Body Temperatures of Antarctic Birds [Aukl Oct

5'•'• EKLUm),Body Temperatures of Antarctic Birds [AukL Oct.

BODY TEMPERATURES OF ANTARCTIC BIRDS

BY CARL R. EKLUND BODY-TEMPERATUREstudies of Antarctic birds were conductedby the authorwhile employed as ornithologist at the EastBase, on the United StatesAntarctic Expedition, from November,19•9 to May, 1941. The East Base was one of two bases established on the Antarctic Continentby the UnitedStates Antarctic Expedition, under the direc- tion of Rear Admiral Richard E. Byrd. It was locatedon a small island,approximately 1,000 miles south of Cape Horn, in Marguerite Bay of[ the BellinghausenSea, adjacentto the west coastof the Palmer Peninsula,in Latitude 68ø 11' S., Longitude 67ø 12' W. Rather limited bird-temperaturerecords from the AntarcticConti- nent have thus far been obtained, and this work was an attempt to add slightly to the present knowledge. During the study a total of 78 recordscovering observations on six speciesof Antarcticbirds were made. All were taken within a fifteen-mile radius of the base. Birds included in the study were the Addlie Penguin (Pygoscelis adeliae),South-Polar Skua (Catharactaskua maccormicki),Kelp Gull or SouthernBlack-backed Gull (Larus dominicanus),Snow Petrel (Pagodromanivea), Antarctic Tern (Sterna vittata), and the Giant Fulmar (Macronectesgiganteus). Nesting recordsof the first four specieswere also obtained during the work. Previousrecords on Antarctic birds have been made by Andersson, Clarke, Gain, and Vallette.

METHOD UsED A 4-inchAsepto rectal maximum-minimum thermometer wasused, with recordingsmade to within a tenth of a degree. The thermometer was inserted at least three inchesinto the intestine, and was kept there three minutes. In each casethe time of day was noted as well as the air temperature,if possible. Wheneverpossible, recordings were takenon uninjuredbirds. All penguin,snow petrel, and mostskua records were taken on birds not injured. Penguinswere readily caughtwith a hand net on land, skuaswere easilysnared with a string,and SnowPetrels were captured after they had momentarilystunned themselves by flying againsta building during the winter night. Temperatureswere taken from woundedbirds immediatelyafter capture,and then only on speci- mens which were but slightly wounded. The one disadvantageof taking recordingsfrom birds which were not woundedwas that sex Vol.1942 •9'] a EKLVND,Body Temperatures of Antarctic Birds 545 was not determined,in many cases,because some of thesebirds were afterward released. The following table gives the family, species,number of records, and maximum,minimum, and mean temperatures.All were rectal recordings: TABLE 1 SUMMARY O1•BODY TEMPERATURE R•CORDS

Temperatures( F) Number of Family and Species Maximum Minimum Mean records

Spheniscidae 106.4(juv.) Pygoscelisadeliae 105.3 (ad.) 100.3 103.8 23

Laridae Larus dominieanus 107.4 104.2 105.77 16

Sterna vittata 106.2 105.2 105.63 3

Stercorariidae Catharacta skua maccormicki 108.4 103.4 106.14 30

Procellariidae Pagedroma nivea 104.1 102.1 103.3 3

Macronectesgiganteus 105.8 104.3 105.03 3

Total 78

PreviousAd•lie Penguinrecords taken by Andersson,ornithologist of Nordenskj61d'sSwedish Expedition, near the Antarctic Circle at the northerntip of the Palmer Peninsula,found temperaturesranging from 100.2ø F. to 104.9ø F. Clarke, biologist for the "Scotia" Ant- arctic Expedition, found temperaturesof this same speciesas high as 106ø F. Vallette, an Argentine meteorologicalobserver in the South Orkney Islands,recorded a South-PolarSkua temperatureat 105.9ø F., a Kelp Gull at 105.2ø F., a Snow Petrel at 99.8ø F., and a Giant Fulmar at 104.5 ø F. This same observer recorded an Ant- arctic Tern temperatureof 107.9ø F., while Gain, biologiston Dr. Charcot'sFrench Antarctic Expedition, found a temperaturefor this samespecies of 102.9ø F.

DIURNAL RISE AND FALL Detailed investigationsof the diurnal rise and fall of bird tempera- tureshave been carried out by •Vetmore,and Simpsonand Galbraith. 546 •.KLvND,Body Temperatures of Antarctic Birds LOct.FAuk

Diurnal species,which are normally active during daylight hours, showeda constantrhythm indicated by a •radual temperaturerise toward the latter part oœthe afternoon,and a correspondingdecrease toward early morning. Nocturnal speciesshowed a reversetempera- ture curve with the high reading late at night and the low during the day. Increased temperatureswere definitely correlated with activity. Peculiaritiesoœ Antarctic Continent weather presentfactors which are not normal to temperate zones. In addition to extreme, cold temperaturesand a reversein seasonsoœ that oœthe northern hemi- sphere,there is a period during the summerin which there is con- tinual daylight, and sight oœthe sun is never lost. Consequently an experimentwas carriedon, under thesenatural conditions,which might throw still œurtherlight on diurnal rhythm.

