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Re: Some thoughts on Allen's Hummingbirds
Tue, 13 Jan 2004 00:31:18 -0800
From: Les Chibana


If you can see the difference between the range of measurements 1.2 to 1.9 mm and 1.8 to 2.6 mm, you may be able to distinguish an Allen's Hummingbird from a Rufous Hummingbird at a feeder. I say this in jest, of course. That's the range of widths for the outer rectrix/tail feather for each species, respectively. You may have noticed that there is an overlap.

I was able to guess these species with a modicum of success while extracting Rufous/Allen's Hummingbirds from a cage trap for Don Mitchell down at the Kern River Preserve. I think I was looking at birds at the extreme ends of their outer rectrix width range, comparing 1.2 mm to 2.6 mm, or thereabouts. But I was holding them while assessing the tails. And, further, my guesses were "confirmed" by Don's measurements. One could develop a level of confidence with this technique if you had someone like Don following up with measurements on the individuals you were looking at. These species are known for aggressively flaring and moving their tails at crowded feeders, so freezing that action is another challenge with watching at feeders.

Don, by the way, is the author of the Allen's Hummingbird species account in the Birds of North America series. He's an avid hummingbird researcher focusing on the Rufous/Allen's species. He has a healthy respect for the difficulty in differentiating these species in the field.

There is another tail feature that banders use to distinguish between the two. The R2 (retrix #2, or second pair from the center) on Rufous Hummingbirds are notched. This means there's a sharp dip in the edge of the wider, inner web near the tip. (Emargination, by the way, refers to a narrowing in width of the narrower, outer web on the outer half of the feather.) Adult males Rufous show an extreme notch (the most noticeable of the ages and sexes), immature males show less of a notch, and females show even less of a notch. I've banded only a couple dozen of these taxa but sometimes this notching is not obvious in-hand.

An annoying detail with some of the field guides: for Rufous Hummingbird, one refers to the notching (inner web) of R2, another refers to the emargination of R2 (doesn't specify inner or outer web). What I recall is that you some- times see both a notch and emargination on R2 of adult male Rufous Hummingbirds.

Some people feel confident with using the flight displays to tell one species from the other. I've read several references about the male's flight displays. I found some contradictory descriptions in the two new hummingbird field guides. Some will say that males displaying locally means Allen's Hummingbirds, but I've also heard that Rufous Hummingbird will display in migration. It's probably noteworthy that many hummingbirds use flight displays as intimidation near food resources and not just for defending or impressing a female. You can argue that a migrating bird wouldn't bother wasting energy on display flight, but hummingbirds always seem to defy this logic of energy conservation.

I've also heard that the vocalizations are too similar to use as a good fieldmark.

So, that's what I think I know about these species....

I like your theory about the effect of the eucalypts and other exotics, but I don't know if this can be proven.

The commentary and effort to identify the hummer on the Cornell web site is interesting. But ultimately, I'll bet the rare bird committee didn't accept it based on the evidence provided there. I think the video stills lack enough resolution to be sure. It's probably fine enough for some people's life lists. And, I think he'll have to look at a lot more specimens to really be confident that what he's seeing in the images makes sense. Thinking in terms of possibilities, I think Rufous Hummingbird is more likely to wander to New York in November than Allen's Hummingbird, given the typical distance that the species travels.

And, I think that your honeycreeper will have descended from a finch and has already gone extinct in Hawaii.  :-)

Les Chibana, Palo Alto

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Re: Mystery "peep" in San Leandro
Tue, 13 Jan 2004 09:37:18 -0800
From: Les Chibana

I wouldn't eliminate Spotted Sandpiper because of your "approximately 6 to 7 inch" size estimation. Sibley lists them at 7.5 inch which, I think, is too close to your size approximation. It's a likely species and otherwise matches your description and was in the right habitat. A dusky central breast spot could be environmental soiling rather than plumage pigment, or even an outside possibility of retained plumage.

Did you notice any leg-flexing, tail-dipping, foraging behavior? Can you provide an impression of relative leg or bill length? Any color noticed on the bill? These kinds of fieldmarks would help to separate it from Least Sandpiper and others.

