The sanctuary also offers habitats for a variety of birds and mammals. On a visit to Merkle, one may see red fox, a groundhog, or a white-tailed deer. In the summer, ospreys nest close to the Visitor Center and the hummingbirds, finches and purple martins are abundant. In the neighboring ponds, visitors are likely to see herons and other water birds. On the trails one can see bluebirds and many different songbirds.