A braided river popular for fly fishing and other recreational pursuits is a fragile breeding ground for an endemic bird that is declining in numbers
Upukerora River, which flows into Lake Te Anau northeast of Te Anau township, is a nesting site and playground for several rare bird species, including the endangered black-billed gull, tarāpuka, and black-fronted tern, tarapirohe.
But it’s the young of the banded dotterel, tūturiwhatu, a petite plover known for its distinctive chestnut breeding plumage, that are most at risk this breeding season from careless beach users.
Hatching a plan
A dozen volunteers, who five years ago formed the Lower Upukerora Restoration Group (LURG), are doing what they can to ensure the survival of the dotterels’ latest fledglings.
Volunteer Anja Kohler spends hours during the birds’ breeding season between late August and early January monitoring and identifying the adult dotterels and their chicks.
Ensuring they get to the fledging stage is a rewarding but sometimes heartbreaking pursuit.
Last season, eight of 25 monitored nests yielded a total of 12 fledged chicks. Three of the nests failed because they were crushed by vehicles or wiped out by storms and it’s unknown what happened to the others.
Kohler says early this breeding season a nest of eggs that had been incubating for 17 days was crushed by someone driving on the beach.
Dotterel eggs are also easy prey for mustelids, rats, cats and other birds and can be mistakenly trodden on by beachgoers and dogs.
The birds nest in clean gravel or sand and sometimes farm land where they can conceal their speckled cream-coloured eggs from aerial predators.
The restoration group has erected signs to educate and warn beach users about the nesting and roosting season. It has also placed boulders in front of the car park to deter people from driving on the beach.
Kohler says the rocks intended to get off-road drivers “to stop, reflect” and go elsewhere were seen by a few as “a challenge to conquer”.
“The first year the rocks were in place people stopped and read the signs but I’ve since seen a lot of tyre tracks going around the rocks.”
If people are fishing during the breeding season, she urges them to walk across the mudflats to the lake shore.
Banded dotterels, which are not usually vocal, become so when their young are threatened and do what the volunteers call the “broken-wing dance” to draw attention away from their nests.
“If you’re walking along the mudflat or gravel and witness this behaviour, it’s a clear sign that there is a nest or chicks nearby. You should stop, go back the way you came and look for an alternative route,” says Kohler.
In the early stage of nesting the volunteers do weekly checks of nesting sites. Once eggs are laid and chicks hatch, they visit daily.
Kohler, a keen photographer, users her camera to identify and monitor the nests.
Last year major floods in September wiped out some nests so this year the volunteers are hoping to see more chicks reach fledgling stage.
Some of the birds nested early this season and some might nest twice, says Kohler. “It’s looking like a good season but I don’t want to jinx it.”
Department of Conservation (DoC) science adviser Clement Lagrue says there are no accurate figures of New Zealand’s banded dotterel population because their migratory nature makes them difficult to count. But they are classified as at-risk and declining.
DoC estimates the population of mature birds will be between 5000 and 20,000 by the end of this year, but expects it to fall by between 10 and 30 percent within the next five years.
“They are in trouble despite the fact they are not the most threatened dotterel species in New Zealand. They are not doing great,” says Lagrue.
Habitat modification is the main threat, he says.
Lagrue leads the Aparima River restoration project that is working to improve a 10km stretch of the Southland river that is a breeding ground for several endangered bird species.
The good news for rare or declining birds that nest on braided rivers is that “as soon as you do a habitat restoration they come back”, he says.
But people using the rivers also need to play their part in aiding their survival.
“It’s a tricky lifestyle for a small bird so we need to help,” says Lagrue.
Although 80 percent of people might read the signs and avoid breeding sites, a single unrestrained dog can destroy numerous nests, as Lagrue recorded last year using fixed cameras.
In one instance a pet black labrador sniffed around a nest after the adult bird fled, crushing the eggs.
“You then see the parent coming back to a destroyed nest. You can guarantee the dog owner didn’t even know what their pet had done,” he says.
“Around Te Anau there are plenty of places you can take your dogs for a swim where they are not going to affect any birds. It’s just a matter of trying to share the rivers with their rightful owners,” says Lagrue.
George Ledgard, co-ordinator of the river-restoration volunteers, says the lower Upukerora’s high use poses problems but also creates an opportunity for community ownership and responsibility for the values of the area.
“It’s not just all about the birds, it’s about people using the area responsibly and recreationally and also trying to get the blend right of a sympathetic sort of recreational use of an area that has biodiversity values as well.”
The Mohua Charitable Trust, which is dedicated to native bird conservation in the South Island, funds the majority of the volunteer group’s work.
Volunteers spend up to 600 hours a year on the project, which includes advocacy work as well as pest and weed control.
Ledgard says their three goals are protecting the indigenous bird species at the river mouth and upstream, restoring and enhancing vegetation near the wetland and river banks and encouraging recreational activities that are sympathetic to the area.
That means off-roaders and roaming dogs avoiding the beach during the breeding season, he says.
Made with the support of the Public Interest Journalism Fund