The curious behavior of our backyard bunnies

In the winter our backyard is always crisscrossed by rabbit tracks. Once it snows it becomes clear that there is a lot of rabbit activity in the area- the tracks are everywhere. This year, before the big Christmas eve snow/ice event, the boys and Jon had created a large snow igloo like structure in the backyard. Then we had the snow/ice thing and apparently the ice wasn't so thick and hard that a bunny couldn't leave tracks. The yard was once again covered, including one intrepid track going right up and over this really rather tall and steep igloo thing. The whole yard is completely covered, except for this mound in the middle that the boys had created. That had beautiful shiny clean ice/snow everywhere except the lone track going up then back down the very apex (is that the right word? The summit?). It kind of looked like there had been a bunny convention out there and they hopped all over, daring each other to take on the hill. Then one brave bunny took the challenge, but no one else followed. And then a few days later another small snow wiped all the tracks out. The yard was fresh when we went to bed- no tracks. In the morning, covered- including once again, the lone track up and over the high point of the igloo. As the days go on, the yard becomes even more traversed, but the igloo remains with only the one clean track. This has now happened three times. Each time I see that one fresh track going up and over it gives me a smile to think of the rabbits out there daring each other. It's supposed to snow again tonight. I wonder if any of them are going to take the dare. I hope so.