Hi Tweets,

Am forwarding a response from Dennis Paulson (who could not post directly to
Tweeters at the time) re interaction between Bewick's Wrens Thyromanes
bewickii and Song Sparrows Melospiza melodia.

>Hi, Michael.
>
>Vis-a-vis your comments on tweeters about Song Sparrow and Bewick's Wren
>song convergence and possible mimicry, I was so convinced of this, and
>its associated interspecific territoriality, years ago that I had a
>student who did a master's thesis on this very thing. He was at U. Puget
>Sound while I was at UW, but I suggested the study and advised him
>throughout. He used tapes and mounted specimens of both and had SOSP come
>and wallop the hell out of "singing" BEWR with a high statistical
>significance (i.e., somewhere near the frequency with which they showed
>the same response to "intruding" SOSP). The other way around also
>happened but not so frequently. He had to replace his mounted specimens a
>couple of times because they got so torn up; a sparrow might land on a
>mount and literally pull feathers out of it. His control was a "singing"
>mounted Black-capped Chickadee, to which neither species paid any
>attention. It was published in the Murrelet in the 70s.

Fascinating!

Off the top of the head, Dennis, the question arises: why would the wrens
devise mimic-songs if a good bashing from an enraged sparrow is the reward?
Wouldn't this give them incentive to diverge pdq? Second, where would the
actual point of competition be? Food? Nest sites? Song posts? Timing (at
this location, the wrens are resident and the sparrows both summer- and
winter-resident and migratory, but I'm not sure who gets down to breeding
first--the wrens or the sparrows)? Does the competition extend into the
non-breeding season, with wrens and both wintering and migrant sparrows
duking it out? And I'd wonder how the allocation of non-breeding and
breeding territories works out when one tosses Spotted Towhee Pipilo
maculatus into the equation as a species which I'd imagine competitive with
the other two.

Michael Price
Vancouver BC Canada
mprice at mindlink.net

"She's psychic....we've decided to find it charming."
--Frasier