We have spent a second week in Yellowstone, at the Mammoth campground. As I mentioned before, it stays a little warmer here, so the elk like to spend most of the year. They especially like the lush green lawns around the developed areas, and hang out by the park headquarters, hotel, etc., causing traffic jams. They also came browsing through our campground most evenings. We saw LOTS of elk, mostly very pregnant female ones. They were just starting to calve while we were there, but we did not see any of the babies - they hide them until they can keep up. We also saw a couple of large bulls with velvety antlers.
We also saw a bear. Actually, we first saw a traffic jam. When we were able to get off the road, there was a bear a long way off across a lake. We had binoculars, and there was a ranger with a telescope so we got a pretty good view. It was a large male black bear. He had found a dead elk that had been frozen in the lake, and was eating it. He was surrounded by lots of ravens and one bald eagle hoping to get some. There were a lot of bear sightings in the area, but this was the only one we have seen so far. A grizzly was spotted just behind the campground one morning.
We took some really enjoyable hikes. One went out to several beaver ponds, where we saw the beavers' lodge, the dam, and even one of the beavers. Another was to the top of Bunsen Peak, a 1300 foot climb with terrific views from the top (there was still some snow of the trail up there, too). And Mammoth has some hot springs, but they are very different from the ones in the southern part of the park. The hot water comes up through limestone, which is too soft to build up pressure for geysers. Instead, the limestone dissolves, and then is deposited as the spring comes to the surface, building up intricate terraces, with formations like cave stalactites, etc. They are very beautiful.