New Zealand Waterfowl Reintroductions
Brown teal (photo: D. Armstrong) is a species that is struggling in the few mainland locations left, and also on islands or mainland areas where they have been reintroduced. They breed well in captivity, and many reintroductions and supplementations have been done, mostly using captive-reared birds produced by Ducks Unlimited NZ as part of “Operation Pateke”. However, reintroductions have had poor success with most populations disappearing shortly after reintroduction. Little research or monitoring has accompanied these reintroductions, but predation is probably a key factor. Places where birds have been released since 1990 are listed below.
Tiritiri Matangi Island (220 ha, Hauraki Gulf east of Auckland). Introduction. 12 birds were released, 1987-90. These have bred and hung on in low numbers, but by winter of 2002 only 6 teal (4 female, 2 male) were known to remain. 11 captive-bred birds were released in June and July 2002 to supplement the existing population. Two of these were preyed on (probably by harrier hawks) soon after release. While there are no mammalian predators on Tiritiri Matangi, predation by harriers and pukeko appears to be a limiting factor. The reintroduction is part of the Tiritiri Matangi restoration programme.
Karori Wildlife Sanctuary (225 ha mainland restoration area surrounded by a mammal-proof fence), central Wellington, North Island. Reintroduction. Brown teal 18 captive bred juveniles (9 males and 9 females) were released between November 2000 and April 2001. The reintroduction is part of the restoration program in the sanctuary following eradication of mammals inside the fence (see http://www.sanctuary.org.nz). Survival of transmittered birds was good with 7/9 still known to be alive in Sept 2001, but breeding was not confirmed until late 2002. At least six of the released birds bred successfully and breeding has occurred every year since then. Good productivity has resulted in increased competition for preferred wetland habitats and, because these habitats are limited in the Sanctuary, losses have occurred as a result. Transfers of surplus juveniles to new sites is a preferred option for management of the population because this would also help establish new populations elsewhere, but suitable release sites are yet to be identified. Therefore supplementary feeding of maize has been largely discontinued since early 2006 to reduce productivity and competition for territories. Genetic analysis of the population in 2006-2007 should clarify whether or not there has been a loss of genetic diversity and whether additional birds need to be released into the population in future. Contact Raewyn Empson.
Coromandel Peninsula (NE North Island). Supplementation. Brown Teal have been released at Port Charles, Coromandel Peninsula. 38 were released 38 in 2003, 42 in 2004, 62 in 2005 = 62, and 72 in 2006, always with birds that were 6-11 months of age and with an approximately 1:1 sex ratio. A release of 50 further birds is planned for January 2007. The release site has about 500 ha of wetland, pasture, and forest, and the species existed at the site in small numbers, down from the large numbers found historically. The aim is to establish a viable breeding population outside the species’ strongholds on Great Barrier Island and eastern Northland. The release site was chosen for a number of reasons, including its situation in the centre of the Moehau Kiwi Sanctuary’s 30000 ha mustelid control area. Specific cat control was established, and is maintained year round by another local landowner. Birds were bred by the Pateke Captive Breeder Network (20 breeders nationwide), co-ordinated by Kevin Evans (Pateke Captive Breeding Co-ordinator), using captive stock originating from Great Barrier Island. Six weeks prior to each release, all birds were transferred to Isaacs Wildlife Centre in Christchurch for quarantine and disease screening. Before release, birds had colour bands and had radio transmitters attached, were transported from Christchurch to Auckland, then flown by helicopter to the release site. Supplementary food was provided at the release site. Released birds are monitored using telemetry and visually monitored by a local landowner daily for first month, then twice weekly for 12 months. Flock counts are done at several locations each February. The released birds have had an average of 65% survival for the 12 months after release. The main cause of death is now vehicle strike, followed by cat predation, and measures are being taken to reduce the incidence of vehicle strike. Monitoring in 2005-06 and 2006-07 will determine wild bred juvenile survival to breeding age. There is ongoing predator and habitat restoration, all with active participation from land owners who have been pivotal to the success of the project. Contact Jason Roxburgh, Department of Conservation, Hauraki Area Office.
Tuhua/Mayor Island (1277ha, Bay of Plenty). Reintroduction. 28 brown teal were released in February 2006 (Forest & Bird 320: 15). Mammalian predators, including Norway rats, kiore, feral pigs and feral cats were eradicated in 2000. Tuhua comproses mainly pohutukawa/hardwood forest with shrublands and wetlands. Ducklings seemed to be abundant in December 2007. Contact John Heaphy.
Travis Wetland Nature Heritage Park (119 ha freshwater wetland in Christchurch, South Island, Grid ref 853 469 NZMS series 260). Reintroduction?. 20 captive-bred teal (10 male, 10 female, 4-6 months old) released 16 May 2007. The teal were sent from captive breeders to Lady Issacc’s Peacock Springs wildlife park for quarantine for 1 month before release, fitted with Sirtrack transmitters on 14-15 May, and transported by road to Travis Wetland and released at 11.00 am on 16 May. They were monitored daily for the first month, then 3 x per week. As of the 30 December 2007 there were 8 birds remaining on site (4 male, 4 female) and signs of breeding behaviour but no sign of ducklings yet. 11 birds have died; 4 due to cats, 1 due to stoat, 5 either due to harriers or scavenging by harriers made it impossible to determine, 1 female due to car 10 km away from the release site (all transmitters and remains have been recovered). The reintroduction is part of the restoration of Travis Wetland, but known to be uncertain due to predation risk. We have set out to provide a predator reduced environment where the pressure from predation is not limiting breeding success of resident wetland bird species. Trapping for mustelids and rats has been in place for 5 years, with 58 traps distributed over 2 trap lines (one around the perimeter and the other through the centre of the wetland). The habitat is a mix of peat sedge/rush swamp, mixed exotic and native grazing marsh on mineral soils, willow forest and restoration planting, permanent and seasonal open waterways and ponds. Contact John Skilton.
