Specific thermoreceptors or putative multimodal thermoreceptors are not known in Crustacea. However, behavioural studies on thermal avoidance and preference and on the effects of temperature on motor activity indicate that the thermosensitivity of crustaceans may be in the range 0.2–2 °C. Work on planktonic crustaceans suggests that they respond particularly to changes in temperature by klinokinesis and orthokinesis. The thermal behaviour of crustaceans is modified by thermal acclimation among other factors. The acclimation of the critical maximum temperature is an example of resistance acclimation, while the acclimation of preference behaviour may be classified as capacity acclimation of some other function. In crustaceans, the use of the concepts stenothermy and eurythermy at the species level is questionable, and it is not possible to divide crustacean species into thermal guilds as suggested for fishes. Thermal preference behaviour contributes to fitness in different ways in different species, often by maximising the aerobic metabolic scope for activity. In crustaceans the peripheral nervous system seems to have retained the capacity for thermosensitivity and thermal acclimation independently of the central nervous system control of behaviour.

The duration of activity bouts by pine martens Martes martes was studied in the pristine deciduous forests in Białowieża National Park (north-eastern Poland). From 1991 to 1996, 14 martens were monitored by radio-tracking throughout 5823 h. On average, male martens were active for 9 h/day and females for 8.5 h/day. The duration of the martens' diel activity varied greatly among bimonthly periods (from 2.8 h/day in February–March to 12 h/day in June–July). Martens decreased their activity from 13 h/day on warm days to 2.5 h/day on cooler days. In the winter months, when martens curtailed their activity, they often hunted larger prey or scavenged ungulate carcasses. On average, 69% of the martens' active time was during the night. The number of activity bouts per day varied from one to six (mean 2.6) and increased with growing ambient temperature. Activity bouts of males were significantly longer (4 h, on average) than those of females (3 h) and were not related to ambient temperature. The duration of short inactive bouts increased in the cold season and inactivity lasted longer in females than in males.

We characterized the day roost sites of four pairs and one solitary tawny frogmouth Podargus strigoides in a woodland in south-eastern Australia. The birds were equipped with radio transmitters which enabled us to locate them daily from autumn 1997 to late summer 1998. Tree species, tree size, roost height and orientation of the roosting bird were recorded. Over the study period tawny frogmouths frequented a large number of day roosts (up to 71 per pair). Birds rarely used the same roost over extended time periods and most roosts were used for less than 3 days. Mature trees with a girth of more than 0.5 m were preferred as day roosts. Tawny frogmouths exhibited a significant preference for the coarse and dark-barked stringybark trees, but other tree species such as the smooth-barked, light-coloured gums were also frequented. However, when roosting in gum trees, dead branches were preferred, presumably as these have a coarser appearance than living branches and therefore provided better camouflaging. Especially during winter, the birds showed a significant selection of branches on the northern side of roost trees presumably to maximize sun exposure. During summer, two pairs maintained a significant northerly preference, whereas the others used roosts with random orientations. Small-scale seasonal movements in the area used for day roosting were also observed, with two pairs selecting a distinct area with a south-westerly aspect during summer which appeared to have less sun exposure. Our study suggests that tawny frogmouths select roosts to (1) minimize visibility from day predators and (2) to facilitate passive thermoregulation by sun-basking.