Marcus Drymon wasn’t expecting a baby shark to barf up a ball of feathers onto his boat.
The shark’s presence wasn’t the weird bit: Drymon and his team of fisheries ecologists regularly assess fish populations along the coasts of Mississippi and Alabama, and every year, they’ll catch, weigh, tag, and release thousands of sharks. In 2010, they were doing just that for the meter-long tiger shark when it coughed up the feathers. “Being an ecologist, I scooped them up and took them back to the lab,” Drymon says.
He passed the feathers to Kevin Feldheim, a molecular biologist at the Field Museum, who analyzed the DNA within them to work out what species they belonged to. The answer: a brown thrasher, a thrush-like songbird that lives in forests. What on Earth was it doing in the belly of an oceanic apex predator?
“I had expected a laughing gull or a brown pelican,” Drymon says. “The brown thrasher was the last bird I would have expected.”
In fairness, a brown thrasher is hardly the weirdest thing to end up in a tiger shark. This species is notorious for eating pretty much anything. Aside from the remains of dolphins, dugongs, sea turtles, and sea snakes, scientists have found tires, license plates, a drum, unexploded munitions, and an entire chicken coop inside tiger-shark stomachs. And when Drymon dug through some old papers, he found a few decades-old records of tiger sharks eating land-based birds. Thinking about his brown thrasher, he wondered, “Was this just a one-off anecdote, or is there some sort of a pattern?”