New Zealand Invertebrate Reintroductions
Middle Island Tusked Weta (Motuweta isolata)
This giant weta (photo: Ian Stringer) was previously found only on Middle Island (13 ha) in the Mercury Group, but was probably present on other islands in the group before arrival of introduced mammals, especially rats. Tusked weta are carnivorous and nocturnal, and spend the day resting in sealed chambers that they dig. They have recently been translocated to 2 islands where mammals have been eradicated:
Double Island (33 ha, Mercury Group off NE North Island). Reintroduction. 82 (19 male, 63 female) released May to September 2001. The weta were reared from 2 females and 1 male taken from Middle Island, and were liberated when half grown to adult. They were released individually in artificial holes and in depressions under plastic plant pot saucers. One large female nymph was found in March 2003 confirming that they have produced a first generation on the island. Contact Ian Stringer.
Red Mercury Island (225 ha, Mercury Group off NE North Island). 64 weta in two releases: 49 (16 males, 33 female) May to September 2001, 15 (6 male, 9 female) September 2002 at a second site >500 m away from the first release. Release methods as for Double Island. In addition, 6 weta (3 male, 3 female) were released (4 under saucers; 2 in holes) in a 5 m by 5 m predator proof enclosure. Tuatara and Little Spotted Kiwi have also been released to Red Mercury, and may prey on the weta outside the enclosures. 8 medium to large sized nymphs were found in March 2003 confirming a first generation on the island. Ian Stringer.
Cook Strait Giant Weta (Deinacrida rugosa)
Before translocations, Deinacrida rugosa (photo: Mike Meads) was found only on Mana Island (where it is common), and Stephens and Middle Trio Islands (where it is rare). In 1976, 43 wetas from Mana were released on Maud Island, where there are now probably thousands (Meads 1994). Translocations since 1990 include:
Matui-Somes Island (25 ha, Wellington Harbour). 34 weta (21 male, 13 female, 1 unknown) from Mana Island were released on 26 March 1996, and a further 28 (11 male, 14 female, 3 unknown) released on 17 April 1996 1997. The population is now well established. Contact Colin Miskelly or Mary McIntyre (Victoria University).
Titi Island (32 ha, Marlborough Sounds off NE South Island). Introduction. 92 animals from Maud Island released at two sites on Titi in February 2001. Norway rats, which had a clear impact on invertebrate fauna, were eradicated from Titi 1970-75. The translocation of Cook Strait giant weta helps to re-establish ecological links which would have formerly existed on the island as well as establishing another population of a species once widespread. Animals were captured by hand at night, held overnight in sealed plastic containers, then released into vegetation on Titi the next day. The first major survey to assess the success of the operation will be four years after the final release (additional animals may be released). Contact Peter Gaze.
Wakaterepapanui Island. 42 giant weta were translocated from Takapourewa (Stephens Island) in October 2003, and 13 captive-bred weta were translocated to the island in May 2004. More details are available on DOCDM-63162 and DOCDM-33695. A search in early 2006 failed to find any giant weta (Gruber 2007 – DOCDM-136250). Contact Bill Cash.
Long Island (142 ha scenic reserve, Marlborough Sounds). 97 weta (39 male, 58 female) were translocated from Maud Island to Long Island in January 2008. A follow-up translocation of about the same number is planned for January 2009. There had not been any follow-up survey as of December 2008. Contact Bill Cash.
Mahoenui Giant Weta (Deinacridasp.)
This species (photo: Mike Meads) was first discovered on a farm near Mahoenui (near Te Kuiti, west central North Island) in 1962. Before translocation, the species was confined to a few hundred ha of pasture covered with dense aged gorse. The gorse (a noxious weed) presumably provides protection from rats and other predators, and the weta are extremely abundant. 160 ha was subsequently purchased by the Department of Conservation and made the Mahoenui Giant Weta reserve. Since the late 1980s there have been translocations to two other reserves with 40 km of the parent population:
Maungaokewa Reserve. 141 weta (83 male, 58 female) released February 1989, and 91 weta (47 male, 44 female) released December 1989. The reserve is fenced from stock, and there is control of browsing mammals. See Sherley (1994). Contact Greg Sherley.
Cowan Reserve. 162 weta (79 male, 83 female) released February 1989, 53 weta (28 male, 25 female) December 1989, 135 (72 male, 63 female) January 1991, 119 (59 male, 60 female) September 1992. See Sherley (1994). Contact Greg Sherley.
Warrenheip (16 ha private reserve near Cambridge, North Island). 287 weta were released at Warrenheip in 2001, two years after an Xcluder pest-proof fence was built around the reserve. The reserve has regenerating forest and shrubland, and is on property owned by David Wallace. There have now been several sighting of young giant weta, giving evidence that they are breeding, and the weta appear to have spread over much of the reserve as of 2007. Contact David Wallace.
