Telemetry Studies of the Internal Body Temperatures of Adelie and Emperor Penguins at Cape Crozier, Ross Island, Antarctica

Home , Emperor penguin

TELEMETRY STUDIES OF THE INTERNAL BODY TEMPERATURES OF ADIgLIE AND EMPEROR PENGUINS AT CAPE CROZIER, ROSS ISLAND, ANTARCTICA

Jo•N C. BoYr) A•r) W•t,t,•A•4 J. L. SLADEN

HO•rEOT•ER•4Sof both tropical and polar regionsare able to regulate internal temperaturesonly within certain environmentallimits. Extension of theselimits is possibleonly by physiologicaland/or behavioraladapta- tions that are often more conspicuousin speciesof very cold environ- ments. Cape Crozier (Ross Island, Antarctica) is the extreme southern locality where comparativefield studiesof the Addlie (Pygoscelisadeliae) and Emperor (Aptenodytesforsteri) Penguinsare possible.With emphasis on investigationof behavioral adaptationsin temperatureregulation, the internal body temperaturewas monitoredand its variation studied during two australsummers of field studies,1965-66 (Sladenet al., 1966) and 1966-67 (Boyd et al., 1967). Previous investigators(Eklund, 1942; Goldsmith and Sladen, 1961; Prdvost, 1961; Prdvost and Sapin-Jaloustre,1964; Mougin, 1966) had determined internal temperature values for these species,but our data present values of abdominal cavity temperaturesmonitored continuously during selectedstates of behavior. The study was aimed at further de- velopmentof a biotelemetrysystem to monitor the physiologyand behavior of unrestrainedbirds. In particular, such a technique might be employed to study the winter-nesting Emperor Penguins in 24-hour darkness and severe weather conditions, as they move around while incubatingor broodingon the sea ice of the rookery. Field investigationswere carried out at the Addlie Penguin rookery (77 ø 26' S, 169ø 18' E), 8 km northwestof Cape Crozier and 7 km west of the Emperor rookery. About 150,000 breeding pairs of Addlie Penguinsare presentin the main rookeryin contrastto the 1,000 to 2,000 pairs of Emperorson the nearby sea ice. The Addlie rookery is part of the large ice-free area at the easterntip of RossIsland and benefits from a northernexposure and frequentwinds, keepingsnow cover at a minimum. Nearby Mount Terror (altitude 3,230 m) and the loweredalbedo of the dark exposedground (in contrastto that of nearby ice fields and the Ross Ice Shelf) considerablyaffect the climate of the rookery. Our 1966 67 weatherobservations (Figure 1) were taken from the Jamesway hut (134 m elevation). Janetschek(1967: 215) givesa summaryof the metereologicalconditions of RossIsland. Most field work was done at a coastal site (27 m elevation) from a hut

366 The Auk, 88: 366-380. April 1971 April 1971] Penguin Temperatures 367 m OCT.I NOVEMBER I DECEMBER I dANUARY IFEB-

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Figure 1. Weather observations at Wilson House (Jamesway), elevation 134 m, Cape Crozier, from 28 October 1966 to 7 February 1967. surroundedby penguin colonies(Figure 2). Local screeningby low hills to the west and by Mount Terror exposedbirds to daily periodsof shade, varying from 7 hours 20 minutes (9 November) to 34 minutes (23 December). Air temperaturesand wind speedswere taken 40 cm above groundand at this site temperatureswere 1ø to 2øC warmer than at the Jameswayand the prevailingwind was southeasterly.Most experimental birds were kept in aluminum pens of 8 cm mesh--the Addlieson their nest sitesand the Emperorson a snowfield (after being flown over from their rookery by helicopter). Adults and the larger immature birds were flipper-banded (Sladen et al., 1968: 214). Nestling Addlie penguins were marked with plastic bands or tape. The terrestrial ecology of the Addlie and Emperor Penguinsis re- viewed by Pr•vost and Sapin-Jaloustre(1965) and Stonehouse(1967) has summarizedwhat little is known of their marineecology. The ecology, behavior, and physiologyof the Ad•lie Penguin are treated by Sladen (1953, 1958), Sapin-Jaloustre(1960), Taylor (1962), and in five articles in the recent monographon Antarctic avian studies (Austin, 1968). Physiologyand breedingbehavior of the emperorare coveredby Pr•vost ( 1961) and breedingbehavior by Stonehouse(1953).

