The average huckleberry is about as big around as a pencil eraser. But now we can spot them from space.
Several years of refinement have allowed researchers in Glacier National Park to tease apart landscape photos and pinpoint huckleberry patches. The method works on both aerial and satellite photos.
That could qualify as classified intelligence for some secrecy-bound huckleberry hunters. U.S. Geological Survey research ecologist Tabitha Graves and biologist Nate Michael joked they could be endangering themselves by revealing berry hot spots.
“That’s partly why we focused on the park, because it has restrictions on how many huckleberries people can pick,” Graves said. “They’re limited to a quart a day.”
But the deep purple berries make up about half of the calories grizzly bears consume during July and August when they’re at peak ripeness. That makes knowing where those berries grow a vital management tool. Glacier supports a big slice of the estimated thousand grizzlies inhabiting the Northern Continental Divide Ecosystem.
Huckleberry bushes turn bright red in autumn, making it possible to pick them out in a landscape. Graves and Michael developed ways of identifying the particular berry patches and winnowing out other red-colored fall shrubbery.
The study team used publicly available aerial and satellite images from Landsat (satellite) and National Agriculture Imagery Program (aircraft) files. Landsat cameras have been taking regular passes at 100-foot-square resolution for the past four decades. The NAIP cameras don’t pass so often, but do take images with a 3-foot resolution. Combining the details from the two systems allowed the researchers to map huckleberries with about 80 percent accuracy.
For proof, the researchers then hiked to the identified spots to ground-truth the results. In the process, they found most huckleberry plants were more than 300 feet away from hiking trails.
The study used Glacier National Park as its test site, although the authors said its methods could apply around the world where important tree and shrub communities need monitoring. The next step involves predicting the timing of huckleberry ripeness. That might help bear managers reduce the odds of people running into bears in the park by selectively closing productive patches that would attract grizzlies.
A Glacier Park spokeswoman said keeping people out of places bears like is a regular chore.
“Some places, you can almost set your watch by when the berries are ripe,” Alley said. “For instance, Rising Sun is a place where we go to hard-sided camping (restrictions) when that happens. Other places like Fifty Mountain (backcountry campground) that are in prime bear habitat, we have to manage that all summer long.”
The image archives also work like a time machine. Incidents like forest fires or bark-beetle outbreaks can be reviewed before and after to see how huckleberries adapt to the change.
“There aren’t that many species that can be identified from space, because most don’t turn that bright shade of red,” Michael said. “We got lucky hucks do that.”