A scientist predicts climate change could have far-reaching effects on the growth of certain berries on Kodiak Island.
Kodiak National Wildlife Refuge supervisory wildlife biologist Bill Pyle just wrapped up a two-year pilot study on the Island. The study helps cement the monitoring methods they’ll use to study berry growth in the future. In this case, that includes using time-lapse cameras.
He explains how in the short term, berries may have success one year and be less fruitful the next, but he also talks about climate change’s unintended consequences – for instance, how warmer winters could affect the deer population, and in turn, their consumption of certain berries.
Salmonberries may be limited or nonexistent this year.
Pyle says winter conditions play a part. This year was unusually dry, and there was little snow pack to insulate the plants.
He says the temperature from November through March for the last two years was six degrees above normal. This year, Kodiak was 1 and a half degrees below normal.
“We really don’t know when the problem started and whether it was a long-term situation this winter, but the bottom line is that it appears that salmonberry and blueberry were affected by the amount of cold and the depth of cold that we had that killed the winter buds and killed the above-ground stems of those plants.”
Elderberries fared better. Pyle says cold temperatures didn’t hack away at them. It was the Sitka black-tailed deer.
“You have the deer stripping the bark, which that girdling action kills the above ground growth. Fortunately, for the species that we’re looking at, they all are very vigorous re-sprouters. They regrow from the base of the plant, and so it’s not like the plants were outright killed.”
Pyle says this year saw a deer die-off later in winter, January through March.
He says while the spruce forests offer some protection for the introduced species, Kodiak’s more exposed terrain could have contributed to the deaths. And he says throughout that time, the deer were surviving off elderberries.
“It really has a lot to do with the fat that they bring into the winter, and [that] determines how long they can last in conjunction with how cold it gets. And they probably had a good year last year with fat supplies, but it was enough to really knock them out. I mean, the elderberry just wasn’t enough to do it for ‘em and to facilitate the survival of most of those deer.”
Pyle says if the deer continue to munch on elderberries year after year, they could kill off the entire plant species.
He says normally every three to eight years a harsh Kodiak winter would sweep through the deer population and keep it at bay.
Without that, they’re free to continue eating the elderberries and other species that bears also survive on, like blueberries. He says because this winter was so dry and lacked significant snow pack, deer had easier access to the areas where those berries grow.
In the short term, it looks like the shortage of berries over the summer may not bode well for brown bears. Pyle says a mixture of food sources like berries and meat help maintain the bears’ nutritional balance.
Throwing off that balance means that more bears may look to human activity for a food source.
“If they encounter a person with, say, they’ve got a deer down, there’s gonna be more circumstances where the bears pursue that shot animal, and once the bear has access to human food, say it’s in a town situation, then usually that’s what they will consider to seek and usually end up in trouble because of that.”
Bears that develop a reliance on scavenging human trash have a tendency to return to town again and again.
Edit 06/05: The lede was edited to be more clear about which effects appear to be short term, such as bad years and good years for salmonberries, and which may be possible in the future if certain climate patterns continue, such as the threat to elderberries.