Dwindling Dunes and Monster Storms

The Santa Rosa Beach Mouse

by Adam Fryska, Panhandle Trail Program Manager

A beach mouse in its natural habitat.

Photo courtesy of Florida Department of Environmental Protection

DWINDLING DUNES AND MONSTER STORMS

Threats Facing the Santa Rosa Beach Mouse

Aregular conversation in our community has been about how the development of Florida’s remaining rural landscapes is challenging our efforts to close the gaps in the Florida Trail (FT). It’s not just our trail corridor that’s being crowded by a loss of open spaces; numerous endangered species are threatened by habitat loss in Florida. On the other hand, it's a happy coincidence that what's good for hikers—a continuous footpath linking Florida's diverse ecosystems—is also good for wildlife. Wildlife corridors connect animal populations that would otherwise be separated by human activity, maintaining biodiversity and extending a lifeline to threatened species. Most Florida hikers have probably heard of the Eastern Indigo Snake, Gopher Tortoise, and Red-Cockaded Woodpecker. These species present inspiring success stories about conservation in Florida, and all can be encountered by hikers along the Florida Trail. But there's one diminutive threatened species that's much less known, much harder to spot, and whose habitat exists on just one barrier island: the Santa Rosa beach mouse. The oldfield mouse, Peromyscus polionotus, can be found throughout the southeastern United States. Its range stretches from the Gulf Coast to Tennessee, and along the Atlantic Coast from South Carolina to most of the Florida peninsula. However, while the species as a whole is doing well—oldfield mice are abundant in protected areas throughout their range—several taxonomically unique sub-species are threatened or critically endangered. One of these sub-species—P. p. leucocephalus, the Santa Rosa beach mouse— is only found on Santa Rosa Island in northwestern Florida. While not yet as critically endangered as the neighboring Perdido Key beach mouse and Choctawhatchee beach mouse, the Santa Rosa beach mouse populations are also facing an uncertain future. It may seem surprising that an animal as ubiquitous as a mouse can become threatened or endangered. But these beach mice, along with their other barrier island relatives, are specifically adapted to the challenges of life on coastal sand dunes. At a weight of just 13 grams and an average length of 3 inches, these tiny creatures dig multiple elaborate burrows among vegetated dunes, using them for shelter, nesting, and caching food. These burrows can be as long as 2-3 feet, with a large main nesting chamber and emergency escape tunnel that ends just below the surface of the sand. If a predator enters the burrow, the mouse can quickly dig its way out to safety. Burrows are usually located among

A view of low dunes along the Gulf Coast of Santa Rosa Island.

Photo courtesy of Adam Fryska

primary dunes located just off the high-tide line, but the mouse habitat extends out to more densely vegetated inland dunes, swales, and scrubby bay-side dunes. Even accounting for their small size, Santa Rosa beach mice are exceedingly difficult to spot. Beach mice have a unique pale brown and sandy coloring that provides excellent camouflage among the dunes. The Santa Rosa mouse often appears almost completely white. They are also primarily nocturnal, sleeping within their burrows during the heat of the day and searching for food during the night. Their foraging range can extend up to 5,000 square meters as they hunt for seeds, nuts, and insects. The majority of their diet consists of seeds and fruits. Sea oats are the favorite, but they also forage for bluestem, ground cherry, evening primrose, beach pea, and dune spurge. Unlike most other mouse species, the Santa Rosa beach mouse avoids human buildings and trash, preferring to forage among the dune vegetation. A beach mouse peaks out of its sandy burrow.

The Santa Rosa beach mouse is the palest of the various beach mouse species, often appearing completely white.

Because of their small size and nocturnal behavior, hikers are most likely to encounter beach mice by their tracks in the sand.