METltODS Conventio,nalmeans of measuringinternal body temperaturesmay reducethe useful- ness of the measurementsbecause of the animal's reactions to repeated human disturbance. Recent electronic developmentshave made the use of implanted telemeterspractical for field experiments.Telemetry was first used for field studiesof animals in the Antarctic in 1957 to determine egg temperaturesof incubating Ad•lie 368 BoYt• ^•u S•^•r• [Auk, Vol. 88

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Figure 2. CapeCrozier, Ross Island, and the study area.

Penguinsand SouthPolar Skuas(Eklund and CharItOh,1959). In 1965preliminary work was doneat Cape Crozier (Sladenet al., 1966) with telemetersimplanted in both adult and chickAddlie Penguins, part of a systemdeveloped by KennethBindle (University of Saskatchewan,Saskatoon, Canada). The presenttelemetry system, designed and constructedunder the supervisionof HowardA. Baldwin(Sensory Systems Laboratory, Tucson, Arizona), was based upon implantableunits measuring 3.7 X 1.5 X 1.8 cm and weighing20 g. The transmitter had a pulsed signal (27 millicycles/see),the rate of which was the inverse function of body temperature.Each telemeterwas poweredby two 1.5-v batteriesin series (both silveroxide and mercurycells were used), with a practicallife of 2-3 weeks, and the unit was encasedin epoxy and urethane,with additionalprotection given the batteriesby Silasticcoating. Use of a crude receivingantenna was necessary after damagein highwinds, and the rangeof the signalfrom an implantedtelemeter in the abdominal cavity of a free-living bird was 9-12 m. A 14-channelreceiver was April 1971] PenguinTemperatures 369 connectedto a digitalcounter that registeredthe signalpulse interval in milliseconds on a chart recorder. The receiver and the cou.nter-recorder were housed in two field cases,each 37 X 15 X 15 cm and weighing7.2 kg, and poweredby nickel- cadmium rechargeablebatteries. Calibration curves were made between 35 ø and 41øC and observed temperature valueswere calculatedfrom the fitted regressionline of the individualtelemeter. A changein resistancecharacteristics with time ("drifting") was notedin eachtelem- eter, but this error could be controlledby choiceof data soo.nafter calibration. Maximumerror in temperaturedetermination occurred during field calibration,and total calculatederror rangedbetween ñ 0.13ø and ñ 0.24øC,depending upon the individualunit. Estimatesof the 95 percentileconfidence interval were made for (1) the wholecalibration li.ne of the individualunit for a giventime period(the intervalsranging between ñ0.6 ø and ñ 1.1øCdepending upon the unit), and for (2) the mean "resting"abdominal temperature value of eachbird (the intervals rangingbetween ñ 0.1ø and _ñ0.2øC). The telemetertime constant,or responsetime, was 90 seconds--thetime requiredby the telemetersto completeapproximately two- thirdsof a totalchange of 10øC(20 ø to 39øC)when shifted between two waterbaths. In the abdominalcavity it was assumedthat the implantedtelemeter and the encapsulatingcyst formedaround it were affectedby changesin temperaturesof the surroundingtissue much as a corresp.o.ndingtissue mass in a similarsituation (Mackay, 1968: 253). The similarityof sucha massto water cannotbe assumed and the responsetime obtainedin the waterbath is reportedonly as a demonstrable characteristicof the system. Thermistorprobes (Yellow SpringsInstrument Co.).--(1) Abdominali.nsertion (Model421): internalbody temperatures of nestlingAd61ie chicks were monitored by a probeinserted 3 cm abdominally,just posteriorto the proventriculus,and sutured externallyto the skin. (2) Proventricularinsertion (Model 401): internal body temperaturesof severalbirds were mo.nitoredby an insertionof 30 cm (Ad61ie adults)and 35-40 cm (Emperoradults). Averagevalues were within 0.4øCof mean "resting"values obtained from telemeters.Control measurements were made with this probeduring telemeter calibration. (3) Surfacetemperatures (Model 421): probes wereattached by tape (5 mm wide) to the palmarsurface of the flipperand to the acrotarsal surface of the foot. Rectal thermometers.--Internalbody temperaturesof severalbirds were monitored by an insertionof 7-8 cm throughthe cloacainto the rectum. Rectal temperatures were recordedwithin a minutefrom experimentalbirds captured for periodicweigh- ing--values were taken after at least 30 secondsof insertion,but within 1 minute of capture. In eight instanceswhen simultaneousreadings were taken, all rectal temperatureswere within ñ 0.3øC of the telemeterrecord. Observationswere read from telethermometers(Yellow SpringsInstrument Co., Models41TD, 43TF and 43TK) and recordedcontinuously on a battery-poweredpotentiometer recorder (Instrument Corp. of America, Model 400). Thermal stability and easeof telemeterimplantation were major reasonsfor the choiceof the abdominalcavity. Complexvariation in thermalcharacteristics over the whole body force any representativeinternal body temperatureto be a statistical abstraction. It was assumedthat temperature measurementin a deep central area will approximatea meaningfulestimate of internal body temperaturemost closely becausethese areas require a minimumof temperaturevariation in order to function correctly. The abdominalarea probably approachesmore closelya steady state conditionof temperature.During the 1965-66season both plastic dummy "telemeters" 370 BoYt) ANt) SLAt)Eta [Auk, Vol. 88 and actual telemeterswere implantedat varioussites. Fifteen autopsiesindicated least complicationand irritation from abdominalcavity implantation; subcutaneoussites, although better suited for data transmission(less signal attenuation), were more labile thermallythan deeperlocations. Surgical procedure was uncomplicatedand anesthesiawas administered with halothane in an open system (plastic bag and cotton wad). Telemeterswere implanted in the abdominal cavity through a 6-cm midline incision between the xiphisternumand the cloaca,and 15 postoperativeautopsies or exami.nationsunder anesthesiashowed formation of a simple fibrocollagenouscapsule around the implant. Two adult Ad61iesautopsied had carried the implant for 1 year and had reestablished territories in the area where captured before implantation. One was incubating a singleegg--significant evidence of recovery.

