LEWISTON – Huckleberries are highly sought after, but the coveted mountain fruit was difficult to find across much of northern Idaho and Eastern Washington this year.

Pickers were able to locate some productive plants and patches, but they frequently encountered healthy bushes that had few berries or none at all.

“In general terms, this is not a very good year,” said Wayne Kasworm, a grizzly bear biologist for the U.S. Fish and Wildlife Service who tracks huckleberry production in the Selkirk, Cabinet and Yaak mountain ranges.

With a changing climate, scientists like Kasworm are increasingly tracking huckleberries that are an important food source for grizzly bears and other wildlife and also coveted by people. Native Americans have harvested huckleberries for thousands of years and continue to do so today. The small berries with a pleasant mix of sweet and tart are also targeted by recreational and commercial pickers. They are used to make pies, ice cream and other desserts, added to pancakes, milkshakes and smoothies.

Grizzlies depend on the berries as a key food source.

“I started looking at huckleberries in part because they are a very large component of bear diets,” said Tabitah Graves, a U.S. Geological Survey scientist. “Glacier National Park, where most of my work is focused, huckleberries are over 50% of their diet in the peak of summer, so that is a pretty large component and during the time period when they are gaining fat to be able to hibernate.”

In the course of studying the plants, she learned how important they are to Native Americans and other people, and how they play a role in rural economies. Small restaurants and stores sell huckleberry products, and some people make extra money picking and selling them.

But others seek the berries.

“The other thing I’ve learned in the process of doing this work is just how many other species rely on huckleberries. It’s really a keystone species,” Graves said. “We have found scats of coyotes and martens and weasels (with berries) and we have recorded pictures of all kinds of birds and small mammals eating huckleberries as well. I don’t know how important they are to all of those species, but I do know they are part of their diet.”

What makes a good huckleberry?

Graves is studying what huckleberry plants need at different stages of their development to produce berries and how the distribution of the plants might change in response to climate factors like larger, more frequent high-intensity wildfires.

She and a graduate student identified five species of bumble bees and other bees that help pollinate the plants. One of those, the western bumble bee, is in decline and a candidate for Endangered Species Act protection.

“The occupancy declined by 93% between 1998 and 2018 – that is across the entire Western United States. It wasn’t quite as bad up here in the Northwest, which is good, but it’s concerning,” Graves said.

Researchers want to know how new fire regimes may affect the plant. Huckleberries need ample sun and tend to like the types of openings that fires often create. When forest canopies close in because of plant succession, berries often are shaded out.

Some Native American tribes used fire to manage huckleberry habitat. But those burns tended to be of low intensity. Now, many fires, driven in part by climate change and a buildup of biomass traced to past fire suppression, burn much more intensely.

“Historically, fire was intentionally used to regenerate shrub fields and make them produce more huckleberries, but now we are under a different system and different climate,” Graves said.

“We don’t really know yet what more severe fires – what kind of impacts that will have on (berry) distribution.”

Graves developed a method to track distribution of huckleberry plants by using aerial photography to key in on the plant’s seasonal color change. They turn red in late summer and fall. She and her team used the color to map huckleberry habitat and then did site visits to determine the accuracy of the method.

Janet Prevey, another USGS scientist, has studied how the plant may respond to climate change. It could be dramatic. The plants may become less prevalent at some lower elevation and drier sites. That could mean huckleberries recede from some of the plant’s southern range and advance in northern latitudes.

Prevey found huckleberry habitat, under some carbon emission scenarios, may be reduced by 5% to 40% in the Northwest and that it could expand 5% to 60% in northern British Columbia, Canada. Similarly, the timing of flowering and fruit could change. She found flowering may move up 23 to 50 days on the calendar and fruiting could advance 24 to 52 days.

“Where there are a lot of huckleberries now, maybe we’ll see less huckleberry growth in the future,” she said. “But this is all based on modeling and climate projections.”

Bear necessities

Kasworm has been tracking the production of huckleberry plants in the mountains of North Idaho and northwestern Montana for several years. He and colleagues also are using grizzly bears to identify huckleberry habitat.

Each summer, he visits huckleberry patches to measure how much fruit they produce. He drops 10-inch by 10-inch frames every 2 feet or so along a random transect through the patches and then counts the berries within them. He also uses data tractors to document climatic conditions.

“My goal is just for the sake of comparing year to year,” he said. “It’s an index – is this a good year, bad year or an average year?”

This year, the Selkirks were better than the Yaaks, and production was the worst in the Cabinet Mountains.

In all the spots, berries were less numerous and smaller than usual. Kasworm employs a refractometer, a tool used by winemakers, to track sugar content. Even though berries were small this year, he said the sugar content was similar and often higher than in previous years.

He noted anyone who has seen bear scat full of whole berries may wonder why bears bother eating them.

“It is the juice, the soluble sugars in that juice – is what bears get out of them, because they do turn over their stomach contents fairly quickly,” he said. “A bear’s approach to doing something is to continue to eat, get what you can quickly and easily, defecate or vacate it out of the system and continue to eat.

“That way, they are trying to capitalize on a food resource that is somewhat short term in nature and get as much out of it as they can when it exists.”

Kasworm has tracking collars placed on several bears. In August, several of the bears localized at mid- to high-elevation southern-facing slopes – an indication they likely found productive berry patches. He and his colleagues are using the bears to identify productive berry areas by noting where they spend time in the late summer and then visiting those sites to see if they are good patches.

Then they record conditions at those sites and use the data to try to predict where berries might occur elsewhere.

“We do that by looking at such things as soils, slope, elevation, aspect, canopy, a whole bunch of different things that are there, in order to ask the bears where the good spots are and use that information to try to project over a larger area where similar sites are.”