Deer are endlessly fascinating; I could watch them for hours. One of my favorite activities for a summer night – and yes, I know this is sad, as most people would prefer a cookout – is to sit in a ground blind or tree stand, watching and photographing deer. Those who conduct deer research take this interest to a much-higher level, and we can learn a lot from the work that’s being conducted in our state.

One of the things that should jump out at us, as hunters, is the length of time that researchers are able to track adult bucks which are radio-collared. What’s more, those bucks are living on state game lands (the study areas include Rothrock, Bald Eagle and Susquehanna state parks).

“It is not unusual to follow many of our bucks for 2 to 3 years,” said Duane Diefenbach, from the U.S. Geological Survey, its Cooperative Fish & Wildlife Research Unit. “This year we had a lot of collars we had to remove from deer because bucks are outliving the battery life of their collars.”

Researchers from the USGS, the Department of Natural Resources Bureau of Forestry, Penn State University and the Pennsylvania Game Commission are working together on a Deer-Forest study, capturing and either applying radio collars or ear tags to bucks. In those areas, the antler restriction for harvest is that bucks have at least three points on one side of their racks.

From 2013 to 2017, researchers captured and ear-tagged 170 bucks. During the same time frame, from 8 to 24 bucks were outfitted with radio-collars and monitored. As they tagged or collared deer, the researchers learned that about 36 percent of yearling (1.5 years old) male deer were legal for harvest, and of the adult male (more than 2.5 years old) deer, about 80 percent of them were legal for harvest.

“This is why antler point restrictions work,” Diefenbach said. “They protect the majority of yearlings from harvest; 90 percent survive to the next hunting season.”

But, you’re thinking, those numbers don’t make sense. How can it be that 36 percent of the young bucks are legal for harvest, but 90 percent survive to the next year?

“Over those five hunting seasons (2013-17), harvest rates of yearling and adult males usually have been very similar – from 8 to 17 percent for adults and 11 to 17 percent for yearlings. Actually in 2015 we didn’t have any yearling males harvested.”

Harvest rates average 13 percent for both age classes. To estimate harvest rates, researchers used a statistical model, using data from both radio-collared and ear-tagged deer. They also used data from hunter harvests.

“This approach to estimating harvest rates has an advantage in that you don’t have to radio-collar and track every deer you capture,” Diefenbach said. “Radio collars are cool, but they cost a lot of money.”

Knowing the survival and harvest rates allows researchers to project the age structure of the population.

“Think about it this way – if we start with 100 8-month-old bucks in January, we know that 90 percent of them will survive to hunting season,” he added. “Then during the hunting season about 13 percent of them are harvested, then 90 percent survive to be 2.5 years old, and so on.”