RESULTS Data are presentedfrom telemetersimplanted in the abdominalcavities of three adult and two 5- to 7-week-oldAd•lie Penguins,and of two adult and one chick Emperor Penguins. Abdominalcavity temperatures, recordedby inserted thermistor probes, are reported from two 2- and l 1-day-oldAd•lie chickswhile they were under broodingadults. Spe- cifics of these birds are listed in Table 1. Data were drawn from simul- taneoussources: from a continuouschart recordingof telemetereddata and from notebooksof bird behavior,ambient conditions, and recorded pulse intervals of the telemeters. Mean internal temp.eraturesof "resting" birds.--For calculation the data were taken at intervalsof not lessthan 15 minutes. An attemptwas made to follow the guidelinesof King and Farner (1961: 269); data were obtainedfrom birds incubating,apparently asleep, or not noticeably disturbed within the preceding 30 minutes. Thermoneutral conditions were assumedto exist 40 cm aboveground at air temperaturesbetween -10 ø and +5øC and winds below 9 m/sec. Penned birds were not fed and data from the free-livingindividual were includedwhen certain that the bird had not returnedwithin the hour from the sea. Data from eight birds are summarized in Table 2. Internal temp.erature variation associatedwith behavior and human disturbance--(1) Preening: an Ad•lie adult (AA1) maintained37.8øC for 50 minutesafter standingup and remainingquiet, endinga period of at least an hour in a prone resting position (ambient conditions: sunny, -0,6øC, calm). After starting to preen its temperaturerose 0.5øC (37.8øC to 38.3øC) in 40 minutes; the bird then returned to a prone position,temperature dropping 0.3øC (38.3ø to 38.0øC) in 15 minutes, and remaining at 38.0øC for 40 minutes. (2) Breeding behavior: (a) Mating: no variation of abdominal temperatureswas noted during or after mountingand copulationin five instancesmonitored from the Ad•lie adult AA1. (b) Nest relief: mon- April 1971] Penguin Temperatures 371 372 BOYD AND SLADEN [Auk, Vol. 88 April 1971] Penguin Temperatures 373

