Campbell Island teal
The third release of Campbell Island teal back onto Campbell Island in August 2006 marked the end of a 20-year conservation project for DOC.
The teal, which was the world’s rarest duck, was driven from its Campbell Island home by rats nearly 200 years ago. In fact, up until 1972, when a small population were discovered on rat free Dent Island, the teal was thought to have been extinct for over 30 years. Until then, only two specimens had ever been collected.
Using this small population, DOC was able to turn the tide and establish a self-sustaining/thriving population back on Campbell Island.
Captive breeding programme
Between 1984 and 1990 11 teal were caught on Dent and taken into a captive breeding programme at DOC's National Wildlife Centre at Mount Bruce/Pukaha and The Isaac Wildlife Trust's facility at Peacock Springs.
At that time it was a bold move to take a small number of the birds off Dent Island, further decreasing the population, to put them into a captive breeding programme.
It was a risk, but a calculated one that paid off for the teal. In 1994 the first two ducklings hatched. By 2000 that number had grown to 60.
Campbell Island teal - a male with two females
Transfer from captivity to predator-free island environment
To increase survival chances, and to make sure the species would be safe, it was decided to move some of the rare and flightless birds to Whenua Hou Nature Reserve/Codfish Island, off the NW corner of Stewart Island/Rakiura and home to the Kakapo Recovery Programme.
In 1999 and 2000 a total of 24 teal were released on Codfish. These birds settled in easily and bred in their first year on the island. They spread rapidly around the coast and up the larger streams.
As well as being an insurance population, it also proved that transferring the birds from captivity to a predator-free island environment was possible, with minimal impact on the teal.
This paved the way for the reintroduction onto Campbell Island, but first DOC had to get rid of the rats.
World's largest rat eradication
Tube feeding Campbell Island teal with supplementary foods, before release
In 2001 DOC carried out the world's largest rat eradication. While the island was not officially declared rat free until 2006, a check using trained dogs, traps, and other detection methods in 2003 found no sign of rats and this gave enough confidence for the reintroduction of the teal to take place.
Return of teal to Campbell Island
The first release of 50 birds, including 22 wild birds from Codfish, took place in September 2004. This was followed by two more releases, in 2005 and 2006, taking the total released to 105.
The birds were released at four sites around the island, but rapidly dispersed to their preferred sites, including some significant traverses over major ridges.
Ironically, in 2003, a scientist visiting Campbell found a single male teal which had either swum over 20km around the coast of Campbell Island, or climbed (remembering they are flightless) across several kilometres of rough country from Dent Island, to the mouth of Six Foot Lake. In order to try and maximise the benefits of having the new genetics of this bird several others were released in the same area.
A DOC team, sent to Campbell to monitor the teal in 2008, noticed that they had bred well, shown by the number of unbanded individuals found, and were widespread around the more sheltered coastline. It was agreed that they had established a self sustaining population, meaning that the captive population could be scaled down and the resources put into other endangered species programmes.