Body Temperatures in California and Gambel's Quail
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150 Baa•oz,o•awand DawsoN, California and Gambel's Quail [1VoL Auk 75 BODY TEMPERATURES IN CALIFORNIA AND GAMBEL'S QUAIL BY GEORGE A. BARTHOLOMEW AND WILLIAM R. DAWSON Tm• paucity of data on the body temperaturesof small gallinaceous birds prompts us to report miscellaneousobservations which we have made over the past severalyears on the body temperaturesof the Cali- fornia Quail, Lophortyxcalifornicus, a commonresident in grasslandand chaparral from southernOregon to southern Baja Cal/fornia, and the Gambel's Quail, L. œambelii,a residentin the desert regionsof south- western United States and northwestern Mexico. The habitats of both speciesare characterizedby high summer temperaturesand moderate winter conditions. We have therefore paid particular attention to capacity for temperature regulation in hot environments. We found that when ambient (environmental)temperature rose, the birds' body temperaturecould rise by as much as 4ø C. (7.2ø F.), without ill effects. Ability to maintain above normal body temperatures higher than ambient temperaturesfacilitates transfer of excessbody heat to the environment. It is probablya major avian adaptationto hot conditions. The data presentedwere acquiredincidental to work on other species and for that reasonare not comprehensive,but they serveto characterize aspectsof temperatureregulation in quail. MATERIALS AND METHODS The observationswere made on 8 adult and 2 juvenile California Quailcaptured on the LosAngeles campus of the Universityof California, and on 5 adult and 2 juvenile Gambers Quail capturedin the Colorado Desert, three miles south of Calipatria, Imperial County, California. The captive animals of both specieswere housedin cagesof half-inch wire mesh wh/ch measured 12 x 12 x 24 inches and had sand-covered floors. Mixed bird seed, water, cuttlebone, and bird gravel were continuouslyavailable and occasionallythe birds were given Tenebrio larvae. The windowless,ventilated room in which the birds were kept wasilluminated by fluorescentlights and the photoperiodwas controlled by an automatictimer. The temperaturein the roomaveraged 22 ø C. (71.6ø F.) during the winter and 25ø C. (77ø F.) duringthe summer; fluctuationsduring any one day were usuallyless than 3ø C. (5.4ø F.). The birds seemed to do well under these conditions and to maintain their weight,which usually approximated 150 gins.in the adults. Temperatures were measuredwith silver-solderedthermocouples made of duplex 30-gauge copper-constanstanwire coated with baked insulating enamel, and were recorded to the nearest 0.1ø C. on a recording potentiometer. A stepping switch 1958J BARTHOLOMEWand Dawsos, Californiaa•id Camb½l'sQ•il 151 driven by an electric motor allowed sequentialrecording from severalthermocouples. During the experimentsthe ambient temperature was controlledto within 1ø C. by an insulatedchamber equipped with heating and coolingunits, a blower,lights con- trolled by a clock-drivenswitch, and an insulated glassport for observation. Long- term temperature records were obtained from thermocoupleswhich had been im- planted in the pectoral musclesbetween the keel of the sternum and the left ventral feather tract as describedpreviously (Bartholomewand Dawson, 1954). Short-term records of deep body temperature were obtained either from an implanted thermo- couple or from a thermocouplesheathed in vinyl tubing and inserted through the the cloaca into the large intestine and held in place by clipping it to the rectrices. Skin temperatureswere obtained from thermocouplessecured in place by adhesive tape. During the period of measurement,the bird was housedin an 8 x 8 x 14 inch cageof haft-inchwire mesh. The thermocoupleleads were secured to the roof of this cagewith rubber bandswhich acted as shockabsorbers. Food and water were avail- ableduring the long-term,but not the short-termmeasurements. The birdsappeared to experienceno particular discomfort from the thermocouples. Recording from intramusculaxthermocouples was not commenceduntil 24 hours after implantation. RESULTS A clear-cut diurnal cycle of body temperature was apparent in both adult and juvenileCalifornia and Gambel'sQuail maintainedat ambient temperaturesbetween 24 ø and 26ø C., as indicatedby recordsfor representativebirds (Figs. 1 and 2). Their body temperaturesusually fluctuatedbetween 40 ø and 41.5ø C. (104ø F. and 106.7ø F.) during the day and were approximately1.5 ø C. (2.7ø F.) coolerduring the night. The diurnal differencein temperatureappears primarily correlatedwith level of activity; the cycleof body temperaturecoincides with the light cycle imposedupon the birds in the laboratory. ? 44 • •2 Ad.• 4O 6 12 6 • PM Fxctm.