Date: 10/28/19 12:54 pm
From: Caleb Centanni <caleb...>
Subject: [obol] Costa's/hybrid Hummer: Notes and sources request
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

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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