Date: 10/30/19 8:03 am
From: Bob Archer <rabican1...>
Subject: [obol] Re: Costa's/hybrid Hummer: Notes and sources request

Those recorded songs are very Anna's sounding indeed. My experience in San
Diego is my basis of how similar their songs can be, plus it is mentioned
in Howell and apparently the BNA. I can't recall how similar I found them
to be, just similar in some cases. Pieplow says some hummers learn some of
their songs and others online have agreed with this.

Another thing Pieplow mentions on his blog is that Costa is the only
hummer in the Calypte/Archilochus group with an upslurred call note. Hard
for me to see the sonograms exactly, but I think the call notes I found all
looked upslurred, but I am no expert on crunching sonograms. It would be
interesting to see if anyone can compare call note structure to Anna's and
this bird.

But a hybrid would still have mixed plumage traits even though they might
superficially look like a Costa's. I did not realize we had nice photos
until this morning, you need to dig around in the rare bird alerts for the
county. This bird seems to have white where Costa's should have white, not
gray. Bill looks slender, bird's shape seems Costa's , Coverts, that I
could find, look long like Costa's, not short and wedge-shaped like Anna's.
I see little that is Anna's. The faded color of the gorget could be simply
age of feathers on an adult male. Below are three links to parts of Sheri
Williamson's account. A wonderful source for all things hummer. It seems
to me that it takes more than a possibly learned song to make it a hybrid.
I would want to see some more gray, a thicker bill, a different shape and
obviously longer tail. Happy to hear other opinions on the fine points,
especially the shape of the coverts. The lower edge of the gorget seems in
between the two species to me? Any photos of an open tail?

Bob Archer

On Mon, Oct 28, 2019 at 2:37 PM Caleb Centanni <caleb...> wrote:

> Hi all,
> Looks like my link doesn't work. Here is a new one:
> Apologies,
> Caleb
> On Mon, Oct 28, 2019, 12:53 PM Caleb Centanni <caleb...> wrote:
>> Hi all,
>> Two excellent birders have written that a Costa's can sing an Anna's
>> song. We weren't aware of this yesterday, and the sources we have consulted
>> indicate otherwise. We would love more information!
>> This is why we came to our conclusion: The Costa's type hummingbird opens
>> its mouth and sings a song which matches Anna's Hummer almost exactly for
>> me. Anna's Hummingbird is one of my 10 or 20 most familiar birds. I have
>> seen 4 Costa's ever.
>> With that being said, while declaring the bird as a hybrid was perhaps an
>> overly quick call, we have yet to find a source online that records Costa's
>> singing an exact Anna's song. Does anyone know of a source, online or in
>> the literature that records this phenomenon?
>> The reason we made this call was because none of the apps or websites we
>> checked for recordings had any documentation of Costa's singing an Anna's
>> song. Courtney also has Hummingbirds of North America by Steve Howell,
>> highly recommended to her, which states that hybrids will look more like
>> Costa's and sing an Anna's song or intermediate.
>> So let's help each other in figuring this out if we can: What sources do
>> we have with info on Costa's singing Anna's songs, and what field
>> observations are there of this? We don't have a BNA subscription, but a
>> preview from Google says young males Costa's can sing a similar song to
>> Anna's but 'fainter and less sustained'. This bird sang at full volume
>> several 12-second songs in perfect Anna's tone. You can hear this on our
>> recordings. Our recordings of the bird's chase calls also sound similar to
>> Anna's.
>> We would of course love if this turns out to be a pure Costa's
>> Hummingbird! We just are trying to represent the truth of the situation in
>> the best way we can. Let us know what you think?
>> Also, if anyone knows hummingbird experts and would like to send the
>> photos along (Nolan took some great ones yesterday), that could be helpful
>> too.
>> The checklist now has our recordings:
>> Good birding,
>> Caleb & Courtney

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