up at J.N. "Ding" Darling National Wildlife Refuge honoring "Wilma", as she was known by the residents. A new crocodile was introduced in May 2010 when she was found on a private property and relocated to J.N. "Ding" Darling National Wildlife Refuge. Plants on the island include the native sea grape, sea oats, mangroves, and several types of palm trees. The Australian pine is an introduced species that has spread throughout the island, to some extent overpowering native vegetation and trees. Once mature, the pine blocks sunlight and drops a thick bed of pine needles that affect the soil's pH and prevents new native growth. The ground is very soft under these pines. The local form of the marsh rice rat has been recognized in some classifications as a separate subspecies, Oryzomys palustris sanibeli. Wildlife refuges Preserving the island's natural ecology has always been important to its citizens and visitors alike. A driving force in the preservation of the island is the Sanibel-Captiva Conservation Foundation which was founded in 1967 with a mission to "preserve natural resources and wildlife habitat on and around the islands of Sanibel and Captiva." of land on Sanibel are under the supervision of the Foundation; included in this land there is a "Marine Laboratory which actively conducts research in areas including seagrasses, mangroves, harmful algal blooms, fish populations and shellfish restoration." Sanibel Captiva Conservation Foundation also has a project called RECON (River, Estuary and Coastal Observing Network) which includes a "network of eight in-water sensors that provide real-time, hourly readings of key water quality parameters." The foundation also serves to protect the wildlife on the island and has a variety of education programs designed to instruct people about the island's unique ecology. The biggest wildlife refuge on the island is the J.N. "Ding" Darling National Wildlife Refuge, Covering more than of land, the refuge strives to ensure that these lands are "preserved, restored and maintained as a haven for indigenous and migratory wildlife as part of a nation-wide network of Refuges administered by the U.S. Fish and Wildlife Service" The lands also serve to provide a home for many endangered and threatened species. Currently the refuge provides a home for over 220 species of birds native to the island. Visitors to the refuge can walk, bike, drive, or kayak though the wildlife drive which takes you through of mangrove tree forests and tidal flats, this