Auckland Tree Weta (Hemideina thoracica)
Korapuki Island (17 ha, Mercury Group off NE North Island). Reintroduction. 52 adult weta from Double Island (also Mercury Island group) were released in May 1997. This is part of the restoration programme on Koropuki following eradication of rabbits in 1986 and kiore in 1987. New Zealand forest ecosystems typically feature a number of weta species and this reintroduction restored one of the more common elements to the invertebrate fauna to Korapuki (the species is widespread over the northern half of the North Island, including other offshore islands). The project also aimed to formulate and improve methods of translocating and monitoring invertebrates in restoration programmes. The weta were attracted into wooden blocks on the source island over several months, then transported in the blocks (which were tied to trees on Koropuki). This method avoided direct handling with the aim of minimizing stress. About 75% of the weta remained site faithful one week after translocation. Additional wooden blocks and short lengths of bamboo have been used as artificial roost sites to monitor both the source population and transferred population. Both populations were thriving at the last census, in March 1999. After two breeding seasons, the Koropuki population had at least quadrupled (based on numbers inside the artificial roosts). Contact Chris Green.
Wellington Tree Weta
Matui-Somes Island (25 ha, Wellington Harbour). 33 weta (14 male, 18 female, 1 unknown) from Mana Island were released on 17 April 1996, and a further 26 (7 male, 19 female) released on 21 August 1997. The population is now well established. Contact Colin Miskelly.
Flax Weevil (Anagotus fairburni)
The species was once widespread throughout NZ, from Northland to Fiordland but is now largely confined to rodent-free islands through its former range. Photo: Mike Meads.
Breaksea Island (170 ha, Fiordland). Translocated from rat-free islets in Breaksea Sound in early 1990s. Norway rats were found on Breaksea until they were eradicated in 1988. Contact Bruce Thomas.
Titi Island (32 ha, Marlborough Sounds off NE South Island). Introduction. 82 animals from Maud Island released at two sites on Titi in February 2001. Norway rats, which had a clear impact on invertebrate fauna, were eradicated from Titi 1970-75. The translocation of Cook Strait giant weta helps to re-establish ecological links which would have formerly existed on the island as well as establishing another population of a species once widespread. Animals were captured from coastal flaxes (Phormium cookianum) and harakeke (P. tenax) by hand at night, held overnight in sealed plastic containers, then released into coastal vegetation (comprising grasses, low scrub, herbs and clumps of flax) on Titi the next day. Each animal was individually marked with a numbered 'bee tag'. The first major survey to assess the success of the operation will be four years after the final release (additional animals may be released). Contact Peter Gaze.
Mana Island (217 ha, off SW North Island). Reintroduction. 70 animals transferred from Maud Island 11 March 2004. Animals were captured from coastal flaxes (Phormium cookianum) and harakeke (P. tenax) by hand at night, held in plastic containers overnight with damp paper towels and trasnferred the following day. Further transfers will occur in subsequent years to a total of c.150 are transferred. Formal monitoring will begin in 2009. Contact Lynn Adams.
Knobbled Weevil (Hadramphus stilbocarpae)
Breaksea Island (170 ha, Fiordland). Translocated from rat-free islets in Breaksea Sound in early 1990s. Norway rats were found on Breaksea until they were eradicated in 1988. Photo: Mike Meads. Contact Bruce Thomas.
Speargrass Weevil (Lyperobius huttoni)
An insurance population of the regionally critical Speargrass weevil (Photo: A. Morrison) is being established on Mana Island (217 ha) off the Wellington coast. 15 weevils (5 males and 10 females), collected from speargrass plants (Aciphylla squarrosa) on the Wellington south coast, were released on Mana Island between March and August 2006. 20 further weevils will be translocated by January 2007. The Wellington south coast weevils represent the only North Island population of L. huttoniand are found at much lower altitudes than south island L. huttoni populations. DNA investigation suggests that they are the same species but the results have not been conclusive. The Wellington population has been decimated following habitat destruction by feral pigs, goats and hares and predation by rodents. Numbers have dropped to less than 200 individuals and management in situ has failed to halt the decline. While there are no records of L. huttoni ocurring on Mana, the island shares a similar climate with the south coast and supports a large population of speargrass in an introduced predator free environment. It is hoped the translocated weevils will establish on Mana Island and provide a source for future relocations to the mainland. Contact Andrew Morrison.
Turbott's Weevil (Anagotis turbotti)
Lady Alice Island (138 ha, Hen and Chickens Group off NE North Island). In September 2006, 30 Turbott's weevils were translocated onto Lady Alice Island from Muriwhenua Island, a small predator free islet in the same group. Weevils were released into cages in West Bay in the hope that they can become established before being released to face native predators including saddlebacks, moreporks, tuatara and Duvaucel's geckos. Half of the weevils were released into a cage placed over a ngaio shrub, one of their preferred food species. The others were released into a cage over a karaka sapling, another favourite food species. The larvae are known to also use these trees/shrubs for boring into. Contact Richard Parrish Richard Parrish or Ian Stringer, Department of Conservation, Science & Research.
