The Chatham Island oystercatcher/tōrea is ranked as critically-endangered. In 1998 DOC began an intensive oystercatcher management programme. Thanks to these efforts, bird numbers have increased and the future outlook for the species looks quietly optimistic.
Chatham Island oystercatcher at nest
Ecology and habitat
Lifespan: The Chatham Island oystercatcher lives for an average of 7.7 years.
Size: Adults measure about 48 cm.
Diet: Marine molluscs, worms, and other invertebrates.
Habitat: Nests are usually built in 'scrapes' on sandy and rocky shores clear of the waterline. Oystercatchers also breed amidst low vegetation.
Chatham Island oystercatcher
Population and range
Breeding pairs are found on South East Island, Pitt Island, Mangere Island, and Chatham Island.
In December 2004 the oystercatcher population included 88 breeding pairs and a total of 311 birds. This is more than double the number of birds counted in 1998, when the intensive management programme began.
Predation of eggs and chicks by cats, hedgehogs and weka has a major impact on species productivity and has been the most significant cause of population decline.
Domestic stock are known to crush eggs and chicks. Vehicles driven on the beach also pose a threat to nests.
Introduced marram grass has formed dense swards along much of the coast and artificially steepened the sand dunes, leaving few open areas the oystercatchers prefer to nest in. This forces the oystercatchers to nest close to the high-tide line where tides and storm waves can wash away nests.
Chatham Island oystercatcher nest
containing eggs, Tioriori Beach,
Banding Chatham Island oystercatcher,
Past oystercatcher management has been piecemeal. Conservation in the early 1990s focussed on predator trapping, and fencing to limit stock access to nesting areas. Some nests were moved away from the high tide mark. Nest manipulation may have helped to increase hatching success. Artificial incubation was also attempted, but did not increase overall productivity.
In 1998 DOC began an intensive Chatham Island oystercatcher management programme.
This plan involved:
- Predator control To protect 16 oystercatcher territories on northern Chatham Island. Modification of fences to exclude stock from managed areas.
- Nest relocation Movement of nests away from the high tide mark.
- Dune restoration This was undertaken to provide more habitat.
- Video monitoring Nests were monitored with video cameras. Some of this footage was even packaged for Chatham Island television, giving helpful publicity to the conservation effort.
In 1999 a joint management/research programme commenced. So far this programme has been very successful, and includes the following outcomes:
- New breeding pairs have been established.
- A significant number of chicks has been produced.
- Many chicks have been colour banded to aid future monitoring.
- Research involving the monitoring of breeding success, nest losses, and bird movements, has been 'more successful then originally anticipated.'
The long-term vision of the Chatham Island Oystercatcher Recovery Plan is to:
'Restore the natural ecology of the coast so that the oystercatcher population is maintained at or above 250 birds with minimal management.'
Chatham Island oystercatcher recovery plan (PDF, 163K)
You can help
Oystercatchers depend on the coast for their food and for a safe place to rear their young.
Nesting birds are easily disturbed by people and will move from the nest to draw you away if you approach. Birds with chicks are often noisy and may swoop to chase you away.
The picnic or fishing spot you choose might be near a nest. If birds appear to be disturbed by your presence, move further along the beach.
- Keep dogs under control.
- Walk or drive below the high tide mark to avoid crushing eggs or chicks.
- Fence the coast to keep stock off the beaches.
- Neuter your pet cats to prevent kittens getting into the wild and keep them indoors at night.
- Help with a coastal restoration project.
Chatham Island oystercatchers – a summer at the beach - Conservation blog 27 February 2012