I don't remember where I read this, but I think I saw this in D&DH magazine. Deer travel mainly on trails in the winter because their food sources are so limited. There really is not much of a reason for them to travel through other areas. In the summer however deer will disperse over a wider area because there is more food available to them away from their main trails. Spring and fall are kind of in the middle as food sources rise and decline. I have also noticed that at anytime of the year when deer want to escape from a situation quickly they will make their way to a trail because that is the fastest way out of the area. Just my few cents worth.