Study shows deer population is long in the tooth

Initial results from a study of hunter-harvested deer in Idaho’s Clearwater Region is yielding interesting data.

It turns out there are some surprisingly old animals out there. The Idaho Fish and Game study pulled data from the teeth of 605 hunter-killed whitetail deer in hunting units 8A and 10A to determine the age structure of harvested animals. It included a doe that was 15½ years old and eight bucks that were 9½.

“I think it was really interesting to see, particularly on the doe end, that we have does that are reaching into their teens — 15½ years old is a very old doe, a very old deer in general,” said Kenny Randall, a wildlife biologist for the Idaho Department of Fish and Game at Lewiston. “It’s cool to see that we’ve got habitats that can support deer of those older age classes.”

Likewise, a buck that has survived beyond its ninth birthday is in its golden years.

“Particularly when we’re expecting maturity at 3½, 4½ years old, and kind of that peak antler development in the 5 and the 6½ range,” said Randall. “It’s cool to see that we’ve got deer that are meeting and exceeding those benchmarks.”

The study invited hunters to submit the front teeth from the lower jaws of deer they killed in the two units that offer some of the better whitetail hunting in the state. The teeth were then sent to a lab where they were dyed and cross-sectioned. The process allows scientists to count cementum layers, similar to counting growth rings on the cross section of a log to age a tree.

Randall said in any breakdown of an animal population, the largest cohort should be the youngest age class. Then over time that cohort dwindles as various causes of mortality pluck individuals from the population.

But studies like this can skew the data because of things like hunter preference for older, more mature animals, whether they are after big-bodied does to fill their freezers or bucks with large antlers for bragging rights. It could also be that hunters who take bigger, older animals are more likely to participate.

The largest number of animals taken were between 1½ and 3½ years old.

Randall said that was expected.

“It is cool to see that we’ve got, you know, a fair number of deer coming into that 2 to 4½ range. We’re starting to see them hit maturity,” he said. “When we have high quality habitat, we can start to see deer, does and bucks, starting to contribute back to that population.”

Fewer older animals were harvested but they were represented in decent numbers.

“That’s something that’s definitely reassuring to see. We’ve got management strategies in place that are allowing deer to reach those older age classes. I think that’s important from a population perspective, but also from hunter-desire perspective.”

The department will repeat the study this fall. Randall is eager to dive into the results and curious if any trends will be repeated.

“One thing that I’ll definitely be keeping track of as we move into our second year is do we see the same trends as we saw the first year?”

More information is available in a blog post authored by Randall at bit.ly/3WtUfhI.

Barker may be contacted at ebarker@lmtribune.com or at (208) 848-2273.