a radio-biotelemetry system for monitoring body temperature and ...

A RADIO-BIOTELEMETRY BODY

SYSTEM

TEMPERATURE IN

THE

AND ZEBRA

VAUGHAN

FOR

ACTIVITY

MONITORING LEVELS

FINCH

A. LANGMAN

IT is important that physiologicaldata be obtained from an animal without disruptingits usual activity patterns. King and Farner (1961) suggestthat avian body temperature should ideally be measuredin darkness,at the time of postabsorption, and taken in the cloaca,proventriculus,or pectoral muscles.Measurementsof this sort are difficult or perhapsimpossibleto obtain accuratelywithout restrictingand/or disturbingthe test animal. Boyd and Sladen(1971) discussthe advantages of radio-biotelemetry overothermethodsfor the measurement of bodytemperature in long-term studies. Long-term investigationof body temperatureby conventional methods introduces the possibility of error from handling. RadiobiGtelemetryhas the advantagesof continuousrecording,ability to monitorfrom a distance,and reduceddisturbance. Severalpapersin the literature pertain to radio-biotelemetry and its use with birds. Tracking studiesusingpigeons(Michener and Walcott, 1966) and owls (Nicholls and Warner, 1968) provide ecologicalinformation on movementsand habitat preferences.Single channelphysio-

telemetryhasgivengoodresultsin the areasof ECG (Owenet al., 1969) and respiration(Lord et al., 1962) withoutnotablyinterruptingnormal behavioralsequences. Multichannelphysiotelemetry hasprovedsuccessful (Roy and Hart, 1963, 1966), althoughthe sizeof the telemetrypackage restrictsits useto birdsaslargeasor largerthana pigeon.To my knowledgeno telemetrywork hasbeendoneon birds as smallas the Zebra Finch

(Poephilaguttata). The techniqueof usingtelemetryto monitorlocational or physiological informationin birdsis still in the developmental stagesalthoughmany problemshave been overcome. MATERIALS

AND METI-IODS

The Zebra Finchesusedin this experimentwere a]] approximately8 months old, in good condition,and successful in raisingbroods of young. All of the Zebra Finches

had been paired and placed in separatecagesbefore • completingadult molt. Both contro]sand the test birds remainedin their breeding cagesduring the experiment. As the surfacetemperaturein leatheredareas of small birds varies only slightly from coretemperaturein the absenceof thermalstress(Bartholomewand Dawson, 1954a, 1954b; Irving and Krog, 1955; Steen and Enger, 1957; King and Farner, 1961) the transmitter was placed on the dorsal feather tract, where it is easily accessible and causesa minimum loss of balance during flight. Birds to be studied 375

The Auk 90: 375-383. April 1973

375

VAUCHAN A. LANCMAN

[Auk, Vol. 90

Figure 1. A modification of the transmitter designedby Spencer (1968) next to a metric scale. This device employsa Hartley blocking oscillatorwith a current drain

of 0.2 ma from a 1.25 volt (RM 312) powersupply. This combinationof characteristicsprovidesa temperature-sensitive transmitterweighing1.7 g with a rangeof 3 m and a life of up to 12 days. were first placed under light Metaphanea anestheticand the feathers of the dorsal

feathertract immediatelyposteriorto the crop were pluckeddown to approximately 0.S cm past the scapulararea. A 24-hour recoveryperiod was allowed for the skin of the dorsalfeathertract to recoverfrom the pluckingeffects. The birds were then again placed under light MetaphaneRanestheticand the transmitter attached by gluingit with Eastman910Rsurgicalcontactadhesive. Feather removal stimulateseach dermal papilla to regeneratean epidermalcollar and to begingrowinga new feather. The new feather growth dislodgedthe transmitter in 3 to 7 days. Test runs did not exceed60 hours, to avoid error due to transmitter displacement.

Figure I showsthe transmitterbefore potting in beeswax.The circuit is assembled in the transmittingcoil and fixed by G.C. Q-Dope. The transmitteris then activated for a week to age the components and avoid frequencyand calibrationalterations during the test run.