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38- - 38 - - Figure 3. Left, abdominal body temperature of Adglie (AA2) during nest relief of an incubatingmate. Right, abdominalbody temperatureof Adglie (AA3) when relieved from brooding by mate. itored twice with a pennedpair (Figure 3, left) and twice with a free- living pair. Maximum variation occurredwith relief of the free-living male (AA3) broodinga 3-day chick, a rise of 0.6øC (38.3ø to 38.9øC) in the 25 minutes following changeover(Figure 3, right) with AA3 preeningand performingtwo mutual displaysbefore going off toward the sea. (3) Human disturbance: (a) Disturbanceof a nearby investigator: a free-livingbird (AA3) was suddenlyawakened with no responsenoted. A pennedAd•lie (AA2) showeda rise of 0.4øC (38.3ø to 38.7øC) in 20 minuteswhen visibly disturbedby the captureof an adult 2 m from the pen, the temperatureresponse first detectableonly 9 minutes after the incident. (b) Tail lift of nestingadult to observeeggs or chicks: no detectableresponse was notedin three casesafter the incubatingor brooding bird (AA3) had beenlifted by the tail and then freed as it scrambled off the nest. (c) Brief handlingto obtainrectal temperature and weight: an Ad•lie chick (AC1), after being held for 2 minutes,showed a rise of 0.4øC (38.7ø to 39.1øC) in 20 minutes,the first responsenoted 8 minutes after capture. Abdominal temperaturereturned to 38.7øC 55 minutesafter release.Another chick (AC2) exhibitedno variationafter being held 2 minutes. An adult Ad•lie (AA1) was twice handledfor weighingduring a 30-minuteperiod, with much struggling(Figure 4). The apparent cumulativeeffect, after an initial 5 minutesof no detectable response,was a rise of 1.2øC (38.0ø to. 39.2øC) in 40 minutes. The bird remainedup and the temperatureaveraged 39.0øC for the next 4 hours. (d) Prolongedhandling: an Emperor chick (EC1) was dressedwith a harness(while insidethe hut with air temperature15øC) and fixed with 374 Bov•) ^m) St^turN [Auk, Vol. 88

