And I recall reading a monograph (sorry, I don't have a citation) in
which the research determined that female Spotted Sandpipers could
delay fertilization of their eggs after mating. I think the research
even went as far as to say that the female may even be able to select
which male's sperm she would allow to fertilize her eggs. That would
be quite a trick... so to speak.
I think I've heard that elephant seals can delay fertilization, too.
Les
---
Les Chibana
BirdNUTZ(tm) - Ornigasmic Birding
Palo Alto Baylands Birding Classes
em <[[email protected]]>
web <http://www.birdnutz.com>
ph 650-949-4335
fx 650-949-4137
snailmail: SR2 Box 335, La Honda CA 94020
On Apr 27, 2005, at 6:59 PM, Alvaro Jaramillo wrote:
Birders
Spotted Sandpipers have very different breeding behaviour than most
birds,
and they are much more like Phalaropes than anything else most
birders are
familiar with. Spotted Sandpipers are sex role reversed, so the
females are
larger and "compete" with each other for access to breeding males.
The males
do all of the parental care, and females are known to have more than
one
male mate (polyandry). Therefore once a female mates and lays a
clutch she
moves on to another male, if available, and repeats the process.
Thus, how
you define a pair is actually very complicated.
Note that sex role reversed is the standard term in behavioural
ecology to
refer to situations where males are the limiting sex in calculations
of
reproductive success, a scenario that selects for inter-female
competition
and usually larger size and ornamentation. It implies that this
situation is
somehow incorrect (reversed) but really this just refers to the
reality of
this breeding system being rarer than the one we are used to. Sex-role
reversal is moderately common in various shorebirds and other birds,
and it
is also known in many amphibians and fish - mammals have about the
most
conservative family values in the animal world, kind of boring in the
wide
spectrum of behaviour.
Cheers
Al
Alvaro Jaramillo
[[email protected]]
Half Moon Bay, CA
Field Guides - Birding Tours Worldwide
http://www.fieldguides.com/home.htm
-----Original Message-----
From: south-bay-birds-bounces+chucao=[[email protected]]
[mailto:south-bay-birds-bounces+chucao=[[email protected]]]
On
Behalf Of Bill Bousman
Sent: Wednesday, April 27, 2005 5:22 PM
To: [[email protected]]; South-Bay-Birds
Subject: Re: [SBB] Western Tanager & Spotted Sandpipers
Dear Randy and everyone,
At 12:24 PM 4/27/05, [[email protected]] wrote:
Hi Everyone,
Another recent sighting has given rise to a question. Yesterday,
Tuesday,
I was birding along San Fransquito Creek at the end of Geng Rd in
Palo
Alto. I saw two Spotted Sandpipers foraging together. Usually
seen as
single individuals in the Bay Area, I was wondering if there have
ever
been any evidence of breeding in or around the South Bay? I think
of
them
breeding being more in the Sierras.
They nested along the Russian River at the end of the 19th century,
but
nesting further south appears more recent, at least if you look only
at
first nesting records. In Santa Clara County our first record was
in 1989
and we found them nesting in scattered locations in four blocks
during the
atlas period of 1987 to 1993. All nest locations have been in low-
gradient
streams on the valley floor. Last year they nested at Almaden Lake.
We have irregularly had birds along the Bay edge in summer and we
have
discussed the possibility of breeding in some area with gravel,
somewhat
like the low-gradient stream beds they use now. But our conclusion
is
that
these are nonbreeding birds.
The next question would be, do they pair up prior to moving to
breeding
areas?
Good question. Another question is how does one define a pair.
Breeding
pairs in the county have been very active with lots of calling to
each
other and flight displays, jumping in the air, etc. Really quite
spectacular. Two birds without courtship behavior may be just two
migrants
or nonbreeders.
Bill Bousman
Santa Clara County records compiler
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