Habitat use and population dynamics of the Azure-Winged Magpie ...

territory is perhaps costly for breeding pairs, especially if the breeding season has already started,
as they would have to familiarise themselves with the new territory and other territory-holders.
Furthermore, good quality territories may already be taken, leaving areas that are inferior.
Fire can be detrimental to populations and species if it is unmanaged or unprecedented in the
history of the region. Especially so if the species concerned has limited dispersal ability, shows
site fidelity, has a narrow range of diet, or is a habitat specialist. The occurrence of fires,
depending on severity, extent, frequency and timing, can individually or collectively affect
breeding success and hence the population structure and dynamics.
For example, eggs and young can perish if fires occur during the nesting season, although adults
are rarely killed in fires because of their advantage in being able to fly (Lawrence, 1966; Murphy
et al., 2010). Fires can shorten or disrupt breeding seasons (Murphy et al., 2010) and can be
especially detrimental for species living in extreme environments where the breeding season is
short, such as in the Taiga or the Arctic.
Fires can affect the territory quality of birds, for example by reducing food and water availability,
nesting substrates or sites, shelter from the elements and reducing or destroying hiding places
from predators (Bendell, 1974; Brooker & Rowley, 1991; Artman et al., 2001; Humple &
Holmes, 2006; Murphy et al., 2010). As a considerable amount of energy and nutrients are put
into egg production and laying (Perrins, 1996; Nager, 2006), a reduction in available resources
may induce birds to reduce output or not breed at all in the same or following season (Brooker &
Rowley, 1991). On the other hand, female birds that reduce their output (clutch size) could be
adapting to the limited resources and nutrients they can provide to their young when they hatch
(Lack, 1954).
Fires may also induce physiological changes in birds that affect their reproductive output in that
season or in subsequent seasons. Fires may lower the immunity ability of individuals thus
rendering them more vulnerable to parasites and diseases. A study of the effects of a late dryseason
fire on the physiology of Red-backed Fairy-wrens Malurus melanocephalus showed that
the mass of affected birds decreased after the fire, but haemoglobin level and parasite load did not
change. The authors did however note that the fairy-wrens reduced their reproductive output in
subsequent breeding seasons (Murphy et al., 2010).
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