Coyotes have a 63 day gestation period. The earliest den I have ever taken was march 28 th. I killed a female 4 or 5 years ago on march 13 th that would have hatched that day or the next. I have also tracked dens out in the middle of June that had pups that were still slate colored (pretty young). Once they are bred up, they will continue to get more and more territorial, thats what you need to monopolize on.