What's hot and what's not: defining torpor in free-ranging birds and mammals

2001 ◽  
Vol 79 (10) ◽  
pp. 1885-1890 ◽  
Author(s):  
Robert MR Barclay ◽  
Cori L Lausen ◽  
Lydia Hollis
Keyword(s):  
Body Temperature ◽  
The Body ◽  
Temperature Sensitive ◽  
The Past ◽  
Data Loggers ◽  
Temperature Thresholds ◽  
Radio Transmitters ◽  
Species Specific ◽  
Free Ranging ◽  
Lowered Body

With the development of small implantable data loggers and externally attached temperature-sensitive radio transmitters, increasing attention is being paid to determining the thermoregulatory strategies of free-ranging birds and mammals. One of the constraints of such studies is that without a direct measure of metabolic rate, it is difficult to determine the significance of lowered body temperatures. We surveyed the literature and found that many different definitions have been used to discriminate torpor from normothermy. Many studies use arbitrary temperature thresholds without regard for the normothermic body temperature of the individuals or species involved. This variation makes comparison among studies difficult and means that ecologically and energetically significant small reductions in body temperature may be overlooked. We suggest that normothermic body temperature for each individual animal should be determined and that torpor be defined as occurring when the body temperature drops below that level. When individuals' active temperatures are not available, a species-specific value should be used. Of greater value, however, are the depth and duration of torpor bouts. We suggest several advantages of this definition over those used in the past.

Phenology and ecology of hibernation in spotted turtles (Clemmys guttata) near the northern limit of their range

1999 ◽  
Vol 77 (9) ◽  
pp. 1348-1357 ◽  
Author(s):  
Jacqueline D Litzgus ◽  
Jon P Costanzo ◽  
Ronald J Brooks ◽  
Richard E Lee, Jr.
Keyword(s):  
Body Temperature ◽  
Temperature Data ◽  
Temperature Sensitive ◽  
Data Logger ◽  
Ambient Temperatures ◽  
Air Temperatures ◽  
Data Loggers ◽  
Rock Cavern ◽  
Clemmys Guttata ◽  
Radio Transmitters

Using mark-recapture techniques, temperature-sensitive radio transmitters, and miniature temperature data loggers we investigated the hibernation ecology of northern temperate zone spotted turtles (Clemmys guttata) in Georgian Bay, Ontario, over 4 winters (1993-1997). We observed 18 hibernacula that were occupied by 34 turtles; 11 hibernacula were apparently occupied by single turtles, and 7 were used communally by up to 9 individuals. Hibernacula were located in swamps and were of 2 types: sphagnum moss hummock (n = 15) and rock cavern (n = 3). Almost half of the individuals (16 of 34) used the same hibernaculum in at least 2 winters. Turtles entered hibernacula between mid-September and October, when their body temperature was between 12 and 16°C, and exited them in mid to late April, when ambient temperatures ranged between 1 and 5°C. A waterproof temperature data logger attached to a turtle indicated that this turtle was protected from freezing in a thermally stable hibernaculum (body temperature range 0.3-3.9°C) despite highly variable (a 37°C change over 5 days) and low air temperatures (minimum -35°C). Loss of body mass (2%) during hibernation was not significant. We observed no mortality within hibernacula over the 4 winters; however, 3 turtles were destroyed by predators near the hibernacula. These data provide insight into the role of climate in limiting the northern distribution of this species.

Body temperature fluctuations in free-ranging eastern foxsnakes (Elaphe gloydi) during cold-water swimming

2006 ◽  
Vol 84 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Carrie A MacKinnon ◽  
Anna Lawson ◽  
E D Stevens ◽  
Ronald J Brooks
Keyword(s):  
Body Temperature ◽  
Water Temperature ◽  
Swimming Speed ◽  
Cold Water ◽  
Temperature Fluctuations ◽  
Temperature Sensitive ◽  
Clear Trend ◽  
Thermal Biology ◽  
Rapid Temperature ◽  
Free Ranging

We examined the thermal biology of free-ranging terrestrial eastern foxsnakes (Elaphe gloydi Conant, 1940) that were voluntarily swimming in cold water during spring, in Georgian Bay, Ontario, Canada. Using temperature-sensitive radiotelemetry, we recorded body temperatures of foxsnakes during 12 cold-water swims, and subsequent warming on shore. During these swims, water temperatures were from 11 to 22 °C and distances of 85–1330 m were travelled. Snakes that were in cold water long enough equilibrated with water temperature and did not maintain a body temperature above ambient. The largest observed drop in body temperature was 22.6 °C (over 11 min) and the largest increase was 23 °C (over 66 min). Such large, rapid temperature fluctuations have not previously been reported in detail from snakes in the field. Twice as many telemetry observations as expected occurred between 1200 and 1400, suggesting that snakes chose to swim midday. Additionally, our results suggest that foxsnakes bask to raise their body temperature prior to swimming in cold water. We compared swimming speed and the coefficient of temperature change among foxsnakes and other snake species. Swimming speed was positively correlated with water temperature, similar to other findings. We found no clear trend between mass and the coefficients of cooling and warming; however, snakes cooled in water 2.8–8.6 times faster than they warmed in air.