Tawharanui Open Sanctuary (588-ha predator fenced peninsula 90 km N of Auckland). Reintroduction. There was an attempt to reintroduce brown teal to Tawharanui in 1995 before the predator-proof fence was erected, but all 8 birds released at that time were killed by cats or stoats. In Feburary 2008, brown teal became the fourth bird species to be reintroduced following the erection of the predator-proof fence and mammal control/eradication programme. 24 captive-bred birds were “hardened off and socialised” at Peacock Springs, Christchurch, and released immediately in one group. Supplementary feeders were installed as a habituation tool. Minimum 69% survival as of December 2008, with 5 known deaths outside the pest-managed zone (fenced area plus buffer). 3 broods of young observed. Further released of >= 40 birds planned for February 2009, and possibly more in 2010-2011. Contact Matt Maitland.
Some reintroduction attempts with little information available are as follows:
Mimiwhangata.175 birds released, 1984-91.
Mouroa Island.20 birds released, 1985-94.
Urupukapuka Island.25 birds released, 1988-94.
Purerua Peninsula.330 birds released, 1989-92.
Hokianga Harbour.167 birds released, 1993-94.
Waikino Inlet.30 birds released, 1994.
Waihoanga Stream.27 birds released, 1996-97.
Parorerahi Bay.28 birds released, 1997-98.
Campbell Island (11,300 ha subantarctic island). Campbell Island Teal were reintroduced to Campbell Island in 2004 (50 released), 2005 (55 released), and 2006 (54 released) following eradication of Norway rats in 2001. Campbell Island teal are flightless, and presumed to have been killed off by rats soon after their discovery on the island in 1810. They survived on 26 ha Dent Island (approx 3 km off the coast of Campbell), and birds from Dent were brought to New Zealand for captive breeding programme in 1984 and 1990. The first breeding occurred in 1995, and 12 birds were released on to Whenua Hou (Codfish Island) in 1999 and 2000 to prepare them for survival on Campbell. Subsequent monitoring has found no evidence of rats. Some birds have stayed close to the release sites (3 sites in the same catchment) while others travelled widely, one bird moving over 5 km around the coast and another moving 1 km up a hill to an altitude of 187 m. A Department of Conservation team that visited the island over the 2005/06 summer found ducklings from that breeding season and unbanded adult ducks from the previous breeding season. Contact Peter McClelland.
The blue duck (photo D. Armstrong) is a river specialist. They were formerly widely distributed in the North and South Islands, but are now mainly restricted to forested mountains where waterways have not been substantially altered by hydro-electric developments.
Egmont National Park (west central North Island). 12 birds were released in Egmont National Park over three separate releases (1986, 1989 and 1991). Of these, seven were captive-reared juveniles and five were wild adult birds from the Manganui-a-te-ao River. So far the establishment of blue duck in Egmont National Park has been of limited success with only 3 known birds remaining, all of which are male. These are distributed widely, one on the Waiaua River (originating from the 1991 release), one on the Waiwhakaiho River (the single male released in 1989) and one on the Manganui River in the area of his release in 1986. Breeding has been recorded in the past. However with an observed lack of females within the present known population, there is no chance of continued natural recruitment, and there is currently a proposal to translocate more animals. See Hutchinson (1998).
Kahurangi National Park. Attempts to protect blue duck in Kahurangi National Park continue to use the technique of raising young in captivity for re-introduction. The first clutch is taken at mid incubation, hatched in captivity and raised until the young are on the point of fledging before being returned to their natal river. The adult female has usually been able to go on and raise a second clutch. The technique has been used most successfully in the Wangapeka catchment where predators are controlled and the injection of many young birds has allowed a rapid response by the population from an initial known population of 3 birds. An attempt to use this technique to re-introduce blue duck into the Flora catchment was not successful. These young were released late in the summer of 2004 into a river that has less invertebrate food and the problems were compounded by a particularly tough winter. The surviving young, however, were recaptured, nursed back to health in captivity and then released the following summer (January 2005) into the Wangapeka where they have flourished. Another attempt to re-introduce birds to the Flora (where predators are also controlled) will be made using wild raised young just prior to fledging. A further 11 ducks were released in the Wangapeka River catchment in Mach 2006, giving a total of at least 27 blue ducks at the time of the release to supplement the populationFrom Peter Gaze.
Karori Wildlife Sanctuary (225 ha mainland restoration area surrounded by a mammal-proof fence), central Wellington, North Island. Reintroduction. 7 captive-bred birds (4 males and 3 females) were released from Wellington Zoo between April 2001 and March 2003. The reintroduction is part of the restoration program in the sanctuary following eradication of mammals inside the fence (see http://www.sanctuary.org.nz). The first ducklings were produced in early December 2002 and scaup have bred every year since then. Given that there were no lakes in Wellington historically, this is probably the first time that scaup have ever bred in the wild in Wellington (the nearest natural populations of scaup are in the Horowhenua or the Wairarapa). Scaup can be seen on both lakes but limited habitat probably means that some are dispersing outside the sanctuary. ContactRaewyn Empson.
Mt Bruce Wildlife Centre wetlands (not captivity). Two birds were transferred from captivity in August 2004. More will be transferred as they become available and if techniques ensure birds stay at the site. Bird wings were clipped to encourage them to stay on the wetland, recognising that they would be free to fly away once wing feathers moult. Birds are feed supplimentary food daily. Contact Raelene Berry.