The latest mule deer count in eastern Idaho and what it means for the wildlife population

The mule deer herd composition counts were finished in December while the winter population counts won’t be finished until early February. The herd composition counts compare how many bucks and fawns there are for every 100 adult does and this gives the Idaho Department of Fish and Game the general health of each major deer population of the Upper Snake River Valley.

“We try to count and comp at least 700 individuals per population area,” Curtis Hendricks, the Upper Snake Regional Wildlife Manager, said. “Most of our data for our portions of the Data Analysis Units (DAU) are merged with data from other Regions that also have areas that are surveyed to add to the data.”

The comp counts have to be completed before the bucks drop their antlers, which usually begins in early January. But this year some bucks were observed with only one antler in mid-December. Whether it was dropped naturally or was knocked off while fighting during the rut is unknown.

There are large populations of mule deer in five DAU’s in the region that are critical for the survival of deer. Deer herd composition is critical for the setting of hunting seasons. In this year’s comp count, the Pioneer DAU (Unit 50) had the lowest fawn numbers with 57:100:27 (fawn/doe/buck), while the Mountain Valley DAU (Units 59A and 58) had the highest fawn ratio at 77:100:21.

“As a general rule, entering winter with fawn ratios of the upper 50s to low 60s means the population, given an average winter, will likely hold even,” said Hendricks. “When you get ratios of upper 60s and into the 70s, we are likely growing some deer. Prior to the 2016-17 winter, we had fawn numbers in the mid 70s and 80s.”

The buck numbers are seriously low in several DAU’s. In the Caribou area (units 66 and 69), the count totals were 13 bucks per 100 does, and in the Island Park DAU there was only 18 per 100 adult females.

“Fawn recruitment is the name of the game and we had hard winter conditions in 2016-17 winter and again in 2018-19,” said Hendricks. “This made us short on three and one-year-old bucks in this composition count.”

Hendricks is concerned about how this winter is shaping up with all the snow in the last two weeks. The winds can be a blessing or a problem for the wintering deer because the wind can keep the south slopes bare so the deer can get to their food, but it can also pack the snow. If the weather warms enough to melt the top layer of snow and then freezes, causing a hard crust to form, the deer cannot dig through it to get to their food.

“Winter is harder on fawns than it is on adults. It is these types of winters when we have likely lost a large proportion of our fawns and then we couple that with significant reductions in the breeding segment of our doe populations that we see lasting impacts to our deer herds,” said Hendricks. “The good news is that just like they can decrease at a seemingly high rate, the deer populations can rebound quickly as well.”

This brings into play what sportsmen and wildlife viewers can do. We must not be responsible for stressing the animals by getting to close to them or making them fight through the deep snow to get away from us. The deer need to get a break and we must do what we can to help them through the hard times by observing them from a distance.

The deer will congregate in large groups where Idaho Fish and Game will be able to count them from the air. Around mid-February, I will let you know what the counts are and what the snow conditions are for the deer. In the meantime, please drive carefully as many of the big game animals may have to migrate across your favorite road.