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Fledgling metabolism; migrants




While nestling birds do require nearly constant feeding, most songbird
youngsters who are out of the nest do not require such constant feeding.
Fledglings can go as much as four hours, maybe a little more, without being
fed.  Yes, it is an attempt to teach the youngsters to fend for themselves
but the adult birds do draw a line between allowing a youngster to become
weak from hunger and encouraging them to find their own food.  I have timed
the frequency of feeding for both Carolina Wren and Eastern Bluebird
nestlings (not fledglings).  The longest absence for the Carolina Wrens was
about 8 minutes and the average absence (the cumulative time of all the
absences divided by the number of feedings) was around five minutes.
Several times the absence was less than three minutes.  The longest absence
for the Eastern Bluebirds was 17 minutes and the average absence was around
8 minutes.  So feeding nestlings is a constant task but feeding fledges is
a bit easier, less time-intensive and less time-critical.

A quick perusal of the Florida listserv (EastBirders) found a few messages
reporting the very first of the migrants, a Louisiana Waterthrush and a
Prarie Warbler.  Combined with the Yellow Warbler found on Monday by Ferenc
Domoki in Winston Salem, it serves as a reminder that cooler weather and
clearer skies are coming.   

And lastly my apologies for the lack of a subject line in my previous post.


Donna S. Bailey		
Winnsboro, SC

e-mail: dsbailey@conterra.com

URL:  http://www.conterra.com/dsbailey
	Where are the Birds?  Migration across South Carolina

URL: http://www.conterra.com/dsbailey/audubon
	Coulmbia Audubon Society