physical condition as the other animals on the island.

There is a marked difference in the quantity and type of vocalization of the male and female California sea lion. If you were to designate a California sea lion as a male because it was barking, you would probably be correct 95 per cent of the time, as the females rarely bark. The vocalization of the male in air consists of barks, growls, snarls, and a variety of threatening sounds including a very loud roar. The female makes a variety of cries, growls, and snarls.

The barks of the bulls usually occur in rapid succession in groups of one to fifteen; the bulls emit barks with their mouths open and their nostrils usually closed. During the interval between groups of barks, the animal may or may not close its mouth, but it opens its nostrils and, if the preceding group of barks has been a short series, it will first exhale and then inhale, whereas if the series has been an extended one, it will immediately inhale. On rare occasions, both the male and female emit a series of clicks while out of water; in such cases the mouth and nostrils are usually closed.

Figure P-3-1 shows sonagrams of some of the more characteristic signals of the California sea lion in air. The animals may bark under water while emitting bubbles from the mouth or nostrils, thereby producing some bubble noise in addition to the other signals. They may bark under water without emitting bubbles and with or without the emission of clicks. Their underwater clicks frequently contain some very high frequencies, but the major portion of the energy is below 20 kHz. Clicking at a low or random rate produces crackles or pops, whereas a high rate which is not completely uniform produces a “squeaking hinge” signal. The combination under water of the sounds normally made in air with the clicking signals produces a great variety of underwater sounds, including a sweep frequency signal and a whinny. Underwater barking and bangs produce very similar sonagrams but actually sound entirely different from each other. The bang has a sudden rise in energy in that all frequencies start at the same time, but in barking the higher frequencies have a delayed start.

Attempting to compare very short duration animal signals such as clicks only by listening to them can be grossly misleading. The rate of onset of a signal may so completely affect the protective auditory reflex in our ears, and the recovery time may be so slow, that we hear only the onset of the signal. Two series of clicks which are very similar except for the initial rise time may sound entirely different. If a tape loop of a series of clicks in which only alternate clicks have a very steep rise time is played in one direction, the alternate clicks will sound entirely different from the intermediate ones, whereas if the tape is played in the other direction, they may all sound identical. How loud clicks sound is greatly affected by the rise time of the signal. One series shown in the first sonagram of Fig. P-3-1 sound like sharply defined clicks, yet they are more difficult to see on the sonagram than are the isolated clicks in the second sonagram, which sound less distinct to the ear.

The military takes advantage of this effect in the firing of large guns in cases where personnel must be close to the gun, as in a tank. The tank crew must wear headphones for purposes of communication. The gun is fired electrically, and just before it is fired a loud pulse is introduced into the headphones. Then, at the time that the auditory reflex has desensitized the ear, the gun is fired and the blast is not painful.

Anyone working in bioacoustics is frequently struck by the great difference in the signals of different animals of the same species and particularly in those of captive versus wild animals. Although the California sea lion does not normally use a large sweep in frequency, one captive two-year-old female California sea lion frequently produced a large downward-sweep signal. Another captive animal, during feeding times at the sea lion tank at the San Francisco Zoo, repeats at intervals of a few seconds a group of about ten clicks within an elapsed time of 0.6 sec. The frequency of the clicks in these groups follows the same general pattern, spanning several thousand hertz, and the group may be repeated as many as 135 times in succession, apparently as an exploratory signal while waiting for a fish to be thrown into the pool. This signal has never been recorded in the wild or from any other captive animal. It is suspected that the difference between captive and wild animals may be even greater in those cases where the captive animals have been raised from small pups.

In spite of the very distinct advantage in working with captive animals, of knowing what species and even what individual animal is making the sound being recorded, there is always the disadvantage of not knowing to what extent the captive animal is performing differently from the way a wild animal would. However, the performance is sufficiently close to use for identifying signals on recordings of wild animals. In this connection most of the animals in the Biological Sonar Laboratory at Stanford Research Institute have been raised from small pups, and we have not been able to prove that any have developed echolocation for purposes of feeding. This is not surprising, since the feeding procedures employed do not require its use. However, our animals do swim freely around in the tank and go in and out of the water in total darkness over a one-foot vertical rise between the water and a deck alongside. We have conducted tests in total darkness so that high-speed photographic film could be left exposed for two hours without producing any fogging. The animals’ behavior during these tests was always accompanied by some clicking, so we suppose that even if they do not use echolocation for locating food, they do use it for orientation.

In his work in target and pattern recognition, Dr. Schusterman has demonstrated that reinforcing the behavior of a California sea lion merely by rewarding it with a small piece of fish will cause it to emit clicks and that not rewarding it in this way leads the sea lion to emit no clicks; the process can be reversed as many as fifteen times in a single test period of less than two hours. In this work Dr. Schusterman has also demonstrated that these clicks can become a part of behavior patterns as well as being used for echolocation.

Anyone who has done much field work with seals and sea lions has undoubtedly had many excellent examples of communication not only between different species but even between different genera. For instance, when one is carefully crawling up to a group of seals or sea lions, he will very likely be spotted by a sea gull which will make its “alert” cry; this in turn will immediately alert the seals or sea lions to one’s presence. Even though they cannot see the intruder, they will immediately head for the water.

A striking example of communication occurred one day when a party of scientists was visiting Ano Nuevo Island. The California sea lion population on the island at that time was in excess of 5000 animals. About 1000 of these were on the sand beach where the boat landed with the party. When the landing was made at one end of this beach, about 500 animals went into the water, but they remained in a pod just offshore and continued barking profusely, as did those that remained on the beach. As the party pulled the small boat up on the beach, the barking all over the island suddenly stopped, and with equal suddenness all of the animals in the pod offshore dove and swam away. The very suddenness of this cessation of barking of 5000 sea lions was almost unbelievable, and the scientists, who had themselves heard nothing, immediately looked around to try to discover what the alert signal had been. After at least thirty seconds of total silence, one or two animals ventured to bark, and within another ten seconds the barking was back to normal levels. No explanation was ever found for this sudden and peculiar behavior.

On another occasion an attempt was made to tranquilize a California sea lion bull by means of a gun dart shot into the bull in a group of about fifty on the rocks on Ano Nuevo. The animal jumped slightly when the dart hit it, moved about two feet, and settled down again. Another bull came over leisurely and smelled the tassels on the dart; he immediately started barking and the entire group went into the water. The barking of the animal which smelled the dart had suddenly alerted the entire group. A second dart was then washed off thoroughly and sea lion feces were rubbed into the tassel. This dart was shot into another bull in a group of about forty. Just as before, a bull came over and smelled the tassel, but this time no alarm was sounded and the animals all remained quietly sleeping.

Trained California sea lions, of course, respond readily to voice commands. The Japanese sea lion Z. c. japonicus and the Galapagos sea lion Z. c. ivollebaeki, two different races of the genus Zalophus Gill, have, so far as is known, essentially the same behavioral, communication, and echolocation capabilities as Z. c. californianus. (See Refs. 14, 32, 54, 100, 101, 102, 103, 118, 130, 135, 137a.)

P-4, Australian or White-Capped Sea Lion, Neophoca cinerea Péron, 1916

The Australian sea lion is generally similar to the Steller sea lion in appearance, behavior, and vocalization (Ref. 6, 121).

P-5, New Zealand Sea Lion, Neophoca hookeri Gray, 1844

The New Zealand sea lion is similar to the California sea lion in appearance, behavior, and vocalization.¹²¹

P-6, South American Fur Seal, Arctocephalus australis

There are three races:

A. a. australis Zimmermann, 1783;

A. a. gracilis Nehring, 1887;

A. a. galapagoensis Heller, 1904.

The author has been unable to locate any recordings of the vocalization of the South American fur seal.

P-7, Australian Fur Seal, A. doriferus Wood Jones, 1925

No recordings of their vocalization are available.

P-8, New Zealand Fur Seal, A. forsteri Lesson, 1828

No recordings of their vocalization are available.

P-9, Philippi Fur Seal or Guadalupe Fur Seal, A. philippii

Two races are recognized:

A. p. Peters, 1866;

A. p. townsendi Merriam, 1897.

The author was unable to locate any recordings of the vocalization of the Guadalupe fur seal, but Dr. Hubbs reports⁵¹ that their vocalization is similar to that of the northern fur seal, and this is confirmed by the author.

