Hi All
It occurred to me as well that all of this is correlative data. Just to add
a little more confusion, Terres (Aud. Soc. Encyclopedia of NA Birds) says
that Ruffed Grouse have been known to drum every month of the year. Spring
is the most intense period, followed by the 2-3 week period in the autumn.

Gill (Ornithology) has some related info:
Pinyon Jays begin their breeding activities when they encounter young, green
pine cones. In sw New Mexico, they sometimes breed in autumn when there is a
bumper crop of pine seeds. The causal connection was researched by David
Ligon (1974). He isolated two groups of 10 male jays. He gave one group
fresh green pine cones daily in the summer, when their testes had decreased
in size after normal spring enlargement, This experimental group showed a
dramatic reversal of their reproductive state. The testes of the control
group (no pine cones) continued to shrink.

I bet there's lots more to learn about this.

Cheers
Gail Spitler
Johnsons Landing, BC
mailto:spitler at direct.ca