72 Monitoring Threatened Species and Ecological Communities
especially of conservation reserves (Russell-Smith et al. 2014). Some other
monitoring programs have focused more sharply on determining the population
trends and conservation status of individual reptile species (Dimond et al. 2012).
Where undertaken, monitoring of Australia’s threatened reptile species has
been done for diverse reasons. Some monitoring programs have been developed to
assess the impacts of major threats, notably fire (Atkins et al. 2015), grazing
(Pettigrew and Bull 2012), habitat fragmentation (Dimond et al. 2012), other forms
of habitat degradation (Fielder et al. 2015), the spread of the invasive cane toad
Rhinella marina (Doody et al. 2006; Brown et al. 2013) and the impacts of
predators, particularly on the clutches and hatchlings of threatened marine and
freshwater turtles (Micheli-Campbell et al. 2013; Freeman et al. 2014). Most of
these monitoring programs are of relatively short duration and typically are
discontinued after the research question has been answered, or after a grant or
other ephemeral funding source finishes. However, some of the evidence relating
to impacts of threats has helped inform priorities for management and, in some
cases, monitoring programs have been continued to assess the effectiveness of such
management (Webb and Shine 2000), including of translocations (Read et al. 2 011).
The fate of Christmas Island’s distinctive reptile fauna provides a notable
example of the role of population monitoring in the conservation of Australia’s
reptile species. Although brief assessments indicated decline for at least four of the
island’s six native reptile species from the 1970s to the 1990s (Cogger and Sadlier
1999), relatively little resourcing was invested by managers in monitoring of this
reptile fauna. Consequently, the rate and scale of decline (and its causation) was
not appreciated in time to prevent the extinction of the endemic Christmas Island
forest skink Emoia nativitatis (to date, the only known case of extinction of an
Australian reptile species) and the extirpation of the island’s population of coastal
skink E. atrocostata (Woinarski et al. 2017), with the last records of these species in
the wild in 2009 and 2010, respectively. Fortunately, the magnitude of the problem
became apparent after establishment of a more intensive monitoring program
(Smit h et al. 2012), in time to secure captive populations of two other endemic
species – the blue-tailed skink Cryptoblepharus egeriae and Lister’s gecko
Lepidodactylus listeri – now both extinct in the wild. An ongoing monitoring
program has since precisely documented changes in the total population size for
these two species, with the entire population of both species now being captive
(Andrew et al. in press).
Another striking example of the role of monitoring for conservation
assessment involved repeated sampling of the assemblage of sea snakes at 1–2 year
intervals from the 1990s around Ashmore and Hibernia Reefs, northern Australia.
Up to 2000, this monitoring reliably recorded, inter alia, abundant populations of
short-nosed sea snake Aipysurus apraefrontalis and leaf-scaled sea snake A.
foliosquama (both then thought to be largely restricted to this location). However,