Hairball whodunit: Guess where this huge hoghair bezoar came from

Think Floofy's the only one hacking up hairballs? Oh, how deeply wrong you are.

In an article posted to the Quality Deer Management Association website, wildlife biologist Dave Edwards recently detailed an interesting discovery he and a colleague made on the coast of southern Georgia. The detective work went down in and around a resort property inland of Cumberland Island National Seashore called Cabin Bluff, where Edwards is general manager.

The first bit of evidence? A "very tightly condensed hairball" the size of a smallish coconut that Jody Smith, a Cabin Bluff hunting guide, had found at the edge of a wetland on the grounds. Edwards recognised the coarse hair as that of a feral hog, common at Cabin Bluff (and across most of the southeastern United States).

A hunting guide found this hairball in the woods near a wetland at Cabin Bluff. Image: Dave Edwards/used with permission

Because wild pigs won't turn up their nose at scavenging their own kind (let's be honest, wild pigs don't turn up their nose at much), Edwards first guessed the hairball was the result of cannibalism, and represented a "bezoar": an undigested mass lodged in an animal's stomach or elsewhere in the gastrointestinal tract.

"In this case, I assumed it was produced by a hog, which died, and the hairball remained after decomposition took place," Edwards wrote.

As chance would happen, a bit of reptilian roadkill just a few weeks later suggested a different origin story for the husky glob.

A good-sized American alligator was struck dead on a nearby highway, and Smith decided to have a look at its stomach contents out of curiosity. Inside? Wouldn't you know it: a hoghair hairball much like the first.

A second hairball was found inside a road-killed alligator just a few weeks later. Image: Dave Edwards/used with permission

Intrigued, Edwards did some digging and learned crocodilians also produce bezoars. "The digestive enzymes in an alligator's stomach are particularly strong and most bones and flesh are rapidly digested," he wrote. "On the other hand, hair and other keratinous substances like hooves and turtle shells are broken down very slowly. Hair sometimes accumulates in balls in the stomach and may later be regurgitated."

Indeed, one analysis suggested that less than one percent of fur alligators eat is voided on the back end of things (if you catch my drift), the vast majority being ralphed out as gator-style hairballs. (Aren't you glad you know this now?)

We checked in with Adam Rosenblatt, a postdoctoral associate at Yale University who studies alligators (and their South American counterparts black caimans) in research focused on the ecology of apex predators. He's scrutinised the stomach contents of many gators and caimans, but he's never personally found a bezoar inside (or out) of the reptiles.

“[…] I've seen hair come out but never in the form of a bezoar," he wrote by email. "In one extreme case, a black caiman I stomach-pumped in Guyana had consumed part of a dead horse and had a huge amount of horse hair in its stomach, but it was not compacted into a bezoar."

He noted alligators puke up more than just tight-packed hairy nuggets. "Gators do indeed regurgitate some of the things they consume but can't digest," Rosenblatt said. He pointed to a Louisiana study* that tracked 140 juvenile alligators outfitted in radio collars. "During the study, 23 were cannibalised by other alligators," he said, "and the radio collars were eventually found just lying on the ground, some of them covered in hair and tooth marks."

Because it's unlikely the collars would have fallen off when the young gators were being consumed, the researchers guessed the cannibalistic gators simply purged them after digesting their meal.

Edwards and Smith's hairball discoveries also illuminate some of the ecological dynamics between feral hogs – an exotic species in the American Southeast – and the region's reigning freshwater predator. Given how numerous both hogs and gators are at Cabin Bluff, Edwards writes in his post, the reptiles' pork nosh isn't necessarily surprising.

A 1990 survey on Cumberland Island just a stone's throw from Cabin Bluff showed mammals featured prominently in the diet of local alligators, wild pigs included.

There aren't a lot of hard numbers out there documenting the extent of gator predation on wild hogs, but the crocodilians' taste for swine has been recognised since the early days of pig colonisation in the US: Rosenblatt notes a reference to the phenomenon way back in 1709 in a travelogue by John Lawson called A New Voyage to Carolina.

Given the huge impact the bulldozer-style foraging of exotic swine has on local ecosystems, the pigs' occasional appearance on the menu of alligators (and other native meat-eaters such as black bears and Florida panthers) may be thought of as some kind of rough justice. Research out of Louisiana shows feral hogs can be significant destroyers of alligator nests, and the animals have also been documented raiding crocodilian clutches in places such as South America, Australia and New Guinea.

If those glamour shots of gator hairballs have you curious about bezoars, meanwhile, you can find out about the more mineralised form they sometimes take – and the magical properties ascribed to these so-called "madstones" – right here.