TABLE 2 HOURLY TEMPERATURE iRECORDSOF Catharacta skua maccormicki

Air Body Temperature Body Temperature Time of Day Temperature No. I Specimen No. 2 Specimen

3 1ø. M. -[-33 ø F. 107.1ø F. 107.9ø F. 4 P.M. -[-33 106.6 108.4 5 P.M. -[-33 107.6 107.5 6 P.M. +32 104.9 106.9 7 P.M. +32 104.3 106.0 8 P.M. +32 104.5 104.6 9 P.M. +32 104.0 103.8 10 P.M. +32 103.8 104.0 11 P.M. +32 103.9 103.5 12 Midnight +32 104.0 104.0 1 A.M. +32 104.4 104.0 2 A.M. +32 104.1 104.1 3 A.M. +32 104.0 104.3 4 A. M. -[-32 104.5 104.4 5 A.M. -[-32 104.3 104.4 6 A.M. -{-32 104.3 104.7 7 A.M. +33 104.2 104.4 8 .•. M. +33 104.3 104.8 9 A.M. +33 104.7 105.5 10 A.M. +33 103.9 105.5 11 A.M. +34 104.4 106.0 12 Noon +34 104.9 105.5 1 P.M. +34 105.4 105.7 2 P.M. -[-34 105.2 105.5 3 P.M. -[-34 105.7 105.2 Mean Average 104.76ø F. 105.12ø F. VoLt94• 59-[ a EI•I•VmD,Body Temperatures o[ Antarctic Birds 5}7

During a periodof continualdaylight, in March, two adult South- Polar Skuas,the mostsoutherly bird in the world accordingto present records, were taken alive. At these times this bird is more or less active for 24-hour periods,and they could alwaysbe observedeating and fighting among themselvesover seal-meatscraps near the husky sledge-dogkennels. Simultaneoushourly temperaturerecordings were taken on both captured skuasfor a period of 25 hours. One bird showeda high readingof 107.1ø F. and a low of 103.8ø F., or an average of 104.76ø F., while the secondhad a high of 108.4ø F. and a low of 103.5ø F., or a mean of 105.12ø F. Highesttemperatures were reachedaround 3 P.M. after which there was a gradual decline to midnight. For the next three or four hours the temperaturesre- mainedsomewhat constant, after which there was a gradualrise up to the middle of the afternoon. Hourly air temperatureswere alsokept, but when comparedto the bird temperaturesno correlation could be found. Light westerly winds, with a foggyand overcastsky causedtemperatures to remain steady,and the highestrecording within this 25-hourperiod was q- 34ø F., with the lowestat q- 32ø F.

TEMPERATURE DIFFERENCE OF SEXES Correlations on temperature differencesbetween sexeswere not worked out in detail, becausemany birds were releasedafter recordingswere taken, and sexwas undetermined due to plumagesimilarity. Most temperaturework on this phaseseems to indicate that the femalehas the higher temperature,although there are exceptionsto this, especiallyin caseswhere the male helps with nestingand is otherwisemore active than the female. In thiswork only recordings of the South-polarSkua and the Kelp Gull wereof sufficientnumber even to indicateany differences. These recordingswere made at the end of the nestingseason. TABLE 3 TEMPERATITREDIieleERENCE BETWEEN SEXES Numbe.____•rofRecord•s MeanTe•mperatur____•e Species

Catharacta skua maccormicki MaleFemale MaleFemale Larus dominicanus , I00: The authorwishes to acknowledgehis appreciationto Mr. Herwil M. Bryant, East BaseBiologist, and other membersof the base for their aid in carryingon thesestudies. 548 EKLUNO,Body Temperatures of Antarctic Birds L[Auk Oct,

BIBLIOGRAPHY ANv•ssoN, K. A. 1908. Das hShereTierleben im antarktischenGebiete. Wissenschaftl. Ergebnisse der SchwedischenSiidpolar-Expcdition, 1901-3, 5. Zoologie, I, VSgel: 19-58. Cr•RKE, W. E. 1913. Ornithologyof the ScottishNational AntarcticExpedition. Section5--On the birds of the South Orkney Islands. Sci. Res. Scot. Nat. Antarctic Expedition, 4: 219-247. GAIN, LOUIS 1914. Deuxi•me expedition antarctique francaise 1908-1910. Oiseaux antarc- tiques, 2:200 p. SIMPSON,S., ANDGALSlCaITrl, j. j. 1905, An Investigation into the Diurnal Variation of the Body Temperature of Nocturnal and Other Birds, and a few Mammals, Jour, Phys,, 33: 225- 238. VALLErrE, L. H. 1906. Viaje Alas IslasOrcadas Australes. Anal. Minist. Agrlc. RepfiblicaArgen- tina (Secc.Zootech. Bacteriol. Vet. y Zool.), 3, no. 2, pt. 1: 3--68. WETMORE, ALEXANDER 1921. A Studyof the Bod•/Temperatureof Birds. Smiths.Inst., Pub1.2658: 5-9. Indian Reservation Wildlife Section U.S. Fish and Wildli[e Service Minneapolis,Minnesota.