Seagull population along B.C.’s South Coast down 50 per cent

WATCH: Experts say we should be concerned about the dramatic drop in the number of seagulls. Linda Aylesworth reports.

VANCOUVER – The seagull population along B.C.’s South Coast has declined 50 per cent since the 1980s and researchers from the University of British Columbia say the decline reflects changes in the availability of marine food.

The Glaucous-winged Gulls are the most common seagull species found in the Lower Mainland and on the island and researchers looked at 100 years of data for these birds. They found the population increased starting in the early 1900s, but started to drop after the mid-1980s and pointed to diet as one factor.

“These birds are the ultimate generalist, they can eat whatever’s around,” says the study’s lead author Louise Blight. “If they are experiencing a population decline, the gulls may be telling us that there have been some fairly profound changes to local marine ecosystems.”

Seagulls mostly rely on a purely marine diet, but over time, with the availability of more human food and garbage, their diet has been adapting.

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WATCH: A new UBC study says the seagull population in the Strait of Georgia has fallen by 50 per cent since the 1980s. Lead researcher Louise Blight joins Global News with more.

“They’re presumably turning to land-based prey sources because the things they prefer to eat are less available,” says Blight, explaining that there are now likely both fewer forage fish and a lower diversity of these fish in coastal waters than there was prior to industrial fishing, and that gulls need fish foods to breed successfully.

“Gulls are an indicator of our coastal marine ecosystems,” she says. “We need to be restoring ecosystems along the coast, and that includes restoring fish populations.”

The study of marine bird populations in the Salish Sea can also show why the Marbled Murrelets and the Western Grebes have also declined by 90 per cent since the 1950s and 70s respectively.

The study “A century of change in Glaucous-winged Gull (Larus glaucescens) populations in a dynamic coastal environment” was published earlier this month in The Condor: Ornithological Applications.