Sept. 11–13. All invited to view chimney swifts gathering at dusk and count them as they enter their roosts in a spectacular swirling tornado of birds. Participants choose a known roosting location and report back to WBNA organizers. Part of a national effort to monitor the migration of this bird species and learn its favorite chimneys for overnight roosting. 8 p.m. until the last swift descends into its chimney. Various locations, preregistration required at washtenawbna.org/events. Free.

Every Mon. Slow/moderate-paced 23-mile ride to Independence Lake on mostly dirt roads. See aabts.org for weather cancellations or delays. 9 a.m. sharp, meet at Old St. Patrick Catholic Church, 5671 Whitmore Lake Rd. Free. (412) 302–9960. 

Every Mon., except Sept. 7. All invited to join this independent local women’s chorus to sing an eclectic program, including classical, folk, Broadway, pop, and jazz. Joshua Marzan directs. 9:30–11:30 a.m., First Presbyterian Church, rear ground level, 1432 Washtenaw Ave. Free to visitors ($175 per semester for those who join; partial scholarships available). [email protected].

Every Mon.–Thurs. (except Sept. 7). The U-M’s highly disciplined 200+ member marching band or sections thereof can be seen and heard practicing on the new Elbel field, across the street from the old Elbel field. All welcome to find a spot in the bleachers and get a sneak preview of upcoming halftime shows. Rehearsals usually last 1–2 hours. 4:45 p.m., new Elbel Field, Hill at Fifth Ave. Free. (734) 764–0582.

Every Thurs., Sat., & Mon. (different AARC locations). Runners of all abilities invited to join a 5K mapped route (Thurs. & Mon.) or either a beginner or advanced group run (Sat.). AARC Colonnade (6 p.m. Thurs.), 2621 Plymouth Rd.; AARC Traver Village (7 a.m. Sat.), 901 W. Eisenhower; and Corner Brewery (6 p.m. Mon.), 720 Norris, Ypsi. Free. annarborrunningcompany.com. 

Every Mon. Moderate-paced 20-mile ride to Dexter and back, often with a rest stop along the way. Riders must wear a helmet and bring water and supplies to fix a flat tire. 6 p.m. (nonmembers must come 10 minutes early to sign a club waiver), Barton Nature Area, 1010 W. Huron River Dr. Free. annarborveloclub.org.  

Every Sun.–Thurs. (different times). All invited to work on their knitting, crochet, weaving, and embroidery projects. 6–8 p.m. (Mon.–Thurs.) & 1–3 p.m. (Sun.), 401 N. Fourth Ave. Free. (734) 780–7867.

Every Wed. & Mon. Runners of all abilities invited to join a beginner or advanced 3- to 5-mile group run, followed by socializing at a downtown coffee shop. 6:30 p.m., meet at the Kerrytown Clock Tower. Preregistration requested at meetup.com/a2runners. Free. [email protected].