A Winter's Tale

Forest and Bird, Volume 21, Issue 4, 1 November 1990, Unnumbered Page

A Winter's Tale

’ YING at the western entrance to Cook Jué Strait about 110 km west of Levin, Stephens Island is a wildlife sanctuary of exceptional importance. Captain Cook named it in 1770 in Honour of Phillip Stephens, Secretary of the British Admiralty, but never went ashore. The island was visited periodically by local Maori, the Ngati Koata, in search of the island’s rich seabird harvest (kaimanu), and it also had significance to the tribe as a boundary marker of a gift of land from another tribe. The island’s Maori name Takapourewa (floating matipou trees), as well as reports by naturalist Emst Dieffenbach in

1843, indicate that Stephens Island was once forested on all but the rocky, encircling cliffs. However, a lighthouse was constructed between 1892-1894 and the combination of forest clearance, wind and salt spray and unrestricted roaming by introduced stock led to rapid loss of about 90-percent of the forest cover. Today, the southern two-thirds of the island above the clifftops is regenerating in a mosaic of scrub, vinelands, silver tussock and herbfields, aided by deliberate strip-plantings of taupata made in the 1950s-1970s by the Wildlife Service. Most of the remaining area above the cliffs is still grazed by sheep while plans for revegetation are formulated. The lighthouse was automated in 1989 and a Department of Conservation officer and his family now reside on the island.

( TEPHENS ISLAND’S immensely rich rep‘4. tile-seabird community has never been exposed to rats, and cats were eradicated within 30 years of their appearance (but not before causing the extinction of the endemic Stephens Island wren). Tuatara are the largest and most famous reptiles on the island, reaching numbers of up to 2,000 per hectare (equivalent to about 750 kg of tuatara biomass). They feed on beetles, wetas, worms, lizards and the eggs and chicks of fairy prions. ener aa a JUVENILE TUATARA are initially brown, unAta eS ) spotted, and much more cryptic than their PO ae parents. Their adult colours develop over the BS Gags eRe 13 or So years it takes them to reach sexual maturity. Recent studies have revealed the surprising discovery that most tuatara nesting takes place in the island's sheep pasture, suggesting that the warm soil temperatures there are attractive to nesting females. Nevertheless, the eggs still take a year or more to incubate. Why rush when you'll probably live another 70 years or more? ~ | "HE SPECKLED SKINK is one of four spe- ". cies of the genus Leiolopisma (smooth shell) to be found on the island. With a total length of up to 240 mm, it is also the largest. Its specific name, infrapunctatum (spotted below), refers to the black spots on its spectacular yellow belly. Like tuatara, it thrives in the forest on Stephens Island and basks discreetly by day. Speckled skinks are not restricted to Stephens Island, being found also in the lower North Island and around Nelson.

L ’ NLIKE the common gecko and the Stephens Island gecko, the Marlborough green gecko is most active by day. The tail is also less frequently dropped, extremely prehensile and used as a "fifth leg’" when climbing. This species belongs to the genus Heteropholis (different scales) which is endemic to New Zealand and represented by six species. The specific name manukanus suggests that it is commonly found on manuka in some parts of the Marlborough Sounds. However, manuka is not seen on Stephens Island and these vivid green geckos are usually found on the foliage of ngaio trees, Muehlenbeckia vines or New Zealand spinach. Needless to say, only their movement gives them away! ‘HE STEPHENS ISLAND TREE WETA, +. Hemideina crassidens (Hemideina — half huge or terrible, crassidens — thick tooth), is renowned for the enormously enlarged heads of the males. Each male defends a hole in a tree in which several females may live. Females in the "harem" are free to come and go, but if another male attempts to enter, a ritualized fight occurs. The males lunge at each other with their jaws extended, each trying to grab the other male above its jaws. Usually one male retreats after a single lunge. Details of the behavioural repertoire of the species have been aided by Project Weta, an ambitious and successful weta breeding campaign led by Paul Barrett at Wellington Zoo. The zoo obtained its first wild adults in 1987, and in 1988 produced 962 youngsters! These are now adult and young from them are eagerly awaited.

| ‘HE SO-CALLED "GIANT WETA" on Ste- ". phens Island is, surprisingly, smaller than the largest Stephens Island wetas and males do not have enlarged heads. Their scientific name, Deinacrida rugosa, honours their fierce appearance (Deinacrida — huge or terrible, and scaly; rugosa — wrinkled) but their archaic-looking armour conceals a placid and benign nature that is a delight to any wildlife photographer. Females are larger than males and are easily distinguished by their tail-like ovipositor. This species is also found on Mana and Middle Trio Islands, and was successfully introduced to Maud Island in 1977. Giant weta on Stephens Island occasionally fall victim to foraging tuatara, but are not endangered. They are particularly common in the Muehlenbeckia vinelands on the southern end of the island.

7" HE COMMON GECKO is one of the most «. widespread and abundant lizards in New Zealand, thriving on the North, South and Stewart Islands and on many offshore islands. It is a small (total length up to 155 mm), nocturnal lizard that climbs trees and occasionally gets eaten by tuatara. Like many lizards, it can drop its tail when in danger. However, the replacement tail is stiffened by cartilage, not bone, and it never appears quite the same as the original. Common geckos belong to the genus Hoplodactylus (hoplon, tool; daktylus, digit), all eight species of which are endemic to New Zealand. The specific name maculatus means "speckled". $4, of

‘HIS CURIOUS, NOCTURNAL WEEVIL is +. endemic to Stephens Island. Only about three specimens of this species, Anagotis stephenensis, have been reported in the last 16 years. The adult (shown here) is about 25 mm long and feeds on ngaio leaves, but the larvae have never been found. Two other weevils of this genus are also present on Stephens Island: A. fairburni (found on flax) and A. rugosus (found on coprosma). Large weevils are abundant only on islands where rats are absent.