P-10, South African Fur Seal, A. pusillus Schreber, 1776

P-1l, Kerguelen Fur Seal, A. tropicalis Gray, 1872

The vocalizations of the six species and four races of southern fur seals and the one species of northern fur seal are sufficiently similar that it would be difficult for a person not thoroughly familiar with each species to detect a difference. The signals of the South African fur seal are in general of somewhat lower pitch because it is the largest of all fur seals.^6,51,118

P-12, Northern Fur Seal, Callorhinus ursinus Linnaeus, 1758

The author spent the 1965 fur seal pupping season on St. Paul Island recording and analyzing vocalizations both in air and under water, and returned with four five-day-old pups to the Biological Sonar Laboratory for further study and to raise them by hand. The vocalization of the domineering bulls in the rookeries seems to be directed at the cows rather than an attempt to communicate with them. Vocalizations of the bulls, cows, and pups are all a bleating type of signal, each characterized primarily by the frequency range it covers; the bulls emit the lowest frequency and the pups the highest. The cows and three-year-old males are about the same size, and their vocalization is in the same frequency range, but there is a noticeable difference in quality. In air, an old bull may use a very low-pitched blat which sounds more like a series of clicks. Sonagrams confirm this and show the signal to be broken up into groups of three clicks of ascending frequency, with the third one as much as 200 Hz higher than the first.

The northern fur seals’ underwater signals strongly resemble their in-air signals, the primary difference being the absence of most of the high-order harmonics from the underwater signals. However, the narrower and sharper the highest-intensity frequency band, the larger the number of harmonics is likely to be. Figure P-12-2 shows sonagrams of the in-air and underwater signals of the bulls and cows and the in-air signals of the pups.

If the tape speed of a fur seal recording either in air or under water is slowed sufficiently, the apparently continuous lines in the sonagrams break up into clicks. It is possible in most cases to determine the sex of the animal merely by determining the number of clicks per second; the males’ clicks range from eight to thirty-two per second and the females’ range from thirty-eight to sixty. In most cases it is even possible to determine the sex of a pup only a few days old by an inspection of sonagrams for its recordings of its signals. (See Refs. 8, 38, 51, 75, 106, 149.)

P-13, Walrus, Odobenus rosmarus

Two races are recognized :

North Atlantic Race. O. r. rosmarus Linnaeus, 1758 North Pacific Race, O. r. divergens Illiger, 1815 The North Atlantic and North Pacific races of the walrus have nearly the same vocalizations, both in air and under water. In air their vocalization consists of loud grunts, groans, and a lion-1ike roar while under the water they produce a rasping sound and clicks or a knocking sound like tapping a board with the knuckles. Their most spectacular vocalization is associated with the pharyngeal pouches and sounds like the ringing of a bell. Although usually made under water the eskimos report that the bell sound will also be made in air.^75,114a,130a

P-14, Harbor Seal, Phoca vitulina Linnaeus, 1758

Five races are tentatively recognized:

Eastern Atlantic, P. v. vitulina Linnaeus, 1758

Western Atlantic, P. v. concolor DeKay, 1842

Eastern Pacific, P. v. richardi Gray, 1864

Western Pacific, P. v. largha Pallas, 1811

Seal Lakes, P. v. mellonae Doutt, 1942

This species is probably one of the least vocal of the pinnipeds, both in air and under water. About the only sound that the adults have been heard to make is a gusty exhalation through the nostrils and mouth with the jaws closed; this is sometimes accompanied by a low, staccato, grunting sound. Their underwater signals consist almost exclusively of the normal echolocation type of clicks which may also be used for communication, as has been found for the California sea lion and others. The pups, on the other hand, are quite vocal. They do not open their mouths as many pups do when they make a sound; instead, the mouth is usually closed or nearly so. They are very tractable when quite young, particularly if they are being raised by hand instead of by the cow. Regardless of the occasion, they make the same sound—whether frightened, wanting attention, playing, in pain, or wanting food. As they get to be two or three months old, this sound begins to disappear, continuing the longest when they want food, but even then at a very low level almost comparable in loudness to the purring of a cat. As they discontinue this sound, they begin to develop the technique of snorting through the closed mouth, vibrating the cheeks, lips, and nostrils. When this signal is used as a threat, it is usually accompanied by clawing with the front flipper. Unless they are worked with extensively, these pups rapidly become less tractable. If a six-month to one-year-old pup is restrained or picked up, it may revert to a loud growl and snorts. Their vocalization under water is likewise very limited, consisting primarily of clicks with an occasional short growl superimposed.^14,75,102

P-15, Ringed Seal, Pusa hispida

Six races are recognized:

Arctic Ocean P. h. hispida Schreber, 1775

Okhotsk Sea P. h. ochotensis Pallas, 1811

Bering Sea P. h. krascheninikovi Naumov and Smirnov, 1936

Baltic Sea P. h. botnica Gmelin, 1788

Lake Ladoga P. h. ladogensis Nordquist, 1899

Lake Saimaa P. h. saimensis Nordquist, 1899

This species is a close relative of the harbor seal. All attempts to record the under-ice signals of the ringed seal have been made when bearded seals were known to be present in the area, so that it has been impossible to isolate the signals for certain. Ringed seals are thought to produce bird-1ike chirps and clicks.⁷⁵

P-16, Baikal Seal, Pusa sibirica Gmelin, 1788

P-17, Caspian Seal, Pusa caspica Gmelin, 1788

These are the only two species confined to single and inland bodies of water, and both are located in Russia. We are not aware of any recordings of their signals in air or under water.

P-18, Gray Seal, Halichoerus grypus Fabricius, 1791

Being of the tribe Phocini, this seal would not be expected to be very vocal. No recordings are available.⁷⁵

P-19, Ribbon Seal, Histriophoca fasciata Zimmermann, 1783

P-20, Harp Seal, Pagophilus groenlandicus Erxleben, 1777

Because their habitats are along the edge of the ice, these seals would be expected to be quite vocal in air and particularly so under water or under ice. However, no recordings have been located.⁷⁵

P-21, Bearded Seal, Erignathus barbatus Erxleben, 1777

This is believed to be one of the most vocal of the species found under the Arctic ice (Fig. P-21-1). Its vocalization covers a very broad frequency range within a long, pulsating continuous signal. This signal starts out at a frequency of about 7 kHz and a pulsing rate so high that it sounds like a continuous signal. Each pulse consists of a sudden jump in frequency of a few hundred hertz followed by a rapid but uniform decrease in frequency to just below the frequency from which it made the preceding jump. Thus, with each hertz signal ends up at a little lower frequency, gradually sweeping downward to form a sawtooth effect on the sonagram. Some signals may continue for as long as a minute and drop to a frequency of less than 100 Hz and a cycling time as low as 1 Hz for a total frequency change of more than six octaves. In addition to this long sweeping signal, it is believed the bearded seal makes a great variety of shorter signals, rapidly sweeping up or down in frequency, or the signal may merely be broken into segments changing rapidly in frequency or leveling off to a nearly constant frequency.

These signals would serve well for either communication or echolocation. There are usually from one to four or five such signals on the recordings at all times. It is inconceivable that the seals could need that much echolocation information, or communication for that matter. One gets the impression from listening to these signals that the seals must be making them for the pleasure of listening to them as a form of singing.^75,112

P-22, Mediterranean Monk Seal, Monachus monachus Hermann, 1779

P-23, Caribbean Monk Seal, M. tropicalis Gray, 1850

P-24, Hawaiian Monk Seal, M. schauinslandi Matschie, 1905

Kenyon and Rice describe the vocalization of the Hawaiian monk seal as falling into two categories: bubbling sounds and bellowing sounds. The bubbling sounds are usually uttered when a sleeping seal is awakened as a rapid series of soft bubbling sounds originating deep in the throat. It is audible to about fifty feet and appears to denote mild alarm. This sound may be made quietly with the mouth closed or with the mouth open in a threatening manner. The primary threatening vocalization of the monk seal is a bellow or grunting bawl sometimes accompanied by a gusty expiration. A mother defending her pup produces a louder version similar to that produced by a Steller cow. The pups produce a similar but higher pitched sound. The mothers affectionate call to her pups is a throaty growl or moan to which the pups respond by bleating. When disturbed, the pups utter a diminutive but sharp version of the grunting bawl.⁵⁸

P25, Crabeater Seal, Lobodon carcinophagus Hombron and Jacquinot, 1842

This is probably the most precocious of the pinnipeds; these seals are born with a full set of teeth, nurse for only two or three days, and are then off on their own. The author knows of no recordings of their vocalization in air or under water, but he has observed them extensively out on the ice, where they are vocal. Since they spend as much time under the ice as they do above it, it would be expected that they would be quite vocal.⁶¹

P-26, Ross Seal, Ommatophoca rossi Gray, 1844

Dr. Carleton Ray describes their vocalization in air as a series of loud, powerful, rapid “glump-glump-glumps,” rising and falling “whowho” trills, and flatulent exhalations. Their vocalization would serve well for communication and echolocation.¹¹⁷

P-27, Leopard Seal, Hydrurga leptonyx Blainville, 1820

Widely distributed in the Antarctic and on sub-Antarctic islands, leopard seals are usually found as solitary animals or widely scattered; their vocalization is minimal, at least in air. While a large adult bull leopard seal was being captured in the Bay of Whales in 1935, its only vocal reaction during the struggle to get it into a crate was a staccato throaty grunting and a snort followed by a gusty exhalation through the mouth with the jaws closed and through the nostrils in a manner similar to the harbor seal, but with a much louder sound.

