BOISE – According to figures released by Idaho Fish & Game, the nationwide survival of mule deer calves and elk calves was above average through late April. Fish and wildlife biologists will continue monitoring through May, but traditionally less than 5 percent of deaths occur after April.
“In years with milder winters like this, we tend to see numbers or mortality decrease in May,” said Rick Ward, Deer and Elk Program Coordinator. “While we anticipate an additional mortality rate by the end of the month, the nationwide survival of mule deer calves and elk calves should be above average this year unless an unusual event occurs.”
Fish and game teams and volunteers catch fawns and calves in winter and equip them with telemetry collars that biologists can use to track the young in first winter and early spring.
Nationwide, 77 percent of elk calves and 64 percent of mule deer fawns survived by the end of April. Compared to 77 percent and 65 percent in the same period of 2020, the final numbers for 2020 (through the end of May) were above average at 73 and 63 percent.
Fish and Game has been monitoring winter calves’ survival for 23 years. During this time, the mean survival of the fawns was 57 percent. If survival in 2021 is expected to be similar to 2020, it would mean an above-average survival of two years for mule deer fawns across the state, meaning mule deer herds are growing.
“Our herd composition surveys last fall were limited to eastern Idaho, but showed encouraging fawn / deer ratios and in some cases were very high, meaning we had a good harvest of calves well into winter.” said Ward. “Fawn weights, which indicate how likely they are to survive the winter, were high in many locations in southern Idaho when we caught and tied up fawns in December and January, and we have seen above-average survival so far. These are the conditions that lead to herd growth. “
Ward added that fawn survival was not uniform across the state and that it was between 50 and 85 percent in 2021, depending on where the fawns were tied up.
Moose have not been caught and tied up for as long as mule deer, and elk calves usually survive faster than mule deer fawns. Since researchers began collaring elk calves in 2014-15, survival has ranged from a low of about 52 percent in 2016-17 to a high of 84 percent in 2014-15.
How the numbers compare to the last few years
Up to May 1, 64 percent of the frilled fawns and 77 percent of the frilled elk calves were still alive. That’s how it is compared to the last few years. The final survival numbers (through May 31) for each year are shown in parentheses.
- 2019-20: Deer 65 percent and elk 77 percent (final 63 and 73 percent)
- 2018-19: Deer 46 percent and elk 77 percent (finals 42 and 69 percent)
- 2017-18: Deer 61 percent and elk 72 percent (final 57 and 66 percent)
- 2016-17: Deer 34 percent and elk 67 percent (finals 30 and 52 percent)