Date: 10/30/20 9:43 pm
From: larspernorgren <larspernorgren...>
Subject: [obol] Hybrid swarms, Larus at least
For those folks handy to downtown Portland go look at the birds on the lawn of Tom McCall park. The number has been remarkably stable throughout the afternoon, in the mid-40s at 2pm and after sunset too. The fireboathouse roof at the east end of the Hawthorne bridge has varied from zero to 135 gulls and back to zero in the same time period.       A true hybrid would be a pure Western Gull mated to a pure Glaucous-winged Gull. This is the exception. Olympics(the cross resulting from the above mentioned pair of species) breed with other Olympics preferentially. The ones tending toward Western(darker mantles) tend to breed with other dark mantled Olympics and those tending towards Gwing(light mantles) usually breed with other light mantled Olympics. A classic Western way down south in California usually has yellow eyes and a classic Gwing in Alaska has dark brown eyes. Olympics have every shade in between, including pale eyes(Western trait) on light mantled(Gwing trait) birds and dark eyes( Gwing trait) on dark mantled (Western trait)birds. The birds on the lawn at Tom McCall park on a sunny day are easy to approach closely enough to see their eyes well. Often not the case with gulls. The Cook Inlet Gulls l have seen this week are very consistently tawny eyed--a dirty yellow brown.  The consistency in itself is noteworthy given the variability of this trait in Olympics. Other field marks were also very consistent, when the Olympic is used as a standard. The latter is highly variable. That's more than enough information for one post. Sent from my Verizon, Samsung Galaxy smartphone
 
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