Does thermoregulatory behaviour of green toads (Bufo viridis) constrain geographical range in the west? A comparison with the performance of syntopic natterjacks (Bufo calamita)

(1)

Behavioural regulation of body temperature (t_b) was monitored in 23 free-ranging Bufo calamita (Bc) and 17 syntopic Bufo viridis (Bv) at Urmitz (Rhineland-Palatinate, Germany) using temperature-sensitive transmitters implanted to the abdominal cavity.

(2)

In field t_b varied between +0.5 and 37.4 °C in Bc and between +0.6 and 33.7 °C in Bv. Maximum t_b of a Bc measured during an experimental trial was 38.8 °C.

(3)

Natterjack toads avoided environmental temperature extremes by burrowing actively into moist sandy soil (2-90 cm deep), whereas green toads hid exclusively in mammal burrows or pre-existing subterranean cavities. Shelter choice did not vary between summer and winter.

(4)

Average t_b of Bc exceeded significantly that of Bv during summer (26.7 °C vs. 24.7 °C), while the reverse was true during winter (4.2 °C vs. 7.2 °C). Following hibernation the body condition of Bv was significantly lower than that of Bc.

(5)

We conclude that green toads fail to colonise regions west of the Rhine valley because of a combination of winter temperatures impeding foraging trips for prolonged periods, the choice of warm hibernacula increasing metabolic costs and/or predation risk and reduced fecundity.

     

Seasonal variations in metabolism and thermoregulation in the striped hamster (Cricetulus barabensis)

(1)

Metabolic rate (MR), thermal neutral zone (TNZ), body temperature (T_b), and thermal conductance were measured in striped hamsters (Cricetulus barabensis) that were live-trapped in winter and summer.     

Thermal ecology of natterjack toads (Bufo calamita) in a semiarid landscape

(1).

To monitor the seasonal variation of body temperature (t_b) in free-ranging adult Bufo calamita, 15 toads were radio-tracked at Mas de Melons (Catalonia, Spain) using temperature-sensitive transmitters implanted to the abdominal cavity.     

Effects of summer- and winter-like acclimation on the thermoregulatory behavior of fed and fasted desert hamsters, Phodopus roborovskii

1.

Thermoregulatory behavior of fed and fasted desert hamsters (Phodopus roborovskii) acclimated to summer- [16 light (L):8 dark (D), ambient temperature (T_a)=26.5 °C] and winter-like (8L:16D, T_a=10 °C) conditions was studied. Body temperature (T_b), selected temperature and activity were measured in hamsters placed in a thermal gradient system for 48 h.     

Seasonal variation on metabolism and thermoregulation in Chinese bulbul

1

Seasonal changes in a bird's physiology and behavior are considered to be a part of an adaptive strategy for survival and reproductive success. To understand modes of metabolic adaptations, the metabolic rate (Vo₂), body temperature (T_b), and thermal conductance (C) of the Chinese bulbul (Pycnonotus sinensis) in the Zhejiang Province of China were determined in the summer and the winter at a temperature range from 5 to 35 °C, respectively.     

Lizards in the slow lane: Thermal biology of chameleons

1.

Field body temperatures (T_b's) of Chamaeleo chamaeleon in southwestern Spain averaged 28 °C in October and 30 °C in June. Slopes of regressions of T_b on T_a (ambient temperature at perch height) indicated that individuals were able to maintain a preferred body temperature of about 30 °C in June but not in October.