I've been mulling these two messages (below) over, and I wonder if anyone has
looked at whether "gonadal recrudescence" is triggered by the fact that the
hours of daylight in October is the same as the hours of daylight in March.
Some birds may have a bit of a hair trigger and they start getting excited
inappropriately in fall. Those hypersexed birds may also react sooner and
stronger in spring. Thus, hyperreactivity to the stimulus may result in both
greater copulatory success in spring AND to gonadal recrudescence in fall.
Thus, fall sexual urges would only be correlated with spring success, not
causal to that success. Thoughts?

== Michael Hobbs
== Kirkland WA
== hummer at isomedia.com


From: WAYNE WEBER <WAYNE_WEBER at bc.sympatico.ca>


> For those of you who are not familiar with it, the phenomenon of
> "gonadal recrudescence" is believed to be responsible for autumn
> drumming by Ruffed Grouse and autumn singing by many other species.
> Singing and other forms of courtship and territorial behavior are
> dependent on high levels of androgens (male hormones). Unlike many
> mammals, most male birds do not produce steady levels of male hormones
> year-round. The gonads are large and active from early spring through
> midsummer, but then they regress, and song and courtship behaviour
> largely cease. However, in some species, under some conditions, there
> is a partial recovery of the gonads for a while in the fall, and a
> resumption of song (or drumming, in Ruffed Grouse), at least for a few
> weeks. Sharp-tailed Grouse, for instance, are known to visit their
> springtime leks (display grounds) during the fall.

From: Gail Spitler <spitler at direct.ca>

> I was about to send a comment that while I haven't heard Ruffed Grouse
> drumming this autumn, our local Wild Turkeys are displaying. Again, not with
> the intensity seen in the spring, but it certainly looks like courtship
> behavior (displaying, toms corralling the hens). Then I happened upon a
> summary of an article in Avian Biology entitled Why do Black Grouse perform
> on lek sites outside the breeding season? It seems that the males who
> possessed central lek locations in autumn had higher copulation success the
> following spring. The autumn behavior may provide the females with an
> opportunity to assess males prior to the breeding season.