A nationally critical gull species might be nesting in Te Anau soon, prompting the Department of Conservation to ask neighbours to take care for the next couple of months.
Regular passersby along the mouth of the Upukerora River might have noticed some regular avian visitors settling in.
The black-billed gull is one of the most threatened gull species in the world, but DOC senior ranger George Ledgard said their large flock numbers along the shores of Lake Te Anau could give people the impression their population was doing fine.
"Even though you see them in big flocks, their whole survival relies on large groups interacting with other groups within Southland.
"Nationally, the trend of flocks of birds is going down. Having multiple locations for breeding, and multiple breeding flocks, is essential for their survival and genetic diversity."
He said the flocks had recently settled in along the mouth of the Upukerora River, indicating they could be ready to nest. To ensure a successful breeding season, people were being asked to avoid driving their four-wheel vehicles or walking a dog without a lead along the open gravel river areas.
"Disturbance is a large thing, and people aren't often aware that driving a four-wheel drive through that open braided river bed habitat, or running their dog through there, can disturb those birds," Mr Ledgard said.
"If they're disturbed multiple times, they just leave their nest and try to nest somewhere else... The more they get disturbed in the front end of the season, the less likely they are to have a successful brood later in the season."
The birds breed from September to January. Mr Ledgard said outside of that season the department was happy for people to use the area for four-wheel driving or walking a dog without a lead.
Key predators to the gulls were feral cats, stoats and weasels.
Mr Ledgard said to get in touch with him if people were interested in setting up a small stoat trap network in the area.
"If we can check them once a week over the breeding season then it's going to benefit all birds, including ducks."
Notes for users of the Lower Upukerora:
• Avoid 4WD and motorbiking on the True Right of the river mouth between August and January.
• Keep dogs on a leash if walking across gravelled areas.
• Eggs and nests are very cryptic and difficult to spot.
• If you see unusual (vocal and distressed) or aggressive bird behaviour they are probably trying to protect nests or young so remove yourself from the area by walking back the way you came. Without disturbance, nesting success improves significantly.