[Tweeters] Annas Notes
flora.fauna at live.com
Tue Mar 17 18:02:37 PDT 2009
Well, I don't agree with Stu that I was suggesting that humans transported Annas here; I did say that Anna transplanted itself. However as a metaphor, we did actually bring them here in the sense that we created the gardens, the open spaces and the feeders that they use. And we cut down the trees and the native understory that Rufous used in the suburbs (see Hal Opperman's note of several weeks ago). Stu does make a good point about insect prey though. If it has been demonstrated that Annas consistently browse on insects that they find within ornamental flowers, (as opposed to sallying)this would mean a fundamental year- round food source for them in gardens. Will check the literature when I have more time.
One other factor in observing hummer behaviour is DENSITY. Have had several amusing conversations with birders and ornithologists. One will say, "Oh I have never seen that at MY feeder" or I'll say something like "Oh they do this amazing thing in Discovery". But the first feeder is out in the country and only has a coupl of regular visitors, while I'm thinking of population of 50 birds living in close proximity. So it might be helpful to think of behaviour as sometimes density-dependent.
There are so many male display territories adjacent to each other in Discovery Park, that one might well call it a "lek", even though spread out over many acres.Females must fly through a gamut of "satellite" male territories. The most active male territories seem to be close to the forest patches where females go to visit native flowers or nest sites. These sites may be "traditional" over many years, though not necessarily occupied by the same bird. Is there anywhere else in Washington, where a similar dense population occurs? The only hummers considered to be lekking species are the Hermits. In the shorebird species the Ruff, the presence of satellite males seems necessary to make the lek work, yet only one or two males in the "best" locations may actually copulate.Tomorrow another challenging question. DH
David Hutchinson, Owner
Flora & Fauna: Nature Books
Discovery Gardens: Native Plants
3212 W.Government Way
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