Ben D. Bell

Leiopelma pakeka, n. sp. (Anura: Leiopelmatidae), a cryptic species of frog from Maud Island, New Zealand, and a reassessment of the conservation status of L. hamiltoni from Stephens Island

Patterns of allozyme variation reveal that frogs from Maud Island, New Zealand, here designated Leiopelma pakeka, n sp , are specifically distinct from L hamiltoni from Stephens Island Previously, the two populations had been thought to be conspecific Leiopelma pakeka shows limited morphological differentiation from L hamiltoni, but is highly distinct genetically Among 12 allozyme loci resolved from toe tissue, the two taxa showed fixed differences at two loci and one significant frequency difference L hamiltoni was genetically more similar to L archeyi (Neis D = 0 18) than to L pakeka (D = 0 24) The discovery that Maud Island and Stephens Island frogs are distinct species increases the conservation significance of both as the single known population of each species L hamiltoni is one of the worlds rarest frogs and warrants the highest level of conservation protection

Habitat distribution and predation on a western population of terrestrial Leiopelma (Anura: Leiopelmatidae) in the northern King Country, New Zealand

Abstract A new population of terrestrial Leiopel‐matid frog was discovered in the Whareorino Forest, northern King Country, New Zealand, in 1991. Searches were carried out from June 1991 to December 1993 to determine the species present and to document variation in external morphology, habitat, and local distribution. These confirmed that a terrestrial frog resembling L. archeyi is present in the area, as well as Hochstetters frog Leiopelma hochstetteri and the introduced Australian hylid frog Litoria aurea. In Whareorino Forest, the terrestrial Leiopelma was mostly above 500 m altitude and L. hochstetteri above 350 m. The terrestrial Leiopelma occupies sites under rocks and logs in forest. It also occurs in vegetation, such as crown fern Blechnum discolor, tree fern Cyathea smithii, hook grass Uncinia uncinata, and rice grass Microlaena avenacea. Egg clusters of this frog were found in crown fern and tree fern, as well as under stones. The terrestrial Leiopelma is susceptible to predation by Litoria aur...

Does Chytridiomycosis Disrupt Amphibian Skin Function

Abstract Chytridiomycosis, a disease caused by the fungus Batrachochytrium dendrobatidis (Bd), potentially disrupts osmoregulation or respiration across the skin of amphibians it infects, releases toxins into the host, or both. We investigated whether infection with Bd alters water balance or metabolic rate of the hylid frog Litoria raniformis. Frogs were held in laboratory conditions simulating those in which Bd epizootics had been observed in the field. We inoculated six frogs with infective Bd zoospores, held the subjects in individual containers, and compared their course of infection and associated physiological measures with those of six controls. Experimental subjects exhibited clinical signs of chytridiomycosis during the early period of infection, one week after they were inoculated, possibly due to invasion of Bd into the skin. These clinical signs were accompanied by significant inhibition of rehydration through the skin. However, we detected no changes in metabolic rate attributable to chytridiomycosis after one week. Five months after inoculation, all but one of the infected subjects had survived. Molecular testing confirmed that surviving frogs, although aclinical, still were infected. Control and infected subjects showed no difference in water balance or metabolism. These results provide evidence of inhibited rehydration in individuals exhibiting clinical signs of chytridiomycosis. However, aclinical chytridiomycosis does not severely affect amphibian skin function. Frogs that survive infection by Bd, even if they remain infected, may suffer no significant impairment in their physiological responses. The disease progression, with initial clinical signs of chytridiomycosis followed by apparent full recovery, is consistent with an adaptive immune response to Bd infection. Further research is needed to determine how Bd causes clinical chytridiomycosis and the immunological mechanisms by which hosts respond to Bd.

An electrophoretic study of genetic variation in the New Zealand frog genus Leiopelma

Abstract Genetic variation at 33 loci in three species of Leiopelma was examined by cellulose acetate electrophoresis of liver enzymes. Heterozygosity is apparently comparable to levels detected in other amphibians. Genetic differentiation between species is extensive. L. hochstetteri is greatly divergent from both L. archeyi and L. hamiltoni, but these two are relatively similar genetically, in agreement with morphological, ecological, and developmental patterns. We tentatively estimate that the divergence of hochstetteri from the other two species occurred during the Miocene, whereas that of archeyi and hamiltoni occurred during the Pliocene. Implications of the genetic data for conservation of these rare species are discussed.

Estimating the complexity of bird song by using capture-recapture approaches from community ecology

Repertoire size, the number of unique song or syllable types in the repertoire, is a widely used measure of song complexity in birds, but it is difficult to calculate this exactly in species with large repertoires. A new method of repertoire size estimation applies species richness estimation procedures from community ecology, but such capture-recapture approaches have not been much tested. Here, we establish standardized sampling schemes and estimation procedures using capture-recapture models for syllable repertoires from 18 bird species, and suggest how these may be used to tackle problems of repertoire estimation. Different models, with different assumptions regarding the heterogeneity of the use of syllable types, performed best for different species with different song organizations. For most species, models assuming heterogeneous probability of occurrence of syllables (so-called detection probability) were selected due to the presence of both rare and frequent syllables. Capture-recapture estimates of syllable repertoire size from our small sample did not differ significantly from previous estimates using larger samples of count data. However, the enumeration of syllables in 15 songs yielded significantly lower estimates than previous reports. Hence, heterogeneity in detection probability of syllables should be addressed when estimating repertoire size. This is neglected using simple enumeration procedures, but is taken into account when repertoire size is estimated by appropriate capture-recapture models adjusted for species-specific song organization characteristics. We suggest that such approaches, in combination with standardized sampling, should be applied in species with potentially large repertoire size. On the other hand, in species with small repertoire size and homogenous syllable usage, enumerations may be satisfactory. Although researchers often use repertoire size as a measure of song complexity, listeners to songs are unlikely to count entire repertoires and they may rely on other cues, such as syllable detection probability.

