They will absolutely still be busy with hen through May. Remember, PA doesn't start until April 28th and I've killed interested toms right to the end of our May seasons. Fear not, your in good shape yet especially if your birds are not pressured. The last day can be just as productive as the first although it's hot right now, don't forget too many hens are also a bad thing. Later on when hens are on the nest more and more, toms are very susceptible to calling.