As I searched for Piping Plover nests and chicks on Monomoy – the daily routine of my job as shorebird monitor – I could walk any stretch of the island, on any day of the week, and see coyote tracks running the length of the beach, or imprinted in the mud along the edge of a marsh. These tracks were a sign of how regularly coyotes visit Monomoy, and what brings coyotes to an offshore barrier island is their search for food and territory. They swim through powerful currents and waters famous for Great White Sharks, then wade across the shallows and sandbars that separate Monomoy from the rest of Cape Cod. I became very accustomed to seeing signs of the coyotes’ visits during my time on the island, but I am still bewildered by the journey they make to get to Monomoy.
According to records kept by the State Department of Environmental affairs, coyotes started breeding in Central Massachusetts in the 1950’s. Using farmland, suburban backyards and even city parks as green corridors, coyotes have successfully expanded their range and established themselves all along the Eastern US. In Massachusetts they occupy every county with the exceptions of Nantucket and Martha’s Vineyard (though there have been many unconfirmed coyote sightings on the Vineyard since 2010 (https://vineyardgazette.com/news/2014/03/26/coyote-concerns )). On Monomoy, the first coyote den was found by Fish and Wildlife staff in 1998.
The coyote’s ability to adapt has allowed this predator to colonize our continent. Coyotes did not exist beyond the prairies and deserts of Central North America before 1700. By eliminating the larger predators that control coyote populations – bears and wolves – people have provided coyotes with new breeding range, and left for them a reserve food supply in the form of our own food trash. There is little risk for coyotes in exploring new territory, and competition for space pushes mature coyotes to leave their parents and claim their own territories every year. This is why coyotes have spent the past eighty years moving East, and why they swim to Monomoy. Coyote stragglers and pioneers stake their claim to the island, and here they find an abundance of voles living in the dry wrack line and dune grass, Fowler’s toads, Sea Robins – a fish that feeds in very shallow water and can easily be caught by a quick enough mouth – and of course, birds.
Monomoy is a unique haven for Common Terns, Piping Plovers and American Oystercatchers – birds that fail to reproduce in many areas on the mainland, but thrive on the island. Absent of people, the island Wildlife Refuge provides some species of birds better reproductive success than anywhere else in Massachusetts. Monomoy is one of the few remaining wilderness areas in the Northeast, along a coastline that is almost exclusively developed and trafficked by people.
Thousands of Common Terns have settled on Monomoy to breed in a dense, cacophonous colony. These ground-nesting birds are attracted to remote barrier islands because they are absent of mammal predators, and given how scarce good breeding habitat is in the Northeast, it is advantageous for the terns to invest their nesting effort into a single, uniquely perfect area of land. The downside of nesting in groups is that a large colony of terns, along with their eggs and chicks, creates a large aggregation of easy prey. By literally placing all their eggs in one basket, the terns attract potential predators to a virgin island.
Common Terns have evolved effective defenses against native predators who might visit their colony. Should a fox, skunk or raccoon walk through the colony in search of tern eggs, the birds will swarm the mammal, pecking and pooping on it, and drive it out of the colony. They will do the same to Peregrine Falcons, Red-Tailed Hawks and Bald Eagles, and their group-defense strategy works a treat.
Coyotes are still an unfamiliar predator to these birds and significantly more imposing than raccoons and skunks, against whom the terns have evolved a successful defense system. When a coyote passes through a tern colony, swarming behavior by the terns can escalate to a point where the entire colony – more than 20,000 birds – will leave its nesting grounds for twenty minutes or longer, exposing chicks and eggs to the cold. This can be deadly to an entire population of terns.
Coyotes are not a native part of this ecosystem, and their intrusion on Monomoy poses a serious threat to the reproductive success of native breeding species. In 2006, the stomach of a coyote killed on the refuge contained 69 Common Tern chicks, which it likely ate in one night. In 2009, the stomachs of two coyotes contained 75 tern chicks between them (USFWS 2016, Appendix J). In an effort to mitigate the damage coyotes cause to native birds, the Fish and Wildlife Service has established a practice of killing coyotes found on Monomoy. This is done only during Spring and Summer, when the predators pose a threat to nesting shorebirds. In April, contracted hunters use dogs to search the island for denning coyotes. The goal is to destroy any coyotes that have made dens on Monomoy and kill their pups, who are usually born in March. David Warren, who works for the USDA’s Wildlife Services division, hunts coyotes that visit the island during the summer months.
