Monogamous Animals Often Have Unattractive Partners  Red-headed
Gouldian finches are more aggressive than black-headed males and
are not as good at providing parental care.   - Constrained mate
choice in social monogamy means that many individuals wind up
with unattractive partners.  - "Unattractiveness" is likely tied
to genetic compatibility, which can include behavior factors.  -
Females paired with unattractive males have increased stress
hormone levels, which may drive cheating and breakups.  In
socially monogamous species, from birds to humans, most
individuals find partners.  A large proportion of females,
however, wind up with unattractive males of below-average
quality, according to a new study that also found such less-
than-ideal relationships raise female stress levels.  The
findings negate prior theories that, in monogamous species
throughout the animal kingdom, each female has a good chance of
pairing with a male that matches her ideal choice of partner.
"In socially monogamous animals, very few