Date: 2/14/18 9:53 am
From: Peter <psaracin...>
Subject: Re: [cayugabirds-l] Bird Signs of Earlier Spring?
Thanks Anne.

Very informative.

Question: how about birds SOUTH of the equator......say an upland
sandpiper in Central Argentina. As Argentina's autumn is coming on the
days are shortening. What cue to these birds then rely on?

Thanks

Pete Saracino


On 2/14/2018 11:43 AM, AB Clark wrote:
> 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.clark...> <mailto:<anneb.clark...>
>
>
>
>
>
>> On Feb 14, 2018, at 10:00 AM, psaracin <psaracin...>
>> <mailto:<psaracin...>> 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 <daven1024...> <mailto:<daven1024...>>
>> Date: 2/14/18 8:30 AM (GMT-05:00)
>> To: Sandy Wold <sandra.wold...>
>> <mailto:<sandra.wold...>>, Upstate NY Birding digest
>> <cayugabirds-l...>
>> <mailto:<cayugabirds-l...>>, psaracin
>> <psaracin...> <mailto:<psaracin...>>
>> 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
>> <psaracin...> <mailto:<psaracin...>> 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.wold...> <mailto:<sandra.wold...>>
>> Date: 2/13/18 9:56 PM (GMT-05:00)
>> To: Upstate NY Birding digest <cayugabirds-l...>
>> <mailto:<cayugabirds-l...>>
>> 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.
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>> //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/>
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