Black-billed gulls are one of the rarest gull species in the world. Photo / Paul Taylor
Black-billed gulls are one of the rarest gull species in the world. Photo / Paul Taylor
A small group of gulls often seen in Waipukurau’s main street has been identified by the Department of Conservation (DoC) as the threatened black-billed gull/tarāpuka.
Black-billed gulls are only found in Aotearoa/New Zealand, with most breeding on braided rivers in the South Island, and a potentially expanding population in the North Island.
A nationwide census of the birds was conducted over the 2023/24 season, led by DoC ranger Claudia Mischler.
“Being endemic, these gulls are special. I’m only guessing as to why they might have chosen Waipukurau as their home, but looking back at some of my North Island records there was a colony on the Tukituki River in 2014/15 of just over 50 nests, which wasn’t too far from Waipukurau,” Claudia said.
“The birds move around a bit in the Hawke’s Bay area, nesting on the Tukituki or in and around Napier. Last season they nested on the Ngaruroro River - approximately 50km in a straight line from Waipukurau and, realistically, CHB isn’t that far away from any of those locations, not for a flying bird. So it makes sense that they have ended up there, especially since the Tukituki flows right past.
Black-billed gulls prefer to feed on bugs found on farmland or rivers. Photo / Paul Taylor
“Black-billed gulls love ploughed paddocks or anything with short grass which is wet and might have insects or worms. Unlike the red-billed gulls, the black-bills prefer to feed more on bugs and things found on farmland or on rivers, whereas red-bills rely on the marine environment. That’s not to say that the black-bills don’t feed at sea, but that is not their primary food source.
“For whatever reason, they have ended up right in the middle of your town, and may have caught on to human food. This is not ideal because they will hang around, leading to people getting frustrated by them. If people don’t feed them they might decide to leave town to get back to their normal source of food.”
The native gulls have long, thin black beaks that are easily distinguished from the shorter and stouter bright red beak of the red-billed gull. The gulls are a similar size to red-billed gulls, but have paler wings and a thinner black border on the wingtips.
During the breeding season, black-billed gulls feed primarily on invertebrates taken from rivers and adjacent pasture. In Southland, most birds forage on pasture invertebrates. Black-billed gulls also feed on fish such as whitebait. During winter, birds continue to use agricultural habitats, but also feed in the coastal marine zone on fish and marine invertebrates, sometimes flying tens of kilometres for food.
The native gulls have long, thin black beaks that are easily distinguished from the shorter and stouter bright red beak of the red-billed gull. Photo / Paul Taylor
They are less likely to be found in towns and cities than the other gulls, and are not commonly observed scavenging for food.
Black-billed gulls are affected by a wide variety of threats. Introduced predators such as cats, stoats and ferrets take eggs, chicks and adults, and native swamp harriers and southern black-backed gulls take eggs and chicks.
After a national count was carried out in 2016/17 the number of breeding birds was higher than expected, allowing the threat classification system to be downgraded from “threatened – nationally critical” to “at risk – declining”.
A census using the same methodology was conducted over the 2023/24 season, led by Claudia, with all suitable rivers in the South Island flown, and aerial photographs taken of all colonies found.
The North Island was surveyed on the ground by BirdsNZ volunteers.
