Going for gross

Wild River State Park, 2-3 p.m. Saturday


Some things in nature have always been thought of as a little gross, but some of them are also interesting. Learn why leeches and maggots are used in hospitals, for example, and discover the difference between snails and slugs. Meet at the visitor center. (651-583-2125, ext. 227, mndnr.gov)

Candlelight walk

Brown’s Creek State Trail, 6-9 p.m. Saturday


The west portion of the trail from Lofton Avenue to Duluth Junction will be lit with candle luminaria. Parking available at the Gasthaus Bavarian Hunter on Lofton Avenue. (651-231-6968, mndnr.gov)

A walk with history

Fort Snelling State Park, 1-2 p.m. Sunday


Giant cottonwoods and tall silver maple trees dominate the park trails. Join a park naturalist for a walk as we investigate their history. (612-725-2724, mndnr.gov)


Minnesota Valley National Wildlife Refuge, 8-10:30 a.m. Saturday


A bird walk starts at the Bass Ponds trailhead in Bloomington. During the fall migration period, the refuge witnesses a mix of waterfowl, raptors, warblers and sparrows. Birders of all levels are welcome. Bring binoculars if you have them. Dress for the weather. (bit.ly/mnfwr)

It’s Bat Week

Minnesota Valley National Wildlife Refuge,9 a.m.-3 p.m. Saturday


The third annual Bat Week Celebration is focused on the creatures who are misunderstood and vital to the health of our environment and economy. There will be bat house building, trivia, related arts and more. Call 952-854-5900 or e-mail minnesotavalley@fws.gov for more information. (batweek.org)


Richardson Nature Center, 2-3:30 p.m. Saturday


Make and taste old-fashioned apple cider, and learn about its deep history in North America. Reservations recommended (763-694-7676, threeriversparks.org)

Night at the races

Murphy-Hanrehan Park Reserve, 6-9:30 p.m. Wednesday


An ongoing series of mountain bike racing rotating between several Three Rivers Parks, the time-trail races cover 10-14 miles of single-track trail illuminated by required mounted bike lights. Preregistration is $12; $15 same-day. Racers must be 14 and older. (763-694-7777, threeriversparks.org)

River investigation

Fort Snelling State Park, 10-noon Sunday


Spend the morning getting a closer look at the Mississippi River and the organisms living in it. Dress for the weather. Meet at the visitor center. (612-279-3550, mndnr.gov)