From: drintoul@matt.ksu.ksu.edu (David A Rintoul)
Newsgroups: rec.birds
Subject: burning birding questions 09/92
Date: 18 Aug 92 16:32:01 GMT
Organization: Kansas State University
NNTP-Posting-Host: matt.ksu.ksu.edu

The following is a regular feature in the _Prairie Falcon_, the
monthly newsletter of the Northern Flint Hills Audubon Society in
Manhattan KS.  This column will appear in the Sept. 1992 issue.  Hope
you enjoy it.

Dave Rintoul            Internet: drintoul@matt.ksu.ksu.edu
Biology Division - KSU     Latitude 39.18, Longitude -96.34
Manhattan KS 66506-4901                         TCN: id2418
(913)-532-5832 or 6663                  FAX: (913)-532-6653
--------------------------------------------------------------

Burning Birding Questions - Birding questions asked anonymously will
be answered by the anonymous answer person.  Send your burning
questions c/o the editor, Dave Rintoul, Ackert Hall, Biology Division,
KSU, Manhattan KS 66506; or call him at (913) 537-0781 (home),
532-5832 (work), or send e-mail to drintoul@matt.ksu.ksu.edu.  All
questions are appreciated (even though you might not appreciate the
answers), so keep those cards and letters coming in!

1.  On a hike this month I saw a strange-looking bird which turned out
to be a young cowbird.  I was able to identify it because it was
hanging out with a bunch of grown-up cowbirds.  I thought about this
for a bit and became confused, so I thought I would ask.  How do baby
cowbirds know that they are cowbirds?  If they are raised by a
cardinal or a meadowlark, why don't they hang out with cardinals and
meadowlarks?  Doesn't "imprinting" work for cowbirds?

Ever since the greylag geese wanted to marry Konrad Lorenz, it became
increasingly clear that many kinds of birds learn their species by
that early, instananeous and irreversible learning process called
imprinting.  You are quite correct in suggesting that this mechanism
would not work for social parasites, like cowbirds, although we still
do not know "how ... baby cowbirds know that they are cowbirds."  It
is assumed that the cowbirds' species recognition is genetically
based, that is, innate.  But that hypothesis has not been tested.
Many species of birds learn their songs by imprinting, and that aspect
has been experimentally investigated in cowbirds.  It turns out that
cowbird song is largely genetically fixed, but there is some
modification of their song as they fit into the social hierarchy of
the males' mobile leks in which copulation occurs.  So learning is
involved, but to a much lesser extent than in most species of birds.
The European cuckoo is also a social parasite.  Individual females of
this species regularly lay their eggs in the same species of host and
have evolved a high degree of egg mimicry.  Female cuckoos that hatch
in garden warbler nests then mate with male cuckoos but lay eggs in
garden warbler nests.  How do they know this?  Species recognition is
probably innate.  Egg mimicry is assumed to be innate (it is hard to
imagine that the female could change the spots on an egg any more than
a leopard could change his spots without the help of R. Kipling).  Is
host recognition innate or learned?  If any of my faithful readers
know of a study in which this question was explored, please submit the
citation to the editor of The Prairie Falcon, who will then dutifully
drop your letter in the hollow oak that we use for our annonymous
communications.


2.  Many species of woodpeckers are colored in high contrast black and
white patterns.  Do you know of any work done on why this is so?
Also, the black-and-white warbler is colored similarly and also does
some of the same behaviors, such as walking up and down tree trunks
looking for insects.  Has anyone figured if the warbler is just
mimicing the woopeckers, or is there an evolutionary advantage to
being black and white if you make your living on the side of trees?

The answer to your first question is no.  The answer to your second
question is that there is indeed an evolutionary advantage to the
patterns of black and white woodpeckers as well as black-and-white
warblers (there is also an evolutionary advantage to being a mimic -
so it's not an "either-or" question).  But there is also an
evolutionary advantage to being a brown-backed woodpecker, e.g.
Strickland's and flickers, or a brown-backed brown creeper.
Williamson's sapsucker males are black and white, while females are
brownish.  There's an assumed evolutionary advantage in that too.  And
why are nuthatches patterned the way they are?  Evolutionary theory
predicts that a bird's plumage pattern is adaptive.  Yet in most cases
such hypotheses have never been experimentally investigated.

P.S.  To my correspondent that asked about the effect of high voltage
transmission lines on birds, be patient.  I'm waiting to be energized.

-- 
Dave Rintoul            Internet: drintoul@matt.ksu.ksu.edu
Biology Division - KSU     Latitude 39.18, Longitude -96.34
Manhattan KS 66506-4901                         TCN: id2418
(913)-532-5832 or 6663                  FAX: (913)-532-6653