Anna's hummingbirds frequently use displays in inter-specific encounters.
Such behavior doesn't necessarily mean they've got breeding on thier mind.
I've seen them perform display dives for scrub-jays, humans and empty
bushes. I've also seen them chase and do thier "shuttle-flight" display in
front of house finches and pine siskins. The litterature attributes such
agonistic behavior to a combination of territoriality, hormones and numerous
other factors.

Anna's have been documented hybridizing with quite a few other hummer
species, but I think that is more a function of their adaptive nature and
propensity for range expansion than lack of brain power. I remember
hearing somewhere that hummingbirds have more brain mass, as a percentage of
body weight, than any other bird, but don't quote me on that.
Dave


David C. Tracy
Bend, OR
----- Original Message -----
From: "Netta Smith" <nettasmith at home.com>
To: <tweeters at u.washington.edu>
Sent: Saturday, April 21, 2001 4:21 PM
Subject: hummingbird behavior


> This morning a male Anna's Hummingbird had appeared in our yard and
> apparently set up its territory, as it perched in the top of one tree for
a
> long time, singing from time to time. It may have been there for several
> days, as we don't get much watching in during the week, but it certainly
> wasn't there last weekend.
>
> As I was watching it at the top of a leafless birch, a Pine Siskin flew in
> and landed near it, causing the hummer to pop straight up into the air
about
> 10' above the siskin, where it hovered, perfectly horizontal, and looked
> down at the other bird. Shortly, the siskin flew into another tree, and
the
> hummer followed it instantly, then alternated perching and hovering about
> 10-12" in front of the siskin in full frontal display, both crown and
gorget
> expanded and presenting a dazzling show of red. I was fortunate enough to
> be in just the right position to view the display, and it was quite
amazing.
>
> My simplest explanation is that such a small bird represented a potential
> mate to the (not exceptionally brainy) male Anna's, as I didn't have the
> feeling it was an aggressive display, but rather a display as I've seen
> other male hummingbirds present to females. But of course I'll never
know,
> as when I asked it, all the hummer said was "tsip, tsip, tsip."
>
> Dennis
> --
> Netta Smith and Dennis Paulson
> 1724 NE 98 St.
> Seattle, WA 98115
>