Leopard seals feed on aquatic birds and cause great depredation around the Adelie penguin rookeries in the Antarctic. They will lie in wait just off the edge of the ice at the penguin rookeries, facing out to sea, to intercept the unwary penguins as they return from feeding at sea. They are very much more vocal under water, apparently in a combination of communication and echolocation. Their underwater vocalization consists primarily of six different types of signals: a low-frequency chirping signal; an intermittent, low-pitched, constant-frequency signal; an intermittent, high-pitched, constant-frequency signal; two sweep-frequency signals; and isolated clicks. These signals are shown in Fig. P-27-1.^6,112

P-28, Weddell Seal, Leptonychotes weddelli Lesson, 1826

Much of the following information concerning the vocalization and associated behavior of the Weddell seal was gained through three expeditions to the Antarctic, 1933-1935, 1939-1940, and November, 1964, and through the analysis of many thousands of feet of magnetic tape recordings of their signals both in air and under water. The Weddell seal is without doubt the tamest of all of the pinnipeds and one of the most vocal, particularly while under the ice.

There is no apparent harem activity among the Weddell seals on the surface of the ice, and it is believed that they may be monogamists, which, if true, is a rarity among the pinnipeds. Be that as it may, confining their breeding activities to under the ice would account for the relatively large portion of their vocalization being carried on under ice for purposes of communication rather than primarily for echolocation.

Their extensive under-ice signals can be recorded over a radius of three to five miles. The fact that the snow-covered ice eliminates essentially all wind and water noise is important in obtaining such ranges, but the additional fact that their signals can be heard through the six-foot-thick ice by a person standing on the ice in the immediate vicinity attests to the strength of their signals. It is therefore probable that they can communicate over distances as great as or greater than those at which their signals can be picked up by the hydrophones.

The vocalizations of the Weddell bulls and cows in the air are entirely different in both quality and quantity, particularly during pupping season. Apparently the bulls come out on the ice primarily to sleep. With the exception of a few minor growls and grunts upon being disturbed, the Weddell bulls have two major signals in air. One is a deep chirping signal apparently generated in the larynx at a slightly fluctuating rate of about fifteen chirps in ten seconds. The other is a drumming signal which sounds like a brass drum being struck. A series of ten to twelve beats usually extends over a period of thirty to thirty-five seconds and starts out very slowly, with seven or eight seconds between the first two beats, and ends at a rate of about one per second. Except for the eight or nine weeks associated with pupping season, the cows also apparently come out of the water only to sleep or sun themselves during the more favorable weather. During these periods they are no more vocal than the bulls. They usually haul out on the ice about one to two weeks before giving birth to their pups, and they spend much of that time sleeping. However, after the pups are born there is an abundance of vocalization. The cows are usually scattered out in the large rookery area, so that there is little occasion for crowding problems.

The cows have several threatening signals which are common as a person first comes into the rookery area, but after a short while the primary signals heard are those of the pups and the exchanges between cows and pups. The threatening calls are made for the most part with the mouth wide open. This appears to be done more for effect than with any intention of using the teeth, as evidenced by an occasion when the lead dog of my team stuck its nose into a cow’s wide-open mouth and smelled around, with no attempt on the part of the seal to bite. Despite the extensive netting and transporting of both bulls and cows for study, no one has ever been bitten to my knowledge.

The most common threatening call is a continuous, steady, lowpitched tone lasting for about thirty seconds and ending in a Bronx cheer effect and a snort. The next most common and specific signal is a series of about seventy-five high-frequency chirping signals in fifteen seconds, starting out at seven or eight chirps per second. A similar, but much softer, signal may be used by the cows in an entirely different context, namely, with the pups without any outside disturbance. In addition, the cows engage in lowing, grunts, snorts, and a low chirping sound as they nuzzle their pups. The Weddell cows seem to suffer much more than most pinnipeds from the loss of a pup and are also unusual among the pinnipeds in that they will adopt and nurse sometimes two orphaned pups in addition to their own and affectionately care for them as if they were their own.

The very young pups may use loud blats or bawl like a lamb or a bovine calf; more commonly they whine, whimper, cry, or coo, resembling a human baby. As the pups get older, they shift more and more to the blat or bawl, so that during the latter part of the pupping season the rookery closely resembles a barnyard of lambs and calves. During Lindsey’s weighing of pups in 1933-1935, a cow would watch with some apprehension the first time a pup was put in a bag and weighed, but on repeated weighings she would crawl to one side and go to sleep even though the pup was quite vocal. On one occasion, while taking close-up pictures, I sat on the ice three feet in front of a cow’s head, and she watched without even raising her head while her inquisitive pup rested its head on my knee to watch the camera.

Because of the normally excellent recording conditions under the ice and the recording range of three to five miles, it is almost impossible to obtain recordings from a single animal or even from two or three. The recordings are usually a bedlam of signals; there is an average of three sets of signals on the tape at all times, with a new signal starting on the average of about every three seconds. From this it is obvious that the average signal length is only a few seconds.

In general, the underwater signals of Weddell seals have a soft quality in contrast to the harsh clicks of many other species. Their under-ice vocalization includes a great variety of calls, but the one most extensively used starts at a frequency of about 2000 Hz or higher and a pulse rate as high as 200 per second; in a period of twenty to forty seconds the signal may sweep down to a frequency of 50 Hz and a pulse every two or three seconds. On some occasions these repetitive pulses may consist of a continuous white noise with upper and lower frequency limits of 3500 and 500 Hz, respectively, at an almost constant repetition rate for ten or fifteen seconds; the pulse then fades out at some lower frequency. On other occasions, instead of making the complete sweep, the signals start at almost any point and just as abruptly stop. It is not uncommon for a signal which starts at 2000 or 3000 Hz or higher to sweep down to 100 Hz within two or two and one-half seconds.

Frequently, a signal that is sounded only once or repeated several times sweeps down over a broad frequency range in a quarter to a half second, or there may be isolated chirps similar to those made by both the bull and the cow in air. There is occasionally a series of clicks, usually at a slow rate as contrasted with the normal pulses, which we would classify as echolocation clicks. It is therefore my belief that the major portion of the Weddell seals’ under-ice vocalization is communicative in nature.^{6,62,112,122,129}

P-29, Hooded or Bladdernose Seal, Cijstophora cristata Erxleben, 1777

This animal is closely related to the elephant seal; this fact, combined with its preference for deep water and thick ice, clearly indicates a very vocal animal. The bladdernose would also indicate that the male has a very low frequency signal if it uses the nose in a manner similar to the way an elephant seal bull uses its proboscis. This would also serve very well as an underwater sound source.⁷⁵

P-30, Southern Elephant Seal, Mirounga leonina Linnaeus, 1758

P-31, Northern Elephant Seal, M. angustirostris Gill, 1866

Since the vocalization and behavioral patterns of these seals are essentially identical, only the northern elephant seal is described in detail here.⁶ The most comprehensive report to be found in the literature on the vocalization and social behavior of the northern elephant seal is that of Bartholomew and Collias. This has been supplemented by the author through five consecutive seasons of study of the breeding colony on Ano Nuevo Island, during which time the number of pups born annually increased from twenty-one to more than one hundred (all of these have been tagged), and from the raising and study of numerous pups and subadult animals over that period in the laboratory.

The breeding bulls start to return to the beaches of Ano Nuevo Island about mid-December. By the time the cows start to arrive in late December or early January the harem masters, after numerous fights, but usually without much bloodshed, have established themselves in areas where they hope to collect their harems. This twoor three-week period is the only time of the year when the bulls will charge any person who approaches too close. After the harems are established or at any other time of the year, if the bulls move at all when a person approaches, it will be to retreat or go into the water.

During the period before the cows arrive, the bulls all around the island can be heard making low-pitched, bullfrog-1ike honking signals. This honk is usually repeated about three times, but occasionally as many as five or six times in succession. Frequently some or all of the honks end in a clacking or Bronx cheer effect as the proboscis, which inflates during their honking, vibrates and resonates; this has been termed by Bartholomew a “clap threat” signal. Also, the last of a series of honks is occasionally followed by a bellow like that of a bovine bull.

