The violent winds and rains of hurricanes can devastate wildlife and their habitats—but human hands can ease the pain
Beached when Hurricane Irma wreaked havoc with the tides on Florida’s Gulf Coast last September, this manatee was rescued by local samaritans and returned to freedom. Racing toward landfall last September, hurricanes Katia, Irma and Jose (below, left to right) cross the Atlantic.
LAST YEAR, ONE OF THE WORST STORM SEASONS IN U.S. HISTORY slammed the East Coast, Gulf Coast and Caribbean. Violent winds and floods led to the deaths of thousands of people, caused hundreds of billions of dollars in damage and devastated untold acres of wildlife habitat, from coral reefs to inland forests.
Mostly to blame: a trio of record-breaking, back-to-back hurricanes. In August, Harvey doused parts of Texas with more than 4 feet of rain, flooding a third of Houston and all 22 of the city’s bayous. In September, Irma savaged Barbuda with sustained winds of 185 miles per hour then roared into Florida, becoming the state’s costliest hurricane at upwards of $50 billion in damage. Maria followed ruthlessly, whipping Dominica and Puerto Rico with winds of 155 miles per hour, stripping forests, crippling infrastructure and leaving homes and lives in ruins.
Unfortunately, the National Oceanic and Atmospheric Administration (NOAA) predicts similarly fierce storm seasons in coming years, largely fueled by a changing climate.
Though the human toll of hurricanes is painfully clear, it’s tough to tally the effects on wildlife. Animals and habitats suffer from seawater surges, flooding, tree-toppling winds, flying debris and the mess left behind. Having evolved with severe weather, most ecosystems historically have weathered big storms. But climate-warming greenhouse gas emissions and human alterations to the land—such as development, levees and pollution—leave habitats and wildlife more vulnerable to storm impacts, as recent hurricanes have shown with a vengeance.
In Florida, for example, Hurricane Irma’s wild tides left 13 manatees stranded, awaiting rescue. On Lake Okeechobee, Irma destroyed all 44 nests of the endangered Everglade snail kite. And down in Texas, Harvey’s floodwaters swamped the Attwater Prairie Chicken National Wildlife Refuge, which had also been hit by record flooding in 2016—a serious one-two punch to the refuge’s endangered ground-nesting birds. Thanks to a captive-breeding program, however, “we have the capacity to inject life into the wild flock,” says Deputy Refuge Manager John Magera. Indeed, how wildlife copes with violent storms may increasingly depend on human hands.
The rare Puerto Rican parrot offers a cautionary tale of loss and tenuous recovery on hurricane-prone islands. Dwindling for decades due to habitat loss, the species’ population was cut in half—to 25 birds—by Hurricane Hugo in 1989. Decades of captive breeding, release and supplemental feeding, led by the U.S. Fish and Wildlife Service (FWS), created self-sustaining wild populations in two areas: El Yunque National Forest in the northeast and Rio Abajo State Forest in the northwest.
This parrot needs canopy fruits, leaves and flowers for food, plus tree cavities for nesting. But “after Maria, there wasn’t a leaf to be seen,” says Nathaniel González, president of Sociedad Ornitológica Puertorriqueña Inc. (SOPI), an affiliate of the National Wildlife Federation.
As a result, El Yunque lost as much as 90 percent of its 50-plus parrots and Rio Abajo lost some 35 percent, says Tom White of FWS’s Puerto Rican Parrot Recovery Program. Such losses validate the team’s strategy of placing parrot populations in separate areas. “If we hadn’t already had birds at Rio Abajo,” says White, “the species would now be nearly extinct in the wild.”
Fortunately, the island’s captive population of some 400 birds remains intact in aviaries and will seed a third population in the wild. And new forest life is sprouting. “Some trees and shrubs are already producing fruit,” White says, “and there’s an encouraging amount of Sierra palm, a prime food source during breeding season.” With continued human help, the parrots will likely survive.
Birds face other hazards during hurricane season—which runs from June through November—particularly along some migration routes. According to a recent study from Duke University, for example, sooty terns that nest in the Florida Keys begin their southern migration in June, crossing the Caribbean to arrive at wintering areas off the coast of Brazil in November. The weary migrants pass right through “Hurricane Alley,” a long stretch of warm water in the Atlantic where hurricanes rev into high gear. “Migration is already taxing and stressful,” says Ryan Huang, who led the study. Then, if strong winds and rains come at them “like a bowling ball,” birds can be blown off course or “simply die from exhaustion.”
