As a biologist, I have been studying whitetail deer for close to a half-century. Most of what they do is not complicated. When it comes dispersal and movement, so many factors are involved, it can become complicated. The loss of habitat, an ever increasing factor now skewes most logical thinking. But to over simplify, a deer will move no farther than is required to find food, water and cover. During the rut, the range of movement widens and some of the deer who venture into new territory, stay. Water is a minor factor. Dispersal is a different matter. Population dynamics, plays a major role.
Dispersal is simply the running off of bucks past 1-yr of age by the matriarch of the family unit. These bucks usually, then, attach to another family unit at varied distances. However, here is a factor most overlook. Once a buck reaches 3.5-years of age, he is most likely to die of something other than a hunter. In short, he becomes less visible. This does not mean he has gone, anywhere. But, he has no defined, home range. He will have a core area, but he is not "territorial". he will move as far as he has to to find, food, water, cover and for a period, a receptive doe. The concept of "family unit" becomes one of "bachelor group". The dynamics within these two nuclei is sometimes stagnant and sometimes ever-changing. In northern areas, where snow is a major factor and deer "yard-up", it can be even more complicated.
The use of trail camera photos can be extremely helpful. It can also be extremely misleading. This is true, simply because the camera covers such a narrow field of view. My research with mock scrapes and rubs taught me more about whitetail behavior than any other factor. It turned what were previously regarded as hard facts into pure myths.
The herd in my "backyard" can vary from 10-35 animals depending on the time of year and the change in preferred food sources-mostly woodland food sources. The bottom line is, in most cases, don't worry about it.
