Sunday, October 28, 2012

Can you ID Selasphorus hummingbirds by call note?

Fall of 2012 has shown a huge invasion of Selasphorus hummingbirds into the northeastern United States. Writing this from Maine, we have had two but Pennsylvania is off the charts: 30+ reports and they keep coming.

Confirmed Rufous Hummingbirds of Fall 2012 - from eBird
The majority of these birds are identified as Rufous Hummingbirds. Banding is necessary for some, but most can be identified with a decent photo of a spread tail. Here is an immature male Rufous Hummingbird I photographed on Monhegan Island, ME on October 5th:

This bird can safely be called a Rufous (rather than Allen's) because of the obvious notch in the tip of R2 (the second tail feather or rectrice from the middle) and also the apparently wide R5 (the outermost tail feather). Perhaps one of the best visual representations I've seen of this is Scott Weidensaul's photo comparing these feathers:

Now what about this bird:

It has been visiting a feeder in Biddeford, ME since October 16th. A larger selection of photos can be seen at:
The amount of rufous on the flanks and base of the tail feathers definitely indicates a Selaphorus hummingbird. BUT R1 looks all green, with just a slight black edging near the tip. R2 shows just a little rufous peaking out from under the upper tail coverts but there does appear to be a minor notch. R3-5 have plenty of rufous at the base but at least we can see the width of R5 rules out Allen's.
One very interesting note was that female hummers can show colored feathers on the gorget. (fun fact for this east coast birder) This bird does show two reddish-orange feathers off-center on the gorget but has been identified as a female. While there are good features here for Rufous Hummingbird, most are also in the realm of Broad-tailed Hummingbird, which has never occurred in Maine before.

How else can this bird be identified?

The easy answer would be to band the bird, except the nearest bander we can find with the proper permits lives about 3.5 hours away and is not immediately available.

Throughout my day watching this bird I was able to make several audio recordings on my phone by either holding it up to the perched bird (which was hard to approach) or once leaving my phone near the feeder for 40 minutes (it only came to feed once during that time). And here are the results:

From the yard (listen to it here):
From the feeder:
For comparison:
Here is a (poor) recording of a known Rufous Hummingbird from xeno-canto:
a known female Broad-tailed Hummingbird:
plus a known male Broad-tailed Hummingbird:
It doesn't take long to realize the our bird has a very similar pattern to the Rufous Hummingbird: both showing that two-layered backward J shape, very different from the down-slured shape of the Broad-tailed.

But is this significant? I have two recordings of our bird and could only compare to what is available on xeno-canto; there are no female Rufous recordings there.

I have to say this bird is looking closer to a Rufous than Broad-tailed. Until I hear an expert opinion on audio or we get the bird in the hand, I think it can only be called a Selasphorus sp.


Anonymous said...

Hi, Doug,

Voice is vastly underrated in hummingbird identification and proved critical to settling a controversy here in Arizona in 2006. One thing I learned in making the sonograms for that analysis is the importance of equalizing the time and frequency scales between/among samples. That's why it's hard to see any consistent differences between the chip notes of Rufous/Allen's and Broad-tailed in your sonograms.

Fortunately, this bird isn't that difficult for those familiar with both species. Its stocky, compact shape is consistent with Rufous/Allen's, and this is confirmed by the presence of rufous on the inner vane of R2, visible in your photo above. Broad-taileds lack visible rufous on the inner vane of R2:

Rufous vs. Broad-tailed female tails

Broad-tailed tail montage

This bird's rectrices, especially R5, appear too wide for Allen's, but that's a very tough call in juvenile females.

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