|Scientific Name:||Leiopelma hochstetteri|
|Species Authority:||Fitzinger, 1861|
|Taxonomic Source(s):||Frost, D.R. 2015. Amphibian Species of the World: an Online Reference. Version 6.0. New York, USA. Available at: http://research.amnh.org/herpetology/amphibia/index.html.|
|Taxonomic Notes:||DNA analyses have indicated that L. hochstetteri consists of ten or more evolutionarily significant units (Gemmell et al. 2003, Fouquet et al. 2010, Gleeson et al. 2010, Newman et al. 2013). Management should maintain these distinctive populations until further research into speciation within the group has been carried out.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||IUCN SSC Amphibian Specialist Group|
|Contributor(s):||Haigh, A., Bell, B., Bell, E., Easton, L., Bishop, P., Burns, R. & Wren, S.|
This species has been assessed as Least Concern. While there are estimated past declines of at least 10% which are expected to continue into the future, and there is continuing decline in the extent and quality of habitat occupied by Leiopelma hochstetteri, none of the thresholds are met for population reduction, population size, EOO or AOO to place this species within a threatened category. This assessment emphasises the need to resolve the taxonomic status of Evolutionarily Significant Units within this potential species complex.
|Previously published Red List assessments:|
|Range Description:||L. hochstetteri is found in numerous scattered sub-populations in the northern half of New Zealand’s North Island and offshore on Great Barrier Island (Aotea Island). Several of these sub-populations are very isolated and are thus considered to represent 13 threat-defined locations. Its extent of occurrence is 68,594 km2 and its area of occupancy of 9,032 km2, which is likely to decline by at least 10% in the next three generations due to ongoing threats, including habitat loss and degradation (Newman et al. 2010).|
|Range Map:||Click here to open the map viewer and explore range.|
L. hochstetteri has been recorded at varying densities, from 5-12 per 100 m2 in the Hunua Ranges (Green and Tessier 1990) through 18-21 per 100 m2 in the Coromandel (Whitaker 1996, Whitaker and Alspach 1999) up to 65-140 per 100 m2 in the Waitakere Ranges (Slaven 1992). The total population has been estimated at c. 100,000 individuals (Bishop et al. 2013) although some sub-populations such as the one at Otawa are known to be very small, possibly as low as just 250 mature individuals, and one population went extinct in Pirongia Forest Park in the 1980s (A. Haigh pers. comm. July 2015, cited in Fouquet et al. 2010).
The population is thought to have declined by at least 10% in the last 3 generations (estimated at 36 years); studies of populations inhabiting pine plantations in eastern Bay of Plenty, Mahurangi and the Brynderwyn Hills have shown poor population recovery or declines after clear-felling (Shaw 1993; Douglas 1998, 1999, 2001) and declines have also been observed in native forests that are managed via predator-control within the Waitakere Ranges (Najera-Hillman et al. 2009) and at the Pureora Forest Park (Richardson 2014). The same rate of declines are likely to continue into the future (Newman et al. 2010).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
Unlike the three other Leiopelma species, L. hochstetteri is semi-aquatic with a stream-dwelling larval stage, and as such has a higher reliance on the presence of watercourses. This species is found predominantly in native forest, but is also able to survive in modified habitats such as in exotic plantation forests, at least in the short term (Easton 2015). There is a continuing decline in habitat quality e.g. when pine plantations are logged it is likely that streams will be rendered un-liveable for this species due to disturbance and siltation. Mature pine plantations have a slightly lower habitat quality compared to native forests (Easton et al. in review). Furthermore, invasive pigs, goats and deer reduce the quality of native forest habitat for Leiopelma hochstetteri (L. Easton pers. comm. July 2015).
L. hochstetteri has a slightly shorter development period compared to the other frog species native to New Zealand and is estimated to have a generation length of approximately 12 years. It lays small clutches of eggs under stones or vegetation alongside creeks; on hatching, the larvae are active, but do not feed until after metamorphosis (Bell 1985)
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Generation Length (years):||12|
|Movement patterns:||Not a Migrant|
|Use and Trade:||There are no records of the species being utilized or traded.|
Loss and modification of native forest habitat combined with the introduction of non-native predators is likely to have caused the fragmentation of sub-populations seen today in this species. While L. hochstetteri is known to exist in non-native forest habitat such as pine plantations, populations here are threatened by the inevitable mechanical disruption and siltation that will come when plantations are logged. As such, subpopulations at non-native plantation sites are likely to suffer local extinctions where habitat connectivity is poor.
Although L. hochstetteri is able to coexist with introduced mammalian predators, including rodents and mustelids, populations have increased at sites where intensive trapping occurs, so it is likely that this species is existing at lower than ideal densities, which could have an impact on reproductive rates, especially in non-native habitats where densities are already depressed. Furthermore, the quality of habitat at native sites is being reduced by the presence of introduced pigs, goats and deer.
Although chytridiomycosis is present in the sympatric L. archeyi, disease screening has found no chytrid-positive cases in L. hochstetteri (Shaw et al. 2013).
Mining within the Coromandel stronghold of this species has been proposed in recent years; should this go ahead it would represent a massive threat to the species from large-scale habitat destruction and modification.
Conservation Actions In Place
Through its Native Frog Recovery Group and 2013-2018 Native Frog Recovery Plan (Bishop et al. 2013), the NZ Department of Conservation (DOC) administers conservation management of this species and permits appropriate species research. At some sites NGOs and local communities are involved with conservation management.
New occupancy monitoring methods are being implemented for this species, which will allow comparisons between sub-populations that have not been possible up to now due to variation in methods used.
Invasive predator control programmes are in place at some sites within the range of L. hochstetteri and have been shown to benefit the species, although existing control covers only a small portion of this species’ range.
Ex-situ populations are held by the University of Otago and Hamilton Zoo, where husbandry techniques are being refined for effective captive breeding.
Some sub-populations have been tested for amphibian chytrid fungus, and this should continue, especially at sites where L. archeyi has tested positive.
Expansion of non-native predator control would be of benefit to this species, and habitat restoration could be of benefit at some sites.
Successful translocations have been carried out for the other three Leiopelma species, and translocation of L. hochstetteri to a fully protected site could be of benefit for this species, particularly in cases where populations are likely to be driven locally extinct e.g. during the logging of pine plantations.
Lack of public awareness of cryptic native frogs does not aid conservation efforts; increased public awareness of this species would be of benefit, particularly at sites where L. hochstetteri are found beyond protected habitats.
Research into speciation within this group is necessary to define whether a species complex exists; should this taxon be split into several species this will have massive implications on the conservation status of species in the group, which will need to be reassessed. Management should maintain these distinctive populations until further research into speciation within the group has been carried out.
Further research on basic life-history parameters is also required, which would be of great benefit for management when population modelling could be of assistance in conservation planning.
Ongoing work to refine captive husbandry and breeding techniques needs to be maintained for the ex-situ populations to act as an effective insurance population.
More research into the benefits of trapping non-native mammalian predators would be of benefit, so that this intervention can be implemented to maximum effect.
|Citation:||IUCN SSC Amphibian Specialist Group. 2015. Leiopelma hochstetteri. The IUCN Red List of Threatened Species 2015: e.T11452A66654724.Downloaded on 23 August 2017.|
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