Hi Tweets,

Dennis Paulson writes:

>3) I have speculated that the white wing patches are actually advantageous
>in making a kleptoparasitic, all dark gull look more like a jaeger. Jaegers
>are surely recognized by gulls and terns, which may be more likely to
>quickly relinquish a fish to an oncoming "jaeger." Total speculation, with
>no evidence whatsoever, but it would be interesting to test if someone
>could watch a large enough sample of white-winged Heermann's (and normal
>birds for controls, of course).

Can't speak to the frequency, but personal observation suggests agreement
with the second point. The profile, flight-style and harassment of other
gulls is very jaeger-like, whether crossing the water low with its
swept-back pointed wing or in chase of smaller gulls and terns, and makes
this gull an ID problem for those looking for distant jaegers. It takes a
little while to get one's eye in on this species, and the call of "Jaeger at
ten o'clock! Just going by that white fishbo-- Damn. It's a Heerman's." is
fairly frequent in August and September. Dunno if one could generalise from
this, but I've noticed that Heermann's Gulls Larus heermanni in a mixed gull
species feeding melee is more likely to chase and steal after a jaeger has
just done so.

>5) I agree wholeheartedly with Jane that it is counterproductive to try to
>assign some human-related environmental problem as the cause of every odd
>thing we see in nature!

I understand that such an impulse would likely be generated by two things,
apart or combined: guilt or ignorance. But human-inspired changes to our
environment are often intangible. In the case of perhaps-increasing numbers
of albino and partial-albino songbirds (and over the last decade, I am
seeing more of them in the places I regularly bird), it is as equally
likely--not, please note, necessarily likely--that the reason has root in an
human influence on the environment (such as ozone-layer depletion, to pick
one from the list--look at the devastating influence that has had on
amphibian reproduction as an indirect result of our industrial activities)
as a natural one.

Michael Price A brave world, Sir,
Vancouver BC Canada full of religion, knavery and change;
mprice at mindlink.net we shall shortly see better days.
Aphra Behn (1640-1689)