Jon -

Isn't it fascintaing to have your own little gull colony at work? For the past three years I've had a 6th-floor view of a "colony" of 4-6 pair that nest on the roof of the building next door (some of you who were around last year may remember my "Gulls of Second Avenue" posts, which unfortunately ended when I took a leave of absence - the day after the first chicks hatched). It's really something to get that daily view of their behavior, from initial territory-staking in the fall to when the chicks fledge in August or September.

Interestingly, my colony seems to be a bit ahead of your birds down in Olympia. Horace and Gertrude hatched their first eggs on June 14th, pretty much right on schedule (1998 - June 15th, 1999 - weekend of June 14-16, 2000 - June 13th). The other three pair hatched out by the end of June (their nests are more concealed, so I don't have exact dates).

Rooftop nesting gulls are a fascinating phenomena. I've seen them in several places in Puget Sound - many places in downtown Seattle, along UW Medical Center, Signs of them in Ballard, On a balcony of a Department of Education or School District building (I can't remember which) in downtown Olympia (right off the central square and a few blocks from the Urban Onion), on one of the factories by the Everett Waterfront.

I've often wondered what the total population of roof-breeding gulls there are, and how this impacts the overall population. N.A.M. Verbeeck, a did a study of roof nesting Glaucous-wings in a section of the Vancouver waterfront, which included both a population survey as well as a lot of info about "habitat" preference and breeding success. Garith Eddy, a Seattle businessman, published a brief article in the Murrellet (1984, I believe) that recorded his own observations of 10-20 years. He estimated a population of 300 pairs in downtown Seattle, including one colony on the roof of one of the piers with almost 100 pair. He also estimated that the population of roof-nesters in the 1960s, when he first started noticing them, was less than 50, so the population has jumped in the past couple of decades.

I suspect that roof-nesters represent a significant proportion of breeding gulls in Puget Sound. As their natural island nesting spots have been lost over the years to development and other human preassures, they have responded by moving in with - or on top of - us. I suspect too that roof-nesting offers protection from some of the predators they face in more wild places. I have never seen a Bald Eagle raid a rooftop gull colony (though I imagine some on the piers are at risk of this), though I have seen them regularly raid island-colonies on the Washington Coast. And in the most recent issue of Seattle Audubon's newsletter Earthcare Northwest, Steve Dang reported that the Glaucous-winged colony on Jetty Island failed last year due to coyote predation. I doubt that the gulls nesting on the roof of a convayor system in the factory down the way experienced any similar predation by coyotes.

John Chapman
The Norton Building Gull Observatory
Seattle, WA
ragweed at igc.org