scholarly journals Validation of Temperature-Sensitive Radio Transmitters for Measurement of Body Temperature in Small Animals

Ardea ◽  
2009 ◽  
Vol 97 (1) ◽  
pp. 120-124 ◽  
Author(s):  
Joseph B. Williams ◽  
B.I. Tieleman ◽  
Mohammed Shobrak
Keyword(s):  
Body Temperature ◽  
Temperature Sensitive ◽  
Small Animals ◽  
Radio Transmitters

Diurnal refuge-site selection by Brown Treesnakes (Boiga irregularis) on Guam

2008 ◽  
Vol 29 (2) ◽  
pp. 284-287 ◽  
Author(s):  
Brad Coupe ◽  
Nancy Anderson ◽  
Thomas Hetherington ◽  
Gad Perry ◽  
Joseph Williams
Keyword(s):  
Site Selection ◽  
Thermal Characteristics ◽  
Boiga Irregularis ◽  
Brown Treesnake ◽  
Data Loggers ◽  
Radio Transmitters ◽  
Natural Range ◽  
Brown Tree Snakes ◽  
Free Ranging ◽  
Arboreal Snakes

Abstract Diurnal refuge-site selection was studied in eleven free-ranging brown tree snakes (Boiga irregularis) in tropical forest on the island of Guam. These nocturnal and mostly arboreal snakes were tracked using implanted radio-transmitters. A vegetation survey of the study site was performed to determine if brown treesnakes non-randomly select certain plants for refuge-sites, and thermal profiles of representative refuge sites were obtained with Hobo data loggers. Brown treesnakes preferentially used Pandanus crowns for refuge-sites. Although Pandanus represents a small proportion (3.6%) of the forest, most snakes used Pandanus most of the time for refuge. The thermal characteristics of Pandanus were comparable to those of other refuge-sites. We speculate that features of Pandanus that provide basking opportunities and moist microhabitats may be important for brown treesnakes. As Pandanus is widely distributed throughout the natural range of the brown treesnake, this genus may represent an important refuge-site for this species.

A songbird adjusts its heart rate and body temperature in response to season and fluctuating daily conditions

2021 ◽  
Vol 376 (1830) ◽  
pp. 20200213 ◽  
Author(s):  
Nils Linek ◽  
Tamara Volkmer ◽  
J. Ryan Shipley ◽  
Cornelia W. Twining ◽  
Daniel Zúñiga ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Environmental Conditions ◽  
Field Studies ◽  
Weather Extremes ◽  
Ambient Temperatures ◽  
In The Wild ◽  
Radio Transmitters ◽  
Save Energy ◽  
Free Ranging

In a seasonal world, organisms are continuously adjusting physiological processes relative to local environmental conditions. Owing to their limited heat and fat storage capacities, small animals, such as songbirds, must rapidly modulate their metabolism in response to weather extremes and changing seasons to ensure survival. As a consequence of previous technical limitations, most of our existing knowledge about how animals respond to changing environmental conditions comes from laboratory studies or field studies over short temporal scales. Here, we expanded beyond previous studies by outfitting 71 free-ranging Eurasian blackbirds ( Turdus merula ) with novel heart rate and body temperature loggers coupled with radio transmitters, and followed individuals in the wild from autumn to spring. Across seasons, blackbirds thermoconformed at night, i.e. their body temperature decreased with decreasing ambient temperature, but not so during daytime. By contrast, during all seasons blackbirds increased their heart rate when ambient temperatures became colder. However, the temperature setpoint at which heart rate was increased differed between seasons and between day and night. In our study, blackbirds showed an overall seasonal reduction in mean heart rate of 108 beats min −1 (21%) as well as a 1.2°C decrease in nighttime body temperature. Episodes of hypometabolism during cold periods likely allow the birds to save energy and, thus, help offset the increased energetic costs during the winter when also confronted with lower resource availability. Our data highlight that, similar to larger non-hibernating mammals and birds, small passerine birds such as Eurasian blackbirds not only adjust their heart rate and body temperature on daily timescales, but also exhibit pronounced seasonal changes in both that are modulated by local environmental conditions such as temperature. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part I)’.

