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UCT RESEARCH REPORT 2012
Hot Birds
The “hot birds” project, initiated in 2009, seeks to predict how climate change will affect birds living in hot, arid
environments such as the Kalahari Desert. During 2012, a team of researchers led by Professor Phil Hockey and Professor
Andrew McKechnie (University of Pretoria) examined the role of body size in determining susceptibility to heat stress,
the links between physiology and behaviour, and how temperature affects the fitness of breeding birds. The team also
expanded the project to investigate the heat tolerance and evaporative cooling capacity of Kalahari birds.
Research Project
A White-browed Sparrow-weaver panting to
dissipate heat
Using data for 35 Kalahari species, PhD student
Ben Smit showed that activity levels and body mass
played a major role in heat dissipation and found data
providing exciting insights into how species cope with
very high temperatures, shedding new light on how
populations inhabiting climatically distinct regions may
vary in their biology. In related research, Postdoctoral
Research Fellow Rowan Martin used heat-transfer
models to predict how birds of different sizes use
thermal landscapes in the Kalahari.
And as part of the project’s Southern Hemisphere scope,
Grace Russell, a BSc Honours student at the University
of Western Australia, examined behaviour among bird
species in the Upper Gascoyne region of Western
Australia to establish whether the same relationships
between heat-dissipation behaviour, body mass and
ecological variables occur in Australian species.
Postdoctoral Research Fellow Susie Cunningham
completed her study of the links between temperature
and breeding success in Common Fiscals
(Lanius
collaris
) at Tswalu Kalahari Reserve. As temperatures
increase, breeding adults spend more time in shaded
sites, reducing their foraging efficiency and thus their
provisioning rates to nestlings. High maximum daily
temperatures also compromise nestling mass gain.
During 2012, PhD student Tanja van de Ven initiated
a study of how temperature affects fitness, and the
threshold temperatures above which fitness costs
begin to increase in the Southern Yellow-billed Hornbill
(
Tockus leucomelas
). Hornbills are vulnerable to high
maximum daily temperatures because the female seals
herself into the nest cavity as a protective mechanism
against predators. She spends most of the chick-
rearing period inside the cavity, and this places high
demands on the male as he is solely responsible for
food provisioning.
In 2012, researchers collaborated with the South
African Weather Service to assess how patterns of
hot weather events have changed over the last five
decades in the north-western regions of South Africa.
Results showed temperatures increasing, with more
heat waves as well, paving the way for the use of the
technique as a conservation planning tool.
And, lastly, MSc student Maxine Whitfield investigated
evaporative cooling and body- temperature regulation
in a variety of species. While resting and inactive, all
species appear able to avoid hyperthermia even at air
temperatures higher than those that currently occur in
the Kalahari.