Three years of field study, 165 captured fawns and more than 200,000 trail-camera photos indicate stable fawn survival in state, the Pennsylvania Game Commission said this week.
The research, which wrapped up in 2017, was started to see if predators — particularly coyotes — were taking more fawns than documented in a two-year study that began in 2000. The Game Commission and Pennsylvania Cooperative Fish and Wildlife Research Unit at Penn State collaborated to design the study and conduct fieldwork.
Although Pennsylvania had more predators and deer when the second study began in 2015 than it did for the earlier study, the results essentially were the same, said Christopher Rosenberry, who supervises the agency’s Deer and Elk Section.
“There was no evidence that predators were taking too many of our fawns in any of our 23 Wildlife Management Units,” Rosenberry said. “They all have stable or growing whitetail populations.”
“Our field studies have shown repeatedly that predators are the No. 1 cause of fawn mortality, and more often than not, black bears are taking the fawns,” Rosenberry said. “But fawn mortality is not causing deer-population reductions anywhere in Pennsylvania.”
But even if the predator-take of fawns did impact deer populations, reductions in antlerless deer licenses would reverse their influence, Rosenberry said.
The three principal predators that surfaced in the first study resurfaced in the second: black bears, coyotes and bobcats, said Duane Diefenbach, PCFWRU unit leader. Despite growing concern about fishers as deer predators, they didn’t take any fawns in the study. To date, no fisher has ever killed a radio-collared study fawn in North America, he said.
In the 2015-17 study, 82 fawns were captured and fitted with radio collars on the northern study area on the Susquehannock State Forest. Another 83 fawns were captured and radio-collared on the southern study area, which included parts of the Rothrock and Bald Eagle state forests.
There were 44 mortalities on the northern study area: 33 from predators, six from humans and five from natural causes. Bears took 18 fawns; coyotes, eight; bobcats, two; and unknown predator, five.
The southern study area had 38 mortalities: 18 from predators, 13 natural causes and five from humans. Coyotes took six fawns; bears, five; bobcats, five; and unknown predator, two.
“Predation was the main source of mortality,” said Tess Gingery, a Penn State graduate student with the PCFWRU. “It’s that way across North America.
“Since Pennsylvania’s fawn survival shows little change over time, this means that it’s stable and that makes it simpler for biologists to make harvest management recommendations,” she said.
Most fawn mortality occurred over the first eight weeks of a fawn’s life. Conversely, most human-caused mortality — roads, fences, farming activities and hunting — occurred in the 25- to 30-week window, Gingery said.
Natural mortality — starvation, disease, abandonment — was more pronounced on the southern study area in both the 2000-01 and 2015-17 studies.
Deer and bears prefer forested settings. But in the southern study area, many does summered in farm areas because it was safer for their fawns to reach a size in which they could escape predators, said Asia Murphy, a Penn State graduate student with the PCFWRU. By the fall, fawns returned to forested areas.
“Does are smart,” Murphy said. “They raise their fawns in safe places.”