Document ID: chunk:federal_register_of_legislation:F2016L01082:reg:1:p12
Version: federal_register_of_legislation:F2016L01082
Segment Type: reg
Provision Reference: reg 1 (pt 12/30)
Character Range: 45516–48639

with overgrazing
The overgrazing of native grasslands by domestic livestock and rabbits (Oryctolagus culiculus), particularly during drought conditions, can result in the temporary displacement of the species from areas of preferred habitat on a local or regional scale, and an increase in the rate of mortality (Baker-Gabb, 2002b; Baker-Gabb et al., 1990; D'Ombrain, 1926; Harrington et al., 1988; NPWS, 2002). Plains-wanderers can co-exist with light to moderate grazing (Baker-Gabb et al., 1990, Deiz & Foreman, 1996), however during droughts and prolonged dry periods very light grazing, or no grazing, is required to maintain suitable habitat structure (Antos, 2013a). The use of strategic grazing, including fenced stock containment or exclusion areas (which are particularly important during drought conditions), may optimise plains-wanderer habitat cover.
Excessively wet periods with insufficient grazing
An absence of grazing, or insufficient grazing, when followed by, or following, widespread rainfall and prolific grass growth, can also be deleterious to the species (Baker-Gabb, 2002b; NPWS, 2002, Radford et al., 2013) because it allows the density and/or height of grasses to increase which, consequently, can render native grasslands unsuitable for inhabitation by the plains-wanderer. Under prolonged wet conditions, a substantial increase in grazing intensity is required (Antos, 2013a). It has been hypothesized that unusually heavy rainfall in winter may be particularly problematic for plains-wanderers as it can result in a proliferation of dense introduced grasses and weeds (Baker-Gabb, 1998). Whereas heavy rainfall in summer may not always lead to the creation of dense grasslands that are unsuitable for plains-wanderers as it is more likely to cause increased growth of native grasses which the birds may tolerate (Wilson et al., 2014). Furthermore, some grassland habitats may become inundated for prolonged periods following significant rainfall events (Wilson et al., 2014) with grassland structure potentially taking three years to return to a suitable condition for plains-wanderers following flooding after heavy rainfall events (Antos, 2015).

4.2.3 Small population
Plains-wanderers may be exposed to increased extinction risk due to their current historically low population size. Small populations are at increased risk of extinction as chance events may have significant impacts on the population (Caughley, 1994). Such events could include random variations in the encounter and breeding rate or the ratio of male to female offspring. Random fluctuations in environmental conditions or the availability of food and other resources may also impact on small populations. Other potential issues that can impact upon the survival of a small population include reduced genetic diversity and fitness, and the potential for inbreeding depression (Caughley, 1994).

4.2.4 Predation by feral species
European foxes (Vulpes vulpes), feral cats (Felis catus) and native birds of prey, such as the spotted harrier (Circus assimilis) and black falcon (Falco subniger) are all potential predators