Mass Audubon’s Boston Nature Center is one of the city’s quiet marvels — meadows, wetlands, and walking trails tucked inside the Mattapan line — and on the second Saturday of each summer month, a staff naturalist leads a group of adults out into it. Each outing takes on a seasonal theme, from pollinators working the meadows to a coastal field trip, so the series adds up to a rolling portrait of a New England summer.

Sessions start with a short indoor introduction, then head out for the better part of two hours in the field, the pace favoring close looking over covering distance. No expertise is required; groups mix lifelong birders with the newly curious. Registration runs through Mass Audubon, and fair warning — one morning has a way of turning into a season-long habit.