Photo courtesy of Florida Fish and Wildlife Conservation Commission

Given their isolation on a single barrier island off the coast of Florida, it should come as no surprise to hear that the greatest threat facing these diminutive rodents is habitat loss. For hikers along the Florida Trail, the development and fragmentation of the dunes habitat is impossible to miss. For its first 28 miles the Florida Trail traverses the island from Fort Pickens to Navarre Beach. The trail begins at the northern terminus marker in Gulf Islands National Seashore, meandering east through pines and scrubby dunes until it spills out onto the coast. After several miles of walking along pristine white sand beaches, hikers suddenly reach the National Seashore boundary at Pensacola Beach. Condos, resort towers, and private homes crowd every available scrap of land in between the beach and the bay. A few miles further east, the dunes reappear along another section of protected seashore, and then the pattern repeats with more homes, condos, and towers at Navarre Beach. The change between the two landscapes is jarring; from vast, windswept sand dunes to bustling seaside communities in just a few steps. Luckily for both hikers and mice, most of the remaining dunes on Santa Rosa Island are forever preserved. Protected properties include the Gulf Islands National Seashore, Santa Rosa Island Authority parkland, a University of West Florida nature preserve, and portions of Eglin Air Force Base. Development of the island has taken a balanced approach that includes consideration for native species. For this reason, the Santa Rosa beach mouse has avoided the critically endangered designation that impacts its relatives on smaller, less protected islands. Even so, the remaining dunes on Santa Rosa Island form a patchwork amidst the roads and buildings. This leads to the isolation of wildlife, a reduction of genetic diversity, and ultimately less healthy and resilient populations. It also means that mouse populations may have a harder time bouncing back from the impacts of hurricanes that regularly reach these shores.

Unfortunately for the beach mouse, development of the coastline is only half the story. Coastal wildlife is also facing the threat of rising sea levels and habitat destruction linked to climate change. According to the National Oceanic and Atmospheric Administration, the sea level around Florida has increased by 8 inches since 1950, and it continues to increase at the rate of 1 inch every 3 years. This rate is forecast to increase in coming years as the melting of polar ice continues. For coastal sections of the Florida Trail, these predictions can be concerning. Take a look at a pessimistic, worst case scenario sea level rise forecast map for 100 years from now, and much of Santa Rosa Island sinks into the sea (maps and models are available at: https://coast.noaa.gov/slr/ and https://coastal.climatecentral.org/map/). It's not just the beaches that are impacted. Further east, much of the St. Marks National Wildlife Refuge faces inundation, as does the Big Bend coastline. This outcome would be devastating for coastal communities, unique coastal ecosystems, and the sections of the Florida Trail that pass through them. The Santa Rosa beach mouse, along with much of the dunes it calls home, could be washed away entirely. Even if the worst sea-level rise impacts are avoided, coastal ecosystems also face the threat of increasingly violent storms. NOAA Development near coastal dunes continues on Santa Rosa Island.

Photo courtesy of Adam Fryska

predicts that hurricane intensities will increase over the next 100 years, and that we will see a greater number of storms that reach Category 4 and 5 strength. Hurricanes are giant heat engines that convert the energy from warm ocean water into wind and waves. The more heat that is available, the more damaging the storm. Pair that with increased sea levels, and the impact on barrier islands and dune habitats can be extremely destructive. For beach mice, survival depends on high, vegetated dune ridges that can withstand storm surge and coastal flooding. Even then, a single storm can have a major effect on population numbers. A study published in the Journal of Mammalogy found that beach mouse populations at Santa Rosa Island sites plummeted almost 50% after Hurricane Ivan hit in 2004; that storm completely destroyed many of the frontal dunes that serve as primary beach

Sea level rise models present alarming possibilities for the future of Florida’s barrier islands. This view shows one potential 100-year scenario.

