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feed until after metamorphosis (Bell 1985). Hochstetter’s frogs have been recorded at densities of
65–140 per 100 m 2 in the Waitakere Ranges (Slaven 1992); 5–12 per 100 m 2 in the
Hunua Ranges (Greene & Tessier 1990); and 18–21 per 100 m 2 at Golden Cross Mine in the
Coromandel (Whitaker 1996; Whitaker & Alspach 1999).
Maud Island frog and Hamilton’s frog are the largest living leiopelmatid frogs (SVL up to
51 mm). Both species are currently found amongst the boulders and moss-covered rocks in
terrestrial areas of remnant and regenerating coastal forests. Like Archey’s frog, they are
terrestrial breeders. However, their breeding behaviour, egg laying and parental care have only
been observed in captivity. Maud Island frogs are considered to be numerous on Maud Island,
reaching densities of 70–230 per 100 m 2 (Bell 1997). Hamilton’s frogs have been recorded at
densities of 53–58 per 100 m 2 (Newman 1990; Thomson 1997), although, based on modelling, they
were estimated to have increased dramatically to 220 per 100 m 2 in 2004 (Tocher et al. 2006).
3.1.3 Status and species recovery phases
In recovery planning for threatened species, the Department of Conservation (DOC) has
adopted a model that identifies four phases of recovery action: ‘Research’ to identify causes and
key agents of decline; ‘Secure’ the taxon from extinction; ‘Recovery’; and ‘Maintenance’. There
remains some uncertainty about the causes and key agents of decline for native frogs and the
threats to both Archey’s and Hochstetter’s frogs still need to be identified. Given this, the plan is
largely focused on the first two phases of recovery—research and secure. Less focus is placed on
Maud Island and Hamilton’s frogs, as they are considered to be in the recovery and maintenance
phases, as previous management has resulted in additional populations being established so
that both species are now considered secure from extinction as long as the populations remain
protected from agent(s) of decline. The national and international threat classifications, and the
current phase of recovery for native frog species are listed in Table 1.
3.1.4 Past and present distribution
Subfossil remains indicate that Leiopelma species were once widely distributed throughout
New Zealand. Subfossil frog bones have been dated at between 200 and 2000 years BP, and it
is thought that the extinction of these frogs may be correlated with the arrival of the Pacific rat
(kiore, Rattus exulans) in New Zealand (Worthy 1987a, b). Remains identified as Hamilton’s and
Hochstetter’s frogs have been discovered on both the South and North Islands (Worthy 1987a, b);
and Leiopelmatidae fossils and a second frog taxon that had not previously been recorded in
New Zealand were recently discovered in Central Otago (Worthy et al. 2009).
All native frog species appear to have reduced distributions and exist in remnant populations
(Fig. 1). Information on the past and present distribution of native frog species has been collated
in DOC’s Atlas of Amphibians and Reptiles of New Zealand (DOC 2009).
Table 1.
Threat classification/status and phase of recovery for native frogs (Leiopelma spp.).
Species name
NZ Threat
Classification
(Newman et al. 2013)
IUCN status
(IUCN 2012;
Version 2012.2)
Phase(s) of species
recovery
(from DOC 2008)
Archey’s frog Nationally Vulnerable Critically Endangered Identify agent(s) of decline
Secure the taxon
Hochstetter’s frog At risk—Declining Vulnerable Identify agent(s) of decline
Secure the taxon
Maud Island frog Nationally Vulnerable Vulnerable Secure the taxon
Hamilton’s frog Nationally Critical Endangered Secure the taxon
4 Bishop et al.—Native frog recovery plan, 2013–2018