My guess from exeperinces up around Bellingham Wa. is that your response is
going to vary with the type of owls you're looking for and techinque.

The larger owls ( Great Horned, Barred) seem to start calling earlier around
Januarary. While the smaller owls (Screech, Saw whet and Pygmy) seem to
delay calling spontanouly....(cold medication is not helping the spelling
today).... untill "later" spring up through june.

There was a symposium on Northern Forest Owls, which has was put out by one
of the governmental agenices (fish & wildlife perhabs) which should be at
your local federal respository library which has further information on
calling and responses.
Fredri7997.aol.com
Fredrick 360-671-8415