Adventure Report: Sherburne National Wildlife Refuge
The central Minnesota town of Zimmerman fits into its giant neighbor, the 30,000-acre Sherburne National Wildlife Refuge more than a dozen times. Here, about 40 miles northwest of the Twin Cities an interesting mix of landscapes awaits nature lovers, especially birdwatchers. Tallgrass prairie, marsh, forest and one of the most expansive swaths of oak savanna in the Midwest provide habitat for a variety of animals, but the annual fall migration of Sandhill Cranes is the busiest time of the year, both for visitors and the elegant birds who can congregate by the thousands. Most of the refuge is designated a wildlife sanctuary and is off limits to humans for a large portion of the year, but some areas like the Blue Hill Trail are open year round. (Source: Refuge website)
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Jen and I met up with Greg Feinberg on a crisp Sunday morning at the Blue Hill Trail parking lot. Greg goes by the handle of Distracted Naturalist and regularly blogs about the natural world as he sees it through his binoculars and sometimes a magnifying glass. The idea was really just to go for a walk on a sunny winter day to get some exercise, and have him point out all the things we step on, overlook or ignore as we tromp through the woods. It’s always enlightening.
The Blue Hill Trail is a series of three loops totaling five miles through relatively flat terrain. The only exception is the actual Blue Hill, which the kiosk in the parking lot told me sticks out 90 feet from the surrounding area and consists of glacial till deposited here by glaciers some 12,000 years ago.
And, just like the sign said, the hike up the hill was steep (and a little slick on the way down) but the views off the observation deck were worth it.
We continued on through clusters of oak trees on a packed trail that had seen lots of foot traffic even though the last snowfall was less than 24 hours ago. Soon, we entered a stand of coniferous trees. It seemed at odds with the oak savanna we had been hiking through and was likely planted. Our best guess is that this stand of pine predates the establishment of the refuge in 1965. A 2015 article in the Saint Cloud Times details the refuge’s oak savanna restoration efforts.
After the pine stands we came closer to Buck Lake and the scenery changed once again, this time to snow-covered prairie with the occasional shrub and small oak poking through the white crust. Farther north, past the lake, the oaks were taking over again with their naked, gnarled branches reaching into the blue skies. Some of the trunks were charred from what we later learned was prescribed burns to keep the savanna ecosystem healthy. “I’m curious to know if all the shrub-sized oaks are a result of the burn”, Greg said. “Were they planted, or sprouted once buckthorn was removed?”
After three hours and a five mile walk, we were back at the parking lot which was now filled with cars. However, we had only seen about a half dozen other visitors while we were out. “It was pretty quiet, critter-wise” Greg said and talked about the fox and coyote tracks, chickadees, nuthatches and beaver lodges he saw along the way. He also mentioned the smooth patch fungus he spotted on the trunk of one oak, his favorite species. “Out of all Minnesota trees they seem to have the most fungal associations, biggest variety of galls and caterpillars”, he said. “Plus they look cool and sort of seem “magical””. I, of course, saw none of these things, but was happy to get a walk in, soak up the sun on a winter day and hopefully retain some of what I learned. And, yeah, oak trees are cool.