Marcia, et al. 

Just to be clear, I wasn't suggesting any advance planning was taking place inside individual birds' brains.  By "signals",  I was referring to environmental cues, which can create chemical/biochemical signals.  It makes sense that certain food types could lead to hormonal signals, as there is a lot of evidence to support this even in humans.

Ross


________________________________
 From: Marcia Watson <>
To: Ross Geredien <>;  
Sent: Friday, March 23, 2012 12:07 PM
Subject: Re: Early arrivals
 

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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