• 1. Continuouslyrecorded body temperaturesof undisturbedCalifornia Quail in ambienttemperatures of 24ø to 26ø C. Weight of adult female,145 gins.; weightof juvenile,47 gms. Photoperiod,$ '•30a.m. to 8:20p.m. 152 BARTHOLOMI•WandDiwsoN, California and Gamb½l's Quail [LVol. Auk 75 ß 44 • 42 m 40 $8 6 IZ 6 AM PM FzGImE 2. Continuouslyrecorded body temperaturesof undisturbed Gambel's •uail in ambient temperatures of 24ø to 26ø C. Weight of adult male, 151 gms.; weight of juvenile, 46 gms. Photoperiod,5:30 a.m. to 8:20 p.m. When thesequail weremaintained in a rapidly warmingenvironment (Figs. 3 and 4), their body temperaturerose as ambient temperature exceeded40 ø C. In somecases they becameas much as 4ø C. (7.2ø F.) warmer under these conditionswithout any apparent ill effect. Leg (tarsometatarsus)temperature in the California Quail approximated ambient temperaturewhile the latter was increasing,but remained relativelyhigh when the ambienttemperature was returned to a moderate level (25ø C. - 77ø F.). Leg temperaturedid not return to its prior level 5O pANTING i d40 , I ', I , I , [ , I , ) , I 20 • 60 • I• 120 140 MINUTES Fm• 3. Effects of increasing ambient temperat&es on rectal and leg (tar- sometat•sus) temperatures of an adult ferule Califor•a Quail. Period in which panting occ•ed desi•ated by horizontal bar. Animal ma•tained in dark t•ough- out experiment. These data obtained with assistanceof W. O. Reeder. 19581 BaRTHOLO•!I•Wand DawsoN,California and Gambel's Quail 153 until the heat storedby the bird duringexposure to the high ambient temperatureshad been dissipated. Panting was not observedin the CaliforniaQuail until bodytemperature exceeded 43.5 ø (110.3ø F.). In the singleexperiment inwhich a Gambel'sQuail was exposed to rapidly increasingambient temperatures,body temperature did not exceed 43.5ø C. and panting was not observed. 45 BodyTemp•. --.+---•. 40 o $0 25 20 - , I , I • I , I , I I , I 20 40 •0 80 I00 120 140 MINUTES FmL*R•.4. Effects of increasingambient temperatureson body (pectoral muscle) temperatureof an adult male Oambel'sQuail. Animal maintainedin dark through- out experiment. A diurnalcycle of bodytemperature was still apparent in theOambel's Quail maintainedin an environmentat 39ø C. (102.2ø F.) but was reducedin amplitudefrom that observedat lowerambient temperatures. Nighttime temperatureswere about 1ø C. (1.8ø F.) abovethe level maintained in coolerenvironments, whereas daytime body temperatures werescarcely elevated. No CaliforniaQuail werestudied during long- term exposuresto 39ø C. DISCUSSION Perhapsthe most striking feature of temperatureregulation in Californiaand Gambel'sQuail is that it resultsnot in a singlelevel of body temperature,but in the restrictionof body temperatureto a rangeof severaldegrees centigrade. Body temperaturein thesequail is influencedby their activity; the contrastbetween nighttime and daytimelevels of activityappears to underlietheir pronounceddiurnal 154 BARTaO•,OM•WandDAWSON, California and Gamb½t's Quail [[Vol. Auk 75 temperaturecycles. This conditionis similar to that long known in birds of other groups (Simpsonand Galbraith, 1905; Baldwin and Kendeigh,1932). In view of this, citationof a singlevalue as representa- tive of the body temperatureof a specieshas obviouslimitations. Body temperature in these quail is readily increasedby as much as 4ø C. (7.2ø F.) in ambient temperaturesin excessof 40ø C. (104ø F.). However,in a sustainedenvironmental temperature of 39ø C. (102.2ø F.) the daytime level of body temperature in the Gambel's Quail was not elevated above the level normally maintained in the absenceof heat stress. The occurrenceof hyperthermia(higher than normal body tempera- ture) at high ambient temperaturesindicates that these quail have the sameresponse to heat as birds of other orders. We interpret this to mean that the major task of birds in hot environments is not to maintain body temperatureconstant but to prevent it from risingabove someupper critical limit, whichis usuallyat least 4ø C. abovethe normal level. This toleranceof elevatedbody temperature allows the establish- ment of a favorable conditionfor heat transfer from body to environment evenwhen environmental temperature equals the level of body tempera- ture characteristicallymaintained by birds in cool environments. Thus toleranceof elevated body temperatureplus behavioralpatterns which minimize metabolicheat productionor heat gain from the environment must comprisethe basicavian adaptationsto hot environments. The fact that birdsstore heat in hot environmentsand consequently undergo a rise in body temperature results mainly from the inability of their panting to produce adequate evaporative cooling (Kendeigh, 1944; Wallgren, 1954; Dawson, 1954). Panting in these quail doesnot commenceuntil body temperature has exceeded43.5 ø C. (110.3ø F.). This is somewhathigher than the level observedin