surface a moribund , Psychroteuthis glacialis. It was taken Project personnel plan to return in the 1988-1989 field season from the seal, and to our knowledge, it is the first intact squid to continue work on oxygen-utilization patterns in freely div- collected in McMurdo Sound and the first record of this species ing seals and penguins. within the . This work was supported by National Science Foundation The emperor penguins were always anxious to enter the grant DPP 86-13729. water and dove without reluctance under the 2-meter thick ice. Swim velocities were about 1.5 times that of the seals. The birds readily swam between holes spaced 100 meters apart and frequently made exploratory dives (>10 minutes) that were well beyond any of the experimental exit holes. Much of their References behavior around the hole was easily observed from the sub- ice observation chamber due to the approximately 100 meters Kooyman, G.L. 1981. : Consummate diver. New York: Cam- of horizontal visibility. Occasionally, would come into the bridge University Press. vicinity of the holes when the birds were absent. When the Hill, R.P. 1986. Microcomputer monitor and blood sampler for freely diving seals. Journal of Applied Physiology, 61, 1570-1576. birds entered the water, some of the fish were avidly consumed Kooyman, G.L., J.P. Schroeder, D.C. Greene, and V.A. Smith. 1973. while the others dispersed rapidly or hid in the under-ice plate- Gas exchange in penguins during simulated dives to 30 and 68 m. let layer. American Journal of Physiology, 225, 1467-1471.

Patterns of underwater calls Collectively, these studies demonstrate that Weddell seals call primarily during the breeding season. Males, females, adults, from Weddell seals and pups produce different kinds of sounds. Weddell seals (Leptonychotes weddellil) from different areas of the Antarctic exhibit different kinds of sounds. during the breeding season During the austral springs of 1976 and 1978, we made hourly at McMurdo Sound, recordings of underwater calls of Weddell seals at the Hutton Cliffs breeding colony in McMurdo Sound, Antarctica. Our objectives were to document changes in underwater call rates JEANETrE A. THOMAS related to annual changes in the population, weekly variations associated with breeding, and diel changes in haulout. Naval Ocean Systems Center Recordings were made automatically for 2.5 minutes every Kailua, Hawaii 96734 hour from 22 October to 10 December 1976, from 19 October 1977 to 4 January 1978, and from 10 October to 21 November LISA M. FERM 1978. Even though bad weather and low batteries caused some loss of data, the number of recordings was large: 1976 = 413, 1977 = 777, 1978 = 497. A Superscope C101A cassette recorder National Marine Mammal Laboratory Seattle, Washington 98115 (frequency response 0.20-10.00 kilohertz) and a battery-op- erated digital timer were warmed in an insulated box with a VALERIAN B. KUECHLE chemical heatpack. An Interoceans R130 hydrophone (fre- quency response 0.03 to 10.00 kilohertz ± 3.0 decibel) was dropped through a seal breathing hole to a depth of 6 meters University of Minnesota and connected to the recorder with a waterproof connector. Department of Ecology and Behavioral Biology Data from a 24-hour period were stored on one side of a 90- Minneapolis, Minnesota 55455 minute cassette. A tone generated by the timer separated each hourly recording on the cassette. The Weddell seal (Leptonychotes weddellii) is an extremely One of two authors listened to each cassette and scored vocal pinniped, producing a variety of frequency-modulated sounds into the five most common McMurdo Sound calls ca- sweeps, pulse trains, and whistles. Initial studies of their vocal tegorized by Thomas and Kuechle (1982): MT, MC, MP, MK, behavior were conducted at the Bay of Whales by Lindsey and MR. Pup calls were assigned the new category of MQ. (1937). In the late 1960s, other investigators made recordings Although the recordings did not cover the entire frequency at McMurdo Sound (Kooyman 1968; Poulter 1968; Ray and range of Weddell seal sounds, enough information was re- deCamp 1969; Schevill and Watkins 1971). Thomas and Kuechie corded for audible recognition of each category. Data were (1982) developed a classification system to describe Weddell sorted into three time intervals: year, week, and hour of the seal sounds. Using playbacks, Thomas, Zinnel, and Ferm (1983) day. For each call in each time interval, we calculated the mean assigned meanings to most sounds that are associated with rate per minute plus or minus the 95 percent confidence in- breeding activities. Thomas and Stirling (1983) documented terval. geographic variation between calls at McMurdo Sound and Yearly variation. The relative proportion of underwater calls Palmer Peninsula. Recordings near Davis Station extended our in each category remained about the same across years (figure understanding of geographic variations (Thomas et al. in press). 1A), with MT being the most prevalent. The total number of