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Figure 4. Abdominal body temperatureof Ad•lie (AAI) when picked up twice and weighed. thermistorprobes subcutaneously in the palmaraspect of the right flipper. After 30 minutesit was releasedinto a pen (air temperature-02øC). The abdominal temperature had risen 0.5øC (38.7 ø to 39.2øC) 55 minutesafter captureand returnedto 38.7øC only 2 hoursafter release. Internal temperaturevariation in Addlie nestlingsassociated with ex- posureto. the ambien't.--AltricialAddlie chicksare heterothermicduring their first 2 weeks(Sapin-Jaloustre, 1955: 67; Goldsmithand Sladen, 1961: 260; LeRescheand Boyd, 1969: 88). (1) Exposureof 2-day-oldchick: AC3 (weight 115 g), aloneunder a broodingparent, was removedfrom the nestand placedon the ground. The abdominaltemperature fell 10.7øC (37.2 ø to 26.5øC) in 20 minutes, then remainedat 26.5øC for 10 minutesbefore dropping again. Shivering started 20 minutesafter first exposure(abdominal temperature29.0øC; surfacetemperature, flipper 11øC and foot 13.8øC) and the abdominal temperaturecontinued to drop but both surfacesites rose to 18øC after 10 moreminutes of exposure(Figure 5). (2) Competitionfor warmthbetween 2 broodedchicks: a 300-gchick was placedwith AC3 (115 g) underthe sameadult and competitionfor spaceresulted in increasedexposure for AC3. Its abdominaltemperature fluctuated between27.5 and 36..5øC (ambient conditions: shadedarea, 0øC, calm). Surfacetemperatures from the flippersand feet maintained high levels(31 ø to 37øC) while still undercover of the adult. (3) Exposureduring nest relief: the abdominaltemperature of a 625-g chick (AC4) dropped6.7øC (36.2ø to 29.5øC) in 9 minutesduring nest relief. It remained near this level (27 ø to 30øC) for 35 minutes (while the adult was arrangingthe chick and itself on the nest) until premature proberemoval. Ambientconditions were overcast,-03øC, calm. Under April 1971] Penguin Temperatures 375

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I I I I I I I OSCO 0400 0450 0500 FJõure 5. AbdomJ.na! body temperature of 2-day-o!d Ad•]ie (AC$) when brooded and when removed from parent. the parent surface temperatures of the extremities were sometimes within 2øC of abdominallevels, but droppedprecipitously when the chick becameexposed during nest relief. In 20 minutesthe proximal flipper and foot temperaturesfell from 36 ø and 37øC to 18.5ø and 14.5øC, respectively. After 30 minutes of low broodingposture by the adult, surface temperatures at these sites had returned to 34øC (flipper) and 38øC (foot).

