I've noted that sometimes the chicks I watch are identical, but
sometimes they are quite distinctively different. This year, for
example, when the two chicks I watch most closely were still in
their spotted phase, one had a distincly more yellow-buff base
color, while the other was more gray-tan. Now they have lost most
of their spotted-body plumage and are starting to get some of their
juvenile gray-brown look. They look like little Emu's, and I can't
tell them apart. The funniest part is when they walk on those
oversized feet - it looks like they are wearing swim fins.

In the 1998 breeding season, the two chicks from nest 1 (Horace and Gertrude's nest - in four years they have never successfully fledged
more than two chicks/year, despite laying three-four eggs) fledged
into notably distinct juvenile gulls, which was really interesting.
I should note that Horace and Gertrude are both hybrid gulls - Horace
is a light almost-pure Glaucous-Winged, Gertrude a much darker
hybrid with black on her primary tips. Of the two juveniles, one
was distinctly darker and had darker primaries than the other. Which
demonstrates one of two things - either a) hybrid gulls don't always
come out a nice even mix between the two parents, but can be a range
of phenotypes between the two (much like human hair color); or b)
the two juveniles had different fathers (like many birds, gulls are
known to engage in extra-pair copulation). 1998 was, incidentally,
the only year where I saw this distinction - in 99 they were
indistinguishable, and in 2000 they died before fledging (and I was
on leave, so I didn't get to see them anyway.

I could go on about these guys all day!

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


Jon wrote:
>Hi Deborah - I was using 'twins' in the vernacular. I don't know whether
>these were identical or fraternal. I suspect the latter.... (although they
>look identical to me - to each other and to the rocks they're hiding
amongst)

Best,

Jon.
----- Original Message -----
From: Deborah Wisti-Peterson
Sent: Monday, July 09, 2001 10:29 PM
Subject: Re: It's Twins (G-W Gull)

> these "twins" came from the same egg? that's the only definition of
> "twin birds" that i've ever run across. if so, this is *quite rare*
> and should be noted in one of the journals.
>
> regards,
>
> Deborah Wisti-Peterson, PhD Candidate nyneve at u.washington.edu
> Department of Zoology, University of Washington, Seattle, Wash, USA
Visit me on the web:http://students.washington.edu/~nyneve/
> Love the creator? Then protect the creation.