>I have heard this same sound from a grouse on one other occasion, in a pine
>forest at the Camas Creek burn in Chelan County. Then too, it was a female
>Ruffed Grouse with chicks.
>
>Questions: Is this a common phenomenon? And what is the purpose of such a
>call?
>
>Dave Nunnallee

I don't think it's *very* common, as I've never heard either call nor
recall reading about them. My guess as to the function of the grouse's
call is that it's a call to distract the potential predator (which you may
have scared away and then perhaps replaced it as a threat) away from the
thicks, the vocal equivalent of the Killdeer's "broken wing."

Some birds, and frogs and rabbits (and perhaps many more animals), emit
ear-piercing shreiks when caught by predators. It has been hypothesized
that a startled predator might release such an animal. It's interesting to
try to equate such a call with the scream made by a person who is suddenly
frightened--is *that* an adaptation? I imagine the grouse call is very
much an adaptation and probably functions well.

Dennis Paulson, Director phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416