Mild winter brings complications for wildlife

IRON MOUNTAIN — How weird is this weak, snow-challenged winter?

Raised in the Upper Peninsula, Brian Roell can’t remember a winter this mild. But the lack of snow is perhaps more significant than the warm temperatures, said Roell, a wildlife biologist with the Michigan Department of Natural Resources’ Marquette office.

Of the past 11 winters, eight in the Upper Peninsula have been classified as “severe” for wildlife — at least 12 inches of snow on the ground for 90 days or more, Roell said.

For deer, such deep snow saps energy reserves and results in more mortality among the old and young that have less fat stored up, he said.

More snow is a result of climate change, Roell said. Lake Superior hasn’t fully frozen over since 1997, and now in most years has only limited ice.

It leaves warmer water open that, when frigid northern air sweeps across the lake, dumps snow on the Upper Peninsula, especially in the north, Roell explained.

“So it’s a big snowmaking machine,” Roell said of the “lake effect” in most recent winters.

This year, however, is truly unique.

With a strong El Nino keeping the cold at bay from the north, it’s a warm winter but one with scant or spotty snow.

The result was no white Christmas, a January with only a week of subzero temperatures and a February that started with highs well above freezing.

Most of the U.P. and northern Wisconsin until this week has been brown, muddy, sodden, with a few charcoal-tinted mini-icebergs around the edges.

So what might be seen in this odd semi-winter? Roell offered some of these potential effects.

≤ It may have woke up the bears, at least temporarily. If warm enough or, even more significant, wet enough from rain or melting snow, den sites could become so soggy bears rouse from hibernation, Roell said. As in the normal spring emergence, they’ll look for some quick calories, so homes and backyard bird feeders or trash could be a target.

≤ Raccoons and skunks definitely got out and about. The two species are not true hibernators and frequently will come out during the winter months to seek a meal. The milder the conditions, the more they will take advantage to get in a snack between sleep sessions. For skunks, it’s breeding season as well, which would explain the sightings and scent in the air.

≤ Insects are confused. Those that normally spend the winter as adults tucked away in leaf litter, earth or cracks in wood or rock may be triggered enough to try foraging.

While that might seem risky, since there are no obvious pollen or nectar sources, it has more benefits than might be expected in terms of honey bees, said beekeeper Gino Venditti, owner and president of the local Stag Farms.

His bees flew last week when temperatures reached into the 40s. They headed for the normal earliest pollen and sugar sources: willow stands and maple groves. The willows might not have buds yet, much less catkins that have reached pollen stage. But he’s already tapping maple trees, producing 7 gallons of syrup so far.

Leaving the hives, too, allows the bees to perhaps shed some of their varroa mites, parasites that can devastate colonies. The mites spread by dropping off foraging hosts, where they wait to climb onto another bee. But the current cold conditions should kill them before they can transfer, Venditti said. He thinks the overall mite count in his colonies has been lower than a normal winter, when the dormant period, with bees clustering, usually is the worst time of the season for parasites.

His bees also have started brooding larvae, weeks earlier than normal. Once the queen starts laying eggs again, the bees have to raise the hive temperature from the 65 degrees during dormancy to a steady 98 degrees as the brood develops, he explained. They’ll use energy doing that but should have enough food to maintain. The mild winter allows them to break from clustering for warmth as well, so they can access more of the hive’s food stores. In addition, Venditti supplies his bees with “sugar boards,” placed atop the hive with a 2-inch hole to raw sugar for an easy meal.

“So I think it’s actually good for them,” Venditti said of the early start.

≤ The year could be a bad one for ticks. Ticks need a blood meal to develop from each stage: larva, nymph, adult — and to lay eggs. In a normal winter, they might drop off into the snow after feeding — they get shelter from even the worst cold underneath a deer’s dense coat — and die from exposure, Roell said. But recent conditions may allow them to survive, he said.

≤ Wetlands could be reduced this spring from less melting snowpack. While that has some positives for humans — fewer mosquitoes and black flies — “it can have a ripple effect” among birds and other species that rely on high insect populations to feed and raise their broods.

≤ Invasive species could get a better foothold. Many of these non-native plants and animals get culled back by freezing temperatures. In particular, he fears hemlock woolly adelgid — so far only detected in western Lower Michigan — might manage to show up in the Upper Peninsula.

Hemlock is important for wildlife, providing food and shelter for deer, and habitat for species such as pine marten and Blackburnian warblers, he said.

≤ Some bird species normally gone for winter have remained — in particular, American goldfinches this year — and some “winter finches” such as purple finches and evening grosbeaks have been absent. This had been predicted due to a strong wild food crop in Canada, but the mild winter only made it that much easier for all of these birds to stay farther north this year, Roell said.


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