Bflood, I may be out there for a while from the third/fourth week in May. Any recommendations specifically for that time? I'd particularly like to know any places where coyotes den or elk calf if you know of any.
My wife gave me a winter trip to Yellowstone as a Christmas gift a decade ago. While we were out on a snow coach tour, I asked the driver/guide his recommendation for the absolute best time to visit Yellowstone. With zero hesitation, he replied the third week in May. The hibernators are all out and feeding, almost everything due to be born has been born or will be soon, which means calves and kits etc everywhere, the chances of a trip-ruining snowfall have become really small, and it's before Memorial Day, which keeps crowding down, especially on weekdays.
He was as right as a person can be. When I retired at the end of April, 2012, I packed up and was in Yellowstone by the middle of May. I photographed more bears than I'd seen in the previous half dozen trips there, saw a 1 hour old elk calf, coyotes all over the park, etc.
The elk calf was born on the Madison River, between Madison Junction and West Yellowstone, MT. There are islands in the river that get almost covered with water during the spring snow melt. Elk cows will wade across to one of these islands to give birth - a defensive move. The water depth is such that an elk can walk over to the island, but a predator like a wolf or bear has to swim, which means climbing up out of the water onto the island. The elk has the advantage in that situation, able to kick severely with her back legs at the predator as it reaches the island and tries to climb out of the water. I happened along such a birth place when the calf was an hour old (according to a couple already there who witnessed the birth). I got shots of it walking, nursing, etc, and then swimming (!) to the bank of the river when only about 2 hours old.