By Teresa Stepzinski 
Posted at 9:18 AMUpdated at 10:17 AM
The survival of a rare mouse considered crucial to the ecosystem of Anastasia Island rests on the restoration of coastal dune habitat destroyed by recent hurricanes, according to wildlife biologists working to protect the endangered species.
The Anastasia Island beach mouse is vulnerable to potential extinction, the biologists say.
The mice once lived on almost all the St. Johns County coastline but no more. Recent habitat loss due to Hurricanes Matthew and Irma as well as past beach development has taken a toll on the shy nocturnal rodent, according to Florida Fish and Wildlife Conservation Commission and St. Johns County scientists.
It’s unknown how many of the mice remain in the wild. It’s likely, scientists say, many perished in the recent hurricanes that destroyed a large swath of their dune habitat.
“Because the dunes got pushed back so dramatically ... Considering how much dune we lost, my gut tells me that we probably lost a large chunk of the population. They probably hunkered down and got washed out,” said Tara Dodson, environmental supervisor for St. Johns County. 
The Florida Fish and Wildlife Commission and St. Johns County have partnered with the U.S. Fish and Wildlife Service, the University of Florida and several other state and federal agencies in a project to restore the dune habitat and evaluate the mice population.
“It’s not that we’re restoring habitat just for beach mice. Because if we do that, then we also are restoring the dunes, which also are protection for the homeowners,” Dodson said.
The other goal is to develop an estimate of the beach mice population — based on quarterly live-trapping, tagging and release of the mice — at Anastasia State Park and Fort Matanzas National Mounument, said Emily Evans, assistant mammal conservation coordinator for the state Fish and Wildlife Commission.
Evans said they’re also looking to better understand the impact of the recent hurricanes to Anastasia Island beach mice and their dune habitats. UF plant ecologists will assess the habitat to get insight into quality and resiliency of the island’s coastal dune habitat, she said.
Evans said the data will be used to help conserve beach mouse populations and increase coastal dune resiliency.
Launched in January, , the $69,443 project is paid for with federal and state money. An Endangered Species Act grant from the U.S. Fish and Wildlife Service will pay 75 percent of the cost while the remainder comes from the state, she said.
Tiny animal, big impact
“The beach mouse is endemic to Anastasia Island. They are the only native animal to the island,” Dodson said of the mouse that grows up to about 5½ inches long.
The rodent, scientists say, is vital to the fragile dune ecosystem. The mice are considered dune builders as well as a beacon for a healthy environment.
“They are an excellent indicator of healthy dune habitat, as they require plenty of diverse plant foods and patches of open sand in order to dig their underground burrows,” Evans said. “Beach mice use multiple burrows and often cache seeds in them. Many of these seeds are not eaten and sprout into important plants that stabilize dunes.”
Sea oats and other plant seeds are mainstays of the mouse’s diet. New plants also sprout from seeds scattered as the mice scurry back to their burrows with the food, Dodson said.
Evans said the mice, meanwhile, are an important food source for other wildlife including snakes, owls and bobcats.
“It’s even more important in terms of diversity,” said Dodson, noting the mouse is one of only two beach mouse sub-species living along the state’s Atlantic coast.
Habitat destroyed
Evans said the Anastasia Island beach mouse once ranged as far north as the St. Johns/Duval County line. They’re primarily found at Anastasia State Park and Fort Matanzas National Monument.
She said some have been seen at the county parks along the dune line connecting those two core populations. But the narrow dune profile and fragmented habitat from development has degraded the quality of the beach dune habitat they historically used, Evans said.
Hurricane Matthew wiped out at least 50 feet of the dunes on the island’s eastern shoreline, and about 400 feet was lost at the inlet on the island’s south end. The situation was similar at the state park on the north end of the island. At least 50 feet of dune profile was lost across the Atlantic coastline for most of the length of the park, according to the state Fish and Wildlife Commission.
“We did not detect beach mice immediately after Hurricane Matthew but a few were observed in the spring that followed,” Evans said.
Evans said the dunes were beginning to recover when Hurricane Irma slammed the coast — hitting the dunes hard. Coastal dunes north of Fort Matanzas National Monument were eroded about 40 feet from the edge of the dune line. There also is a large escarpment/cliff where the dunes were chipped away and eroded from the storms.
Afterward, scientists saw some beach mice at the state park and national monument, which seemed to have been impacted less by Irma than Matthew, Evans said. 
“However, there are concerns over reduced dune habitat and loss of connectivity in areas where dunes and vegetation were completely swept away,” she said.
PROJECT PROGRESS
Last week marked the halfway point in the ongoing habitat restoration project.
Evans said they’ve used traps, game trail cameras and track tubes — baited PVC pipes containing an ink pad and paper to record the paw prints when the mice enter and exit the tube — to ascertain the presence and relative abundance of the island’s mice without harming the animals.
“We have established over 150 track tubes across the island that are checked twice per month, and have just completed our first round of live-trapping,” Evans said. Those efforts will continue through the winter. The scientists also are preparing to begin habitat surveys to understand habitat quality and impacts from the recent hurricanes, she said.
Dodson said residents and tourists can help the species.
“The most important thing people can do is stay out of the dunes and stay off the pioneering and stable vegetation,” Dodson said.
Teresa Stepzinski: (904) 359-4075