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A B 14.0- MT 6.0 MC 1O7 147R 120 210.0- 4.0- 100 f C-) H ii 80 u, 2.0 CD I 60 2.0- hf lii 0 I I 1 0 I 40 I- Ui -J Z 2.0- MP 2.5 MR I- 4 20 Ui z Cl) 1.5- ILl 1.5 • 1.0- 2 1977 1977 U. 120 I f fI 0.5. 100 0.5 LLJ 1 4 ff1 a- U Oil 0 80 I I I I 1 , I I cc cr MK MO LIJ 60 1.2 LLI 40 1.0 0.8- 20 f 0.6 Z 0 Ui Tf ffffff 04 X. + } 0.2- 1 q7 Z 2 I 120 1 0 0 i 4 0246 8 10 12 14 0 246 8 10 12 14 Ui 100 I OCT 1 NOV I DEC IJANI I OCT I NOV I DEC IJAt4 Pup I I 80 WEAN U U 60 MATE I I 0.CC 4 DISPERSE U L...J 40 ccUi 20 Figure 2. Mean number of calls per minute (± 95 percent confidence 0 interval) for the five most common adult and pup calls (MO) by ALL MT MC MP MK MR MO TOTAL PUPS ADULT ADULT week. Data are from 1976, 1977, and 1978. Concurrent, reproductive FEMALES MALES activities are summarized below. CALLS SEALS into the water or to proclaim territorial control to neighboring Figure 1. A. Mean number of calls per minute for each call category males. at Hutton Cliffs during the austral springs of 1976, 1977, and 1978. Chugs (MC) are loud, aggressive pulse series ranging from B. Maximum number of seals for each age/sex category at Hutton 0.5 to 4.7 kilohertz and lasting up to 18 seconds. There is a Cliffs during 1976, 1977, and 1978. slight diel pattern in MC that corresponds with female haulout. This pattern also may reflect an increase in male territorial disputes when females are on the ice. calls recorded was highest in 1976. However, the change in MP is a submissive chirp series ranging from ito 12 kilohertz vocalization rate did not seem to be related to the number of and lasting up to 24 seconds. MP shows a diel pattern that is seals at Hutton Cliffs (figure 1B). the opposite of the female haulout pattern. When females are Weekly variation. Changes in the weekly average call rate out of the water, the rate of submissive calls decreases. (figure 2) reflect the transition between periods of pupping MQ are frequency-modulated, pup cries with harmonic (weeks 2-6), mating (weeks 6-10), weaning (weeks 6-8), and structure that range from 0.1 to 5.0 kilohertz and last up to 3.0 dispersing (after week 12). Call rates gradually increased dur- seconds. The diel pattern of pup calls is the opposite of their ing pupping and nursing, peaked during mating and weaning, mothers haulout pattern. When mothers are on the ice, pups and declined during dispersal. Week 4-5 shows an abrupt called more often, probably to attract them into the water for increase across all call types, indicating the onset of mating. nursing or to elicit assistance in hauling out of the deep breath- High call rates from weeks 5-9 probably correspond with peak ing holes. maintenance of underwater territories. The maximum rate of Cricket calls (MR) are frequency-modulated sounds that range pup cries (MQ) during week 9 may indicate the peak weaning from 0.5 to 10.5 kilohertz, are produced singly or in a series, period. and last up to 36 seconds. Knocks (MK) are low-frequency Diel variation. Diel variations in calls during 1977 are illus- pulses (0.2 to 0.7 kilohertz) produced in series up to 4.5 seconds trated in figure 3A. The hauling pattern of females and their long. MR and MK calls, although common in breeding colo- pups at Hutton Cliffs in 1977 is shown in figure 3B. Some call nies, showed no distinct diel pattern. Playbacks of these calls patterns generally track haulout and others are counter to the elicited few responses (Thomas et al. 1983) and their functions haulout pattern. are unknown. Because haulout pattern does not affect the use Trills (MT) are loud, frequency-modulated sweeps ranging of MR and MK, their function probably is not related to per- from 12.0 to 0.1 kilohertz, last up to 42 seconds, and are pro- suading other seals to enter or leave the water, i.e. not related duced only by males. The diel pattern of MT is similar to the to males attracting females into the water, males evicting other haulout pattern of females. When females were on the ice, males from their territory, or pups attracting mothers into the territorial males produced more trills, perhaps to lure females water.