Spencer's (1968) transmitterwas designed to providea pulsationfrequencyof 2 to 20 pulsesper secondover a temperaturerangeof 10øC to $0øC. In our studies the low pulserate provedinadequateto detectchangesof the order of 0.1øCin the

bird's surfacetemperature.Thereforethe numberof pulsescorresponding to temperaturewere increasedby changingthe capacitorof the RC pulsingcircuit (Ca, Figure 2) to 0.001 1VIFDinitiatingpulserangesof 500 to S,000pulsesper second

April 1973]

Monitoring Zebra Finch Temperatures

C2

377

-- C3 +

--

1.25V

D26-E6 R 2

.1( Figure 2. The circuit diagram for the temperature transmitter designed by

Spencer (1968), The componentsused in this application are R• = 300K YSI thermistor bead at 25ø; R2 = 1 K 1/8 watt Allen-Bradley; C• = 0.001 MFD electrolytic Capacitors Inc. Biddleford, Maine; C2 :

Guyton Electronics; C, :

0.001 MFD

chip capacitors

0.001 MFD chip capacitorsGuyton Electronics; Male,

L• : 25 turns, L2 : 8 turns (90 Khz); Female, L• = 30 turns, L2 : (120 Khz); D26-E6 • General Electric micro-tab transistor; Battery :

13 turns RM 312.

in the range of 30ø to 40øC. This made the pulse rate approximately 500 pulsesper

1.0øC. Body temperatureand activity patterns were monitored from the male and female pair simultaneously on two separate frequendes (90 Khz and 120 Khz) obtained by changing the number of windings on the oscillating coil (Figure 2). The current drain was 0.2 ma giving a transmitting life of 12 days using a RM 312 battery. Accuracy is maintained by using Mallory R series mercury cells to reduce calibration drift due to ageing. The transmitters were calibrated in an oil bath in which the temperature was increasedby 0.5øC incrementsfrom 30ø to 40øC. A calibration curve (temperature versusfrequency) was plotted by regressionanalysis of the 2øC segments. The three primary methods used for data recovery were direct frequency conversion (Figure 3B), qualitative temperaturechange (Figure 3A), and qualitative temperature change combinedwith activity level measurements.The secondof these three methods was discontinued when it became possible to recover the same data in less time using a Grass oscillograph. It is included here for researcherswho may not have accessto an oscillograph.

Direct frequency conversionas illustrated (Figure 3B) was accomplishedby samplingfrom the frequencycounterat intervals and convertingto degreescentigrade. The conversionwas accomplishedby reading the equivalent temperaturesfrom a calibration graph completedfor each transmitter by regressionalanalysis.

378

VAUOItAN A. LANOMABr

[Auk, Vol. 90

FARADAY

CAGE

Figure 3. Data collection and data reduction systems. The signal is received by commercial Panasonicn AM-FM transistor radios placed inside the Faraday cage. The receivedsignal is processedby Schmitt triggers (R.C.A. CA-3001) acting as low band pass fitters and recorded on magnetic tape (Sony TC-9540 1.). The recorded data are analyzed through channelsA and B. In channel A the signal pulsesare fixed as to duration and amplitude by a monostablemultivibrator (F.G.S. 914) and integrated onto an oscilloscope(3) for photographing. In channel B the signal pulses are passedthrough a monostablemultivibrator for pulse shaping to a frequency counter (Hewlitt Packard 522B) where the frequency is sampled for quantitative surface temperature

measurements.

Patterns of temperature change were obtained by photographing the integrated signal from an oscilloscope(Figure 3A). Although this method gives usable results, much time must be spent in photographing, developing, and sampling. If an acceptable oscillographis available, it will give superior results and save time. Activity levels and qualitative temperature change were recorded on a Grass oscillograph.It was possibleto recover activity data becauseof the inability of the receiversto follow rapid changesin the positionof the transmittingcoil. Therefore when the birds flew or moved quickly on the perch a temporary signal null was recorded. The recordedsignalwas integrated and played into a Grassoscillograph and each of the signal nulls correspondingto movementswere recorded as high amplitude deflections(Figure 4). The deflectionswere counted and graphed to give the activity levels of the test birds (Figures 5 and 6).

April 1973]

Monitoring Zebra Finch Temperatures

•,a[ b[

379

MALE

• AM ....................... 14_:30AM

6:00 AM

Figure 4. Oscillographicrecordingof male and female Zebra Finches illustrating the method for determining activity levels. Incipient early morning behavior has been selectedto show the three types of activity discernibleby this method. (a) and (b) in the male trace, and (c) in the female trace, show high intensity movements typical of flying. (d) is a trace commonly found with movements on the perch such as preening or bill-wiping. (e) shows the complete absenceof activity that occurs in the nestbox during the nighttime rest period.