There are frequently bulls in some of the narrow passages or small areas around the island, enclosed or partially enclosed by nearly vertical rock walls, where their honks reverberate. The bulls spend considerable time, day and night, resonating these areas with their honks, frequently with just their heads above water. The importance of this type of practice becomes apparent as one studies the harem masters’ guarding of the harems.

The total number of harems on Ano Nuevo does not exceed five or six, and these are rather loosely organized. By the time the harems are established, there seems to have been a very definite understanding among the harem bulls as well as the bachelors as to who the harem masters are and where their harems will be located. The harem masters may remain within their harems or may patrol in the water in front of the harems. However, this does not prevent the bachelor bulls from trying to sneak into the harems. If a harem master sees such an intruder, he merely raises his head and makes a few wellchosen honks; the intruding bachelor invariably departs as suddenly as if the harem master were right behind him.

With the exception of a snort and a certain amount of low-1evel vocalization within the harem, the honks with and without the clack ending or Bronx cheer effect, and the bellow that follows some series, constitute most of the elephant seal bulls’ vocalization. The vocalization of the elephant seal cows and pups makes up for any shortage on the part of the bulls, both from the standpoint of variety and quantity; and while the rookery season is at its height, they are probably among the most vocal of the pinnipeds.

The cows do not develop a long proboscis as do the bulls; much of the cows’ vocalization is high-pitched, although they have some very low-pitched, staccato, threatening signals. Both the cows and pups have a high-pitched chirping or parrot-1ike cry, and the rookery at times could almost be mistaken for a large number of wild parrots in a tropical jungle.

A newborn pup’s first calls are a shrill yapping cry. The mother answers with a warbling soft call which she apparently uses in answering the pup or when looking for or calling it. The cows are extremely protective of their pups; they will cluster around the pups on the beach and defend them against all comers, charging and threatening any person who comes too close, with the mouth held wide open while emitting a high-pitched chirping cry or a lowpitched staccato growl. The latter somewhat resembles the roar of the bull Steller sea lion.

The cows and pups produce a raucous array of pulsating honks, whines, whimpers, squeaks, squeals, roars, moans, snorts, grunts, croaks, chuckles, snores, snarls, moos, bellows, barks, cries, cackles, ar!d about anything that one can imagine. Figure P-31-1 shows characteristic sginals of the bulls and cows, and Fig. P-31-2 shows sonagrams of sixteen pup signals which were repeated from two to more than ten times by two pups in a single forty-five-minute period.

The normally gregarious elephant seal cows and pups may frequently be piled much closer together than the crowding condition of the beach dictates. There is, therefore, much threatening vocalization as one cow encroaches upon another cow or her pup. The bulls are completely oblivious to the pups; if a bull steps or rolls on a pup, any amount of squawking of the pup elicits no recognition by the bull that the pup even exists. The cow may make threatening calls at the bull, but only from a distance, whereas if it were another cow, she would be quite aggressive.

The underwater vocalization of the northern elephant seals in shallow water is extremely limited, but numerous clicks have been recorded for both captive and wild animals. The author has observed elephant seal cows lying motionless under water for periods as long as thirty minutes. Deep diving and deep feeding where echolocation is required are, of course, associated with the ability of an animal to stay submerged over long periods.^{6,9,102,118,137}

SIRENIANS

S-1, Dugong, Dugong dugon P. L. S. Müller, 1776

S-2, Steller Sea Cow or Great Northern Sea Cow, Hydrodamalis gigas, Zimmermann, 1780

S-3, Caribbean Manatee, Trichechus manatus Linnaeus, 1758

S-4, West African Manatee, Trichechus senegalensis Link, 1795

S-5, Amazon Manatee, Trichechus inunguis Natterer, 1883

The Steller sea cow has been extinct since 1768, and no recordings have been made of the Dugong or the West African manatee. The signals of the Caribbean manatee were first recorded by Kellogg and published on a phonograph record in 1955. He described the sounds as squeaking like a mouse. The Narragansett Marine Laboratory subsequently obtained recordings of the Caribbean manatee, and in 1965 Schevill and Watkins made recordings of its underwater signals and published sonagrams and a description of the signals.^54,82,131׳

CETACEANS

Subfamily Platanistinae; Genus Platanista Wagler, 1830

C-1, Ganges Dolphin (Susu), P. gangetica Lebeck, 1801

There are no known recordings of this species.

Subfamily Iniinae; Genus Inia D’Orbigny, 1834

C-2, Amazon Dolphin (Boto; Bufeo), L geoffrensis Blainville, 1817

The echolocation and communication signals of the Inia consist of chirps, squawks, thumps, and clicking with rates up to 200 per second. All of their signals have a wide range of random but closely spaced frequencies. (See Refs. 60, 81, 82, 88, 109, 114, 115, 132.)

Genus Lipotes Miller, 1918

C-3, White Flag Dolphin, L. vexillifer Miller, 1918

There are no recordings on this species.

Subfamily Pontoporiinae; Genus Pontoporia Gray, 1846

C4 -, La Plata Dolphin, P. blainvillei Gervais, 1844

There are no recordings on this species.

Subfamily Monodontinae; Genus Delphinapterus Lacépède, 1804

C-5, White Whale (Beluga), D. leucas Pallas, 1776

The white whale has been known as the “sea canary” for more than 150 years. It has one of the widest ranges of signals found in marine mammals, including clicks, whistles, modulated whistles, yelps, trills, blares, rasp whinnies, squawks, growls, roars, cackles, and squalls.

The most comprehensive study and analysis of the signals of the white whale were made by Fish and Mowbray in 1961 with high-frequency-response magnetic tape recordings and synchronized color motion pictures. They report that, as the regular feeding time approaches, instead of whistling expectantly at the surface of the water, as does Tursiops, the whale swims at mid-depth often with its underside up, slowly oscillating its head and continually emitting echolocation-type clicks, with an occasional rasp, yelp, squawk, bang, and canary-1ike whistle. Many of its signals are above the range audible to humans and can be heard only by slowing the tape speed. In a continuous forty-seven-minute recording, Fish and Mowbray report that twenty-four characteristic cetacean whistles were heard and at least seven sounds were partially concurrent with preceding whistles.

The modulated whistle consists of a principal frequency with concurrent sideband frequencies having a much lower modulating frequency and not harmonically related to the principal frequency, but with a constant difference of 330 Hz. The yelps were short, highpitched emissions which spanned the feeding period; they were usually heard with a rising inflection and had as many as ten higher harmonics. When the male was pursued by the female, two extremely loud and sustained defensive blares by the male were heard in rapid succession.

The rasp consists of a series of very high amplitude pulses extending over approximately 0.6 sec, and the taps are very loud shortduration events. The squawks are commonly heard following yelps and bangs during periods of increased activity. Loud bangs are produced immediately after a yelp or squawk or during a squawk, but never independently. Bird-1ike trills are frequently heard when feeding is concluded, and the loud bangs obviously represent a threat or warning. The blare and the modulated whistle are unlike any cetacean emission previously recorded. Fish and Mowbray include Vibragrams of the principal signals of the white whale. (See Refs. 11, 21, 28, 38, 40-42, 76, 82, 128, 132, 147, 148.)

Genus Monodon Linnaeus, 1758

C-6, Narwhal, M. monoceros Linnaeus, 1758

There are no known recordings of the narwhal.¹⁰⁹

Subfamily Delphininae; Genus Phocoena G. Cuvier, 1817

C-7, Harbor Porpoise, P. phocoena Linnaeus, 1758

C-8, Gulf of California Porpoise, P. sinus Norris and McFarland, 1958

C-9, Spectacled Porpoise, P. dioptrica Lahille, 1912

C-10, Burmeister or Black Porpoise, P. spinipinnis Burmeister, 1865

This genus produces both echolocation and communication signals consisting of clicks, squeals, whistles, grunts, clucks, chirps, etc. This is the first genus recorded for Navy sonar training in connection with the Navy’s 1944 study of sounds of unknown sources.^{16,82,18,109,145,150}

Genus Neophocaena Palmer, 1899

C-1l, Black Finless Porpoise, N. phocaenoides G. Cuiver, 1829

There are no known recordings of this species.

