Have you seen any colour-banded gulls or terns?
As the long, hot dry summer gives way to autumn and winter over the next few months, New Zealand eBirders are encouraged to keep an eye out for colour-banded black-billed gulls and black-fronted terns when out birding in their local ‘patch’.
Both black-billed gulls and black-fronted terns are being banded as part of ongoing monitoring projects being carried out on rivers in the Marlborough and Canterbury regions.
Black-billed gulls are being banded on the Wairau, Clarence and Buller Rivers as part of a study being carried out by Wildlife Management International (WMIL) staff member Claudia Mischler, with the assistance of Marlborough Birds New Zealand members. “By colour-banding the chicks that fledge from colonies on these rivers each season, we’re hoping to keep track of juvenile survival and recruitment rates in local populations of this nationally endangered species” says Claudia. “We’re also hoping to build a better picture of where the wintering grounds of Marlborough’s black-billed gulls are”.
Each banded gull has been fitted with a large coloured leg band inscribed with an alpha-numeric code, with the colour of the band corresponding to the river on which that particular bird has been caught and banded. Birds carrying white bands have been caught at breeding colonies on the Wairau River, whereas birds carrying yellow and red leg bands have been banded on the Clarence and Buller Rivers, respectively.
Another research project investigating the breeding success of black-fronted terns on the upper Clarence and Acheron Rivers in inland Canterbury is being carried out by WMIL staff and is jointly funded by the Department of Conservation and Environment Canterbury. The aim of this project is to test a novel combination of intensive predator control and habitat management in the vicinity of black-fronted tern colonies, in order to improve the breeding success of this embattled shorebird. Black-fronted tern chicks that fledge on these rivers are being fitted with either coloured bands or flags, each of which is inscribed with a unique two-letter combination. As with the black-billed gulls, terns that fledge on the Clarence or Acheron Rivers are being fitted with yellow bands or flags. In addition, a number of terns have also been banded on the Wairau River in previous years, and have been fitted with white bands or flags.
If you are fortunate enough to spot one of these banded or flagged birds on your travels, please make a special effort to record the band colour and number in the species’ comments field in your eBird checklist, and if possible upload a photo of the bird or birds that you saw. That way, you’ll be making a valuable contribution to our growing understanding of the status and movements of these two highly-threatened shorebird species. To date, only a handful of South Island-banded gulls and terns have been re-sighted in the North Island, so any reports of banded birds from the North Island would be particularly interesting.
A banded black-billed gull, copyright Nikki McArthur
Handy tip: Black-fronted tern bands in particular can be a difficult to read, due to their smaller size and the birds’ short, stubby legs. If you don’t have a spotting scope handy, another easy way to read the band is to take a good-quality digital photo of the bird, then use the optical or digital zoom function on your camera to zoom in and read the band’s two-letter code from the photo.
Even if the birds that you see are not banded, it would be very useful to add a comment to your eBird observations specifying that the birds that you saw were unbanded. Sightings of unbanded birds are also valuable to researchers, as this helps to build a picture of the sites and habitats which these banded birds aren’t visiting.