RESULTS

Surface body temperatureand activity data were recordedfrom six mated pairs of Zebra Finches for a total of 209 hours (Table 1). A statisticalcomparisonof activity and thermoregulatorydata betweenthe TABLE

1

ACTIVITY AND TEMPERATURE VARIATION •'OR MALES AND FEMALES DURING 209 HOURS O•' RECORDING Tem-

pera-

Activity periods Test run 1. 24 hours

2. 24 hours 3. 45 hours

Sex Male

Maximum

Minimum

variation

04:00-07:00

07:00-15:00

1.9øC

Female 03:00-07:00 07:00-15:00

1.7øC

Male

24:00-04:00

2.0øC

Female 14:00-19:00

15:00-18:00

22:00-04:00

1.9øC

Male

21:00-03:00

09:00-12:00

Female 12:00-15:00 21:00-03:00 4. 36 hours 5. 24 hours 6. 56 hours

ture

Male

15:00-18:00

21:00-03:00

2.4øC

2.3øC 1.5øC

Female 15:00-18:00 21:00-03:00

1.7øC

Male

2.1øC

15:00-18:00

18:00-03:00

Female 15:00-18:00 18:00-03:00

1.7øC

Male

2.2øC

14:00-18:00

24:00-04:00

Female 14:00-18:00 24:00-04:00

2.OøC

Room

Photoperiod 11 hours of

tem-

perature

21ø-22øC

light 11 hours of

20ø-22øC

light 12 hours of

20ø-22øC

light 12 hours of

21ø-22øC

light 12 hours of

22øC

light 12 hours of

light

20ø-22øC

380

V^•J•^N A. LAIgGlVIAN

[Auk, Vol. 90

4o01

so•-

•o•_ to

•0

30 • ZO •

6•

lO

2

6•

lO

2

6• lO 2 11•œ (HOUI1S)

6•

lO

2

6•

lO

Figure 5. Graph showing the relationshipbetween body temperature and activity levels for the male (top) and female (bottom) in test run 6. Body temperature is representedas follows: A horizontal bar for the mean, a vertical bar as the range, a solid black rectangle for the standard error, and an open rectangle for the standard deviation. The activity levels are represented as solid circles, the sum of the nulls recordedon the oscillographfor each 2~hour period.

males and females showed no significant difference between the two groups. The average daily temperature variation for the test group (males and females) was 1.95øC. The mean skin temperature for all of the males and females tested was 37.3ø and 37.1øC respectively. Maximum activity occurred during the daylight hours between sunrise and sunset with characteristicactivity peaks between 15:00 and 18:00

(Figure 5). Figure 6 representsroom temperatureduring the 56-hour test period. The variation is 2øC over a range of 20ø to 22øC. Skin temperaturein birds differs from core temperatureduring hypothermia (Steen and Enger, 1957) and hyperthermia(Bartholomewand Dawson, 1954a), but the effectsof relativelyslightchangesin ambienttemperatureduring the absenceof thermalstressneedfurther study. Figure 5 represents56 hours of continuousrecordingsof male and

April 1973]

Monitoring Zebra Finch Temperatures

381

22ø

6pu'tO 2 •t10 2 6pu•O 2 6•tl0 2 6p• tl0 Figure 6. Room temperatures during the 56-hour test period.

female body temperatureand activity levels. The first 12 hoursof both recordings showactivity and skin temperaturelevelsthat are not characteristic of the majority of the nocturnal patterns recorded for the animalstested. These atypical recordingsare probably the result of a disturbanceextremeenoughto make the birds fly in the dark. After the first 12 hours both graphs show the activity and skin temperature patternsmore typical of all the animalstested. The daily cycle begins with low nocturnalactivity when the birds are asleepor unable to fly becauseof darkness. This period is followed by a marked increasein activity beginningat sunriseand reachinga peak between 15:00 and 18:00.

The periodsbetween 15:00 and 18:00 that show the highestlevels of skin temperatureand activity correspondto the feedingperiod characteristicof Zebra Finches,both in the wild (Immelmann, 1965) and in the laboratory.

Similar body temperaturepatterns occur in the Ruby-throatedHum-

mingbird (Archilochuscolubris) (Pearson,1953) and Gambel'sQuail (Lophortyx gambelii) (Woodard and Mather, 1964). The metabolic rate of both birds reachesits maximum just before 18:00. No explana-

382

VAUGHANA. LANGMAN

[Auk, Vol. 90

tion is offeredfor this metabolicclimaxin eitherof the above,but in the caseof Zebra Finches,which exhibit active searchand feedingduring this period,I suggestthat the combinedeffect of increasedactivity and the chemicalthermogenesis of digestionare probablyresponsible for the bodytemperature peaksexhibitedin Figure5. DISCUSSION

The 24-hourthermoregulatory cyclesin Zebra Finchesare comparable to the data presentedfor variousother birds by Bartholomewand Cade (1957), Bartholomewand Dawson (1958), and Dawson (1958) and many others. Althoughlittle has been written concerningthe thermoregulatorycyclesin Old World finches (Ploceidae),Dawson (1954,

1958) hasdescribed thesecyclesin species of Fringillidae. Daily cyclesof thermoregulationand activity appearto be mechanisms for energy conservation.The extremelysmall body size of Zebra Finches and the consequentlarge surface-to-volumeratio necessitateenergy conservation.The methods of solving energy problemsin nature are quite varied although 24-hour rhythmictry as it applies to activity and body temperatureis by far the most common. ACKNOWLEDGMENTS

