Ross and Dave and all,

For over 20 years, I conducted basic research on the
synchronzation of reproduction with environmental
cues. My own research model was the golden hamster,
but the lab that I worked in was closely associated
with the lab of the late Dr. Donald Farner at the
University of Washington, which conducted research
on a variety of avian species, including
white-crowned sparrows and Peking ducks, among
others.  I learned a little about avian cycles from
my colleagues there.

My understanding is that the coordination of annual
cyclic events in birds, particularly migratory
species, is more complicated than that in mammals.
While many mammals respond to changes in daylength
as the overriding primary cue for synchronicity of
reproductive events and migration, some birds (and
other taxa such as reptiles and amphibians)
integrate information about temperature, rainfall,
and food supply. In regard to food supply as a
trigger, nutrients in the food being eaten may
trigger hormonal  changes that in turn lead to
changes in migratory behavior and in  reproductive
capacity.

I don't think that there is any evidence for birds
performing analytical reasoning to predict what will
happen to them if they arrive ahead of schedule on
their breeding grounds. We are talking about innate
reflex-type cycles here, not reasoning or advance
planning.

If fellow MDOspreyites Michael Moore and Richard
Donham, both formerly from Dr. Farner's lab, are
reading this, they can no doubt supply more and
better information on this complicated topic.

Marcia

_________________________
Marcia Watson
Bowie, MD


---- Original message ----

  Date: Fri, 23 Mar 2012 08:41:21 -0700
  From: Ross Geredien <>
  Subject: Re: Early arrivals
  To: 
  >Dave, this is a great question.
  >
  >I think that weather conditions that are stable
  and provide gentle assisting winds (i.e. from the
  south) are generally favorable to migrants.  And
  if food is available at each stopover, the warm
  weather tells these individuals that conditions
  are favorable to "keep going".  The warm weather
  has provided ample early insect hatchings, so food
  is not a question.
  >
  >The number of early migrants is still small,
  however, when compared to the main wave for most
  species.  That's because celestial and solar cues
  are probably still very powerful for many species
  and individuals.
  >
  >A very quick opinion, but I'm short on time.
  >
  >Ross
  >
  >
  >________________________________
  > From: David Mozurkewich
  <>
  >To: 
  >Sent: Friday, March 23, 2012 11:25 AM
  >Subject: [MDOSPREY] Early arrivals
  >
  >Can anyone help me understand why there are so
  many early arrivals?
  >
  >Yes, this is a weird year.  It's been a
  crazy-warm winter and so far an
  >even crazier spring.  I understand that birds
  seeing this warm weather
  >may be tempted to move north, start singing,
  nesting, etc.  So far so
  >good.
  >
  >B U T
  >
  >The problem I'm having is understanding the
  pattern of early arrivals.
  >Sure, species like Gnatcatcher and Louisiana
  Waterthrush should already
  >be in the southern part of the country so they
  know the weather is
  >warmer than usual and may head north faster.  But
  species like Wood
  >Thrush and Ruby-Throated Hummingbird spend the
  winter in the tropics.
  >I have not yet had the pleasure of meeting a bird
  that can operate a
  >weather radio or visit the internet.  They don't
  know the weather up
  >here is warm and they should not be arriving
  early due to *our* warm
  >weather.  Yet they're being reported.  Is there
  something I don't
  >understand?  One possibility is there is always a
  vanguard of early
  >migrants but with normal weather, they either
  starve or freeze before
  >they have a chance to be reported.  Other idea?
  Data?
  >
  >Dave
  >David Mozurkewich
  >Seabrook Prince George's, MD
  >
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