3 Dec 2018

A gravel island built in a wetland reserve near the estuary is proving a lifeline for up to 300 endangered black-billed gulls.

The gulls are nesting on the island in the Charlesworth Wetland Reserve, Ferrymead, which is protected from the heavy rain and flooding that has destroyed other river nesting sites.

It was reported last week that the nests and eggs of about 2500 black-billed gulls were washed away by flooding on the Ashley/Rakahuri River in North Canterbury.

The island in the reserve, which is about 25 metres long and a metre above the tide line, was built by Christchurch City Council staff in 2003 in the hope of creating a safe nesting habitat for the black-billed gull, which is critically endangered in New Zealand. 

Council Ranger and Ornithologist Andrew Crossland says this is the biggest breeding colony of black-billed gulls and their coastal cousins red-billed gulls seen at the site since before the Canterbury earthquakes and provides a “glimmer of hope”.

“We have up to 300 birds nesting there at the moment. This location is safe from river flooding and we think the chicks have got a really good chance of surviving. It’s a signal to other councils and organisations that if we create these islands on tidal or freshwater wetlands then the black-billed gulls will come, and we can help boost the population which has been in rapid decline. It’s a great result for the survival of this species.”

Predators such as black-backed gulls, ferrets, cats and stoats have impacted on the threatened birds’ numbers, along with a reduction in habitat, mainly from weed invasion of riverbeds.

Charlesworth Wetland Reserve is made up of 20 ha of land, separated from the Avon-Heathcote Estuary by Linwood Ave and Humphreys Dr. Restoration of the area, which had been drained and used as pasture, began in 1991 and expanded in 2003 when tidal pools were re-created to attract native wetland birds.

Over 135,000 trees, shrubs and marsh plants have been planted since then in a project led by Council Park Rangers. Volunteers from the Avon-Heathcote Estuary Trust play a major role in caring for them.