Abstract:
Climate change has the potential to trigger social change. As a first
step towards understanding mechanisms determining the vulnerability
of animal societies to rising temperatures, we investigated interactions
between social rank and thermoregulation in three arid-zone bird
species: fawn-coloured lark (Mirafra africanoides, territorial); African
red-eyed bulbul (Pycnonotus nigricans, loosely social) and sociable
weaver (Philetairus socius, complex cooperative societies). We
assessed relationships between body temperature (Tb), air
temperature (Ta) and social rank in captive groups in the Kalahari
Desert. Socially dominant weavers and bulbuls had lower mean Tb
than subordinate conspecifics, and dominant individuals of all species
maintained more stable Tb as Ta increased. Dominant bulbuls and
larks tended to monopolise available shade, but dominant weavers did
not. Nevertheless, dominantweavers thermoregulated more precisely,
despite expending no more behavioural effort on thermoregulation
than subordinates. Increasingly unequal risks associated with heat
stress may have implications for the stability of animal societies in
warmer climates.
