10 Feral Animals Wreaking Environmental Havoc

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Gone wild

Photo: Dan Armbrust/Flickr

Zoo escapees. Natural-disaster refugees. Throwaway pets. Runaway farm animals. However they end up in the wild, feral animals are on the rise — and we don’t just mean cats and dogs. Give any domesticated animal a hospitable environment in the great outdoors with opportunities for breeding, and chances are they’ll end up thriving.

Some feral animals are relatively harmless — charming additions to their adopted ecosystems. Others, though, are tenacious and often deadly — invasive transplants spreading mayhem wherever they roam. Read on to learn more about some of the planet’s most improbable feral creatures. (Text: Sidney Stevens)

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Nile monitor lizards

Wikimedia Commons.

These African natives, cousins to the Komodo dragon found in Indonesia, have moved well beyond nuisance status in south Florida, where escapees from exotic pet stores and homes have taken to the wild and multiplied over the last couple of decades. These giants (some up to 7 feet long with razor-sharp fangs and claws) aren’t usually aggressive toward humans unless threatened, but it can be disconcerting to see them wandering across backyard patios, climbing on roofs and sliding into swimming pools for a dip. Most troublesome, though, is their propensity for snacking on native wildlife and fish.

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Burros

Wikimedia Commons.

Drive through the gorgeous desert landscape of Nevada’s Red Rock Canyon National Conservation Area — just a 30-minute trip from the Las Vegas strip — and you can’t miss them: feral burros wandering as freely and abundantly as squirrels. These descendants of burros abandoned by Spanish explorers in the 1600s and miners in the 1800s now roam most of the western U.S. under the protection of the Bureau of Land Management. If you’re looking to own an iconic piece of Americana, good news: you can adopt up to four burros a year for about $135 a piece.

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Red-eared sliders

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Red-eared sliders are one of the most common turtles sold in pet stores. But these darlings of the domesticated reptile world are also flourishing in ponds and lakes in New York’s Central Park and Prospect Park, as well as in waterways in several other states. Mostly escapees and discards from homes, these feral turtles have been multiplying since the 1930s with their peak occurring in the late ‘80s and early ‘90s when “Teenage Mutant Ninja Turtles” were all the rage.

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Camels

Wikimedia Commons.

Used in the 1800s by settlers in the Australian Outback, camels fell by the wayside once automobiles came along — or so the old-timers who ditched them hoped. Unfortunately, feral camels now number in the millions in Australia, eating their way through native vegetation and even terrorizing towns as they search for water in drought-stricken regions. Some camel haters even blame their intestinal gas (i.e., methane) for climate change and propose culling herds of feral camels from helicopters or corralling them for slaughter.

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Hogs

Wikimedia Commons.

Roving packs of hogs — descended from escaped farm pigs — have taken to the wild in several states, including Arkansas, Texas, Alabama and Wisconsin. These boarish bandits — millions of them — seem bent on destroying agricultural crops, residential property, wildlife habitats and even attacking humans and livestock in their relentless search for food. Many communities now encourage hunters and residents to shoot or trap them. Not so on the island of Big Major in the Bahamas, though, where beach-loving feral swine have been delighting tourists and locals for years.

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Guinea pigs

Wikimedia Commons.

Granted, they’re not as big or scary as real pigs, but these cuddly critters are fast becoming a major nuisance on the Hawaiian island of Oahu. Authorities speculate that most of the island’s guinea pigs are descended from fugitive pets (or perhaps from just one pregnant runaway). Either way, these furry ferals are devouring residents’ shrubbery and ornamental plants at an alarming rate, and taking a significant toll on native plants and crops as well. Nor is the problem likely to go away anytime soon. Each female guinea pig typically gives birth twice a year to up to four pups per litter.

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Wallabies

Wikimedia Commons.

Deep in the Forest of Rambouillet, west of Paris, wallabies are flourishing, thousands of miles away from their native Australia. These kangaroo-like creatures (escapees from a nearby wildlife park decades ago) don’t appear to do much harm to local ecosystems, but they do occasionally startle unsuspecting drivers, often winding up as roadkill. Several other colonies of feral wallabies exist around the world as well. There’s one on Lambay Island, off the east coast of Ireland. The Dublin Zoo released them in the 1980s after experiencing a sudden wallaby population explosion. Another colony of farm escapees thrives in Cornwall in the U.K. There’s even a colony in the Kalihi Valley on Oahu, descendants of runaways from a local zoo nearly 100 years ago.

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Chickens

Photo: russellstreet/Flickr [CC by 2.0]

Hurricane Katrina brought many problems to New Orleans, not the least of which was an explosion of chicken gangs that wander pecking and squawking through many neighborhoods, particularly in the city’s famed 9th Ward. Authorities believe they’re descended from backyard hens and roosters that somehow survived the deluge. Philadelphia, Miami, Los Angeles and Key West have also had their own run-ins with feral fowl in recent years — a problem that keeps animal-control officers hopping as they struggle to capture and transplant these poultry pests to local farms.

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Cows and water buffalo

Photo: wwikgren/Flickr [CC by

On Lantau island, the largest in Hong Kong, cattle and water buffalo were once used to plow rice paddies. With the decline of rural life in the 1970s, the cattle were set free and now wander the island grazing in herds. Many people find them picturesque, an endearing part of the Lantau experience. Others, though, want them gone, claiming the seemingly placid beasts destroy fences, eat crops, block traffic on local roads, and even attack people. Last year, for instance, a young water buffalo charged and gored a tourist, severely injuring him.

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Burmese pythons

Robert Sullivan/AFP.

Nile monitor lizards aren’t the only feral foreigners plaguing Florida. The Sunshine State is also being overrun by Burmese pythons, which were introduced to the wild by errant pet owners. Tens of thousands of these monsters — some growing up to 20 feet long — inhabit the state’s Everglades National Park where researchers suggest they may be responsible for a precipitous decline in populations of native mammals (including opossums, bobcats, rabbits and deer), birds and reptiles. Even more alarming, pythons and other feral serpents, like boa constrictors, are notoriously difficult to manage in the wild and adapt easily to colder climates — meaning they may be making their way to a state near you!