The guidanceand monetary support of M.D. Arvey made this investigation possible.H. Runion's challengeand quiet faith provided much appreciateddirection and energy for this research.Specialthanks must also go to M. Okuda, W. Meyers and L. Bonkowski,who all assistedin various stagesof development. SU/V[MARY

A telemetry systemhas been designedto monitor surfacebody temperature and activity levelsin the Zebra Finch (Poephila guttata). The use of radio-biotelemetryallows for continuousrecordingsof body temperature, perching, feeding, and preening activity in mated pairs of Zebra Finches,without interrupting usual daily behavior patterns. Under light Metaphane• anesthetic,a temperature transmitter was glued to the dorsal intrascapular surface of the birds. The transmitters weighed approximately 1.7 g and were sensitive to 0.1øC temperature changeover a 30øC to 40øC range. The telemetereddata were radiodetected, demodulated,and stored on magnetic tapes for later analysis. LITERATURE CITED

BARTHOLOMEW, G. A., ANDT. J. CADE. 1957. The body temperaturesin nestling Western Gulls. Condor, 54: 58-60. BARTHOLOMEW, a. A., AND W. R. DAWSON. 1954a. Body temperature and water requirementsof Mourning Dove, Zenaldura macroura marglnella. Ecology, 35: 181-187.

April 1973]

Monitoring Zebra Finch Temperatures

383

B^RTaO•.O•rEW,G. A., ^m) W. R. D^wso•. 1954b. Temperature regulation in young pelicans,herons,and gulls. Ecology,35: 466-472. B^RTaO•.O•VrEW, G. A., ^m) W. R. D^wso•. 1958. Body temperaturesin California and Gambel'sQuail. Auk, 75: 150-156. BoYI), J. C., ^•) W. J. L. S•.^i)•. 1971. Telemetry studies of the internal body temperatures of Ad•lie and Emperor Penguins at Cape Crozier, Ross Island, Antarctica. Auk, 88: 366-380. D^wso•, W. R. 1954. Temperature regulation and water requirementsof Brown and Albert Towhees, Pipilo fuscus, and Pipilo aberti. Univ. California Publ. Zool., 59: 81-124. D^wso•, W. R. 1958. Relation of oxygen consumptionand evaporative water loss to temperature in the Cardinal. Physiol. Zool., 31: 37-48. I•vr•vrm.•vr^N•,K. 1965. Australian finches. London, Angus and Robertson, Ltd. I•v•c, L., ^m) J. K•oc. 1955. Skin temperatures in the Arctic as a regulator of heat. J. Appl. Physiol., 7: 354-363. K•N½, J. R., ^Ni) D. S. F^•. 1961. Energy metabolism, thermoregulationand body temperature. Pp. 215-279 in Biology and comparative physiology of birds, vol. 2 (A. J. Marshall, Ed.). New York, Academic Press. Lorn), R. D., F. C. B•.•.•os•, ^Ni) W. W. Coc•r•^•. 1962. Radiotelemetry of the

respirationof a flying duck. Science,137: 39-40. MmaE•, M. C., ^m) C. W^Lco•. 1966. Navigation of single homing pigeons. Science,154: 410-413. NIcaOL•.s, T. H., ^•) D. W. W^•. 1968. A harnessfor attaching radio transmitters to large owls. Bird-Banding, 39: 209-214. Ow•, R. B., W. W. Coc•r•^•, ^m) F. A. MOOR•. 1969. An inexpensive, easily attached radio transmitter for recording heart rates of birds. Med. Biol. Eng., 7: 565-567.

P•^•soN, O. P. 1953. Metabolism of hummingbirds. Sci. Amer., 188: 69-72. Roy, O. Z., ^m) J. S. H^•r. 1963. Transmitter for telemetry of biological data from birds in flight. IEEE Trans. Bio-med. Elec.: 114-115. RoY, O. Z., ^m) J. S. H^•. 1966. A multi-channel transmitter for the physiological study of birds in flight. Med. Biol. Eng., 4: 457-466. SP•c•, H. 1968. Thermally stable telemeter for thermoregulation studies. Science, 161:

574-575.

STE•, J., ^m) P.S. E•½•. 1957. Muscular heat production in pigeons during exposureto cold. Amer. J. Physiol., 191: 157-158. WooI)^m),A. E., ^m) F. B. M^ra•. 1964. Effect of photoperiod on cyclic patterns of body temperature in the quail. Nature, 203: 422-423.

Mammal Research Institute, University of Pretoria, South Africa. Present address: Department of Zoology, University of Natal, Pietermaritzburg, South Africa. Accepted10 May 1972.