Mild Winter Helps Mule Deer Fawn Survival

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Mule deer entered this year’s winter with good fat supplies and with the lack of snow and cold Fish and Game biologists anticipate high fawn survival rates for the region this year.

Earlier this week, the second of 25 radio collared fawns in the South Hills died.

“This is the highest survival rate we have had this time of year since the program started,” said Randy Smith, regional wildlife manager. “If the survival trend continues we could see a substantial increase to the mule deer population in the region.”

The fawn mortality program is in its fifth year. After the winter of ‘92-’93, Fish and Game biologists from the state devised the plan to enable them to gather better data.

An average of 25 to 30 fawns are captured each fall on mule deer winter ranges in the Magic Valley, Salmon, Pocatello, Idaho Falls and Boise regions. Biologists monitor the radio-collared animals three to four times a week recording their range movements and survival.

Each of the deer collars emit a tone on different radio frequency. When the animal is alive and moving around it sends a slow beeping tone. If the animal dies, the beeping sound speeds up and biologists then know the animal is dead.

“Our goal when we get a mortality tone is to get to the animal as quickly as possible,” said Jared Baecker, wildlife technician. “The sooner we can get to the animal, the easier it is to determine how it died.

“If the animal is dead for any amount of time before we get to it, it has often been eaten,” he said. “It makes it a lot harder to determine the cause of death.”

The first of the two fawns that have died was such a case. By the time biologists found the animal, all that was left was the lower jaw and the radio collar. The second fawn found died from starvation and parasites.

“We found the fawn whole, so we took it to Boise (the State Wildlife Health Lab) to do a complete workup on it,” Baecker said. “Even though its stomach was full, it had lost nearly 14-pounds since we captured it early this winter.”

Biologists will continue monitoring the collared animals for the next few months. Data collected by the research is discussed weekly.

The fawn mortality study helps biologist track mule deer population trends. It is just one of the tools they use to determine mule deer permit levels for each hunting season.