Deep snow hampers Mitkof Island deer study

a doe walking through a clearing
A doe fitted with a tracking collar walks through muskeg on Mitkof Island in 2020. (Photo courtesy of Dan Eacker/ADF&G)

The fourth heaviest December snowfall on record has had widespread impacts on buildings and people around Southeast Alaska. Conditions haven’t been easy for deer, either — or for the scientists who study them.

Alaska Department of Fish and Game deer biologist Dan Eacker was planning on another winter of collecting DNA information from the deer of Mitkof Island. But he said this month that effort was turned back by the snow pack.

“At one point we were going through waist-deep snow, and it was just difficult to even see the pellets because they were just actually falling down in the snow,” Eacker said. “We tried that for a little bit until we were just completely snowed out there in December. Under those conditions that we saw in December, with that extreme snowfall, the method really doesn’t work that well.”

Eacker’s been using the DNA from deer droppings to help estimate numbers of Sitka blacktails on the island. It’s part of pilot study that was expected to wrap up this year but will likely go longer.

“You know I was a little disappointed to not be able to collect another year of data but we should have three solid years of the trend data from the DNA,” Eacker said. “So if we end up sampling one more year next winter, we’ll still be able to look at what the change was from our last estimate.”

Eacker’s pilot study also uses game cameras at remote spots around the island, snapping photos of deer and other animals. And the researchers have put collars on around 30 blacktails. Both the GPS locations from those collars and the game camera images are helping fine tune estimates.

In 2020, Eacker released some preliminary estimates from his work. But he now says he should have waited until getting it peer reviewed. He’s since consulted with others in the field and thinks it’s unlikely his initial conclusion on the buck-to-doe ratio on Mitkof Island is correct.

Eacker said those calculations assumed bucks and does had the same range, a mistake that made it look like there were more male deer. He has since adjusted his work based on another collaring study done on Chichagof Island.

“There was some males collared, and it looked like males on average used about 1.35 times more space, so about 1.35 times larger home range size,” Eacker said. “And so once I made that adjustment to the model, just based on that study it seems like our buck to doe ratios were a lot more reasonable. Instead of like an even ratio, the model is suggesting somewhere around 40 bucks per 100 does.”

Eacker does not expect the overall deer density will change dramatically from the adjustment. He’s hoping to complete a peer reviewed report this year on the results of the first three years of the pilot study.

The snow and cold are already impacting local deer, who are unable to walk the snowy muskegs and forests. Some animals are bedding down on shorelines or by houses. Others are walking the plowed streets looking for anything to eat.

One of the animals collared by scientists was reported dead near Ohmer Creek in December, but so far, others in the study have survived.

Eacker expects a few more will succumb to tough winter conditions. And while that’s not good for deer, it will help inform the research. Eacker’s had several winters of study that have been relatively easy on the population. He says that this year, his data may show the other extreme.

“I think it’s a potential for, you know, a pretty decent die-off this winter as we’ve seen in the past, and people have been worried about that,” he said. “You know because we’ve seen season closures and stuff that have happened in the past, especially on Mitkof and that area.”

The hunting season is one of the most restricted in the region. It was closed in the 1970s and 80s after the population crashed. Hunting on the island reopened in 1991, and the Board of Game agreed to lengthen the season in 2019. Eacker’s research could help inform future decisions by that board on season length.

Meanwhile, the scientists have expanded the number of game cameras installed on remote parts of Mitkof. Eacker said there are now 88 being used for the pilot study. Another 40 cameras have been placed elsewhere on the island. That’s part of an effort to see if cameras alone can be used to estimate deer numbers.

The scientists are also hoping to put tracking collars on more deer. So far, Fish and Game has only collared one buck and would like to add more. The collars drop off the deer after two years. Researchers recover those and the location data they’ve recorded. The first batch will be ready for collection in September.

KFSK - Petersburg

KFSK is our partner station in Petersburg. KTOO collaborates with partners across the state to cover important news and to share stories with our audiences.

Member support ensures trusted, fact-based news is always available for you and your neighbors. Support your reliable news source today. Donate to KTOO.

Read next

Site notifications
Update notification options
Subscribe to notifications