ISSN:
0032-8332
Keywords:
Behavior
;
Thermoregulation
;
Habitat selection
;
Biometeorology
;
Microclimate
;
Papio
;
Amboseli National Park
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract This paper examines the effect of thermal environment on movement patterns of free-ranging yellow baboons (Papio cynocephalus). For Amboseli baboons, one source of potential thermal stress is intense midday heat, and a plausible thermoregulatory response is for animals to simply move into the shade. I therefore examined the hypothesis that baboons would choose quadrats with higher shade availability (as measured by vegetation cover) in response to increasing midday heat loads (as measured by air temperature and solar radiation). Surprisingly, this was not the case—neither ambient air temperature, ambient solar radiation, nor quadrat plant species composition had a significant effect on shade availability of quadrat selected. Instead, thermal conditions affected a different aspect of baboon movements; namely, spatial displacement rates. At high air temperatures, baboons as a group traversed woodland habitats more slowly, and bare pans more quickly, than at lower air temperatures. I surmised that this relationship might reflect thermal effects on movement patterns at a smaller scale: if individuals exposed to high heat loads spent more time resting in shade under clumps of vegetation, they would thereby traverse densely-vegetated (hence shaded) quadrats more slowly. To address this question directly, I obtained focal sample data on activity and microhabitat budgets of individual baboons in relation to environmental temperature. The frequency of most combinations of activity state (e.g., grooming, social behavior) and microenvironment state (e.g., elevation, proximity to vegetation) did not vary monotonically with air temperature. However, baboons in shaded locations (but not those in unshaded locations) spent more time resting and less time moving at high air temperatures than low. In other words, baboon activity budgets depended on both microclimate and microhabitat—animals reduced their activity, particularly movement, when they encountered shade under hot conditions. This pattern of microhabitat choice in turn led to temperature-dependent changes in travel rate at the habitat level. These observational studies of movement patterns suggest that Amboseli baboons employ opportunistic thermoregulation—they do not seek out densely-shaded habitats or individual patches of shade at high air temperatures. Instead, they respond to environmental heat loads by resting, and thereby slowing down, when they happen to encounter plant shade. Aspects of baboon ecology that favor such an opportunistic mode of thermoregulation include large body size and non-thermal constraints on movement patterns.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02380852
Permalink
