>
>At Point Piedras Blancas, San Luis Obispo Co., there will probably be at
>least two (pair) of Anna's nesting in late March and April, then by May,
>there will be several (pairs) of Allen's, with Anna's mostly gone. I put
>'pairs' in (parantheses) because I NEVER see any males of these two species
>out on the Point -- no courtship, copulation, nothing. Why??? and where are
>they??? Perhaps they just do the 'dirty deed' elsewhere, then scram. I do
>find males of both species slightly inland, on the east side of CA rt.1
>(anywhere 'east' of the scenic coastal highway, CA rt.1, is 'eastern'
>California to me, since I can't seem to ever drag myself away from PB) up and
>down the coast, Big Sur and San Simeon, but NEVER out there on the Point.
>

I don't think that any hummingbird that has been studied has been found to
be monogamous or even to form pair bonds. Males mate with females, that is
their only investment in the brood. Lots of hummers lek, like Ruffs or Sage
Grouse, but it is more common for males to perform incredible displays to
attract females. Some of these may actually be 'exploded leks' where there
isn't a central display ground, but the males are clumped nonetheless and
relatively close to each other. I imagine that even in situations where
males display solitarily, most males do not mate. In any one region there
will be a few extra sexy males that perform most of the matings. This
intense sexual selection (i.e. high variance in the reproductive success of
males) is what drives the evolution of the wonderful plumage, ornamentation
and displays of male hummingbirds- analogous to ruff plumages, displays and
the crazy displays of lekking grouse. In other species, male hummers defend
a resource such as a patch of flowers and attract females to them in that
way (resource defence polygyny). In some cases the male will not give the
female access to the flowers unless she mates with him (prostitution
polygyny). The high level of polygamy and general promiscuity of
hummingbirds likely accounts for the large number of reported hybrids in the
group, similar to the duck situation. The exact nature of the mating system
of hummingbirds is closely tied to the distribution, availability and
defendability of flowers. Whoops, almost forgot to mention the important
variable of how quickly a particular flower can replenish its available
nectar. Competition with other species of hummers in areas that are
hummingbird rich (the Andes) likely affects the evolution of flower choice
as well as mating system. Here in the west, the early nesting of Anna's
Hummingbirds may have its roots in competition with the migratory Allen's
and Rufous Hummingbirds that arrive and nest later on.

Alvaro Jaramillo "You are better off not knowing
Half Moon Bay, CA how sausages and laws are made"
alvaro at quake.net Otto von Bismarck,
but I saw it in a fortune cookie!

http://www.quake.net/~alvaro/index.html