Comments posted to the Arizona New Mexico Listserv


From Sheri Williamson

Subject: Re: Gilbert hummingbird photos added to AZFO.org
From: Wood/Williamson <sabobird AT MINDSPRING.COM>
Date: Sun, 12 Feb 2006 15:11:39 -0700

In my previous post about the controversial hummingbird at Gilbert
Water Ranch, I neglected to address the anomalous vocalizations
reported by Rich Hoyer and the possibility of hybrid origin. I
appreciate the opportunity to correct that oversight:

Much as I would like to see (and hear) the bird in person, I haven't
and probably won't, so I have no first-hand experience with the
vocalizations that Rich has described as characteristic of Archilochus
(Black-chinned or Ruby-throated). I do know that Rich Hoyer has ample
experience with Archilochus vocalizations from hosting Arizona's first
documented Ruby-throated Hummingbird last winter, but I can't
objectively address the issue of how much or little the bird's calls
resemble those of either species without hearing the bird in person or
reviewing video or sound recordings. The ultimate objective test would
be sonographic analysis, but that's way beyond the scope of the
current discussion.

My identification of this bird is based on objective examination of
the evidence available to me, which consists of seven high-quality
digital photos. The characteristics visible in these photos,
individually and collectively, are consistent with a second-year male
Broad-tailed and inconsistent with Ruby-throated or a Broad-tailed x
Archilochus hybrid. As I mentioned in my previous message, the stage
of molt supports this identification, but it doesn't absolutely rule
out a hybrid (see below). On further reflection, I believe that this
bird is more likely to be a slightly early migrant at an unusually low
elevation rather than a rare overwintering individual, but early
timing of migration would also support Broad-tailed.

Though it's certainly not out of the question for a hybrid to take
after one parent parent species more than the other in a
characteristic or two - in this case, the voice of one and the molt
cycle and migration schedule of the other - hybridization in
hummingbirds typically manifests itself as a fairly balanced blending
of parental characteristics throughout the offspring. For example, the
well-known male Magnificent x Berylline at Beatty's Guest Ranch sings
a Magnificent-like song which is probably learned rather than
inherited directly, but its innate call notes are intermediate between
the two parent species. The available photos don't give any clues
about voice, but they also don't show anything that I would identify
as suggestive of an intergeneric hybrid.

As an example of what I'd expect to see in a Broad-tailed x
Archilochus hybrid, note the adult male hybrid illustrated on Plate 30
of A Field Guide to Hummingbirds. This bird was originally identified
as a Ruby-throated but was confirmed on capture for banding to be a
hybrid. For an example closer to the plumage we're seeing in the
Gilbert bird, note the intermediate tail shape, R5 shape, and color of
R3-5 visible in this female Broad-tailed x Archilochus hybrid:

http://www.trochilids.com/hybrids/bassett.html

The Gilbert bird has been described as smaller than Anna's, but
comparisons of published body lengths for Anna's and Broad-tailed may
be misleading. Broad-taileds are similar in length to Anna's but much
smaller in body size. Males are only slightly heavier than male
Black-chinneds and just two thirds the weight of male Anna's.

As difficult as it may be to reconcile a non-Broad-tailed voice with
the absence of hybrid characteristics, my holistic sense leads me to
give more weight to the strong morphological evidence. Nevertheless, I
endeavor to keep an open mind on ID issues, especially those that may
involve hybridization. If anyone can provide additional evidence that
might help us resolve this issue to the satisfaction of all parties,
please pass it on.

Good birding,

Sheri Williamson
Bisbee, Arizona
tzunun [AT] mindspring.com
http://home.mindspring.com/~tzunun


From Rich Hoyer

Subject: Gilbert hybrid hummingbird
From: Richard Hoyer <calliope AT THERIVER.COM>
Date: Tue, 14 Feb 2006 11:00:23 -0700

Dear Birders,

It appears from the lack of reports that no one has refound the
apparent Broad-tailed X Archilochus hybrid at the Gilbert Water Ranch,
but has anyone looked?

I have no arguments with the details in describing what the photos
show, and I haven't actually tried to analyze them myself yet. In fact,
with Sheri's careful scrutiny, as well as the essentially identical
analysis by hummingbird bander Bob Sargent, I have little incentive to
take the time. But given that the photos on the AZFO site label the
bird as a Broad-tailed Hummingbird, and lest one feel that I've
acquiesced, I feel I need to respond to some of the comments in Sheri
Williamson's otherwise fine analysis of the photos. It would be
unfortunate if the false appearance that the ID of the bird has been
settled has the effect of discouraging birders in the area from looking
for or trying to get audio recordings of it.

On Sun, 12 Feb 2006, Wood/Williamson wrote:

> Much as I would like to see (and hear) the bird in person, I haven't
> and probably won't, so I have no first-hand experience with the
> vocalizations that Rich has described as characteristic of Archilochus
> (Black-chinned or Ruby-throated).
Sheri actually knows these voices quite well and knows how distinctive
and unmistakable they are. So when I say the bird sounded exactly like
an Archilochus, there should be a fairly concrete understanding here.


