High-tech deer counts vary widely
Not all deer woods are created equal.
Aerial surveys done over vast tracts of the U.S. Army Corps' Raystown Lake property and over state forests managed by the Department of Conservation and Natural Resources are showing that to be true.
The two government agencies paid the Idaho firm Vision Air Research Inc. to fly over their woods and count deer using forward-looking infrared, or FLIR, technology.
The Army Corps actually had two surveys done, one last fall just as hunting season was beginning and another over the winter, after sportsmen had removed deer from the landscape. The results of that second survey effort have just been released. They show that the condition of the habitat, far more than hunting pressure, determines where deer will be found and in what concentrations, said Jeff Krause, a Corps biologist at Raystown Lake.
Overall, the deer population at Raystown stood at 52 deer per square mile before hunting season started. After hunting season, the average was 24 deer per square mile.
One the western side of the lake, though, where the deer habitat is best, hunter access is easiest, and the most deer management assistance program, or DMAP, coupons were available, three of the survey areas actually saw increases in deer numbers after hunting season.
Conversely, deer numbers on the eastern side of the lake -- which might seem like a refuge, given that it's steep and hard for hunters to access --dropped from almost 47 to 13 deer per square mile over the winter.
"Several compartments on the poor habitat and low browse areas of the eastern side of the lake dropped as low as five deer per square mile, even without much hunting pressure," Krause said.
"These facts demonstrate that the deer simply move from the poor food areas into the good food areas."
Officials with DCNR suspect that their aerial survey work will ultimately prove much the same thing. While the agency has just one year of deer counts to work with --final results of its survey were released about a week ago -- they, too, show that deer numbers vary widely.
Vision Air Research counted deer on 10 tracts of state forest encompassing 207,527 acres. Some places had relatively high numbers of deer. The Promised Land area of Delaware State Forest in Pike County, for example, still had 23.69 deer per square mile after hunting season.
The Denton Hill area of Susquehannock State Forest in Potter County had 20.29 deer per square mile.
Other places, though, had relatively few deer. The southern section of Sproul State Forest in Clinton and Centre counties had just 8.63 deer per square mile, and the Cedar Run area of Tioga State Forest in Tioga County had just 9.64.
DCNR officials used those numbers to make some adjustments to their participation in the DMAP program, changing some DMAP boundaries to give hunters opportunities to get more than one coupon and decreasing the number of coupons available in others.
What they're really hoping, though, is that the deer surveys can be used in conjunction with vegetation studies set to begin this summer to see if deer are in fact causing problems with forest regeneration, and if so where.
Some, like DCNR biologist Merlin Benner, believe that some areas of forest land are seeing regeneration, thanks to the aggressive deer control strategies of the last few years. It's still true in other places, though, that wildflowers and other woodland plant and animal species are either missing from most of their former range or are found only in limited numbers because of overbrowsing by deer.
The job now is to balance deer numbers at a level where all of those other things can survive, too. That's where the aerial counts come in.
DCNR plans to continue its survey program this fall -- just prior to the rifle deer season -- and expand it to include some areas of state game lands.
"Our goal is to manage the herd so we can have time to allow forest regeneration," said DCNR Secretary Michael DiBerardinis. "Then, with regeneration established and more food for deer, to allow herd numbers to rise, while keeping them in balance with the habitat's ability to sustain itself."