Birds are usually a lot more quiet, noisy on the roost and then quite for the rest of the day. Pretty well split up so you don't see as many big groups out in the fields. Trees and brush are much more leafed out so they can be harder to see and can disappear easier. Tom's I've called in in May seem like they come in much more quietly. Weather is warmer and daylight comes much earlier than I sometimes want to get out of bed for. Usually there are virtually no other hunters, but if it opens late that could change. Ticks are very active in that warmer may weather and usually the snakes are out and about.