4.1. Rediscovery
There are various circumstances surrounding rediscovered populations
of presumed-extinct animals. In reviewing cases for terrestrial vertebrates,
Scheffers et al. (2011) report the strict rediscovery of some106
species. They summarised that rediscoveries primarily occur through
additional survey effort in remote or inaccessible areas, essential for
species with naturally or anthropogenically-induced narrow ranges.
Patterns of rediscovery differed by fauna group (e.g. mammals and
birds more typically in low- and mid-lands, amphibians in high-lands)
and by particular biological attributes of species such as behaviour, habitat
preferences, population abundance and ‘charisma’. Nocturnal or
behaviourally cryptic species, habitat specialists, those occurring in
low abundance, and more drab or obscure species are harder to find
(e.g. George et al., 1996;Marsh et al., 2003; Ostrovsky and Popov, 2011).
Aquatic environments are characterised by spatially restricted,
fragmented, structurally heterogeneous and temporally variable habitats
(e.g. Ward, 1989). Thus populations of aquatic biota are prone to
fluctuation and being localised, meaning that a higher level of targeted