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Invasive Pig Goes From Pest To Savior For Saltwater Croc

The American perspective on Australia is always an entertaining one. In large part because of the distance between the Land Down Under and the U.S. — even the closest flights are 14 hours minimum — Australia is often relegated to a few common beats. The usual suspects include vague allusions to “the Outback” without any elaboration to show that they aren’t referencing the steakhouse chain or the mention of the Sydney Opera House as an underrated sight-seeing gem. 

The most familiar trope may be a palpable fear of Aussie wildlife. Years of online videos showcased various super-sized lizards, spiders, and even 3-foot-wide crabs. Some of these stereotypes accurately depict the continent more than others, though the measurements and pictures of these terrifying critters are tough to deny. Still, one creature has ascended above the rest and is incredibly accomplished despite being unwanted by definition. 

The invasive feral pig is in a league of its own as far as Australian pests go. There isn’t anything dramatically different between these wild pigs and normal, domesticated ones. These animals are descendants of pigs brought to the continent for slaughter by European colonists. A growing number of smarter-than-average pigs escaped into the wild. 

Those pigs were incredibly lucky. In the years that followed, no species emerged as predators to impede their development, a fact made possible because the pigs were artificially introduced to the outback environment.

More than two centuries later, their descendants have taken over biomes across a startling 40% of the continent. 

Photo Courtesy Dusan Veverkelog

The species’ spread continued through the mid-20th century, at a time when another Australian staple saw its populations seriously declining. The saltwater crocodile has long been an essential part of the local biome, sitting as an apex predator due to the strength of its bite and the infamous “death roll” it uses for killing prey. 

But the growing development of the early 1900s in Australia gave way to a generation interested in conquering the Outback. The saltwater croc became a prime target for 40 years of trophy hunting from the 1930s until its eventual ban in 1971. 

When the Northern Territory hunting ban came into effect, many thought it would be too late to save a species that had dwindled in population from more than 100,000 in the 1930s to just a few thousand. Thankfully this wasn’t the case. In the decades since then, the crocodile population has exploded to numbers reminiscent of the pre-industrialized era, an impressive mark for a species of notoriously lazy hunters. Researchers like Charles Darwin University’s Dr. Mariana Campbell offer a clear yet surprising explanation: the crocodiles were engorging themselves on the same pigs.

Photo Courtesy David Clode

Campbell and her team concluded after studying decades of bone data between modern crocodiles and those that lived before feral pigs came to the region.

When looking at the crocodile recovery by area, the data showed that populations saw better recovery rates in environments that contained these pigs, primarily due to the ease with which they were hunted. 

“Crocodiles eat whatever is easiest, and feral pigs are the perfect size,” Campbell said to ZME Science. In her eyes, a feral pig is a no-brainer for a crocodile looking for food. “If you’re a crocodile, what is easiest? You stay near the bank and wait a few hours for a pig? Or do you go and hunt for a shark, an animal that can swim five times faster than you?”

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