Ask A Scientist© Biology Archive

name         Jim
status       other
grade        other
location     LA

Question -   My question relates to the Eastern Screech Owl.
How are their eggs fertilized?   
Does his sperm have to penetrate an egg shell or is the
shell formed after mating/fertilization?  If the shell is formed after,
how long does it take to form and how long after mating will the egg be
laid? Must the pair mate once for every egg laid or may the usual clutch 
of three eggs be fertilized after one mating?
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In general reproduction in birds follows this pattern: during copulation 
semen and sperm are put in the female's cloaca, from which sperm swim up the 
oviduct and fertilize the eggs. Shells form as the eggs develop, and fully 
formed eggs may be laid by the female within a few days. A clutch of eggs 
may come from a single or more than one mating. I don't have specific 
information on screech owls but they follow the basic pattern.

J. Elliott
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