When Hurricane Allen struck the Caribbean, Mexico and Texas in August 1980, for instance, the Category 5 killer took out some 45 percent of this migrating population of sooty terns. If storms occur in quick succession, Huang adds, weaker storms can have a “cumulative effect” and be as hard on birds as one powerhouse.
Sitting tight on the ground is likewise perilous for many species caught in the path of a storm. The endangered Key deer, which lives only in the Florida Keys, suffered when Hurricane Irma shot 6-foot storm surges across the low-lying islands, killing 21 of some 650 deer in the population. Those losses were relatively light—but that wasn’t the end of the trouble.
Key deer rely on fresh water from “solution holes,” depressions in limestone rocks where fresh water floats atop salt water. This source “is precarious to begin with,” says FWS veterinarian Samantha Gibbs. After Irma’s salty storm surge depleted freshwater abundance, she says, “we ended up with a lot of very thirsty deer.” An emergency response team put out baby pools of fresh water until rain boosted the natural supply. It helped, though with intensifying storms and sea-level rise, Gibbs says, “many animals remain in a tenuous situation.”
Less fortunate have been Florida’s endangered Lower Keys marsh rabbits—the smallest subspecies of marsh rabbit—which live in a limited range across the Florida Keys. Though the rabbits are able to swim, says FWS biologist Sandra Sneckenberger, “a hurricane is typically such a large, sustained event it is hard to escape.”
During Hurricane Irma, marsh rabbits near the eye’s landfall at Cudjoe Key “took a severe hit,” says Sneckenberger. Researchers from Texas A&M University estimate roughly 96 percent fewer animals and an 82 percent decrease in the species’ distribution in that location. Another population at Boca Chica Key seems to have fared better, but because of habitat fragmentation from development and roads, “there aren’t a lot of options or corridors for movement in the Keys,” Sneckenberger says, so one population may not be able to quickly seed another.
What rides in or out with the tides can be equally harmful to wildlife—and people. During Harvey, snakes and alligators moved inland to escape rain waters in Houston-area bayous. The storm also brought in vast flotillas of venomous fire ants, which raft together in clusters of up to 100,000 to reach dry land, a clever adaptation. The nonnative stingers are expanding their range northward as the climate warms.
A hurricane’s ability to spread invasive species adds insult to stormy injury. When Hurricane Andrew sliced across southern Florida in 1992, for example, it destroyed a reptile-breeding facility, releasing Burmese pythons. These ravenous reptiles have been breeding and devouring native wildlife in the Everglades ever since.
In Texas, the U.S. Geological Survey (USGS) is now using “storm tracker” maps to monitor the potential spread of some 226 nonnative aquatic plant and animal species impacted by the 2017 hurricane season. Of particular concern: Harvey’s unprecedented amounts of freshwater rain and runoff created temporary freshwater zones along the Gulf, allowing aquatic species to spread into new habitats. Nonnative sailfin catfish, for one, appear to have spread to watersheds around Galveston Bay. Because it burrows into canals and river banks to lay eggs, it could exacerbate Gulf Coast wetlands erosion.
Rainwater runoff—and the contaminants it carries—poses other problems. “Heavy rains can lower salinity to levels not well tolerated by coastal and estuarine dolphins,” says Erin Fougères, NOAA’s Marine Mammal Stranding Program Administrator, “and runoff from land, ponds and rivers may contain dangerous pollutants or pathogens.” Flooded sewage treatment ponds can carry E. coli into the sea, harming marine life. And chemicals and excess nutrients from farmlands washing into the Gulf of Mexico can cause algal blooms and fish kills, says USGS biologist Matthew Andersen, and create hypoxic zones “where few animals can survive until oxygen returns.”
Conversely, some freshwater species suffer when seawater surges into wetlands, estuaries and bays. “For a time after a storm surge, salt-tolerant species may dominate,” says Andersen. But in these dynamic systems, he adds, pulses of salinity generally get flushed out naturally, so “there’s a natural ebb and flow.” Unfortunately, construction of coastal levees, canals and other structures can throw nature out of whack. Because of human activity, says Andersen, “the ebb and flow is disrupted.”
Despite such challenges, many creatures have evolved strategies to survive even the nastiest of storms. In 2014, researchers were startled to discover that golden-winged warblers nesting in Tennessee fled the area well before devastating tornadoes struck. Reporting in Current Biology, they speculated that the birds may have been sensing low-frequency “infrasound” waves traveling long distances from the approaching storms. Likewise, sharks sense impending storms, likely detecting a drop in barometric pressure, says Michelle Heupel of the Australian Institute of Marine Science. They’ll head to deeper water until the fury passes and normal salinity returns.
