According to the Metro Parks Naturalist, they don't like to do owl walks once it gets to I think she said nesting season, or maybe it was breeding season, I can't remember exactly, but the basic idea was that we try to do fewer things that might distress them or put them in stress. Then through the spring and summer they are usually raising babies, which can also be sensitive if bird watchers are all over them. For our local Metro Parks system and birding groups it seems like they only do organized owl walks from near the end of October until about the end of February.