Rats – The Biggest Threat to Campbell Island Teal:
The Campbell Island Teal ran in to trouble when Norway rats were introduced from sealing and whaling ships that visited Campbell Island in the early 1800’s. Rats are known to prey on birds, their eggs, and their chicks, and so are a significant threat to the survival of many land birds.
Because they are flightless, they weren’t able to escape this predatory species and many were killed. When naturalists arrived on the island in 1840, they recorded that there wasn’t a land bird in sight, which suggests that they were already threatened with extinction just 40 years after rats were introduced.
The Re-Discovery of a Species:
Rumours circulated that the Campbell Island Teal existed and after several supposed sightings but no live specimens, hope began to fade. It was assumed that the Campbell Island teal was extinct. However, in 1975, visiting conservationists Christopher Robertson and Rodney Russ could hardly believe their eyes when they pulled a female Campbell Island teal from behind a moving tussock on Dent Island.
The Department of Conservation moved quickly to remove some of the birds to a predator-free sanctuary in Pukaha Mount Bruce. They took 3 males and 1 female and attempted the first ever Campbell Island teal captive breeding programme.
Initially, the programme failed and so they returned to Dent Island in 1984 where they captured another 4 males and 3 females. Only one female, named Daisy, had laid eggs in the past but was not particularly interested in any of the male ducks.
Finally, after years of anguish, Daisy accepted a mate and in 1994, the world was over-joyed to see the first captive-raised ducklings and hope was quickly restored in the conservation of the Campbell Island teal.
The Back-Up Population:
In 2000, the captive breeding population had gone from 11 adult birds to a total of 60 birds. A number of these birds were quickly re-located to Codfish Island (Whenua Hou), off the coast of Stewart Island, to act as a “back-up population” in case disease threatened the group.
The Return to Campbell Island:
After a major eradication operation in 2001 that removed rats from the island, a number of birds were re-located back to Campbell Island. In 2004, 50 birds were released on the island. Another 55 were released in 2005, and 54 in 2006, which boosted to total estimated wild population number to 159.
Many of the birds were fitted with radio tracking devices that allowed them to be monitored by biologists. This gave them an idea of how many birds were able to surive in the wild, windy conditions of Campbell Island. For example, these devices allowed scientists to confirm that 35 of the 50 birds released in 2004 were alive.
The eradication of rats from Campbell Island saw vegetation, wildlife, and invertebrates flourish and in 2006, the first island-born ducklings were observed on the island. Conservationists finally had the evidence they needed to see that all their hard work had paid off in saving a tough little flightless duck from extinction.