[rec.birds] monogamy

gmr044@leah.Albany.Edu (Gregg Recer) (09/11/90)

In article <151022@felix.UUCP> reynolds@felix.UUCP (David Lee
Reynolds) writes:


  ..... various things regarding doves/pigeons deleted...


>  This meaning that the dove and
>pigeon is monogynous, and will only look for a new mate upon the death of the
           ^^^^^^^^^^ 
>current one. 


Aside from the picky point that the word for having only one mate is
_monogamous_, (monogynous would, I guess, mean having only one female
mate) it's worth noting that the idealized view of monogamy in many
species is falling apart the more people make a systematic effort to
look at this question.  Traditionally species like canada geese and
bald eagles, for example, were thought to fit this mold; individuals
would mate with only one partner until separated by death.  A lot of
passerine species are usually thought to be monogamous within a
nesting season.  No doubt many species have a majority of mated pairs
who attempt to get no other matings (extra-pair copulations as they're
termed).  However, when people have looked, in many cases where
monogamy was thought to be the rule some portion of the population
can be attempting to gain extra-pair matings.  

     Often in birds this may only amount to some extra-pair
solicitations by females or some attempts by males to cuckhold another
male.  These efforts may or may not be successful but there can be
selective advantage to attempt to get such extra-pair copulations.  If
females mate with more than one male they may get parental care help
from both males (matings with more than one male can lead to mixed
paternity in the insueing brood -- this is referred to as sperm
competition).  This can allow the female to raise a second clutch
easier or might improve her over-winter survivorship since she doesn't
have to work as hard raising her clutch.  Also, nestling survivorship
can be increased when three adults provision the nest instead of two.
Males who get extra-pair copulations have the opportunity to father
more offspring.

     This kind of thing is being seen a lot more now that
DNA-finger-printing and similar techniques are in fairly common use
among ecologists.  A year or so ago a woman gave a seminar here
concerning supposed monogamy in a desert rodent species.  Her research
showed mixed paternity in many broods in her study population.  When
someone asked if she thought there were any truly monogamous species
she said she didn't think so.  After a short pause she added "except
maybe people".  Now that's _really_ idealizing things :).  



Gregg



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     "In future you should delete the words crunchy frog and 
     replace them with the legend crunchy raw unboned real
     dead frog!!"  
                 -- Inspector Bradshaw, The Hygiene Division

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