DISCUSSION An internal body temperature is necessarilydynamic--changing in spaceas well as time--and the first task of the investigatoris to define which "body temperature"is to be monitored. Sophisticationof instru- mentation and more accurate realization of this temperature must be further defined by specificationof method used and of site being sensed, seasonof the year, as well as activitiesof the animal and other factors. Pr•vost (1961: 54) demonstratedthat the internal temperature level is registeredon the inserted rectal thermometer after an average of 1 minute of insertion under antarctic field conditions. Farner (1958) in a study of the Yellow-eyed Penguin (Megadyptes antipodes) gives evidence that internal temperature measured by rectal insertion, if com- pleted approximately 1 minute after capture, was probably very close to the rectal temperature at the time of capture. Farner found that rectal temperature change was statistically significant after the bird had been held for 5 minutes; our data showa detectablechange in the continuous record after 7 minutes at least. Our data from the proventricula of Ad•lie and Emperor Penguins approachedclosely the means from the 376 BOYD A•V SLAVE• [Auk, Vol. 88 abdominaltelemeters, but birdswith proventricularinsertion, with probes strappedto the gape,appeared irritated by the wires. In addition,neither the exact positionof the thermistornor the nature of its surroundings (gas, liquids,or food particles) may be known. The swallowingof snow by an Ad•lie resulted in a drop 1.4øC (from 39.3ø to 37.9øC) in 3 minutesin recordedproventricular temperature. The telemetry technique utilized provided a means of monitoringtemperature variations at a thermally stable site, while noting simultaneous,apparently normal, behavior. With data segregatedby behavioran approachis made towardsfield determinationof a "standarddeep body temperature"(King and Farner, 1961: 269). Our telemetry data from fasting and incubating Ad•lie adults and data from the large sampleof Pr•vost and Sapin-Jaloustre (1964: 76) differ by 0.1øC and the valuesfrom the olderchicks and those reportedby Pr•vost and Sapin-Jaloustre(1964: 76) and Mougin (1968) are within 0.7øC. Nestling Ad•lie Penguinsshowed considerable variation dependingupon the ageof the bird, the attentivenessof the parent (during early stages),and the ambient conditions,and rangedbetween 25 ø and 39øC in chicks monitored on the nest with adults. When the chick's weighthas attained 0.5 kg or more,at leasthalf the chickis exposedto the ambient. This situation arrives earlier when two chicks are brooded. The temperedmicroenvironment encountered by experiencedbreeders in the center of a colonymight be an important factor in the survival of very young chickssubjected to exposureeither becauseof competition for spacewith a sibling or during nest relief of the parents. Guarding by the very youngchicks of the radiativesurfaces appeared in chicksonly a day or two old, and when these chicks first sit erect• protectedby the parent, at 7 to 10 days of age, they are able to cover the acrotarsal surfaceof the foot by assuminga posture commonlyseen in adults: sitting upon the tarsometatarsaljoint with feet raisedup under the ab- domen. Pr•vost and Sapin-Jaloustre(1965: 611) reported that Emperor Pen- guins in enclosuresat the Terre Ad•lie station registeredmean rectal temperaturesconsistently above 38øC when studieswere first started in 1952. They foundlater that rectal temperatures,when taken immediately from birds captured in the rookery, gave lower mean levels. As our studies were limited to birds in enclosures and with the added factors of a warmer climate than at their rookery and human disturbance,it is not surprisingthat our mean levelswere 1.2ø and 1.5øC higher than those from Pr•vost'srookery birds. The mean values for temperaturesof older Emperorchicks agree with thosegiven in Pr•vost (1961: 131). Much of the data on internal temperaturevariation presentedhere April 1971] Penguin Temperatures 377 was from two pennedpairs of Ad•lies each incubatingon a territory and, in contrast to the Emperor Penguinspenned in an abnormal environment, there is no reason to believe that the penned situation affected their abdominal temperaturereadings. Abdominal temperaturevariation ap- pears to be related to muscular activity: preening and nest relief with mutual display are followedby someresponse, whereas the act of mount- ing and copulating gave none (where the male's activity is mainly a rapid flipper movementof short duration). The studies of human disturbance show at least a 5-minute period after a bird is captured before any temperature responseis evident, in agreement with Farner's sug- gestion (1958). After a struggling bird is handled continuously for severalminutes or longer,its abdominaltemperature may remain IøC or more aboveprecapture levels for as long as severalhours after release. The mean values proposedby different investigatorsusing the three techniquesseem to be in good agreement. As during both rectal and proventricular insertionsthe bird must always be restrained to some degree,these techniquesare not suited for repeateduse on the same individual. Implantation is rapid under anesthesiaand human contact is kept to a minimum, but it involves surgical incision trauma and possiblepostoperative effects. The investigator must choosecarefully dependingupon the desired goal: implant telemetry is advisable for long-term studies of individuals, whereas the continuousrecord from proventricular insertion should be viewed primarily as a short-term method for controlledexperiments. Technical and financial aspectsof telemetrylimits the numberof individualsthat can be monitored,and the results are less convincingstatistically as a measureof the population. Rectal insertionwith behavior noted just before capture enablesthe in- vestigatorto samplea larger number of individualsand gather data for seasonalcomparisons of mean temperaturelevels. Pr•vost (1961: 55) demonstratedseveral levels of mean rectal tem- peraturefrom EmperorPenguins and Pr•vost and Sapin-Jaloustre(1964: 76) measuredrectal temperaturesof two Ad•lies sleepingin the rookery at 36.3 ø and 36.4øC. We found a mean abdominaltemperature of a resting, fasting male to be 38.4øC in early November,in contrast to the 39.4øC level of a resting,brooding bird in late December. The marked overlap of mean "resting" values in both species,obtained by the same technique (Figure 6) but under varying conditions, emphasizesthe problemof attemptingcomparative data. Both speciesapparently exhibit internal temperaturevariability of several degrees,which is not excep- tional in birds (Stonehouse,1967: 187), and the behavior of both species, their level of activity, varies seasonally. Prgvost and Sapin-Jaloustre (1964: 68) emphasizethat the lowestlevels of the Emperor Penguinare 378 BOYD AND SLADEN [Auk, Vol. 88

