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

Some effects of fire may be long term and may not be apparent immediately post-fire. Continued
presence of a species does not indicate that fire does not have any effect on the breeding success
and hence the population dynamics of resident populations. In one study, apart from a delay in
the onset of egg-laying 1-2 years post-fire which shortened the breeding season, birds suffered
from a high rate of nest failures even though nesting attempts were increased 1.5-2 fold, and
reproductive success was less than in pre-fire years (Brooker & Rowley, 1991). Similarly, in a
Mediterranean shrubland, population decrease post-fire was suggested to be a result of an
increase in non-breeding individuals and a decrease in recruitment of new individuals (Pons et
al., 2003). However, most published literature appears focussed on post-fire species composition
and density, but neglects the survival, breeding success and demography of species. This is
perhaps partly due to constraints that limit study duration to the short-term (less than five years).
Long-term effects of frequent, unmanaged and uncontrolled fire regimes can result in the
fragmentation or loss of suitable habitat, thus affecting re-colonisation or recruitment of species
and consequently leading towards genetic bottlenecking in the population. An already small
population could suffer from demographic or environmental stochasticity, resulting in even
smaller populations or meta-populations (extinction vortex), and could ultimately lead to local,
then larger scale extinctions (Gilpin & Soulé, 1986). In Australia, inappropriate fire regimes have
caused, or contributed to the loss of two species and three subspecies of birds (Woinarski, 1999).
On the other hand, the suppression of fire has resulted in the decline of Florida Scrub-jays, as a
result of loss of suitable habitat usually maintained by fires (Woolfenden & Fitzpatrick, 1990;
Breininger et al., 2006).
1.2 Cooperative breeding
Cooperative breeding is one potential advantage of group living. Cooperative breeding involves
breeding and non-breeding individuals (usually offspring from the previous year(s), or relatives
of either male or female) assisting the breeding pair, or showing parent-like behaviour towards
young that are not their own offspring (Skutch, 1961). Recent reviews report the presence of
cooperative breeding in about 3-4% of the extant bird species (Arnold & Owens, 1998; Ligon &
Burt, 2004). Cooperative breeding may be either facultative or obligative (Ford, 1989).
Two main theories have been proposed to explain cooperative breeding: one theory proposes that,
in stable and predictable environmental conditions, a high population density near the carrying
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