There are certainly more knowledgeable ornithologists to answer but this 
touches on some questions we are trying to answer with crows over 30 years.  
(Over that time, no directional change in average winter-spring temps, in part 
because 1990 is a VERY warm year.)  

Gonadal development is typically related to day length and the direction of day 
length change in birds, and goes on regardless of temperatures.  

There are some semi-known, semi-hypothesized mechanisms by which birds detect 
longer days. Essentially it goes something like this:  sunrise re- sets the 
bird’s “endogenous” or innate rhythm of behavior and neural activities.  (That 
is another story..)  After that there is a period in which the bird is happily 
unresponsive to dark vs light.  But that period ends about 4 in the afternoon, 
and after that the bird is increasily senstitive to light being present.  If it 
isn’t, as for short days around the solstice at this latitude, the bird just 
goes to sleep without worrying about hormones (so to speak).  BUT if the light 
is still there when it is sensitive later in the day, that information 
stimulates or begins to stimulate gonadal development.  As days go by, the 
other part of the cue is the lengthening or later availability of light:  the 
day is not only 11 hours long but it is 2 min longer than yesterday. 

Note that birds that are spending the winter near the equator cannot be using 
this mechanism as a decision as to when to migrate.  The circannual clock is 
probably involved here, although birds could then come part way and finish 
migration using day length.( I forget the recent literature here.)  But birds 
that are migrating definitely don’t benefit from making big gonads to carry 
along on migration. 

Actual decisions to move to nesting habitat, develop testes and sing or begin 
developing ova preparatory to laying eggs have to be more fine tuned…to weather 
(not climate), to personal condition and food resources, etc. So the whole 
thing is a layered process of information gathering, some quite codified, some 
quite flexible.

OK—I am no specialist in this, so I will be happy to bow to more educated 
answers, or to try to find answers to specific questions.  For those of you who 
do “skulling” to age birds, that thin skull permits light to penetrate directly 
to the pineal gland in birds…something mammals cannot do, so they use an 
eye-brain connection.

Anne

PS for birds like budgerigars in Australia that breed erratically when there is 
rain, rain seems to cue migration to breeding grounds and greening foods (wild 
millet for instance) and dark nest holes spur ovarian development in females. 
Anne B Clark
147 Hile School Rd
Freeville, NY 13068
607-222-0905
anneb.cl...@gmail.com