ADI•LIE ADULT AA2• ! .' AA5 I EAI • EMPEROR ADULT ! , EA2 I I '

ADELIE CHICK ACI AC2 EMPEROR CHICK IECl ; ß 'ß

37I 38I 39I 40I

RANGEOF MEANS I.OøC (38.4 to 39.4) Figure 6. Mean values and ranges of abdominal body temperatures of "resting" Ad•lie and Emperor Penguins obtained by telemetry. during the period of fasting. Our data from individual Adalie Penguins suggesta seasonalvariation in body temperature levels for this species, apparently governedby marked activity levels at different periods during the terrestrial breeding cycle, though limitations must be placed on inferences from a few individuals to allow for variation between individuals. A recent study (Miiller-Schwarze, 1968) showsa daily activity cycle in an Ad•lie rookery; our observationsdid not determine daily internal temperature cydes. Miiller-Schwarze does describe differing circadianpatterns at differing times during the breedingseason, but makes no mention of differing activity levels. Our data may describewith the fastingAd•lie a normal feature of loweredtemperature in fasting homeo- therms (King and Farner, 1961: 235). The variability is more pro- nouncedin the winter-breedingEmperor Penguin,but the length of fasting and associatedbehavior appearsmore important than any climate-induced biGenergeticlevel. These variations are perhaps in concert with variation in metabolic rates and probably take the form of rising temperature valuesfrom the long fastingand incubationperiod to the active periodof chick~raising.

AC•IX,TOWLEDG2ViENTS

The support of this study by the following organizationsis gratefully acknowledged: the National ScienceFoundation for the field facilities and financial support (grants GA-248 and GA-655 to Sladen), the U.S. Navy Task Force 43 for logistic support, April 1971] Penguin Temperatures 379 and the Air Development Squadron VX-6 for helicopter support. Flipper bands for marking the experimentalbirds were provided by the USARP BirdsBandingProgram. The following are acknowledgedwith si.ncerethanks: R. LeResche, J. M. Pedersen, R. L. Penney, and R. C. Wood for aid in the field and in Baltimore; G. Harrow and A. Anderson for aid in the field; H. A. Baldwin and K. Bindle for electronic guidance; M. Gambrill, E. M. Holcomb, and R. W. Fleischman for aid in Baltimore; rand the senior author's wife, Maja, for help and patience. This paper is taken from a thesis submitted to the School of Hygiene and Public Health of the Johns Hopkins University in partial fulfillment of requirements for the degree of Master of Science.

SUMMARY Field studies at Cape Crozier, Ross Island, Antarctica, concernedthe internal temperaturevalues of Ad•lie and Emperor Penguins. The most thermally stable area was consideredthe abdominalcavity and telemeters were implanted for remotemonitoring of temperaturelevels from relatively unrestrainedbirds and, in one case,from a free-livingindividual. Ad•lie adult meansranged from 38.4ø to. 39.4øC, dependingupon the part of the seasonwhen monitored,and two. chicks 5 and 7 weeks old averaged38.7 ø and 39.2øC, respectively. Nestling chicks being brooded were monitored with thermistor probes; their abdominal temperatures varied between 25 ø and 39øC. Two Emperor adults had means of 38.4ø and 38.7øC and an Emperor chick a mean of 38.7øC. Short-term variations of abdominal temperature of over iøC were monitored after human handling, but only after an initial period of at least 5 minutes after capture with no detectable responsein monitored temperature. Telemetry is recommendedfor long-term studies of individual birds, whereasrectal thermometermeasurements seem best for larger samplesof the population. Evidence is presentedof seasonalfluctuations in the mean internal body temperatureof the Ad•lie Penguin.

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Department of Patho.biology,Schaol of Hygiene and Public Health, JohnsHopkins University, Baltimore, Maryland 21205. Present address of first author: Service Chasseet P•che, Inst. Galli-Val•rio., 37 C•sar- Roux, Lausanne,Switzerland. Accepted30 March 1970.