Hamilton's frog

Leiopelma hamiltoni

TAXONOMY

Leiopelma hamiltoni McCullough, 1919, Stephens Island, New Zealand.

OTHER COMMON NAMES

German: Hamilton-Frosch

PHYSICAL CHARACTERISTICS

This species is virtually indistinguishable from the Maud Island frog, Leiopelma pakeka, but differs by usually being paler. Like the Maud Island frog, it reaches 2.0 in (50 mm) in length; females tend to be larger than males, but the sexes are otherwise identical. Dorsolateral glandular ridges are underlined with dark spots, and parotoid glands are present behind each eye. These frogs generally are pale brown or tan with a pale patch on the snout. The upper part of the iris is bright gold. The hind limbs are fairly short, and the feet are not webbed.

DISTRIBUTION

The species is restricted to a deforested, 6,460 ft² (600 m²) bank of rocks at an elevation of 900 ft (275 m) near the summit of Stephens Island, which is located in the Cook Straight off the northern tip of the South Island of New Zealand.

HABITAT

The frogs inhabit a bank of rocks, which, though previously bare, lately has been allowed to become overgrown with grass

and shrubs. The interior of the rock pile maintains conditions cool and moist enough to sustain the frogs.

BEHAVIOR

This nocturnal frog squeaks repeatedly if molested. There is evidence that it may be preyed upon by tuatara (Sphenodon punctatus).

FEEDING ECOLOGY AND DIET

This frog most certainly eats small insects and other terrestrial arthropods.

REPRODUCTIVE BIOLOGY

Hamilton's frog lays five to nine terrestrial eggs. The white embryos undergo virtually all their development within the egg and emerge as small frogs, about 0.4 in (11 mm) long. Males attend the eggs and hatchlings, which climb onto its back and legs.

CONSERVATION STATUS

This is one the rarest and most localized species of frogs in the world. Its habitat and population status, as well as the whole of Stephens Island, are monitored and patrolled carefully. The frog is ranked Vulnerable by the IUCN (encompassing both Leiopelma hamiltoni and L. pakeka), and it is protected under New Zealand's Wildlife Act.

SIGNIFICANCE TO HUMANS

None known.