Genus Phocoenoides Andrews, 1911

C-12, Dall Porpoise, P. dalli True, 1885

C-13, Dall Porpoise, P. truei Andrews, 1911

This genus produces both echolocation and communication signals of clicks and squeals.^9092103,109

Genus Cephalorhynchus Gray, 1846

C-14, Commerson or Piebald Dolphin, C. commersoni Lacépède, 1804

C-15, White-Bellied or Black Dolphin, C. eutropia Gray, 1849

C-16, Tonine or Heaviside Dolphin, C. heavisidei Gray, 1828

C-17, Hector Dolphin, C. hectori Van Beneden, 1881

No recordings are available on this genus.^93,109

Genus Lagenorhynchus Gray, 1846

C-18, White-Beaked Dolphin, L. albirostris Gray, 1846

C-19, Atlantic White-Sided Dolphin, L. acutus Gray, 1828

C-20, Pacific White-Sided or Striped Dolphin, L. obliquidens Gill, 1865 (= L. thicolea Gray, 1849)

C-21, Dusky Dolphin, L. cruciger Quoy and Gaimard, 1824

C-22, Broad-Beaked Dolphin, Peponocephala, 1966

This genus produces both echolocation and communication squeals, cries, squeaks, and clicks.^{82132,109,107,91,145}

Genus Lagenodelphis Fraser, 1956

C-23, Sarawak Dolphin, L. hosei Fraser, 1956

Known only from a skeleton.

Genus Delphinus Linnaeus, 1758

C-24, Common or Saddleback Dolphin, D. delphis Linnaeus, 1758

C-25, Cape Dolphin, D. capensis Gray, 1828

C-26, Red-Bellied Dolphin, D. roseiventris Wagner, 1853

This genus produces both echolocation and communication clicks, whistles, squeals, cries, etc. Many sonagrams are available in the literature.^{16,17,82,83,109,132,145,146}

Genus Stenella Gray, 1866

C-27, Long-Beaked Dolphin, S. longirostris Gray, 1828

C-28, Blue, Blue-White, or Euphrosyne Dolphin, S. caeruleoalba Meyen, 1833

C-29, Spotted Dolphin, S. plagiodon Cope, 1866

C-30, Bridled Dolphin, S. frontalis G. Cuvier, 1829

C-31, Narrow-Snouted Dolphin, S. attenuata Gray, 1846

This genus produces echolocation and communication signals of clicks, squeals, cries, and squeaks.^{82132,109,83,}

Genus Lissodelphis Gloger, 1841

C-32, Northern Right-Whale Dolphin, L. borealis Peale, 1848 C-33, Southern Right-Whale Dolphin, L. peroni Lacépède, 1804 There are no known recordings of this genus.

Genus Steno Gray, 1846

C-34, Rough-Toothed Dolphin, S. bredanensis Lesson, 1828

This species produces both echolocation and communication signals of clicks, whistles, jeers, etc.^{89,95,109,136}

Genus Sousa Gray, 1866

C-35, Amazon River Dolphin (bufeo; tucuxi; pirayaguara), S. pallida Gervais, 1855

C-36, Guiana River Dolphin, S. guianensis Van Beneden, 1864

C-37, Chinese White Dolphin, S. chinensis Osbeck, 1765

C-38, Bornean White Dolphin, S. borneensis Lydekker, 1901

C-39, Speckled Dolphin (bolla gadimi), S. lentiginosa Owen, 1866

C-40, Plumbeous or Lead-Colored Dolphin, S. plumbea G. Cuiver, 1829

C-41, West African Dolphin, S. teuszi Kükenthal, 1892 There are no known recordings of this genus.¹⁰⁹

Genus Tursiops Gervais, 1855

C-42, Bottle-Nosed Dolphin, T. truncatus Montagu, 1821

Vocalization studies of captive Tursiops truncatus have exceeded those of all other cetaceans combined. McBride first noted that whistling appeared to be correlated with excitement and different emotional states, and McBride and Webb considered whistling one of the noises with “language” value. F. G. Wood reported the underwater sound production and concurrent behavior of captive porpoises (Figs. C-42-1, C-42-2, and C-42-3). Schevill, Lawrence, and Kellogg studied their auditory response. Dreher showed that the twelve most used whistles of Tursiops followed a log probability of occurrence, as would be expected if they were being used for communication. Lilly and Miller studied the vocal exchanges between two dolphins under a variety of conditions, and in his book Man and Dolphin Lilly outlined what he considered might be in store in the future through research with Tursiops. He is continuing his studies with respect to the possibility of communication between man and Tursiops.

Dr. Lilly reported on experiments with two isolated dolphins in nonswimming states; the vocal exchanges are recorded on two channels of magnetic tape for purposes of analysis. He demonstrates that both animals can click and whistle independently and separately as well as simultaneously. The whistles alternate from the two animals at a rate of about one exchange per second. The click exchanges are more complex and hence difficult to analyze. Each animal tends to maintain silence in whatever mode the other animal is emitting until that transmission is terminated, but the first animal may be transmitting in the other mode. It appears that they have two transmission modes, one in clicking and the other in whistling. They use these modes independently, unless one animal is mimicking the other, in which case both animals emit the same signal simultaneously. (See Refs. 4, 10, 11, 14, 19, 20, 27, 29, 33-35, 45, 46, 52, 53, 55, 56, 59, 63-70, 73, 77, 82, 92, 95-98, 104, 109, 116, 119, 123, 127, 132, 139, 141, 145, 150.)

C-43, Gadamu T. aduncus Ehrenberg, 1833

Considered conspecific with T. truncatus.

Genus Grampus Gray, 1828

C-44, Grampus, Gray Grampus, or Risso Dolphin, G. g riseus G. Cuvier, 1812

This species produces both echolocation and communication signals of clicks, squeals, cries, rasps, etc. The species has been recorded extensively, although the identification has frequently been poor.^82,132,145

Genus Globicephala Lesson, 1828

C-45, Common Pilot Whale or Common Blackfish, G. melaena Traill, 1809

This species has been extensively recorded from well-identified specimens. It produces a great variety of echolocation and communication signals of clicks, independently or simultaneously with whistles, blats, squawks, and squeals. The vocalization can be characterized as having a rather large number of separate, singing bird-1ike short squeals, whistles, chirps, and cries, many of which may sweep rapidly up or down (or both) through a wide frequency range; these sounds are stereotyped and interspersed randomly with other signals, including whining and belching sounds and many clicks. The clicks, like the other signals, are themselves somewhat stereotyped in that they have approximately the same duration with a concentration of their maximum energy in a narrow frequency range and in a background of uniform-intensity white noise of the same time duration. Sonagrams of typical signals of G. melaena are available in the literature.^{4,11,16,18,46,80,82,109,132,145}

C-46, Short-finned Pilot Whale; Short-finned Blackfish, G. macrorhyncha Gray, 1846

This species produces frequency-modulated whistles and bird-1ike calls with clicks superimposed that would serve well for both echolocation and communication.

C-47, North Pacific Pilot Whale or North Pacific Blackfish, G. scammoni Cope, 1869

The signals of this species resemble C-46 above but modulated frequency sweeps cover wider frequency ranges from 6500 to 2000 Hz, or a frequency modulation cycle of 4 per second.

Genus Orcaella Gray, 1866

C-48, Irrawaddy River Dolphin, O. brevirostris Owen, 1866 There are no known recordings of this species.

Genus Feresa Gray, 1871

C-49, Slender Blackfish, F. attenuata Gray, 1875

The vocalization of this species, consisting of frequency-modulated whistles with superimposed clicks, would serve well for both echolocation and communication.^80,82,95

Genus Pseudorca Reinhardt, 1862

C-50, False Killer Whale P. crassidens Owen, 1846 >

This species produces echolocation and communication signals of clicks, squeals, cries, squawks, rasps, whistles, etc. There are many recordings attributed to blackfish which undoubtedly contain false killer whale signals, but their signals have not been studied sufficiently to identify them positively.^{7,76,82109,132,145}

Genus Orcinus Fitzinger, 1860

C-51, Killer Whale, O. orca Linnaeus, 1758

The killer whale is discussed in detail at the end of this chapter.

Family Ziphiidae (Beaked Whales); Genus Tasmacetus Oliver, 1937

C-52, Tasman Beaked Whale, T. shepherdi Oliver, 1937

Known only from three stranded specimens in New Zealand.

