Hello. I have two chickens that are 1.75 years old and they live in a 4 by 4 coop which is on one side of my open topped run which is about 15 by 23 feet. The other day, while my girls were free ranging a falcon swooped down, luckily I scared it away and I've seen this falcon once again. I want to make my run more secure and make it covered, but I want to do it as efficiently and inexpensively as possible. On one side of the run there is a tall fence probably 5 ft. 3 in. tall and there is one about 4'9 perpendicular to it. There are two trees parallel to each other that I could maybe attach wire to, but it snows a lot in midwinter and I'm afraid it might collapse. What should I do?