Evaluation of the accuracy of body temperature measurement using external radio transmitters

1996 ◽  
Vol 74 (9) ◽  
pp. 1778-1781 ◽  
Author(s):  
Doris Audet ◽  
Donald W. Thomas
Keyword(s):  
Body Temperature ◽  
Core Temperature ◽  
Field Conditions ◽  
Temperature Sensitive ◽  
External Temperature ◽  
Ambient Temperatures ◽  
Body Temperature Measurement ◽  
Radio Transmitters ◽  
The Difference ◽  
Skin Temperatures

The facultative depression of body temperature represents an important energy strategy for small homeotherms. However, measuring body temperature under field conditions by means other than externally attached temperature-sensitive radio transmitters is problematical. We show that skin temperatures measured by external radio transmitters can accurately reflect core temperature for the bat Carollia perspicillata. We compared body and skin temperatures at three ambient temperatures (Ta; 21, 26, and 31 °C). The difference between skin and body temperature (ΔT) was linearly correlated with Ta and can be predicted by ΔT = 4.396 − 0.118Ta. We argue that external temperature-sensitive radio transmitters can provide a reliable index of core temperature and so permit the study of torpor or facultative hypothermia under field conditions.

scholarly journals Facultative Rest-Phase Hypothermia in Free-Ranging White-Throated Sparrows

The Condor ◽  
2004 ◽  
Vol 106 (2) ◽  
pp. 386-390 ◽  
Author(s):  
Andrew S. Dolby ◽  
John G. Temple ◽  
Laura E. Williams ◽  
Emily K. Dilger ◽  
Katrina M. Stechler ◽  
...  
Keyword(s):  
Skin Temperature ◽  
Significant Negative Correlation ◽  
Published Data ◽  
Temperature Sensitive ◽  
Body Density ◽  
Zonotrichia Albicollis ◽  
Radio Transmitters ◽  
Para Determinar ◽  
Free Ranging ◽  
Skin Temperatures

Abstract Shallow facultative rest-phase hypothermia has been reported in a number of passerine families, but few published data exist about its use by free- ranging birds. We used temperature-sensitive radio- transmitters to determine whether White-throated Sparrows (Zonotrichia albicollis) employ nocturnal hypothermia during winter. We measured skin temperatures of 24 free-ranging sparrows between 13:00 and 14:00 and between 02:00 and 03:00 for each of three days and nights per subject. The average nightly skin- temperature reduction per individual was 3.4 ± 1.0°C (SD). Skin temperature reductions ranged from 0.2°C to 7.0°C among all individuals. There was a significant negative correlation between the magnitude of skin temperature decline and nighttime ambient temperature. Additionally, we found a negative trend between depth of hypothermia and a body density index. Fase de Reposo Hipotérmica Facultativa en Individuos de Zonotrichia albicollis que se Desplazan Libremente Resumen. La fase de reposo facultativa somera ha sido mencionada para un número de familias de paseriformes, pero existen pocos datos publicados sobre su uso por parte de aves que se desplazan libremente. Usamos radio transmisores sensibles a la temperatura para determinar si Zonotrichia albicollis emplea hipotermia nocturna durante el invierno. Medimos la temperatura de la piel de 24 individuos que se desplazan libremente entre las 13:00 y 14:00 y entre las 02:00 y 03:00 durante tres días y tres noches por individuo. La reducción nocturna promedio de la temperatura de la piel por individuo fue 3.4 ± 1.0°C (DE). Las reducciones de la temperatura de la piel variaron entre 0.2°C y 7.0°C considerando todos los individuos. Hubo una correlación negativa significativa entre la disminución de la magnitud de la temperatura de la piel y la temperatura ambiental nocturna. Adicionalmente, encontramos una tendencia negativa entre la profundidad de la hipotermia y el índice de densidad corporal.

Basking behaviour and torpor use in free-ranging Planigale gilesi

2009 ◽  
Vol 57 (6) ◽  
pp. 373 ◽  
Author(s):  
Lisa Warnecke ◽  
Fritz Geiser
Keyword(s):  
Body Temperature ◽  
Energy Requirements ◽  
Temperature Sensitive ◽  
Internal Temperature ◽  
Torpor Bout ◽  
Bout Duration ◽  
Energy Conserving ◽  
Unpredictable Environment ◽  
Free Ranging

We investigated the importance of energy-conserving strategies for free-ranging Planigale gilesi in arid Australia. We monitored torpor use and basking behaviour using internal temperature-sensitive transmitters. Torpor was used every day; the maximum torpor bout duration was 18.2 h and the minimum body temperature was 10.5°C. Basking behaviour was observed during rewarming from torpor as well as during normothermia. The use of torpor and basking is likely to reduce the energy requirements of P. gilesi, thus helping it to survive in a harsh and unpredictable environment.

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