On Wed, 28 Jun 1995, Dennis Paulson wrote:

> (Condor 59: 166-191, 1957). I think hybrids in waterfowl, and in birds in
> general, are more common within than between genera, but there have been
> some between fairly distant genera, as (I think) Mallard x Muscovy Duck.
> We have a hybrid in the Slater Museum one parent of which was surely a Wood
> Duck, and I cannot figure out who the other parent was. My guess is that
> the reason we don't detect female duck hybrids is just that they don't
> stand out like the males do.

According to Kortright's "Ducks, Geese & Swans of North America," pg 44:

"The great scarcity of females and an excess of males among hybrids is
another feature. Thus, in a list of 248 duck hybrids, 72% are males and
28% are females; from a list of duck-merganser crosses only 17% are females.

"The prevalence of sterility and the unbalanced sex ratio among hybrids
are the factors which control the perpetuation of hybrid birds. The
chances of two fertile hybrids mating with one another in the wild state
are remote."


My understanding is that Kortright's data comes from captive breeding and
is not influenced by our inability to detect female hybrids.

----------
Joe Morlan
Albany, CA
jmorlan at slip.net