Subject: Re: Rufous and Allen's Hummingbirds
Date: Feb 21 13:17:03 1995
From: Eugene Hunn - hunn at u.washington.edu


Mike,

What still puzzles me is whether there is a gap in the breeding range of
Selasphorus hummers on the Oregon coast and, if so, just where it is. My
impression is that Rufous Hummers are common nesters all along the
Washington coast.

Also, the contrast between the chattering squeal of Rufous and the whine
of Allen's. Could it be due to the sharpness of the angle that Rufous
Hummers make at the bottom of their dive versus the shallower pendulum
curves on Allen's? Or is it due to some structural difference.

Gene Hunn.

On Mon, 20 Feb 1995, Mike Patterson wrote:

>
>
> A friend loaned me a copy of the most recent Washington Birds and
> gave me chance to look over the description of the hummingbird
> identified by the authors as Allen's x Rufous. I thought there
> might be some interest in a study I did in 1990 on back color
> in Rufous Hummingbirds.
>
> In that study, which was subsequently published in Oregon Birds
> (16(3):218-222), I found that most Rufous Hummingbirds show some
> amount of green. I divided the back into quadrants and assayed
> the amount of green in each sector. The sectors where then
> averaged. Of the 37 males captured, only 16% showed no green.
> 52.7% showed between 1 and 25% green on the back. 27.8% showed
> 26 to 50% green (almost certainly discernible in the field) and
> one bird had nearly 70% green on the back. All birds fell well
> within the expected measurement range for Rufous Hummingbirds.
>
> M. Ralph Browning of the National Museum of Natural History
> checked his collection and reported the following to me:
>
> "...I checked our collection of _S.rufus_ for green-backed
> 'adults.' I found a few, including a couple with backs that would
> fall into category 3(51-75%). My general impression was that we
> have more green-backed birds from the Pacific Northwest and Alaska
> than from elsewhere in the breeding range of _rufus_."
>
> There is evidence to suggest (though a lot more work needs to be
> done), that green-backed birds are first alternate males.
>
> I believe the bird in the photo in WB is one of these green-backed
> male _rufus_. This judgment is based upon the deeply notched
> 2nd rectrices which show up well in the photo. There have only
> been one or two credible _sasin_ x _rufus_ records each
> describes reduced or absent 2nd rectrix notching. The description
> of the display flight is not particularly "Allen-like". For a
> good comparison of _Selasphorus_ displays see Tyrrell's
> _Hummingbirds: Their Life and Behavior_. This book also has some
> amazing photos of both Allen's and Rufous that you can quite
> literally see to bird lice on.
>
> I do have a few photocopies of my report from _Oregon Birds_.
> Anyone interested can send me their address and I will send them
> a copy while supplies last.
>
>
> --
> ********************************
> * Mike Patterson, Astoria, OR * God abhors a naked singularity
> * mpatters at ednet1.osl.or.gov * S.Hawking
> ********************************
>