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A when females are out of the water. Chirps (MP) show a sharp MT MC 10.0, 4.0 increase during mating and are highest when females are in the water. Pup cries (MQ) increase slightly when females are out of the water and show a dramatic increase at weaning. 8,0 C-) 3.olJHIIuTHhhluTllHIIjII Use of cricket calls (MR) and knocks (MK) is not related to haulout pattern, but does show a seasonal trend. U, 6.0 2.4 +1 IIiijjjflhiI1IIIiIjJffi Grants from the National Science Foundation (DPP 73-09316 and DPP 77-21591) awarded to Donald Siniff from the Uni- UJ 0 01, I I I I- versity of Minnesota supported this research. D 2.0 MP 1.3- MR z jI T cc w IIiIijI}tI1 111 11 III jjlj References 0. 0.7 1 U) -J Kooyman, G. 1968. An analysis of some behavioral and physiological -I 1.2 0.3 4 characteristics related to diving in the Weddell seal. In C. Schmidt C) 1 ,111 1.60,t 0, I I and C. Llano (Eds.), Biology of the antarctic seals III. (Antarctic Re- I search Series, Vol. 11.) Washington, D.C.: American Geophysical w MK 0.81 Union. Lindsey, A. 1937. The Weddell seal in the Bay of Whales, Antarctica. 0.6- Tj z Journal of Mammalogy, 18, 127-144, z 0.4 t i} 1l 11I1f 111111111 Poulter, T. 1968. Underwater vocalizations and behavior of pinnipeds. 4 IL In R.J. Harrison, R.C. Hubbard, R.S. Peterson, C.E. Rice, and R.J. 0.2 Schusterman (Eds.), The behavior and physiology of pinnipeds. New York: Appleton-Century-Crofts. 0 Ray, C., and M. deCamp. 1969. Watching seals at Turtle Rock. Natural o 0 0 - - P..) P.) 0 0 0 - -. P.) 1..) A P.) 01 0 A - A K) 01 0 A o 0 0 0 0 0 0 0 0 010 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 History, 78, 26-35. Schevill, W., and W. Watkins. 1971. Directionality of the sound beam HOUR in Weddell seals (Leptonychotes weddelli). In W. Burt (Ed.), Antarctic B pinnipedia. (Antarctic Research Series, Vol. 18.) Washington, D.C.: 100 American Geophysical Union. PUPS/ Thomas, J . , and V. Kuechle. 1982. Quantitative analysis of Weddell 0 seal (Leptonychotes weddelli) underwater vocalizations at McMurdo 50 Sound, Antarctica. Journal of the Acoustical Society of America, 72(6), 4 ADULT FEMALES 1730-1738. WITH PUPS Thomas, J., and D. DeMaster. 1983. Diel haulout patterns of Weddell 0 0100 1200 2400 seals (Leptonychotes weddelli) females and their pups. Canadian Journal of Zoology, 61, 2084-2086. HOUR Thomas, J., and I. Stirling. 1983. Geographic variation in the under- water vocalizations of Weddell seals (Leptonychotes weddelli) from Figure 3. A. Mean number of calls per minute (±95 percent con- Palmer Peninsula and McMurdo Sound, Antarctica. Canadian Journal fidence interval) for the five most common adult and pup calls (MO) of Zoology, 61(10), 2203-2212. by hour of the day at Hutton Cliffs in 1977. B. Percentage of females Thomas, J , K. Zinnel, and L. Ferm. 1983. Investigation of Weddell and their pups hauled out on a given hour at Hutton Cliffs in 1977 . seal (Leptonychotes weddelli) underwater calls using playback tech- (determined by telemetry, Thomas and DeMaster 1983). niques. Canadian Journal of Zoology, 61, 1448-1456. Thomas, J . , R. Puddicombe, M. George, and D. Lewis. In press. Var- In conclusion, trills (MT) always are prevalent, but are high- iations in underwater vocalizations of Weddell seals (Leptonychotes est during the mating period and when females haul out. Chugs weddelli) at the Vestfold Hills as a measure of population discrete- (MC) are most abundant during mating and increase slightly ness. Hydrobiologia.

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