mouse habitat. Hurricanes Erin and Opal almost led to the extinction of the Perdido Key beach mouse, a neighboring mouse sub-species. A higher frequency of major storms can also impact the plant communities upon which beach mice and other wildlife depend. Plant roots are the glue that hold sand dunes together. Dune revegetation is a slow process, and repeated flooding can prevent plant populations from regaining a foothold, destroying dunes and further fragmenting the mouse habitat. All of this amounts to some big challenges for a small mouse. Beach mice literally have nowhere else to go. Entire populations are isolated on shrinking islands, scoured by hurricanes and surrounded by beach-going tourists and towering resorts. Still, the fate of these little creatures can seem insignificant when compared to the big picture of human economic activity and our own needs and desires. Growing hurricane threats and rising sea levels will be a major challenge for the human populations of these islands, let alone the wildlife. So why do these mice matter? Why should we be concerned about the fate of a creature that most people will never even see? For many of us who work as stewards of Florida's natural landscapes, the answer feels simple and obvious, even if it’s a bit sentimental. We value our natural environment and the wildlife that lives there. These things have an intrinsic value, their own right-to-be, as well as having value for how they enrich our lives. The dunes, the creatures that live there, all of the myriad ecosystems in Florida... we want all of this to be here for future generations to experience. This is what the founders of the Florida Trail recognized when they set out to blaze this trail, and what Congress recognized when they designated this footpath as a National Scenic Trail. Then there is also the ecologist's answer: that the beach mouse is one small but vital part of a vast interconnected web of life, along with every other dune-dwelling bird and insect, grass and shrub, no matter how small or seemingly insignificant. A healthy population of beach mice indicates a healthy dune ecosystem. The mice are an important part of dune formation; their cached but uneaten seeds will sprout, leading to new vegetation that stabilizes the sand and expands the dunes. The mouse burrows provide shelter for other small wildlife. And the mice themselves are hunted by dune predators such as snakes and owls. If there's a lesson that wildlife conservation has taught us, it's that if you take out any one link in this system it will all start to unravel. So what can you do to help protect the beach mouse? Many of the big challenges can seem beyond our individual or even collective ability to address. After all, any meaningful mitigation of climate change impacts has to occur at a national, or even international, level. Even on the local level, there's simply no going back once a beach has been developed. But there are meaningful actions we can take to help protect this species. To start, the Florida Fish and Wildlife Conservation Commission has shared a list of eight simple steps that beach residents and visitors can take to protect beach mice and other dune-dwelling wildlife:

A view of the Santa Rosa Island dunes habitat from the perspective of a beach mouse. These low-lying coastal areas are often flooded by storm surge.

Photo courtesy of Florida Department of Environmental Protection

 Avoid walking in dunes. Use crosswalks and boardwalks (along the

Florida Trail Dunes Section, stick to the marked route).  Do not drive in dunes or on the upper beach near dunes and dune vegetation.  Keep pets out of dunes. Keep dogs on leashes and cats indoors.  Do not feed stray cats.  Properly dispose of trash to keep predators away.  Keep outdoor lighting to a minimum.  Don't use rodenticides in coastal dunes.  Plant native plants around residences and businesses.

Stewardship of our environment is a shared responsibility, and it's encouraging to see how the beach communities of Santa Rosa Island have embraced efforts to restore dunes, plant native species, and protect their remaining open spaces. The Florida Trail Association is committed to working with the Santa Rosa Island Authority, Gulf Islands National Seashore, and all of our partners to advocate for the continued conservation of this delicate ecosystem. Our Western Gate Chapter is also currently working to restore sections of dune trail that were impacted last year by Hurricane Sally. These parts of the Florida Trail are an important local recreational resource, and encouraging the public to visit and appreciate this coastal habitat is a central part of our organization's mission. Conservation only happens when people feel that they have a stake in what's being preserved. Every tourist, local resident, and thru-hiker who sets foot on our trails is a potential advocate for the continued protection of dunes and the wildlife that calls them home. That's some good news for the Santa Rosa beach mouse.

Photo courtesy of Adam Fry s ka

Gulf Islands National Seashore has implemented a popular magnet campaign to raise awareness about threatened beach mouse populations. Pick yours up at Fort Pickens!