Mar 19 2009
Question: How soon will the eggs hatch?
Answer: Peregrine eggs hatch about 32 days after incubation begins(*), but it is hard for most people to tell when incubation begins in earnest.
I have tracked the “first egg” and ”first hatch” dates at the University of Pittsburgh and Gulf Tower nests for about 7 years. The average at both sites is 39 days from first egg to first hatch, though it varies a bit from year to year and nest to nest.
All of the eggs in a nest usually hatch on the same day.
The photo above shows hatched eggs and chicks at the University of Pittsburgh nest in 2008. The father bird is standing next to the nestlings who are in a pile with the one unhatched egg. The white fluff in the center are the baby peregrines, the curled white things scattered about are the insides of the discarded egg shells. The reddish pieces are the outside of the discarded egg shells.
For more infomation on incubation, see: http://www.wqed.org/birdblog/2009/03/23/the-big-sit/
(photo from the National Aviary webcam at University of Pittsburgh, 30 April 2008)
(*) The incubation time span used to be listed as 33-35 days. It is very hard to tell when it begins.
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