Les Chibana, Palo Alto

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Hooded Mergansers in Walnut Creek
Tue, 13 Jan 2004 12:25:35 -0800
From: Larry Tunstall

I am forwarding this message to the list for Nathan Crawford:

Date: Tue, 13 Jan 2004 11:45:59 -0800


Today on a break from work I spotted 4 Hooded Mergansers: 2 males and 2 females in Walnut Creek. They were spotted along a creek trail that starts at Civic Park. You take the first bridge across the creek where you will pass several buildings, take the trail to the north and keep on it till you come to a nature area, with interpretive signs of the local flora and fauna. You will come to a split, make a left towards a giant bridge (may have been a railroad bridge) - if you look back towards Civic Park where you started from along the creek edge is where I spotted the mergansers.

Nathan Crawford

Posted to EBB by Larry Tunstall

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Re: Great Horned Owl versus Long-eared Owl
Tue, 13 Jan 2004 12:59:40 -0800
From: Paul Webster

Thanks to Joseph Morlan for correcting my carelessness in calling the Great Horned Owl the largest North American owl. The Snowy Owl is larger than the Great Horned Owl by up to a couple of inches in length and up to a full pound in weight, which puts it in a size class of its own. The Humvee of North American owls?

I also cast my net too far in bringing in the Barred Owl, which at perhaps 1.5 pounds is about the same weight as the Spotted Owl, though the Barred Owl averages longer. There's a psychological difference, too, if I can call it that. Our owling group once had a good look at a Spotted Owl for a couple of minutes, when a Barred Owl called and the Spotted Owl flew off into the woods as the Barred Owl settled down just above us. The bird was not merely larger than the departed Spotted Owl, but it's aggressive behavior seemed to accent the difference. It acted as if it owned the entire forest.

The size discrepancy between the Great Horned Owl and the Long-eared Owl is pretty dramatic - anywhere from 5 to 12 inches and perhaps as much as 2 to 2.5 pounds.

I enjoyed all the contributions to the discussion of identifying Long-eared Owls, too. Sorry for the misstatements in my own!

Paul Webster

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Tilden Nature Area, Berkeley Hills
Tue, 13 Jan 2004 16:40:26 -0800
From: Patrick King

Three Ring-necked Ducks (2 male, 1 female) were on Jewel Lake in Tilden Nature Area (Tilden Regional Park, Berkeley Hills) this afternoon, joining the female Common Goldeneye and Buffleheads. I also heard the wing buzz of Allen's/Rufous Hummingbird in two spots - and repeatedly at the bottom of Loop Road Trail near Jewel Lake. A male Townsend's Warbler was foraging near the pond that is located below Little Farm. Two tries for the Yellow-bellied Sapsucker went unrewarded. Hermit Thrush were quite visible in and around the upper corral area. A couple of Red-breasted Nuthatches were calling, one visible along the Loop Road Trail. A lot of local birds visible today. Last evening, had great fun watching numbers of American Robin and Northern Flicker battle here for position in an oak tree.

Patrick King
Martinez / Berkeley

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Newspaper article on windmills and bird kills at Altamont Pass
Tue, 13 Jan 2004 19:54:05 -0800
From: Akira So

Apparently a slow news day - on the front page of today's San Jose Mercury News was a report concerning the Altamont Pass windmills and their effects on birds. (A lawsuit has been filed over this.) Since it is in the East Bay Birds territory I would like to pass it along in case anyone is interested:

Actually what caught my eyes was not so much the article, but the wrongly labeled photo of one of the windmill victims - Golden Eagle. It was a picture of Osprey. Oops!  :)

(You can't see that photo in the on-line version of the article, by the way. It was on the front page of today's paper.)

Happy birding,
Pleasanton, CA

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Re: Some thoughts on Allen's Hummingbirds
Tue, 13 Jan 2004 22:49:03 -0800
From: Derek Heins

Got home tonight and was surprised to find all of the e-mails in response to my posting of the Allen's Hummingbird. To clarify, it was a male I saw, once for an extended period of time perched near the boardwalk. From my poor viewing angle it looked like it might have just taken a bath. I unfortunately didn't see any displays.

My biggest mistake was not looking for the Yellow-bellied Sapsucker!

Derek Heins

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