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