58 Monitoring Threatened Species and Ecological Communities
has decreased over the last decade, with several well-established monitoring
programs discontinued. Even when resources are adequate, frog populations can
be difficult to reliably monitor due to large variation in detectability across years
associated with weather conditions, and large changes in abundance, driven by
major, periodic recruitment events. To overcome these challenges, we suggest an
increased focus on improving design quality, with an emphasis on ensuring that
the information obtained by monitoring meets management and policy objectives.
Introduction
Monitoring the distributions and abundances of threatened species is a core
principle of conservation biology. Information on a species’ trajectory can be used
to inform assessments of extinction risk, determine responses to threatening
processes and evaluate the effectiveness of management (Marsh and Trenham
2008). In contrast, the absence of robust information on species’ trajectories can
lead to poor allocation of conservation resources, limited understanding of
threatening processes and failure to identify species declines (Campbell et al.
2002; Marsh and Trenham 2008). Ultimately, a lack of monitoring information
can result in preventable species extinctions (Lindenmayer et al. 2013; Woinarski
et al. 2016).
Amphibians are a group that have typically received limited research and
monitoring attention (Lawler et al. 2006), despite being the most threatened
vertebrate taxonomic group globally (Stuart et al. 2004). In Australia, 33 of 238
described frog species are currently listed as threatened (in the categories Extinct
(4), Critically Endangered (5), Endangered (14) or Vulnerable (10)) under the
Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
The historical pattern of frog declines in Australia is very different to that of
birds and mammals, which have experienced near constant rates of extinction over
the past two centuries, largely due to habitat loss and introduced predators
(Ga rnet t et al. 2011; Woinarski et al. 2014). Although habitat loss and introduced
predators have also contributed substantially to frog declines, in contrast to birds
and mammals, there were no recorded frog extinctions in Australia before 1970
and other threatening processes have played a major role (Hero et al. 2006;
Gillespie et al. 2 011).
Uniquely among vertebrate groups, disease is a demonstrated major driver of
frog extinction and endangerment in Australia (Scheele et al. 2017). The amphibian
chytrid fungus, which causes the disease chytridiomycosis, emerged in Australia in
the late 1970s and has subsequently spread throughout all environmentally suitable
areas of the continent (Scheele et al. 2017). Chytrid fungus is implicated in the
decline or extinction of 43 Australian frog species and remains an ongoing threat
for many species (Scheele et al. 2016; Scheele et al. 2017). Preventing further frog