deerlawyer said:
if i am reading your graph correctly, it is not uncommon for a new buck to show up that ends up staying on the property and becoming a "resident", correct? i would think better habitat, feed, or less pressure could cause this?
When I first started working on this research, no "terms" existed for what I was seeing in the data, so I had to use something and came up with the terms "seasonal range-shifting" and "rut-season range-expanders/shifters." Although it was impossible to know what was really going on, all of my camera data from different locations kept displaying the same patterns from year to year, in that it appeared that bucks were displaying shifts in their ranges seasonally.
Below is a similar graph of just the older bucks (2 1/2 years old or older). I eliminated yearlings because they have some unique behaviors that confuse the issue (Yearling Buck Dispersal). This graph was produced for an article and so I removed all of the "diamond" data points for each date photographed to keep from confusing issues. I only displayed the first and last date a buck was photographed (or known to exist) on the property:
Classically, I was finding two primary times that older bucks would suddenly appear or disappear from a ongoing photo-census of a property. The first occurs right at antler velvet shedding time. Some summer resident bucks would suddenly disappear from a property just at antler velvet shedding time, not to be seen again until the following summer. At the same time, "new" bucks would suddenly appear on the monitored property right at antler velvet shedding time. Many of these new" bucks would then stay for the entire fall hunting season. On occasion, I would see the same bucks appearing from year to year at this time. Again, from all appearances, it seemed as if these bucks would only use a given property during the fall months, and they would do so each year. I call the bucks that leave a property at antler velvet shedding time or appear on a property at that time "seasonal range-shifters," as they appear to change their normal ranges right at the same change of season each year. More recently, these seasonal changes in range have been confirmed as "normal" in GPS-collar studies of older bucks conducted at Remington Farms in Maryland. Sometimes bucks have completely different ranges from summer to fall, but most often they simply shift only part of their range. A percentage of their range remains unchanged, by they start using areas in fall they did not use at all in summer. For smaller properties, a particular buck may not cross the property at all in summer (his summer range is near or adjacent to the property, but he doesn't cross the property line hence won't be picked up in a summer census). Come fall he abandons part of his summer range and starts using a different area that is on the monitored property, hence suddenly appears in the census.
On every monitored property I have data for, some bucks shift away from the property at the end of the summer. Sometimes the property loses as much as 50% of their summer resident bucks, but 20-30% is more common. However, those bucks are usually replaced by bucks shifting into the property in fall, producing a "zero net change" in total bucks using the property from summer to fall. On the other hand, some properties lose fewer bucks after summer, yet still gain new bucks in fall, producing a net gain in total bucks from summer to fall.
The second major and consistent period where "new" bucks show up on camera censuses is around the rut. It has been known for a long time that bucks dramatically increase the size of their ranges around the rut, as they seek out estrus does. This "rut-season range-expansion" can bring a buck whose normal range is close to a monitored property (but doesn't cross the property line during most of the year) onto the property only during the rut as the buck expands the size of his range. These rut-season range-expanding bucks are generally only photographed for the peak of the rut on a given property (2-4 weeks). They expand their range onto the property just prior to the peak of the rut, use the property occasionally during peak breeding, and then disappear from the property as soon as peak breeding is over. Again, like seasonal shifts, I would often see the same buck appear on a property
only during the peak of the rut from year to year. I
assumed range
expansions were the only reason for these bucks' appearances and disappearances, but some new GPS-collar research out of Auburn is finding something very interesting. With their GPS-collared older bucks, they are finding that some of these bucks have completely different ranges than normal during the rut. In essence, they actually completely leave their normal range and move to a different location for the rut, only to return back to their original range after the rut. So now I've expanded my definition of these bucks from rut-season range expanders to rut-season range expanders/shifters because some of the new bucks that appear only during the rut may actually be shifting their range onto monitored properties only during the breeding period instead of just expanding their range from an adjacent area.
Now "why" bucks make these seasonal and rut-season range shifts is unknown and will probably stay that way. It's impossible to get inside a buck�s head and figure out his decision making process. However, the most likely reason is access to needed/desired habitat. A particular type of habitat is needed/desired at only certain times of the year, hence is only used during particular seasons of the year.
The practical application of all this is twofold. First, bucks shift around during the year, hence the standard late-summer baited photo census will not pick up many bucks that will be using the monitored property during the hunting season. In addition, some of the summer censused bucks won't be using the property during the hunting season. That's why so many hunters report killing bucks during the hunting season that they didn't get pictures of on their census. This has caused many hunters to question the value of photo-censusing. They kill bucks they didn't get on their summer census thus assume the census was bad. Yet the reality is that buck they killed in fall that wasn't in the summer census literally wasn't on the property in the summer. He only uses the property in the fall. In addition, hunters that never see bucks during hunting season that were summer photo-censused think hunting pressure drove the buck totally nocturnal. That may be part of the problem, but some bucks that use a property all summer long and are picked up on summer photo censuses and/or are seen feeding in fields on the property literally are not on the property come fall hunting season. They may have shifted their range off the property come hunting season, and this would have occurred hunting pressure or no hunting pressure.
Second, many more bucks than just the summer resident photo-censused bucks can use an individual property over the course of an entire hunting season. Due to seasonal and rut-season range shifts/expansions, a single property may end up having three times the number of bucks as what was found in the summer census use the property at some point during hunting season and be "harvestable" bucks. For example, a property that identifies 10 unique bucks in summer may end up photo-censusing 30 different bucks using the property at some point over the course of an entire hunting season.
Too often I hear hunters/managers trying to calculate how many bucks they have to manage/hunt. The conversation always starts, "Let's see, I have half of a square mile, and the deer density is 30 deer per square mile--giving my 15 deer, and if 1/3 of those deer are bucks I've now got 5 bucks to work with...." Yet those type of calculations are a HUGE mistake. Not only is the hunter/manager forgetting that deer cross square-mile boundaries, they aren't accounting for seasonal range-shifts and rut-range expansions/shifts. As an example, the deer density in my area runs around 35 deer per square mile, and I have 3/4 of a square mile to work with. Theoretically that means I only have 26 deer to manage. Yet from the August 1st to January 31st I may photo census over 150 unique individual deer using my property at some point. Now at no time are all those deer on the property at the same time. In fact, the number using the property at any given point in time remains about the same. But over the course of 6 months, 150+ deer cross the property, making them "manageable" deer (they are using the resources of the property). That's why a single well-managed property can positively influence a large number of deer from the entire surrounding area. Now not all deer we census over 6 months are harvestable. Some were only on the property in summer and left the property before the hunting season opened. But still, the point is, many more deer�and especially bucks�cross a property and are manageable, harvestable animals than �deer densities� suggest. Deer, and especially bucks, move around quite a bit from season to season.