In July I spent an evening with David, and he told me a little about his routine hunting coyotes. David spends part of his summer living on Monomoy. The island is usually uninhabited by people, and the only permanent structure on the Monomoy is a lighthouse at the South end of the island. Built in 1849, the lighthouse is the only building that remains of Whitewash Village, abandoned by its residents in 1876. David has outfitted the lighthouse with a propane-powered fridge, a stove, and decorated one wall with skulls of coyotes he has killed. Just before sunset, he and I walk to a dune that he uses as a lookout. Dave’s hunting routine begins at dusk, when he sits on the ridge of the dune and scans the landscape with binoculars. His rifle is positioned in a stand to keep it steady, in case he has to take a long shot. Perched on his lookout, David waits for a glimpse of a coyote that might be stalking the overgrown dune slopes.
Every night, David also sets up leg-hold traps that are baited with sardines, cat food, or coyote urine to attract the predator’s curiosity. These traps are padded and articulated, which means that they don’t break a coyote’s foot when triggered, don’t cut a wound, and don’t cause the animal to dislocate its limb as it struggles to escape. David checks his traps at least once every twenty-four hours, so he can quickly shoot a coyote that may be caught in a snare.
As I describe David’s work, I can’t help but feel that I am writing about a practice that is brutal and inhumane. No matter what precautions are built into the design of a leg-hold trap, a coyote caught in the trap will still panic and exhaust itself trying to break free. It seems paradoxical that a protocol of killing animals should be implemented on a Wildlife Refuge. Aren’t these places designed to protect wildlife? I think this feeling may resonate with many people, especially because it is so easy to sympathize with coyotes – they are intelligent, social, playful, curious. However, this paradox should be considered in light of the very difficult choice that biologists who manage the Monomoy Wildlife Refuge must make every spring.
Coyotes have very recently expanded their historic range, which never included Massachusetts, and the native bird species they depredate on Monomoy have not yet adapted to the impact of coyote predation. Being preyed on by coyotes is, on an evolutionary timeline, completely new to these birds. If coyotes are allowed to hunt and even breed on Monomoy, their presence may reduce the populations of native Piping Plovers and American Oystercatchers, and could completely wipe out one of the largest Common Tern colonies on the East Coast. The prospect of such damage makes the choice to kill coyotes on Monomoy more comprehensible.
Tern and plover populations declined during the 20th Century because the habitat they need to breed – open beaches and sparsely vegetated dunes – has been taken over by people. Just as these birds love the beach for nesting, people love for it for sunbathing, playing beach volleyball and developing oceanside property. It is easy to think of human effect on beach ecosystems as unnatural – in the literal sense of the word, beachfront homes and ocean pollution are made by man, not by nature. Establishing a wildlife refuge where birds may thrive free of human-made obstacles to their reproduction makes sense in this frame of thought.
A coyote is obviously different than a plastic bag floating in the ocean or a backhoe on the beach. It is a wild animal, and the coyote’s arrival on Monomoy seems like a natural process that shouldn’t be tampered with by people. However, there is strong evidence that coyotes would never have made it to the East coast without the influence of people.
There are numerous examples of invasive animals introduced by people to North America, which are now thriving all over the continent and damaging native ecosystems. In 1890 and 1891, a Bronx drug manufacturer named Eugene Schieffelin released a hundred European Starlings in Central Park as part of an effort by a group named The Acclimatization Society to introduce all birds mentioned in Shakespeare’s plays into America. By 1950, starlings could be found all over the US and south into Mexico (Mirsky, 2008). Starlings have been implicated in the spread of 25 avian diseases that have have killed native North American bird species (Pimentel et al. 2000).
The Brown, or Norway Rat is another obvious example; likely originating in Asia, the rat is living commensally with people in cities all over Europe and the US, and has decimated ground-nesting bird populations in New Zealand, while similar black rats have taken their destructive toll on the Seychelles and the Galapagos (Harper, Bunbury 2015).
Introducing completely new, invasive species isn’t the only way that people can affect wildlife populations. By modifying habitat, we promote the success of select animal species, while placing others at a disadvantage. Animals that are uniquely advantaged by human presence will expand their natural range and in that process threaten local, specialist species, who may need a specific habitat or source of prey to survive. For example, crow and raven populations are increasing worldwide due to urbanization – crows love to eat our trash, and thrive around human-built structures. American Crows can now be found in habitats they didn’t occupy before human development, like ocean beaches and deserts around Las Vegas (Marzluff 2001). Crows prey on shorebird eggs and chicks along Atlantic beaches, and ravens are driving down desert tortoise populations in Nevada. In central California, Ravens and Steller’s Jays are predating on the nests of Marbled Murrelets, a species that nests only in the upper canopy of old-growth coniferous forests (Percy, Golightly 2007). Marbled Murrelet populations are crashing, in large part due to corvid predation. In Northern California, Barred Owls are taking over territories formerly occupied by the declining Spotted Owls, because the old-growth forests that Spotted Owls prefer have been heavily logged. Because Barred Owls are less particular about the habitat they will use for breeding, and are more aggressive than Spotted Owls, they have further advanced a decline of Spotted Owls that was first initiated by people.
