BIO 3302 Chapter Notes - Chapter 2: Heterothermy
4 Nov 2017
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Exposed wild-caught birds to progressively increasing air temperature (ta) Heat tolerance limit (htl, max body temp reached) As body temp increased to reach the air temp. Rmr became 1. 7, 1. 9 and 2. 0 times the minimum resting values at htl. Max rates of evaporative heat dissipation equivalent to 237-424% of metabolic heat production. Gular fluttering to increase heat loss (50-123%) with only small increase in rmr. Cavity nesting/roosting owlet-nightjar had lower htl and less efficient evaporative cooling compare to desert nesting species. High efficiency of gular flutter for evaporative cooling, combined with mild hyperthermia. Physiological basis for defending tb well below ta in extreme heat and is comparable to the efficient cooling observed in arid-zone columbids in which cutaneous. Need to balance ewl to have evaporative heat loss but not dehydrate. A lot of things to do though which takes away from things like foraging and taking care of chicks. How will these capacities be challenged by future changing weather.
