All species nesting on North Deer Island are migratory to some degree. In the winter, island marshes are used by migrating waterfowl. North Deer island provides high quality nesting habitat for 15 species of colonial waterbirds which are an important part of the coastal ecosystem. Island marshes provide foraging and nursery areas for Galveston Bay vertebrates and invertebrates in a part of the bay that is rapidly losing its salt marshes. North Deer Island is one of the few natural islands left in Galveston Bay and it supports a high quality salt marsh.
Several groups conduct educational field trips around the island on boats during the nesting season.
Bird watchers and other interested bay users frequently boat by the island to observe the large numbers of birds. Fishing activities take place around the island. Some of the boating trips around the island are by commercial tourism companies catering to avid birders. One third undivided interest in the island is owned by the National Audubon Society, one third undivided interest in the island is owned by the Houston Audubon Society and one third undivided interest is owned by a private individual. No trespassing signs are posted on the island and predators on the island are removed.