The record-breaking snowfall that buffeted Central Oregon has mostly melted in Bend and other cities, but it continues to cause problems for deer that are nearing their annual migration.
Early spring is often the time that migrating mule deer begin their trek from their winter range — low-elevation areas outside Bend — to the high-elevation territory in the Cascade Mountains that they use during the summer months. This year, however, an already difficult journey has been compounded by the massive snowfall in late February, which experts say leaves them vulnerable to predators and stretches their thin reserves to the breaking point.
“Always, the hope is that spring gets here before starvation gets here,” said Corey Heath, wildlife biologist for the Oregon Department of Fish and Wildlife.
Between Feb. 25 and Feb. 27, around 2 feet of snow fell in parts of Bend, prompting school and business closures and forcing residents indoors. The storms contributed to the snowiest February in Bend history. Some high-elevation areas of Central Oregon exceeded 60 inches of snow at the end of winter.
Heath said deer can struggle with deep snow, which makes it harder to reach the bitterbrush and other woody vegetation that the deer rely on during the lean winter months. Without access to the grass and shrubs they prefer, most deer have burned through much of their fat reserves by the time March rolls around.
“When we have deep snow late, it’s very difficult,” Heath said.
Making matters worse, predators like bobcats and cougars tend to do comparatively better in the snow, thanks to their pad-like paws that allow them to tread atop deep snowdrifts, Heath said. Lauri Turner, wildlife biologist for the Deschutes National Forest, added that predators are more likely than deer or elk to use human activity to their advantage in deep snow drifts, following ski and snowmobile tracks to move more efficiently in deep snow.
“We help compact the snow a little bit,” Turner said.
These factors mean that the percentage of young deer killed off before spring increases during particularly snow-filled winters, Heath said. In a mild to moderate winter, about 20 percent of fawns die between December and March, Heath said. In severe winters, that figure can rise above 60 percent.
“It really is survival of the fittest,” Heath said.
This becomes a larger problem because the overall population of mule deer in Central and Eastern Oregon has been in decline for years. While mule deer are a common sight in and around Bend, a combination of factors — diseases, displacement by humans, being hit by vehicles — has caused deer populations to drop off in the area, Heath said.
ODFW records show that 5,748 deer lived in the Metolius range, northwest of Bend, in 2018. The total is below the agency’s management objective, and represents a decline of nearly 40 percent from 2014, according to the agency. Other management units in Central Oregon showed declines over the same period.
Somewhere between 20 and 25 percent of adult does die during a typical year, Heath said. If too few fawns make it through the winter to replace the does that die, it causes big problems for the species.
“We’re not even replacing our adult mortality,” Heath said.
Deer living in winter range east of Bend tend to begin migrating in April, once the snow starts melting. While different groups of deer choose different paths and depart at different times, Turner said deer tend to follow new, green grasses and flowering plants up to their summer habitat.
“If it has a flower, it’s probably going to be eaten,” Turner said.
However, migration is fraught with challenges for deer as well. Karl Findling, conservation director for the Oregon Hunters Association, said Bend is located in deer winter range, meaning typical migration patterns force deer to cross city streets or highways. Consequently, around 200 deer die annually after being struck by vehicles in Bend alone.
While most of the deer haven’t begun their spring migration through Bend yet, there’s a population of deer that stays in the city through the winter, opting to graze in town rather than take its chances with foliage elsewhere. Findling said an unintended consequence of removing bitterbrush in the forest near Bend for fire-prevention purposes is that it forces deer living in the area to find food in other spots, including in Bend.
Though deer populations in the city have declined more slowly than those that migrate, Findling said they still face challenges in the city. In addition to being at increased risk of being hit by vehicles, they’ll often eat leaves from ornamental tress growing in town that can harm or kill them.
Heath said deer have begun to form larger groups, which makes them more visible in Bend and elsewhere. Findling added that drivers should be on the lookout for deer through the end of spring. Drivers should go slowly on city roads, and keep in mind that where there’s one deer, more are likely around as well.
“We’re going to see an uptick in deer strikes,” he said.
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