Northern short-tailed shrew. (Patterson Clark / The Washington Post) Northern short-tailed shrew. (Patterson Clark / The Washington Post)

Every city is its own little bubble of biodiversity, according to a study out last month. In other words, metropolises aren’t just for rats and pigeons; they’re unique habitats unseen elsewhere in nature. Here are three local critters to keep an eye out for this spring:

Northern short-tailed shrew: These chubby little guys have a venomous bite. But they aren’t dangerous to humans, generally reserving their poison for their favorite prey: earthworms. Find both in your garden after it rains.

Red fox: These cuties have been seen at Hains Point, on the National Mall and near the U.S. Capitol. Spot adults around dusk, and look for cubs in hollow logs and dense shrubbery.

Black-crowned night heron: About 400 of these short-necked herons build nests near the National Zoo’s Bird House every March. Even though they’re not captives, zookeepers feed them mice at 2 p.m. daily.