> The characteristics visible in these photos, individually and
> collectively, are consistent with a second-year male Broad-tailed and
> inconsistent with Ruby-throated or a Broad-tailed x Archilochus
> hybrid. As I mentioned in my previous message, the stage of molt
> supports this identification, but it doesn't absolutely rule out a
> hybrid (see below). On further reflection, I believe that this bird
> is more likely to be a slightly early migrant at an unusually low
> elevation rather than a rare overwintering individual, but early
> timing of migration would also support Broad-tailed.
Since no one has ever claimed a first-winter Broad-tailed X Archilochus
hybrid before, one cannot stand by the first assertion here. The second
sentence is more honest, but then again, the third sentence seems to
presume we know something about the wintering habits and/or migration
schedule of hybrids. Furthermore, were this a simply a first-winter
Broad-tailed Hummingbird, this would actually be a ridiculously early
spring migrant, rather than slightly early. Only very scattered *adult*
male Broad-tails start showing up in the last week of February, but the
main migration does not begin until March, with the bulk moving through
in April.


> I do know that Rich Hoyer has ample experience with Archilochus
> vocalizations from hosting Arizona's first documented Ruby-throated
> Hummingbird last winter...
It's thoughtful of Sheri to bring attention to the bird that she helped
document in my yard last year., but actually I was quite familiar with
the voices well before the Ruby-throat showed up. I first learned to
identify Black-chinned and Broad-tailed by voice on my first visit to
Arizona 17 years ago. When I started doing bird surveys for the US
Forest Service in SE Arizona in 1994 I became intimately familiar with
them (it was my job, after all), and for the past 9 years
distinguishing such vocalizations has been my full-time profession. I'm
not cursed with perfect pitch, but I do have an excellent memory for
sounds.

The call notes of Archilochus (Ruby-throat and Black-chinned are so
similar that I haven't quite convinced myself I can tell them apart)
are a short squeak, which I liken to the sound of a rubber eraser on
glass. The only other hummingbird I've heard make a remotely similar
sound is the Fiery-throated Hummingbird of the Talamanca highlands in
Costa Rica and Panama. Broad-tailed is a more electronic and percussive
"tsiwk" or "chip" sound, more on the lines of other Selasphorus (though
clearly different than Allen's/Rufous) and lighter and thinner than
Anna's Hummingbird. The scold chatters are also distinctive, but
contain so many notes in such a short time to be almost impossible to
describe in words. Steve Howell's photographic guide to the
Hummingbirds of North America has excellent, nearly exhaustive
descriptions of their voices.


> Though it's certainly not out of the question for a hybrid to take
> after one parent parent species more than the other in a
> characteristic or two - in this case, the voice of one and the molt
> cycle and migration schedule of the other - hybridization in
> hummingbirds typically manifests itself as a fairly balanced blending
> of parental characteristics throughout the offspring.
The first part of this sentence is a good observation, not to be taken
lightly, especially considering we really know nothing of the
characters of first-winter hybrids. To make the point clearer I would
modify this statement to say that "...hybridization in THE PLUMAGE OF
ADULT MALE hummingbirds typically manifests itself..." I've seen
hybrids of Annas X Rufous/Allen's, Berylline X Magnificent, Costa's X
Anna's and Magnificent X Black-chinned, all males, and this was true
for them. However, I'd never seen a female or immature that could have
been identified as a hybrid, and few people would dare to make such a
claim.


> The Gilbert bird has been described as smaller than Anna's, but
> comparisons of published body lengths for Anna's and Broad-tailed may
> be misleading. Broad-taileds are similar in length to Anna's but much
> smaller in body size. Males are only slightly heavier than male
> Black-chinneds and just two thirds the weight of male Anna's.
Indeed, published measurements can be misleading, not just lengths but
also weights. In my experience, Broad-tailed does not appear
appreciably smaller than Anna's, certainly not 2/3 the size. Next to
either of them, Black-chinned appears obviously smaller. And next to
Black-chinned, Ruby-throated appears smaller yet. My observations in
the field showed that the bird in question was obviously smaller than
Anna's Hummingbird, present in the same area for direct comparison.
I'll be the first to admit that judging size in the field can be very
tricky, and indeed I tell this to my tour participants all the time.
But with current acknowledgment of the pitfalls as well as extended
observation of a bird sitting still as well as moving around at a
distance of less than 3 feet, the chance of my erring here is greatly
diminished.


> As difficult as it may be to reconcile a non-Broad-tailed voice with
> the absence of hybrid characteristics, my holistic sense leads me to
> give more weight to the strong morphological evidence.
Unfortunately, we only have several good photos and no "solid
morphological evidence." One can come to the conclusion that the bird
in the photos is simply a Broad-tailed Hummingbird only by completely
disregarding my account of its voice. This is neither "weighing
evidence" nor "holistic." Either the bird sounded like an Archilochus
or I've completely lost it. (Another theory to add to the list of
possibilities, and something I fully considered after having first seen
the photos. But no, I'm dead certain of what I heard.) In any event, a
truly open-minded approach to the identification of hybrid hummingbirds
(especially first-winter birds) should lead one to admit having learned
something from this bird.

Good Birding,

Rich
---
Rich Hoyer
Tucson, AZ