Published On: Thu, Feb 7th, 2019

Endangered and Threatened Species on Sanibel, FL

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Sanibel is one of a string of subtropical barrier islands on Florida’s lush Gulf Coast. Although the island is a bustling tourist resort, over 6,000 acres are set aside for wildlife in the J. N. “Ding” Darling National Wildlife Refuge. Hundreds of species find shelter in the refuge, including several that are listed as threatened or endangered under the federal Endangered Species Act (ESA).

Endangered and Threatened Species on Sanibel, FL

Wildlife Habitats on Sanibel

The Sanibel refuge is an estuarine ecosystem, where salt water and fresh water mix. Estuaries create a nutritionally rich environment for plants and animals. Three important habitats found on Sanibel are coastal beaches, mangrove swamps, and freshwater wetlands.

The coastal beach zone provides feeding and nesting space for hundreds of bird species, including plovers, gulls, terns, and sandpipers. Offshore seagrass beds shelter small fish and invertebrates, which in turn provide food for larger fish, marine turtles, and mammals.

The mangrove forests of Sanibel are part of the largest undeveloped mangrove ecosystem in the United States. With their massive, tangled root systems, mangroves protect coastal areas from erosion and provide a rich habitat for fish, shellfish, birds, and reptiles.

The freshwater wetlands of Sanibel’s interior feature marsh vegetation as Spartina, leather fern, sedges, and cordgrass. Waterfowl, alligators, turtles, and small mammals nest and forage in the wetlands.

Threatened and Endangered Species on Sanibel

American alligator. The American alligator, once hunted almost to extinction, has become abundant in Florida, but it is listed as threatened because of its resemblance to the crocodile. On Sanibel, alligators can be seen basking in the mangrove swamps and wetlands. They are considered something of a nuisance, and city personnel are authorized to relocate them when they wander into town. The Ding Darling refuge for many years was home to one American crocodile, but the croc died in January 2010.

West Indian manatee. Manatees are marine mammals with seal-shaped bodies, flippers, whiskered muzzles, and paddle-shaped tails. Adult manatees weigh about 1,000 pounds. The West Indian manatee is listed as endangered, and Sanibel is within its federally designated critical habitat. As a result, some waters around Sanibel are off-limits to powerboats.

Wood stork. Wood storks are large, long-legged wading birds that nest in the mangroves and wetlands. They eat mostly fish, but sometimes dine on shrimp and crabs, snakes, and even small alligators. They are listed as endangered, and the Sanibel refuge is considered a core foraging area.

Loggerhead sea turtle. Every spring, female loggerhead turtles crawl out of the ocean to nest on the beaches of Sanibel. Commercial fishing, coastal development, and marine pollution have taken a toll on loggerhead populations, and the species is listed as threatened. Two other species of marine turtles, the green turtle and Kemp’s Ridley turtle, both endangered, also occur in the waters around Sanibel, though they are not known to nest on the island.

Eastern indigo snake. This glossy black snake is a threatened species. Suitable habitat occurs throughout Sanibel Island, but the last confirmed sighting in the refuge was in 1999.

Piping plover. These small shore birds feed on the wet sands of coastal beaches, tidal flats, and salt marshes. They do not breed in Florida, but Sanibel provides wintering habitat. They are considered threatened throughout their wintering range.

Gopher tortoise. These large land turtles inhabit dry areas and dig burrows for refuge from predators. They feed on grasses, fruits, and flowers. The gopher tortoise is considered threatened in Florida and is thus protected on Sanibel. It is under review for possible listing under the ESA.

Sanibel island rice rat. This small mammal is listed as a species of special concern in the State of Florida and is protected within the Sanibel refuge.

Protecting the Health of the Refuge Ecosystem

The continued survival of Sanibel’s wildlife depends on the health of the “Ding” Darling National Wildlife Refuge and its estuarine ecosystem. This in turn depends on the health of the Everglades watershed. Unfortunately, the fragile Everglades environment is affected by pollution from commercial agriculture and urban development. Conservation efforts are critical.

People’s enjoyment of the beautiful barrier islands has created additional problems for wildlife. Recreational boating affects fish and marine turtles, and public use of beaches interferes with migratory birds and nesting sea turtles. Over 800,000 visitors a year tour Wildlife Drive, the public roadway through the Sanibel refuge. The challenge for refuge managers is to protect wildlife from disruption while providing visitors an enjoyable, educational experience.

About the Author

- Paul Linus is an eminent online journalist who has been writing news, features and editorials on different websites from across the world for about a decade. He can be contacted at

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