[CT Birds] STFD Boothe Park hawks & western Nashville Warbler!

Scott Kruitbosch kbosch at gmail.com
Mon Sep 14 19:11:29 EDT 2009

 From Scott Kruitbosch & Charlie Barnard:
09/14/09 - Stratford, Boothe Park -- 1 "ridgwayi" race (western) male

Today was the randomly selected first day of hawk watches at Boothe Park in
Stratford. Our small sample size there shows it to provide decent numbers
and an excellent variety of species. Migrants were steady in the early to
mid afternoon, but it shut down quickly with the late afternoon clear sky.
Here are the migrants Charlie, myself, or both of us had over about 5 hours
this afternoon:

4 Turkey Vulture
10 Osprey
2 Bald Eagle (imm. & adult)
21 Sharp-shinned Hawk
9 Cooper's Hawk
3 Accipiter sp.
1 Red-shouldered Hawk
40 Broad-winged Hawk
1 American Kestrel
2 Peregrine Falcon

Other migrants included:
7 Chimney Swift
8 Ruby-throated Hummingbird
3 Eastern Kingbird
5 Barn Swallow

Now for the huge hit - in mid-afternoon I spotted what was likely a warbler
midway up near the trunk of a large pine. Charlie and I both had and lost
it, as it stayed hidden. A bit later I saw it fly into a shrub near where we
were conducting our count. It was shockingly difficult to dig out of small
bushes. I finally saw it had a hood, and Charlie got a good view to confirm
it as a Nashville. We then had a minute or so of decent views before losing
it again.

This took several minutes, and the glimpses I had of the bird while looking
through branches revealed that it was pumping and bobbing it's tail
incessantly. It was not a fleeting action, or even a periodic one - it was
nearly constant. It exceeded that of a Palm Warbler. It was unmistakable,
and both of us saw this immediately. Charlie and I agreed in the fact
neither of us had seen anything like it before from a Nashville. The bird
moved much differently on the whole. Fortunately Charlie made a fantastic
recollection that the western subspecies is prone to this tail behavior.

Research via various species accounts confirms this. *Warblers *from the
Peterson Field Guide series states, "Western birds (ridgwayi) frequently bob
their tails in a down-up motion with a slight lateral component so that the
tail bob describes a deep arc; this tail-bobbing behavior is much less
frequent in eastern nominate birds." Others describe it as essentially
absent from the eastern population. There are several minor physical
differences, two of which are a longer tail and a brighter rump in the
ridgwayi. I would certainly say the latter was correct, as the contrast
stood out for a fall bird. While I feel the tail was a bit longer, I would
not be able to say my impression of this was not jaded by the constant

Charlie just mentioned another great but much more subtle behavioral
"One thing which may or may not be of significance about the Nashville
Warbler besides the constant tail bobbing is where it was feeding.  It
stayed deep within the hemlock and even when it moved into the shrub with
few leaves, it stayed feeding deep within the shrub, making observation
difficult.  It did not feed out near the branch tips, which Nashvilles often
do.  This may have been coincidental, or it may be a behavior feature which
is more unique to the western race."

I agree with all of his observations there, as that is what was driving me
crazy initially. I cannot find information on the foraging behavior yet, but
we would love to have input from someone who has further knowledge of the
race or first-hand experience. Hopefully this bird will stick around for
some photos or video.

Do we have any warbler subspecies records for CT in general? Some are
certainly more common than others (such as Palm), but I can't imagine there
have been many ridgwayi here. In breeding season the disjunct western
population goes as far east as western Montana! According to Birds of North
America Online it was originally classified as its own species, the
Calaveras Warbler, so perhaps that could bring up records. I'm looking at
you Dennis, Nick, Greg, etc. ;)  - thanks for any help there as well. We
will look for him and keep researching.

Scott Kruitbosch
Connecticut Audubon Society
Stratford, CT
kbosch at gmail.com

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