Gulls... food for thought

Forest and Bird, Volume 18, Issue 3, 1 August 1987, Page 34

Gulls... food for thought

) be you are a hungry seagull soaring on the breeze high above a sandy beach wondering what might be on the lunch menu. Fish and shellfish are getting a bit scarce these days, but look . . . there are some picnickers — they'll leave some crumbs. And a flight inland might turn up something _..a freshly ploughed field, the local rubbish tip, a freezing works. There’s always plenty to choose from if you're a hungry seagull! No doubt that’s why there are large numbers of seagulls — as humans have spread, seagulls have followed, surviving off left-over food scraps and waste. Life never used to be quite so good for New Zealand's three gull species the black-backed, red-billed and blackbilled. Last century, for example, the karoro as the blackbacked was called by Maoris who hunted it — was relatively uncommon. Today large flocks of these seabirds even nest in tall city buildings. In fact, although they can be found breeding in these unusual places, black-backs prefer islands, headlands and riverbeds where they breed either in isolated pairs or in colonies. You can also find them living as high as 5000 ft.

Both black-back parents incubate the purple or brown spotted eggs for up to four weeks and the emergent chicks are fed on regurgitated food. Within only two weeks the chicks desert the nest and by seven or eight weeks they can fly. They will eventually grow up to 60 cm long. Red-billed and black-billed gulls are almost half the size of the black-backed gulls and are easy to tell apart because of the different colouring of their bills and legs. Both have webbed feet with strong toes for clinging firmly when gale force winds threaten to blow them away. The red-billed is the most common, living on the coast; the black-billed on the other hand breeds and lives mainly in inland areas of the South Island, although it has breeding colonies in the North Island. These two species of gull usually return to the same breeding spot year after year where they lay a clutch of two or three eggs. After three weeks the chicks emerge into the world, using their pronounced egg tooth to chip their way out. If you do discover a breeding colony, do not approach too close as you will panic the chicks into running in all directions. That could mean that they lose their parents or are pecked to death by neighbouring gulls. Gulls take up to four years before they can finally be described as adults, with a full adult plumage. That is why you often see flocks of immature gulls roosting and scavenging in cities all year round, rather than going off to breed as the adults do. Humans have created difficult situations for themselves and seagulls. We have built rubbish dumps or sewage outfall pipes near airports and made it more likely that an aeroplane might hit a gull because there are now so many of the birds nearby. And so today we have to look at ways of getting rid of gulls in such dangerous areas — perhaps if we had thought about it beforehand, we could have avoided the problem.