Other animals simply hunker down and hide. “Some ground-dwelling animals, including snake, frog and toad species, plus some small mammals, can burrow to create DIY storm cellars,” says Purdue ecologist Ben Gottesman. Frogs in particular “are presumably more resilient to pulses of flooding because they can breathe through their skin,” he says. And for surviving frogs, “storms provide a good dispersal mechanism to bring them or their eggs towards new habitats.”
Bolstering natural buffers such as coral reefs, barrier islands and coastal wetlands is essential if ecosystems are to withstand future storms—and efforts abound to lend nature a hand.
Offshore, coral reefs help mute the power of surging seas. But when storms hit back to back, corals can break apart or get buried in sand, and suspended sediments can linger, lowering oxygen levels and blocking sunlight needed for growth. “Reefs are already hit hard by so many stressors—pollution, temperature changes, bleaching events—that losing more to storms is something we need to avoid,” says Tom Moore, manager of NOAA’s Coral Reef Restoration Program.
After last year’s Florida storms, Moore’s team and partners did triage on injured reefs, reattaching coral fragments with cement and maneuvering coral heads back into place. Biologists are also cultivating adaptable species for reef propagation. “Losing coral reefs would be like losing forests,” Moore says. “It’s just not an option.”
Above water, ecologists aim to soften “hard shorelines,” reduce erosion and restore wetlands. “Using nature’s own strategies,” says Emily Powell, a coastal resilience specialist for NWF, “we’re boosting the ability of coastal systems to recover from and adapt to all kinds of disturbances.”
Hurricanes aren’t all bad. These natural events can prune forests, deposit vital nutrients, flush out pollutants and provide other ecosystem benefits. But in a warming climate, more-intense, frequent storms can push already-stressed natural systems to the brink, so scientists and policymakers must commit to building coastal resilience. After all, it’s not just wildlife but all life at risk when storm clouds rush in.
As climate change and worsening storms add pressure to already overtaxed coastlines, the National Wildlife Federation and its affiliates support finding sustainable, natural ways to reduce damage from storm surge, floods and wind. This includes efforts to build up barrier islands and coastal wetlands, restore hydrologic systems, control sediment and construct oyster reefs. Among their endeavors:
Living Shorelines. Flood barriers such as concrete breakwaters often stymie nature’s own protective processes. One way to “green the gray” (make hard infrastructures function more naturally) is to turn them into oyster reefs. In the Chesapeake Bay, NWF and partners are planning a pilot project “to retrofit existing structures to support oysters, whose shells form little pockets that break up wave energy,” says NWF conservation specialist Avalon Bristow. Other pluses: Oysters nourish birds and filter nutrients and sediments from the bay—improving water quality for aquatic life—while the porous structure adds habitat value, drawing fish, crabs and other animals to otherwise barren surfaces.
Marsh Renewal. Coastal wetlands are nutrient-rich habitats vital to both wildlife and coastline durability. The Great Marsh in Massachusetts, a vast salt marsh that encompasses barrier island, river and tidal creek ecosystems, was hit hard by Hurricane Sandy in 2012, but NWF and partners are working to restore what was lost. Efforts include expanding marsh-grass beds to help dissipate wave action (reducing flooding and erosion), managing invasive reeds and assessing artificial structures that interfere with natural marsh hydrology.
Coastal Restoration. In the Gulf of Mexico, up to $16 billion in legal settlements from the 2010 BP oil spill could help improve coastal resilience. One such effort aims to rebuild Louisiana’s first line of defense—barrier islands—such as the beaches and dunes of Whiskey Island. Dredging and moving some 10.4 million cubic yards of sand from an offshore shoal for reconstruction will ultimately reduce storm surge for nearby coastal communities, lessen saltwater intrusion and wetland loss in the estuaries behind the barrier islands and create habitat for migratory and breeding shorebirds and seabirds.
Such natural approaches not only benefit the environment but make good economic sense. A team of U.S. and Swiss researchers reported in April that nature-based solutions are seven times more cost effective than artificial ones (such as seawalls and levees) and could prevent some $50 billion in Gulf Coast property damage over 20 years. “The goal,” says NWF staff scientist Ryan Fikes, “is to have communities, both wildlife and human, persist long term despite the chronic threats facing our coasts.”
Jennifer S. Holland wrote about helping turtles cross roads in the June–July 2018 issue.
Hurricane Season is Here: Preparing our Coast for the Future »
Florida: Paradise Unwound »
Puerto Rican Parrot Comeback »
The Great Marsh: Nature's Flood Insurance »
Our Work: Protecting Floodplains »
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