Coyotes seem to thrive where people are present, and human influence has allowed coyotes to populate areas well outside their historic range. In his book about coyotes on Cape Cod, Suburban Howls, biologist Jonathan Way describes the effect of human presence on coyotes, “many of the things we most cherish about comfortable suburban living, such as lush woods surrounding properties and open grassy yards teeming with wildlife, are also some of the key attributes that make suburban areas perfect coyote habitat” (Way, 124). Coyotes have taken advantage of the habitat people have created, and used it to expand their range throughout the US. However, their success isn’t limited to rural and suburban areas; coyotes are also thriving in cities. In 2010, a coyote was seen in the Holland Tunnel, which connects New Jersey with downtown Manhattan (Rovzar 2010). In April 2015, a coyote was seen on the roof of a bar in Queens and later that same month, NYPD officers from the 10th precinct spotted a coyote running through Chelsea, a busy neighborhood in Manhattan (Bittel 2015). Coyotes have successfully denned and reared pups in Van Cortland and Pelham Bay Parks, both in the Bronx, and are likely establishing territories on Long Island. Because coyotes are nocturnal, they can hunt and roam city parks and alleys when most city residents are asleep, and New York’s large supply of rats and squirrels provides them with an interminable food supply.
A few weeks ago, I was talking to Kate Iaquinto, wildlife biologist at the Monomoy National Wildlife Refuge. It’s hard to understand that coyotes are here on the East Coast because of people, I said to her. Wild animals are not the same as pollution or litter, and even invasive animals appear to be a part of the natural world. “A lot of people have a simplistic vision of natural selection,” she replied, “and they think, ‘well the coyotes made it here because they’re awesome,’ but it’s not quite so simple.”
If people are the reason why coyotes have come to Monomoy, and if we are to blame for the damage that coyotes inflict on native bird populations, what should we do about it?
Because Monomoy is an island, it is sensible to kill every coyote that swims there and continue the practice indefinitely, with good success. But what about all the mainland beaches that are home to nesting threatened shorebirds? What happens when coyotes reach Long Island and start eating Black Skimmer eggs, or preying on the Least Terns that nest all along the peninsula? It seems laughable to try and shoot or trap every coyote on Long Island.
In his recent New York Times editorial called “Stop Killing Coyotes,” science writer Dan Flores described a coyote adaptation known as “fission-fusion.” When adult coyotes are killed, surviving coyotes go into colonizing mode. “They have larger litters. If alpha females die, beta females breed…In full colonization mode…coyotes could withstand as much as a 70 percent yearly kill rate without suffering any decline in their total population” (Flores 2016).
Outside the bounds of an island, killing coyotes is not an effective conservation practice. But, there are alternatives. Because coyotes are intelligent and observant predators, taste aversion and negative conditioning seem to hold potential as effective measures to protect nesting birds from coyote predation. On a mainland Refuge, it may be useful to leave dummy plover or tern eggs and bodies, laced with a repulsive or mildly toxic chemical, for coyotes to find before nesting season begins. Resident coyotes will then learn to avoid similar birds and eggs in the future, and through territorial behavior keep away straggler coyotes who have not developed the aversion.
In a taste aversion study conducted in California, sheep carcasses were laced with lithium chloride, which causes symptoms of poisoning in coyotes but is not lethal, and left for the predators to find and eat. When lithium chloride bait was removed and replaced with poison-free sheep carcasses, wild coyotes continued to avoid the bait for nine weeks, or as long as the study was able to continue. It is unknown how long the effect lasted after that time, but the practice certainly shows promise as an effective way to diminish coyote predation. A coyote’s curiosity, adeptness and memory may give us an advantage when it comes to predator control.
***
As David Warren and I get ready to leave our lookout dune, having spotted no coyote, I ask Dave if he ever feels proud of the coyotes he’s hunting when they avoid his traps, or when they run to cover before he is able to fire a shot. “Oh yea,” he laughs, “Oh yea. My wife says to me, ‘So they outsmarted you again, huh Dave?’” As he says this, Dave smiles, slings his rifle over his shoulder, and starts down the sliding sands of the dune and back toward his lighthouse hunting lodge.
The Monomoy Common Tern colony had a banner breeding year in 2016, and reached its largest recorded population of 10,505 pairs. In April, before the birds arrived on Monomoy, two adult coyotes and eight pups were killed in their den on the island. The decision to do so was a big part of what allowed the terns to have such a productive year. However, during the summer months, Dave wasn’t able to shoot or trap the two coyotes that visited the island almost every night. I saw their tracks on my bird-monitoring walks every morning, running parallel to mine.
They outsmarted us, again.
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