John and Tweeters,

Your discussion of gulls returning to resume breeding activity in
November reminded me of Western Gulls on the Farallon Islands in
California.

The gulls at the Farallones are absent from the islands only a couple
months at the end of the breeding season, from September through October.
They begin reoccupying nesting territories in November, typically on
territories early in the day, then roosting in "clubs" later in the day
and at night. By December and January, many birds may be on territories
most of the day when the weather is good, although during big winter
storms they remain in roosts all day. Even though they don't start
laying eggs until April, some birds will be on territories through the
winter and early spring (that is, whenever they are at the island --
they're obviously not on territories when they are away feeding).

The best argument I've heard about why they return so early is
competition for nest sites. At the Farallones, nesting space has
historically been limited for gulls, because pinnipeds hauled out on the
lower elevations of the island and because other seabirds (murres and
cormorants, especially) nested over more extensive areas of the islands
and excluded gulls from these areas. From observations of banded birds,
we know that the gulls on territories in November are established
breeders occupying territories they used during previous years. So the
argument goes that these birds increase their reproductive success by
returning earlier, thereby insuring and protecting their nesting space.

One caveat to this argument is that it will only work if food is reliable
close to the breeding colony through the winter. If food is not
available nearby, the gulls cannot afford to visit territories. The lack
of close food during winter may be typical for many other populations and
may explain why early arrival does not happen at other colonies. The
Farallon gulls apparently can find food close to the islands during most
winters. Proof of this occurred during the El Nino winter and spring in
1983, when very few Farallon gulls visited nest sites, apparently because
they were spread so far and wide looking for food.

This scenario may also work for other species. Common Murres at the
Farallones also begin visiting nest sites in November, but only briefly
during mornings. By mid-winter, they, too, may remain at sites much
ofthe day. Murres similarly show intense competition for the best
nesting areas on the islands, so early arrival seems to have evolved in
these populations to protect access to nest sites. At other murre
colonies, perhaps food is not reliable close to the colonies through
winter, so they don't arrive until later.

Whether all this applies to your gull colony is another matter. Is the
"best" nesting space limited on the rooftop? Can your gulls find food
close to the colony during winter? Since the colony is very young,
early-arrival behavior must have already be present in the population
before they began nesting on the roof. Any ideas about the origin of the
gulls nesting on the roof? What do you think?

Bob Boekelheide
Sequim

John Chapman writes:
>I wanted to report on an interesting increase in activity on the Second and
>Marion GLAUCOUS-WINGED GULL colony that I have opportunity to observe. Since
>about mid November there has been a notable increase in the amount of gull
>activity on the nesting roof, and particularly an increase in territorial
>behavior.
>
>For the most part, all breeding behavior dropped off in September as the
>juvenile birds finally headed off. I saw occasional adults in basic
>plumage, as
>well as some distinctive 3rd-year gulls that were clearly not the resident
>breeders. It's almost impossible to identify specific gulls, so I can't say
>for
>certain if there were residents around. However, there is one resident female
>who is identifiable because of a leg injury that results in a pronounced
>limp. I
>did not see her in October.
>
>In November, the limping female returned and gull activity in general
>increased.
>Several adult gulls started showing territorial behavior, including
>choking (a
>behavior where they lean forward and warble their necks like they are
>about to
>regurgitate) and some aggressive posturing toward other gulls. I observed one
>actual "fight" on a specific territory in late November.
>
>Last year the building where the gulls nest was being re-roofed through
>most of
>November and December, and I was not working here the fall before, so I do
>not
>know if this is normal behavior for this time of year. Last year I recall
>things
>being pretty quite in January, with a sudden increase in territorial
>behavior in
>mid February. I have not run into any reference to fall territorial
>activity in
>the literature I have read, but Kees Vermeer does report evidence of winter
>territory (however, his data is sparse for November - January).
>
>It will be interesting to see if this continues. One possible speculation is
>that the behavior is linked to daylight hours, as has been discussed here in
>reference to various Grouse species. Doesn't late November have about the
>same
>hours of daylight as early February?
>
>Any thoughts?