Genus Mesoplodon Gervais, 1850

C-53, Sowerby Beaked Whale, M. bidens Sowerby, 1804

C-54, Gulf Stream Beaked Whale, M. europaeus Gervais, 1855 (= M. gervaisi Deslongchamps, 1866)

C-55, True Beaked Whale, M. mirus True, 1913

C-56, Longman Beaked Whale, M. pacificus Longman, 1926

C-57, Scamperdown Whale, M. grayi Haast, 1876

C-58, Hector Beaked Whale, M. hectori Gray, 1871

C-59, Saber-Toothed Whale or Stejneger Beaked Whale, M. stejnegeri True, 1885

C-60, Japanese Beaked Whale, M. ginkgodens Nishiwaki and Kamiya, 1958

C-61, Strap-Toothed Whale, M. latjardi Gray, 1865

C-62, Blainville Beaked Whale, M. densirostris Blainville, 1817

Although the species of this genus are rare and no recordings are available for analysis, their vocalization is reported to contain roars, lowing, and sobbing groans which would serve well for echolocation and communication.^36,109

Genus Ziphius G. Cuvier, 1823

C-63, Goose-Beaked or Cuvier Beaked Whale, Z. cavirostris G. Cuvier, 1823

Its roars, lowing, sobbing, groans, etc. would serve well for both echolocation and communication.^36,109,111

Genus Berardius Duvernoy, 1851

C-64, Arnoux Beaked Whale, B. arnouxi Duvernoy, 1851

C-65, Giant Bottle-Nosed Whale or Baird Beaked Whale, B. bairdi Stejneger, 1883

This genus is believed to generate a specific set of vocalizations consisting of roars, lowing, sobbing, and groans. These have been recorded in the North Pacific but apparently do not occur in the Atlantic Ocean. These sounds are currently being investigated by the Narragansett Marine Laboratory.^36,109

Genus Hyperoodon Lacépède, 1804

C-66, Northern Bottle-Nosed, or Flat-Headed Bottle-Nosed, Whale, H. ampullatus Forster, 1770

C-67, Southern Bottle-Nosed, or Flat-Headed Bottle-Nosed, Whale, H. planifrons Flower, 1882

Their vocalizations are reported to contain roars, lowing, sobbing, and groans, but they have never been recorded or reported for certain in the North Pacific.³⁶•¹⁰⁹

Family Physeteridae (Sperm Whales); Genus Physeter Linnaeus, 1758

C-68, Sperm Whale, P. catodon Linnaeus, 1758

It was reported as early as 1840 that the sperm whale made creaking sounds, but in 1957 Worthington and Schevill reported a muffled smashing noise, a low-pitched groan, a rusty-hinge crackling sound, and clicks from the sperm whale. Four years later Gilmore reported clicking sounds when a live harpooned sperm whale was brought alongside the catcher boat. In 1962 Schevill and Watkins published a phonograph record including the sounds of the sperm whale. Schevill states that the clicking sound is the only sound ever heard from the sperm whale; he published sonagrams of these clicks in 1962. However, in 1966 Backus and Schevill state “We are now able to say that the ‘muffled smashing noise’ and the ‘grating sort of groan reported by Worthington and Schevill in 1957 in addition to clicks were merely other clicks distorted by the echo-sounder receiver over which they were heard.”

Sperm whales are reported to be able to instantly alert others of their species of impending danger or to call for help over distances of six or seven miles. This strongly indicates that they also have a welldeveloped hearing, particularly in the high-frequency range. Whalers have known for a long time that they cannot approach very close to sperm whales if their boats are making any high-frequency sounds or if they are using their sonar or fathometer apparatus.

In Dr. Fish’s review of marine mammal sounds recorded by United States submarines, she attributes many of the recorded marine mammal sounds to sperm whales. In a private communication from the Narragansett Marine Laboratory, Dr. Fish reports that they have successfully recorded communication singing from the sperm whale.^{3,5,13,25,36,43,49,94,108a,109,126,147}

Subfamily Kogiinae; Genus Kogia Gray, 1846

C-69, Pygmy Sperm Whale, K. breviceps Blainville, 1833

C-70, Pygmy Sperm Whale, K. simus Owen, 1866

These species are rare, shy, and usually travel singly. The probability of approaching close enough to two to obtain recordings is very remote.

Suborder Mysticeti (Baleen Whales); Family Balaenidae (Right Whales); Genus Balaena Linnaeus, 1758

C-71, Black Right Whale, B. glacialis Müller, 1776

Four races are recognized:

North Atlantic B. R. W., B. g. glacialis Müller, 1776

North Pacific B. R. W., B. g. japonica Lacépède, 1818 (=B. g. sieboldi)

Southern B. R. W., B. g. australis Desmoulins, 1822

Bowhead Whale, B. mysticetus Linnaeus, 1758

The echolocation and communication signals of this genus of Balaena consist of clicks, pulses, and moans in many combinations.

During March, April, and May of 1966, the author made more than 70,000 feet of magnetic tape recordings of bowhead whales on their migration past Point Barrow toward Banks Island. About 25 per cent of this tape was four-channel recordings using a hydrophone array with 90-foot spacing, suspended 25 feet below the 6-inch-thick young ice at a point 1000 feet from the edge of the ice. It was therefore possible to track the bowhead whale within the recording radius, which was at least 5 miles and probably much more. We were most fortunate in that we were recording on the afternoon of May 3 when the Eskimo whalers, operating from the edge of the ice about 500 yards from our recording station, shot a bowhead whale with a 2-inch-diameter explosive projectile. The whale was less than a mile from our hydrophone array. A preliminary analysis of this tape shows the bowhead whale to have an extensive and very loud vocalization, at least under these conditions.

Their signals are sufficiently low in frequency that, by running the tape at four times the recording speed, the frequency range of the sonagram was 20 to 2000 Hz and the signals of the two species of seals that were present in the area were above the frequency range of the sonagrams. By so doing, the sonagrams also had four times as much time compressed into them.

Figure C-71-1 contains a number of such sonagrams from which the following signal characteristics were obtained. The signals start at any frequency from less than 50 to nearly 1000 Hz. In general, they decrease in frequency with time but may also sweep up in frequency. The very loud, lowest-frequency signals sweep up rapidly from a very low value to 125 Hz and then, over the next six or seven seconds, go up to 500 Hz. These signals have a very loud series of narrow-frequency-range clicks associated with them, with a frequency just above that of the main signal. The clicking rate is about six per second throughout such a signal.

If the signals start at a frequency of several hundred hertz, they may have a pulsing rate of six to ten per second and gradually decrease to as low as one per second. There may be merely a broadening of the frequency range of the signal, or there may be a sudden rise in frequency followed by a less rapid decrease in frequency, producing a sawtooth effect on the sonagram. The sudden rise in frequency may be as much as one full octave at these low frequencies.^{6,79,109,110,125,132,140}

Genus Caperea Gray, 1864

C-72, Pygmy Right Whale, C. marginata Gray, 1846

Nothing is known of the sounds produced by this species.¹⁰⁹

Family Eschrichtiidae (Gray Whales); Genus Eschrichtius Gray, 1864

C-73, Gray Whale, E. gibbosus Erxleben, 1777

The echolocation and communication signals of the gray whale consist of clicks, grunts, mumbles, groans, rasps, and a loud resonant bong, etc.^{26,30,31,37,39,82,104,109,114b,134}

Family Balaenopteridae (Rorquals); Genus Balaenoptera Lacépède, 1804 C-74, Minke or Little Piked Whale, B. acutorostrata Lacépède, 1804

C-75, Sei Whale, B. borealis Lesson, 1828

C-76, Bryde Whale, B. edeni Anderson, 1878

The echolocation and communication signals of these species consist of moans, trills, sighs, etc.^{48,50,82,86,87,95,109,132,134}

C-77, Fin or Finback Whale, B. physalus Linnaeus, 1758

The echolocation and communication signals of the fin whale consist of moans, screams, high-pitched whistles, cries, chirps, and squeaks.^132,145

C-78, Blue Whale, B. mus cuius Linnaeus, 1758

The echolocation and communication signals of the blue whale consist primarily of clicks or groups of clicks which merge together to form buzzes, rasps, etc., with some rather low frequency intermittent tones distributed through them. Sonagrams of characteristic signals are shown in Fig. C-78-1.^109,145

Genus Megaptera Gray, 1846

C-79, Humpback Whale, M. novaeangliae Borowsky, 1781

Humpbacks are the biggest showoffs and the noisiest and best performers for the bioacoustician! As long as there is more than one whale in the general vicinity, there will be communication. This whale has a large variety of sounds (Fig. C-79-1). Off Bermuda in April, and off Hawaii in March and April, humpback whale sounds are common. Sound communication appears to play a large role in the courtship of male and female.^{2,36,78,80,99,105,108,109,132,133}

C-51, Killer Whale, Orcinus orca Linnaeus, 1758

The vocalization of the killer whale is unusual in several respects. It is very loud, particularly when one can observe the sounds from close range, as is the case with a captive animal. If the killer whale is at the surface of the water, with its blowhole open, its signals can be heard for a distance of half a mile. There has seldom, if ever, been an opportunity to study the vocalization of the killer whale in a systematic manner, and I welcomed the opportunity to make such a study of the male killer whale Namu.

I arrived in Seattle shortly after Namu was put on exhibit by Ted Griffin at his Seattle aquarium on Pier 56. Over the following week approximately 30,000 feet of magnetic tape recordings were made with the hydrophone 6 feet below the surface of the water and just outside the rubberized canvas tank. In order to avoid as much traffic and ferryboat noise as possible, recordings were generally made between midnight and morning.

