12 – A tale of threatened frogs: demonstrating the value of long-term monitoring^171Case studies of species with limited or no monitoring
Most other threatened frog species in eastern Australia have had no thorough
monitoring (see Chapter 5). The large brown tree frog Litoria littlejohni, giant
burrowing frog Heleioporus australiacus and southern form of the stuttering frog
Mixophyes balbus occur along the eastern fall of the Great Dividing Range from
central NSW to Eastern Victoria. Concerns were first raised about population
declines of these species in the 1990s (e.g. Gillespie and Hines 1999), and all have
subsequently been listed as Vulnerable under the EPBC Act. In Victoria, all three
species have been considered rare and threatened since the 1980s (see Gillespie and
Hines 1999; Gillespie et al. 2014, 2016); in particular, the stuttering frog was last
seen in the southern end of its range in the early 1980s (Gillespie et al. 2014). The
risks posed by forest management practices on these species have been repeatedly
raised (e.g. Gillespie and Hines 1999; Gillespie et al. 2014, 2016). However, despite
these concerns both in Victoria and NSW and the emergence of Bd, efforts to
properly assess the population status of these species have been very limited and no
systematic monitoring programs have been established. Within south-eastern
NSW, monitoring at a small number of sites has been undertaken for both the large
brown tree frog and the giant burrowing frog in recent years, and within Victoria
monitoring of some large brown tree frog breeding sites has recently commenced
(unpublished data). It now appears that all three species may have undergone
marked declines across significant portions of their respective ranges; in particular,
the southern form of the stuttering frog may be extinct (Gillespie et al. 2014).
However, empirical data supporting evidence of these declines are limited.
Benefits of long-term monitoring
The long-term monitoring programs for the corroboree frog, Baw Baw frog and
spotted tree frog have either delivered, or enabled delivery of:
● (^) up-to-date knowledge of patterns of population changes across each species’
range. Current distributions of populations are known. In some cases precise
population sizes are known.
● (^) confident assessments of current extinction risk and conservation status. In
some cases, this information is known for individual populations.
● (^) accurate evaluation of threatening processes operating on each species
● (^) data-rich, robust population modelling and prediction, and management risk
assessment. In some cases, data are adequate to predict the fate of individual
populations under different management intervention scenarios, enabling well-
informed policy and management decision making. These assessments provide
clear and transparent justification for the need for, and type of, intervention.