On Thu, 16 Jan 1997, Paul Talbert wrote:
>
> Question from a naive gull-watcher:
> (also relating to Patrick Scott's question: "with hybrids ... how
> does one find out for sure what species the bird is?")
>
> I am curious to know what the evidence is that the "Olympic Gull" is
> really a hybrid of western and glaucus-winged. And if these two parental
> "species" really interbreed so successfully and commonly, why aren't all
> three forms considered to be subspecies of the same species? When these
> are called "hybrids", I presume this isn't taken to imply that each of
> these birds has one western parent and one glaucus-winged parent (or is it?)
> I am imagining that the case is more similar to the red wolf, which
> recent DNA evidence suggests may be a "hybrid" of the gray wolf and
> coyote. (Not everyone accepts this interpretation.)

(snip)

To quote a sometime contributor to Tweeters on the question of what
constitutes a species: "That always seemed to me to be one of those
questions where the more you know, the less you know"

To quote Darwin: "But to discuss whether they are rightly called species
of varieties, before any definition of these terms has been generally been
accepted, is vainly to beat the air."

To answer some of Paul's questions a little more practically,
Glaucous-wings and Westerns are known to hybridize. You can find mixed
pairs, and the center of the hybrid zone is around Gray's Harbor and
Willapa Bay, as has been mentioned. The offspring are fertile, and do
back-cross with the allegedly pure parental varieties, whence the highly
variable mix we get in Puget Sound

Chris Hill
Everett, WA
cehill at u.washington.edu