Be sure to throw some salt in those brush piles. The does need it for gestation. I buy cattle salt blocks and bust them up with hammer. Push some chunks down in the piles. Cheaper than buying regular rabbit salt. If you have what might be called "trash " trees at about 6" dia, cut them half to 3/4 thru at about 18" high and push them over. Pile brush up on that. Remember, rabbits are mostly edge creatures, so make you piles around the edges of fields. Feral and farm cats used to be the bane of our rabbits but now it's damn coyotes. They are on my hit list anytime , anywhere. I have a friend who actually live traps groundhogs (they are kinda scarce around here too, damn coyotes !) from barns and out buildings for folks and transplants them to a back corner of his property. Their dens are wonderful rabbit cover too. I hope before I pass from this earth I can once again hunt one of my favorite small game animals.