Large Darkling Beetle (Mimopeus opaculus)
Lady Alice Island (138 ha, Hen and Chickens Group off NE North Island). In September 2006, 42 large darkling beetles were translocated onto Lady Alice Island from Muriwhenua Island, a small predator free islet in the same group. Most beetles were released into a cages to protect them from native predators, but a few were released outside the cages. Some of both species will be released outside the cages once breeding in proven. Contact Richard Parrish Richard Parrish or Ian Stringer.
Amborhytida tarangensis
Lady Alice Island (138 ha, Hen and Chickens Group off NE North Island). In September 2006, 43 Amborhytida tarangensissnails were translocated onto Lady Alice Island from Taranga (Hen) Island. The snails were released into an area previously chosen as suitable near Koputotara Point, and released in two groups a few metres apart. Fourteen of the snails were fitted with transponders so their fate/movements can be followed in one year's time. Contact Richard Parrish or Ian Stringer.
Flax Snail (Placostylus ambagiosus)
P. ambagiosus (photo: Mike Meads) is confined to the Te Paki Ecological Region at the northermost tip of the North Island. 25 colonies have been found, most of which are designated as different subspecies. There is a small population on Motutakapu Island resulting from a translocation in 1984. There were also several unsuccessful translocations to islands in the 1980s, as well as several mainland translocations that appear to have had little success. Since the 1990s, there have been local translocations at three populations:
P. a. paraspiritus, Cape Maria van Diemen. 31 snails were released at each of two sites within 500 m of the source population in May 1990. The two areas did not have any P. ambagiosus but appeared to have good habitat. The northern site has dense low scrub and kikuyu grass, whereas the southern site has much taller scrub with more open ground cover. The population was monitored each year from 1993-1996 and 1999-2004. Original animals were found at both sites up to 2000. At the northern site, the number of adults found each year increased from 2 in 1993-1994 to 13-33 from 2001-2004, and number of juveniles found each year increased from 15-20 in 1993-1994 to 40-84 from 2001-2004. In contrast, no adults have been found at the southern site since 2001, and 1-5 juveniles have been found each year from 2001-2004. See Sherley (1994), and contact Contact Richard Parrish or Greg Sherley.
P. a. annectens, Te Huka Enclosure. 82 snails released into enclosure in total, with 77 of these released in October 1990. Initially, very few were recaptured. However, over the years to 2002 a thriving population of new snails has developed with 109 snails including 60 juveniles found in 2002. Contact Contact Richard Parrish or Greg Sherley.
P. a. whareana, Whareana Enclosure. About 70 snails were translocated in total, starting with 18 in October 1990. Snails were moved within their type localities into fenced enclosures in areas where they were known to have occurred in the recent past. Rat poisoning was conducted around the enclosures. Snails have survived but as of 2005 no breeding within the enclosure has been detected. Several adults attempted and some succeeded (some more then once) to make their way home up to 70 m away. See Sherley (1994), and contact Contact Richard Parrish or Greg Sherley.
Placostylus ambagiosus ssp., Haupatoto Bush. A fenced enclosure was established here in 1997. Unlike the releases at Te Huka and Whareana, it was decided to wait 5 years before transferring snails from outside into the enclosure to allow the vegetation to recover from stock browse and pig rooting. In 2002 9 adults and 9 juveniles were translocated into the enclosure from above the enclosure. Transponders were fitted to 17 snails. In 2003, 4 snails were found using the harmonic radar. It is assumed the other 14 snails had made their way back to whence they came, but we had insufficient time to search for them. Contact Richard Parrish or Greg Sherley.
Leaf-veined Slug (Pseuaneitea maculata)
Quail Island (off Banks Peninsula, Canterbury Region, South Island. Reintroduction. Quail Island's restoration program (Norton et al. 2003, Otamahua/Quail Island Restoration Plan) has included revegetation, rat and hedgehog eradication, and mouse control, and inventory (Bowie et al. 2003, New Zealand Natural Sciences 28: 81-109) and restoration of the invertebrate community. A total of 25 slugs and 32 eggs (laid by slugs in incubators) were released at the centre of a 3500m2 patch of 6-year-old native vegetation in April 2004 and December 2004. The slugs were collected from rotten logs, weta motels and wooden discs placed at Orton Bradley Park, held in ice-cream containers with leaves covered with sooty mould, maintained in incubator at 10° C, and released under wooden discs on Quail Island. Predator-proof weta motels were put out as a safe refuge, and a mouse eradication is planned. Predator-proof weta motels have been put out as a safe refuge. Monitoring of slug and egg numbers to date suggests that that the population is at least stable as of 2007. From Mike Bowie.