Wednesday, December 16, 2009

Rush hour.

On cold winter mornings, Vs of large, pale birds fly south over this city, low and mostly silent. You might not even notice them. Then in the day’s waning light, they fly north again.

That sounds vaguely mysterious. What are these birds, and what are they up to?

Well, they’re about as commonplace as you get –seagulls. But it’s a good question, what are these ubiquitous, not particularly admired birds up to?

For starters, the fact is there is no one species officially called “seagull.” There are many kinds of seabirds known as gulls, and about a dozen kinds regularly are found in British Columbia. Five or so are seen commonly in Greater Vancouver at various times of year. But the large one on the lamp post outside your window, the one that epitomizes “seagull,” is by far the most numerous species, and it goes by the hefty name of Glaucous-winged Gull.

Glaucous means silvered or frosty. Other large gulls, such as the widespread Herring Gull, have wings tipped in jet black. The wingtips of Glaucous-wings are pale gray, or graphite.

These gulls live near the shore, ringing the northern Pacific Ocean from Japan to California. They shift northward in summer months and south in the non-breeding season. There are Glaucous-winged Gulls in Greater Vancouver throughout the year, with the highest numbers occurring in early winter. They can be seen along the river, in farm fields, school yards, and in particular, at garbage dumps.

This latter attraction explains the daily flights. The birds are heading from night roosts along the Burrard Inlet, English Bay, or the lower Fraser River to the Vancouver Landfill in Delta, where they swarm amid the bulldozers and trucks, searching for edible trash. (One of the reasons they are so beloved.)

Their natural diet is mostly seafood, consisting of small fish and invertebrates, including hard-shelled molluscs that they drop onto rocks to break open. During the breeding season, most revert to these foods, because the rocky islets along the BC coast that provide most of their breeding habitat tend to be isolated from waste dumps. Most breed in colonies, although some will breed singly.

Numbers of Glaucous-winged Gulls have increased perhaps four-fold in the past 60 years, due in part to their ability to capitalize on the garbage produced by an ever-expanding human population. As a result, increasingly they are breeding in and around cities, including on flat rooftops. Thankfully, they do this as singles, not colonies. Interestingly, perhaps wisely, the urbanized birds with their fondness for human scraps tend to collect natural food, small shallow-water fish such as herring and sand lances, to feed their growing young.

At this time of year, the now full-sized young of the year flock with the adults, off to the dump. They are identifiable by their dingy brown plumage. Gradually, over four years, white and grey replace brown, and the dapper adult plumage appears. Note that in winter even the adults look a little shabby. The head and neck lose the pure white characteristic of the breeding season and appear barred or smudged with brown.

This may be more information about a gull than the average person cares to know. It’s still a seagull, among the most disdained of urban wildlife. There are profane names for these things. This harsh recognition, if anything, is a sign of success. We tend to frown upon animals that succeed as well as humans, in concert with humans, even in spite of humans. They do so by doing much that we do—they cooperate, they squabble, they care for their young, and now here, in Greater Vancouver, as the sun rises and sets, they commute.


PSYL said...

As also read in the physical copy of the Richmond News, or online here:

Wanted to say great article over the weekend, but forgot to. But great blogging it!

Victoria said...

I like gulls. I think they're kind of sentimental and nostalgic. But they always do surprise me with how wide they can open their beaks when they call or swallow something - it's a bit disconcerting. Great article.

Karen said...

Thanks for this careful look at a much-maligned branch of the bird kingdom. I did read somewhere that they have learned to herd flocks of songbirds into skyscrapers to kill them for food, but don't know whether this is just an urban myth or, instead, proof of their smarts.