JB, God only knows the total reason ....lol. However, from past experiences I agree with Grizzly Creek. I was taught by a seasoned trapper rabbits are much like humans when it comes to getting out of messy weather. Rabbits like humans will find a shelter out of the rain and a cold wind, which typically comes from the North. Rabbits go to the Cheesewheel trap for food so it doesn’t matter, but they go to a box trap to either get out of the weather or because they smell another rabbit. Because rabbits are extremely territorial, if you spray rabbit urine on/in or put rabbit turds in the box, if there is one around, it is going to investigate. You can pick up rabbit turds while hunting and put in a ziplock bag, and you can buy rabbit urine online unless you know someone who has pet rabbits, and if so make you a catch pan and collect their excretions.
Good Luck!!