A review of the status of New Zealand Leiopelma species (Anura: Leiopelmatidae), including a summary of demographic studies in Coromandel and on Maud Island

Abstract Six species of Leiopelma frog endemic to New Zealand have been described, but three are extinct. Field surveys have extended the known contemporary ranges of L. archeyi and L. hochstetteri, though sub‐fossils reveal that both L. hochstetteri and L. archeyi/hamiltoni were formerly more widespread in New Zealand than they are now. A new North Island population of terrestrial Leiopelma resembling L. archeyi has recently been found. Introduced predators and food competitors, especially Rattus, have probably had a major detrimental impact on Leiopelma. No extant species is immediately at risk of extinction, but L. hamiltoni on Stephens and Maud Islands is very restricted in range and/or numbers. Leiopelma reaches high densities (up to 8 frogs/ m2) in suitable rock‐strewn habitats and can be relatively long‐lived (L. archeyi 17+ years, L. hamiltoni 23+ years). Population levels of L. archeyi have fluctuated in a Coromandel study plot sampled approximately annually over 1982–93, but on Maud Island L. ha...

Conservation status of New Zealand frogs, 2009

Abstract A reappraisal of the conservation status of the New Zealand frog fauna is presented using the 2008 version of the New Zealand Threat Classification System. Of New Zealands four extant endemic species, three are judged to be ‘Threatened’ (Leiopelma hamiltoni being ‘Nationally Critical’, and L. pakeka and L. archeyi being ‘Nationally Vulnerable’) and one ‘At Risk’ (L. hochstetteri ‘Declining’). Three Leiopelma species are listed as extinct—they are known from bone deposits in caves throughout the country until some time in the last 1000 years. Three introduced and naturalised Litoria species are abundant in New Zealand although two (L. aurea and L. raniformis) are threatened in their country of origin (Australia). An additional unidentified frog taxon from northern Great Barrier Island is listed as ‘Data Deficient’.

The fate of a population of the endemic frog Leiopelma pakeka (Anura: Leiopelmatidae) translocated to restored habitat on Maud Island, New Zealand

Abstract We assess the fate of 100 Leiopelma pakeka transferred in two batches from remnant forest on Maud Island to a new site at Boat Bay, 0.5 km away, in 1984–85. Seventy of the original 100 individual frogs were recaptured, plus 35 young recruits into the population. The 43 frogs released in 1984 settled closer to the release site than did the 57 released a year later, suggesting that many of the later arrivals avoided sites already occupied by frogs. Boat Bay frogs became heavier than frogs in the source population, presumably a reflection of lower population density and greater per capita food supply. Numbers declined initially, but the frog population remained relatively stable after losses of founder individuals began to be offset by local recruitment. The mean annual survival rate after initial settlement was high (97%), indicating an average life expectancy of 33 years.

Short records of marsh warbler (Acrocephalus palustris) song provide indices that correlate with nesting success

The migrant Marsh Warbler (Acrocephalus palustris) has a complex song repertoire, but such complexity makes quantitative comparison of songs between individual males both time consuming and challenging. We investigate a streamlined method of song analysis that uses 2-min records of song to provide simpler relative indices of repertoire size, including the use of capture-recapture and species-richness models. For each male, three attributes of song were determined: the song complexity, the total repertoire elements and the estimated repertoire size based on the Burnham and Overton jackknife method. Males with higher song indices tend to have greater nesting success, suggesting that even short records of song can indicate male quality to prospective female mates. Why should male Marsh Warblers have long and sustained songs when only 2-min records correlate with nesting success? Assuming that song advertises the quality of the male, and that the quality of such advertisement is sustained throughout the male’s song period, we argue that the female may need to have only brief exposure initially to that song to assess its quality and hence the quality of the male. More continuous periods of song may reinforce that initial choice by the female, and allow males to remain conspicuous to transient females moving around the territories of potential male mates.

Local distribution, habitat, and numbers of the endemic terrestrial frog Leiopelma hamiltoni on Maud Island, New Zealand

Abstract Systematic surveys in the 16 ha forest habitat of the Maud Island frog Leiopelma hamiltoni show that frogs are not uniformly distributed throughout the forest. They live at higher densities in the lower section of forest where the forest canopy is higher and rocks more abundant. Other habitat variables have less effect on frog distribution. The minimum population estimate, based on frogs seen out at night on two surveys, is c. 6500, though the actual number present in the forest remnant is estimated to be c. 19 000.