Jon. Anderson and Marty Chaney
festuca at olywa.net
Wed Sep 18 18:24:05 PDT 2002
----- Original Message -----
From: Daniel Eiben
Thanks for the deeply informative and helpful post. Based on it, I may have to back off and say merely that they're definitively scrub jays (they just passed by again about a half hour ago)... snips .... I was also intrigued with your point that they displaced Steller's jays in part of the Willamette Valley. There have been several Steller's in this neighborhood in the past couple months; previously they've been pretty rare in the CD. I hope both the Scrub and Steller's can work out a joint habitation agreement here. It's a joy to have both.
Hi Daniel - I am not certain that I would go so far as to state that Scrub Jays "displaced" Steller's Jays in the Willamette Valley - or that they'd do the same thing here in the Puget Trough.
What does make some sense is that, over the past 150 years, 'European' settlers and their descendents have done a pretty good job of changing the vegetative species and structures in western "Cascadia". The scrub jays are certainly more amenable to the open-scrub habitats that we have hewn from the primeval forests, and have followed the plow and axe and sub-divider and Interstate 5 up from their former haunts (at least as far as we knew about those haunts 50-75 years ago....) in the south.
You can't really say that the one species has 'displaced' the other, because the modified habitat isn't all that good for the 'old' species. This is not that much different from the expansion of the Barred Owls into the second-growth forests where Spotteds used to be found. Sure, there are Barred Owls on Bainbridge Island now, but no self-respecting Spotted owl would try to nest at Battle Point. It takes a few generations for species that have fairly small and static 'home ranges' to move from one place to another. Species that are more mobile (House Sparrows, etc.) seem to spread and expand their ranges pretty quickly. I don't know why; perhaps a 'real' biologist can weigh in on this point.....
Species such as Cinnamon Teal can take almost immediate advantage of changes in water conditions to move their nesting... When the Great Basin is going through a dry period, and all the Pleistocene lakes are blowing alkali dust, the cinnamons will up and fly over to Montana or even Nort' Dakota to nest for the season. When Malheur is full of water, the Cinnamons will be back in Harney County and year listers in Billings have a hard time finding the Cinnamon among all the Blue-wings..
festuca at olywa.net
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