Since there were periods of as much as one or two hours when there were no signals, and since a recording speed of thirty inches per second was being used, there was no attempt to keep the recorder running continuously. A second hydrophone and headset were used for monitoring; as soon as a signal was heard, the recorder was turned on and invariably a fiveto thirty-minute period of good recording would follow.

Namu was subsequently moved to winter quarters in a cove on Rich Passage closed with a submarine net. Over a period of the next few weeks an additional 30,000 feet of magnetic tape recordings were made and the same intermittent nature of signals was observed. From a cursory examination of some 500 sonagrams* made from Namus recorded vocalizations, it was at once obvious that there was little of a random nature in them and that they were an array of systematically formed signals (Fig. C-51-1). As these sonagrams were arranged in an order of increasing complexity, it became increasingly apparent that they could be divided into a number of systematic groupings.

Sonagrams were then made from the killer whale recordings made in Dabob Bay by the Applied Physics Laboratory of the University of Washington. To our surprise, none of these sonagrams could be considered duplicates of any of Namu s sonagrams. Sonagrams were then made from tape recordings of a killer whale in the Atlantic and from recordings of a group of about fifteen in the Antarctic. The sonagrams of the recordings made in Dabob Bay and those from the recordings made in the Atlantic duplicated each other quite accurately, and the Antarctic recordings contained both types of signals.

This suggested that the difference might be one of sex, and since Ted Griffin had by this time captured a female killer whale, Shamu, and had her in the same cove with Namu, an array of three hydrophones was mounted in the cove. Recordings from this array were made on three channels of a tape recorder, and a running commentary was recorded on the fourth channel. The relative positions of the two animals in the cove were also made a matter of record on the fourth channel. It was thus a simple matter to determine which animal made each of the signals. From these recordings, it was definitely established that there were essentially no duplications in the signals from the male and the female killer whales and that the sex of a killer whale could reliably be determined from an inspection of sonagrams of the recordings of their underwater signals.

However, in the process of analyzing these signals, overlapping female killer whale signals were found on several occasions. Triangulation measurements showed that one of them was out in Rich Passage, outside the cove. This, then, explained the sudden bursts of vocalization on numerous occasions from both Namu and Shamu and at times when the two animals were apparently ignoring one another. We had been surprised, at the time, at such apparently excited vocalizations with no aggressive activity toward one another.

This also suggested a possible explanation for the intermittent nature of Namu’s vocalizations during the previous recording periods. A reexamination of these recordings did, indeed, show numerous weak killer whale signals in the background, particularly throughout all but the latter portion of those vocal periods from which sonagrams had not originally been made because they were so weak. The fact that solitary animals are invariably not vocal should have given us the necessary clue, but we did not know, at that time, at what distance they could communicate.

Subsequent measurements showed that very good recordings could be made at three miles; an intervening point of land prevented recordings over a greater distance. From the attenuation of the signal at distances up to three miles, it was estimated that it would not be unreasonable to suspect that the whales could communicate over ranges of seven or more miles, and Pier 56 is relatively open to Puget Sound. Now that we know this, it is easy to pick up these signals in the background of the original recordings and to obtain sufficiently good sonagrams to determine whether they were made by males or females.

More than 1000 killer whale sonagrams were analyzed to determine to what extent communication theory and computer analysis techniques can be used to study this problem. It was felt that, to obtain the most meaningful analysis of the vocalization of the killer whale, the signals used should be from recordings as nearly consecutive as possible and acquired under nearly uniform circumstances. Charts were therefore assembled of the sonagrams of the vocalizations of the male (Fig. C-51-1) and female (Fig. C-51-2) killer whales. The chart for the female killer whale contains sonagrams from several females taken under separate and unrelated circumstances; in some cases the background noise was so strong that the sonagrams are not very distinct. They do, however, serve to show the great difference in the signals of the two sexes, which appears to be equally true for most marine mammals, including Tursiops truncatus.

A chart was assembled containing 189 sonagrams from 210 signals recorded of Namu between midnight and morning on two consecutive days. (The remaining 21 signals were so obscured by water or other background noise that they were not included.) The sonagram chart therefore represents signals made by Namu when he was exchanging vocalizations with noncaptive killer whales. The sonagrams are divided into groups, which are numbered 1 through 9 in order of decreasing number of sonagrams in the groups. The number of sonagrams in each group represent 30.5, 14.8, 11.4, 8.1, 5.7, 4.7, 3.8, 3.3, and 3.3 per cent, respectively, of the total of 210 signals.

The signals of group 1 of this chart, more than those of any other group, identify the animal as a male killer whale. Mass spectral density and computer analyses as well as other methods confirm complex but orderly structures of the killer whale signals. For the most part their vocalization consists of isolated and discrete signals ranging from 0.25 to 5 sec in duration, in addition to very short, isolated clicks. About 90 per cent of the signals fall within the range of 0.2 to 2.2 sec, for an average signal length of 1.5 sec.

With the exception of the characteristic white noise or broad frequency range of the clicks, the vocalization consists almost exclusively of a fundamental tone with its associated and sharply defined harmonies. The fundamental signal makes numerous changes up or down in frequency, some of them very sudden. However, when the change is abrupt it is never a random change but is always by some whole number of harmonics or even a full octave.

If we examine the signals in group 1, we find that the starting frequency covers a range from 340 to 1400 Hz and that whatever frequency is selected remains constant or fluctuates only slightly for somewhere between 0.25 and 3 sec. At the termination of this period, the signal suddenly drops one octave in frequency. This puts it in a frequency range between 175 and 700 Hz, where it remains for only 0.1 to 0.2 sec and then jumps just as abruptly by two full octaves to somewhere between 700 and 2800 Hz, or an octave above its starting frequency. It continues to rise until, at the end of another 0.2 or 0.3 sec, it has increased by another factor of 50 per cent to somewhere between 1050 and 4200 Hz.

At this point a discontinuity in frequency occurs and the signal abruptly jumps up another 25 per cent, resulting in a frequency somewhere between 1310 and 5225 Hz; again the signal proceeds to between 1640 and 7500 Hz within the next 0.1 to 0.5 sec. The frequency then decreases at an accelerating rate; within about 0.1 to 0.2 sec it has returned to its original starting point and then rapidly dies out.

This most characteristic male killer whale signal may therefore start anywhere within a two-octave range, go through essentially the same sequence of frequency changes, and terminate on the starting frequency. The over-all duration of these signals may vary over a tenfold range from less than 0.5 sec to nearly 5 sec. The male killer whale therefore has an extremely complex signal framework which can be recognized against almost any background noise and which he can accent, abbreviate, punctuate, syllabify, hyphenate, prefix, and give numerous endings and inflections without affecting its ease of recognition. By this I do not mean to suggest that the killer whale’s reason for making any of the changes that these operations would imply to us would in the remotest sense have any relation to what those operations mean to us.

On the other hand, I suspect that the different signals do make sense to other killer whales. If we were to consider the sonagram charts to be sonagrams of Namu’s vocabulary, and if we had the nearest equivalent that exists in the English language for each of those signals, I suspect that we would still be orders of magnitude away from being able to make any combination of them that would make sense either to us or to the killer whale.

The frequency of the first portion of this signal may start by a very brief sweep up into the desired frequency; it may then continue to rise gradually or may fluctuate slightly up and down.

In the lower half of the second column of group 1, some of the sonagrams have about a 0.1-sec section missing and have some special effects inserted in that space such as sweeps up and down of as much as 4000 (Fig. C-51-3). This is illustrated in sonagram IE. In some cases the first section may be abbreviated or even missing entirely, as in sonagram IF. At any point throughout the first section a first, second, third, or even fourth subharmonic may be superimposed which will continue to the end of the first section. This introduces one, two, and three parallel lines between the already existing harmonic lines, as illustrated in sonagram ID.

The first 17 sonagrams in group 1 have a prefix resembling an integral sine at the beginning of the signal, showing an upsweep in frequency of more than 700 Hz in less than 0.1 sec. A closer examination of these shows that some of them have a short section missing, have one or two short bands crossing them, or may be preceded by one or more dots representing extremely short-duration and narrowfrequency range notes.

Again this signal may start with a downsweep from a very high frequency (1A, Fig. C-51-3), or there may be the downsweep with only the first portion of its signal attached (IB), or the downsweep may terminate without going into the rest of the signal (1C). On the other hand, in the early portion of this signal a subharmonic may be introduced; ID shows the fifth subharmonic, IE illustrates a sudden jump in frequency of two octaves about one-fourth the way through the signal, and in IF the first portion of the signal has been omitted. It is significant that all of these special modifications of the group 1 type of signal, as well as comparable modifications of signals of some of the other groups, were made while Namu was exchanging signals with a female killer whale.