> On Feb 14, 2018, at 10:00 AM, psaracin <psara...@rochester.rr.com> wrote:
> 
> Thanks Dave but that data does not address the issue of daylength (which has 
> remained essentially the,same for the time period you mentioned). Again I say 
> the behavior is much more related to photoperiod (day length) than any other 
> thing.....
> Anyone else care to weigh in.
> 
> 
> 
> Sent from my Verizon, Samsung Galaxy smartphone
> 
> -------- Original message --------
> From: david nicosia <daven1...@yahoo.com>
> Date: 2/14/18 8:30 AM (GMT-05:00)
> To: Sandy Wold <sandra.w...@gmail.com>, Upstate NY Birding digest 
> <cayugabird...@list.cornell.edu>, psaracin <psara...@rochester.rr.com>
> Subject: Re: [cayugabirds-l] Bird Signs of Earlier Spring?
> 
> I have heard Cardinals, titmice, chickadees, and carolina wrens sing on 
> clear, sunny mornings with light winds and temperatures near zero in February 
> for years. Plus, looking at the long term temperature records for Ithaca NY 
> (from the Cornell U. site), surprisingly there has been no long term trend in 
> temperatures, even in the winter. I checked Jan-March, no trend and annually, 
> which was slightly negative(probably not statistically significant). This 
> means that from the late 1800s to present, there has been no warming and 
> possibly even slight cooling at Ithaca! There has been a warming trend since 
> the 1960s, which was the coolest part of the 20th century. Many people are 
> comparing today's temperatures locally to the 60s.  If you look before that 
> time period it was warmer and for some locations, like Ithaca, slightly 
> warmer than today. So the argument about earlier spring weather locally does 
> not apply to our birds based on this long running dataset. Of course, this is 
> just locally. Not speaking to what is happening globally! 
> 
> On Tuesday, February 13, 2018, 11:13:11 PM EST, psaracin 
> <psara...@rochester.rr.com> wrote:
> 
> 
> Sandy, I, too, have heard titmice and cardinals. I believe such behavior is 
> more tied to hormonal responses brought on by increased daylength but am no 
> ornitholigist.....
> 
> 
> 
> Sent from my Verizon, Samsung Galaxy smartphone
> 
> -------- Original message --------
> From: Sandy Wold <sandra.w...@gmail.com>
> Date: 2/13/18 9:56 PM (GMT-05:00)
> To: Upstate NY Birding digest <cayugabird...@list.cornell.edu>
> Subject: [cayugabirds-l] Bird Signs of Earlier Spring?
> 
> Maybe this is obvious to everyone on this list with people reporting the call 
> of a cardinal or "raven with nest material" in February.  But I also have 
> been noticing sounds of spring (cardinal, titmouse, Carolina Wren, ...), 
> crows checking out tree tops and pairing, crows bombing raptors,... since 
> February 1st (maybe even second or third week of January?).  I meant to write 
> dates and temps in my notebook this year, but didn't.
> 
> It seems like all of this is happening a month or two early, am I wrong? Are 
> there any scientific studies that show what triggers the timing of these 
> territorial behaviors? Could it be a certain number of days above freezing?  
> I know the media talks about the growing seasons lengthening and things 
> blooming earlier,... but I haven't seen anything written on bird nesting 
> behavior.  Just curious, thanks!
> Sandy
> ---
> Climate Change Action: 30-day Ithaca VEGAN CHALLENGE (pledge for Earth Day 
> 2018)
> No-blame, no-shame support here: https://www.facebook. com/groups/ 
> IthacaVeganChallenge/ <https://www.facebook.com/groups/IthacaVeganChallenge/>
> Less meat = Less heat, 4 min. video  www.youtube.com/watch? v=lLhEmGx8YQE 
> <https://www.youtube.com/watch?v=lLhEmGx8YQE>
> ---
> Sandy Wold
> Author/Originator of Cayuga Basin Bioregion Map 
> (available at Wegmans (near ATM), Autumn Leaves, Cornell Plantations, and 
> Ithaca Visitor's Bureau)
> https://www.linkedin.com/in/ sandy-wold-877114a7/ 
> <https://www.linkedin.com/in/sandy-wold-877114a7/>
> https://sites.google.com/site/ cayugabioregionmap/about- author-and-artist 
> <https://sites.google.com/site/cayugabioregionmap/about-author-and-artist>
> www.Sandy-Wold.com <http://www.sandy-wold.squarespace.com/>
> --
> Cayugabirds-L List Info:
> Welcome and Basics <http://www.northeastbirding.com/CayugabirdsWELCOME>
> Rules and Information <http://www.northeastbirding.com/CayugabirdsRULES>
> Subscribe, Configuration and Leave 
> <http://www.northeastbirding.com/CayugabirdsSubscribeConfigurationLeave.htm>
> Archives:
> The Mail Archive 
> <http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html>
> Surfbirds <http://www.surfbirds.com/birdingmail/Group/Cayugabirds>
> BirdingOnThe.Net <http://birdingonthe.net/mailinglists/CAYU.html>
> Please submit your observations to eBird <http://ebird.org/content/ebird/>!
> --
> --
> Cayugabirds-L List Info:
> Welcome and Basics <http://www.northeastbirding.com/CayugabirdsWELCOME>
> Rules and Information <http://www.northeastbirding.com/CayugabirdsRULES>
> Subscribe, Configuration and Leave 
> <http://www.northeastbirding.com/CayugabirdsSubscribeConfigurationLeave.htm>
> Archives:
> The Mail Archive 
> <http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html>
> Surfbirds <http://www.surfbirds.com/birdingmail/Group/Cayugabirds>
> BirdingOnThe.Net <http://birdingonthe.net/mailinglists/CAYU.html>
> Please submit your observations to eBird <http://ebird.org/content/ebird/>!
> --
> --
> Cayugabirds-L List Info:
> Welcome and Basics <http://www.northeastbirding.com/CayugabirdsWELCOME>
> Rules and Information <http://www.northeastbirding.com/CayugabirdsRULES>
> Subscribe, Configuration and Leave 
> <http://www.northeastbirding.com/CayugabirdsSubscribeConfigurationLeave.htm>
> Archives:
> The Mail Archive 
> <http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html>
> Surfbirds <http://www.surfbirds.com/birdingmail/Group/Cayugabirds>
> BirdingOnThe.Net <http://birdingonthe.net/mailinglists/CAYU.html>
> Please submit your observations to eBird <http://ebird.org/content/ebird/>!
> --


--

Cayugabirds-L List Info:
http://www.NortheastBirding.com/CayugabirdsWELCOME
http://www.NortheastBirding.com/CayugabirdsRULES
http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm

ARCHIVES:
1) http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html
2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds
3) http://birdingonthe.net/mailinglists/CAYU.html

Please submit your observations to eBird:
http://ebird.org/content/ebird/

--

Reply via email to