I was curious about the days in Pa, so I emailed my local WCO..
His reply:
Crows are part of the Migratory Bird Treaty Act between the U.S., Canada and Mexico. As such the U.S. Fish and Wildlife Service, as part of the treaty, only allows each state a certain number of days that each species can be hunted. The same applies to ducks, geese, dove, woodcock, snipe, etc.
Pennsylvania elects to allow crows to be hunted during a longer period of the year but only three days a week (Friday, Saturday and Sunday) while still providing the maximum number of days allowed within the framework of the days and times allowed by the treaty.
Season runs from September through May.
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so, I guess each state mixs/matches days & season lengths to come up with the total of allowable hunting days.