The group 2 type signals start with a series of clicks at a rate of 10 to 15 clicks per second and then shift to a 3-50 to 400-Hz signal. Group 5 signals start out in a manner similar to group 1, with a similar frequency jump at the end of the first section, and terminate with a rapid upsweep in frequency.

It is believed significant that many more modifications of Namus signals occur when he is exchanging vocalization with a female killer whale than with another male. A vast amount of work remains to be done with the signals of the killer whale, and a plot of the data from this chart of the logarithm of the frequency of usage of the particular signals against the log rank of that signal according to Zipfs law does indeed give a straight line (Fig. C-51-4), as it should if these signals are actually being used for communication.

The system of signals of the killer whale seems to supply the strongest argument (from the standpoint of communication theory) that “animal language” is statistically valid; we feel the killer whale signals are more important in this regard than are the signals of any other species. Yes! We believe that marine mammals talk and that what they talk about makes sense to other marine mammals of the same species.

* In the preparation of the sonagrams reported here, no attempt has been made to include all of the higher harmonics. Rapid techniques for analyzing bioacoustic signals for frequency and harmonic content, in which the frequency is limited only by the recording, are presented by Singleton and Poulter.^137b

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68. Lilly, J. C., Communication Studies on Tursiops truncatus, Communication Research Institute, Miami, Florida, Mar. 13, 1964.

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72. Lilly, J. C., Sonic-Ultrasonic Emissions of the Bottlenose Dolphin, Whales, Dolphins, and Porpoises, University of California Press, 1966, p. 503.

73. McBride, A. F., Meet Mister Porpoise, Natural History 45, 16-29 (1940).

74. McLaren, I. A., The biology of the ringed seal (Phoca hispida Schreber) in the eastern Canadian Arctic. Fisheries Research Board of Canada, Ottawa, 1958.

75. Mansfield, A. W., Seals of Arctic and Eastern Canada, Fisheries Research Board of Canada, Arctic Unit, Montreal, 1963.

76. Marineland of the Pacific, Pseudorca crassidens emits squeals and other sounds in air (personal communication).

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78. Navy Electronics Laboratory, San Diego, California. Recordings made of humpback whales at Point Sur, California.

79. Nishiwaki, M., and Norris K. S., No. 20 Sci. Rep. Whales Res. Inst., 1966.

80. Narrangansett Marine Laboratory, University of Rhode Island. Slender blackfish recordings, R/V TRIDENT cruise to South America, 1965. Reel No. TRI-9-31.

81. Ibid. Unpublished data regarding underwater sound production of Inia geoffrensis by NML personnel, 1962-1966.

82. Ibid. Reference file of biological underwater sounds, 1967.

83. Ibid, personnel recording, Marineland, Florida, 1964.

84. Ibid. Common dolphin sounds recorded from R/V TRIDENT on different cruises, 1960-1966.

85. Ibid, personnel R/V TRIDENT cruise, 1960-1966.

86. Ibid. Finback whales—recordings from a submarine in the Pacific; submarine used the identification card as a guide to identification. Range was 1000 yards to a pod of finbacks, apparently feeding, 1964.

87. Ibid. Finback Whale Sounds, forthcoming NML paper on recordings made from R/V TRIDENT by NML Bioacoustics personnel, 1960-1966.

88. Ibid. Personnel recording made at Sea World, San Diego, and at Steinhart Aquarium, San Francisco, 1966.

89. Ibid, personnel recordings at Sea Life Park, Oahu, Hawaii, 1964.

90. Ibid, recordings of Dall porpoise (two in tank) at Pt. Mugu, California, Cal. 65-6A 5 A+B, 1966.

91. Ibid, personnel monitoring from SEAQUEST cruise, 1961, Channel Islands, California, 1961.

92. Ibid, monitoring at U.S. Naval Missie Center, Pt. Mugu, California, 1966.

93. Ibid. Various recordings of pilot whale sounds filed at Narragansett Marine Laboratory by TRIDENT, SUB PAC, etc., 1960-1966.

94. Ibid. Sperm Whale Sounds, forthcoming paper on recordings made from R/V TRIDENT by Bioacoustics personnel, and private communication from Marie P. Fish, 1966.

95. Norris, Kenneth, Howard A. Baldwin, and Dorothy J. Samson, Open Ocean Diving Test with a Trained Porpoise (Steno bredanensis), ONR Research Grant, NONR G-0007-64, 1965.

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97. Norris, K. S., J. H. Prescott, P. V. Asa-Dorian, and P. Perkins, An Experimental Demonstration of Echolocation Behavior in the Porpoise Tursiops truncatus (Montagu), Biol. Bull., 120, 163-176 (1961b).

98. Naval Ordnance Test Station, Pasadena, California, tape of “Knotty,” 1966.

99. Naval Research Laboratory recordings made of humpback whales in Auckland, New Zealand area, 1960.

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102a. Orr, Robert T., and Thomas C. Poulter, Some observations on Reproduction, Growth, and Social Behavior in the Steller Sea Lion, Proc. California Acad. Sci., ser. 4, 35, 193-226 (1967).

103. Padberg, L., U.S. Naval Missile Center, Pt. Mugu, California, report, April 1965.

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106. Peterson, R. S., Behavior of the Northern Fur Seal, D.Sc. Thesis submitted to the School of Hygiene and Public Health of Johns Hopkins University, 1965.

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108. Perkins, P. J., Recordings made of Humpback Whales, Hawaiian Island Area, 1955.

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108b. Perkins, P. J. Communication Sounds of Finback Whales, Norsk Hvalfangst-Tidende, 1966, No. 10, 199-200.

109. Perkins, P. J., NML data card file on 35 cetacean species, 1966.

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113. Poulter, T. C., Recording made at Sea World, San Diego, Calif., 1966b.

114. Poulter, T. C., Recording made at Steinhart Aquarium, San Francisco, 1955-1966.

114a. Poulter, T.C., Recordings made on 3-year-old walrus at the Marineland of the Pacific, 1966d.

114b. Poulter, T. C. Vocalization of the Gray Whale in Laguna Ojo de Liebre (Scammon’s Lagoon), Baja, California, Mexico (in press).

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126. Schevill, W. E., R. H. Backus, and J. B. Hersey, Sound Production by Marine Animals, in M. N. Hill, ed., The Sea, I, John Wiley & Sons, New York, 1962, p. 557.

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129. Schevill, W. E., and W. A. Watkins, Underwater Calls of Leptonychotes (Weddell Seal), Zoologica 50, 45-46 (Spring 1965) Woods Hole Oceanographic Institution.

130. Schevill, W. E., W. A. Watkins, and C. Ray, Underwater Sounds of Pinnipeds, Science 141, 50-53 (1963).

130a. Schevill, W. E., W. A. Watkins, and C. Ray, Analysis of underwater Odobenus calls with remarks on the development of the pharyngeal pouches, Zoologica 51 (3): 103-106, plates I-V, phono, record.

131. Schevill, W. E., and W. A. Watkins, Underwater Calk of Trichechus (Manatee), Nature 205, 373-374 (1965).

132. Schevill, W. E., and W. A. Watkins, Whale and Porpoise Voices, a phonograph record, Woods Hole Oceanographic Institution, 1962.

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134. Schultz, Jack and Carter Pyle, Cat Bites Whale, Yachting, Dec. 1965, p. 48.

135. Schusterman, Ronald J., and Stephen H. Feinstein, Shaping and Discriminative Control of Underwater Click Vocalizations in a California Sea Lion, Science 150, 1743-1744 (1965).

136. Sea Life Park, Oahu, Hawaii, Park personnel recordings, 1965-1966.

137. Sebeok, Thomas A., Animal Communication, Science 147, 1006-1014 (1965).

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146. Vincent, F., Etudes preliminaires de certaines emissions acoustiques de Delphinus delphis L. en captivité, Bull. Inst. Oceanog. Monaco, 57, 1-23 (1960).

147. Vladykov, V.-D., Chasse, biologie et valeur economique du marsouin blanc on beluga (Delphinapterus leucas) du fleuve et du golfe Saint-Laurent, Department des Pecherles, Quebec, 1944, pp. 121-124.

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149. Wilson, T. M., Behavior and husbandry methods for captive northern fur seal pups, M.S. Thesis, Cornell University, 1966.

150. Wolftrap, Dobrin, Harbor porpoise recordings, NML R/V TRIDENT, 1960-1965.

151. Wood, F. G., Jr., Underwater Sound Production and Concurrent Behavior of Captive Porpoises, Tursiops truncatus and Stenella plagiodon, Bulletin of Marine Science of the Gulf and Caribbean, 3(2), 120-133 (1954).

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