Who Moved My Seed?

A rare animal found a rare plant. Then, it seems, the two teamed up.

Courtesy of Claudio Monteza

Zamia pseudoparasitica is a paradox packaged into a Panamanian plant. Its sticky yellow seeds are absolute chonksters, each about the size of a Sour Patch Kid—perfectly designed, it would seem, to pop off the plant and drop straight into the soil. And yet, that’s exactly the fate the plant doesn’t want to befall its progeny. The real estate the plants seek is in the cloud-forest canopy, some 25 to 70 feet off the ground. Among the world’s known gymnosperms, a group of more than 1,000 types of flowerless plants, pseudoparasitica is the only species that refuses to root properly in soil. It prefers instead to grow on top of other plants, draping itself across tree branches, or nestling into the crooks of trunks at four-story-building height, its roots dangling like dreadlocks. Knobby cones and frondlike leaves give it the look of a stunted palm uncannily “growing in a tree,” says Lilisbeth Rodríguez Castro of the Smithsonian Tropical Research Institute. But for years, scientists couldn’t explain how pseudoparasitica was nabbing its penthouse perch—or who or what might be helping it along.

The stakes for the seeds are high. Should they fall to the forest floor, “they basically have no future,” says Michael Calonje, a Zamia expert at the Montgomery Botanical Center, in Florida. But seeds don’t tend to do much moseying about on their own, especially ones this chubby. The guilty party can’t be wind: The seeds are far too heavy to be easily buffeted about. That means “something else, something big, should be responsible,” says Claudio Monteza, of the Max Planck Institute of Animal Behavior, in Germany—perhaps a winged or tree-climbing animal accomplice that snacks on the seeds and stashes them, or scatters them as scat. Only, no one had ever caught a potential seed chauffeur in the act.

A couple of years ago, Monteza, Rodríguez Castro, and their colleagues decided to change that by getting on the plants’ level. In October 2019, the team located three cone-laden pseudoparasitica specimens in forests across western Panama, and fit the branches of nearby trees with camera traps. Over the next four or so months, the devices captured 271 days’ worth of photos, the final shots taken in March 2020, right before the COVID-19 pandemic sent the country into mandatory quarantine.

Then the search for the seed bandit began. Monteza, the team’s resident camera-trap expert, analyzed thousands of images. He remembers wondering whether he’d see a bat or a toucan, two creatures that had been posited as pseudoparasitica-seed dispersers. But neither ever appeared on film—just seven totally flightless mammals. One was a dwarf squirrel, only a few inches in length; two were opossums known to nosh on insects and fruit; another was a tamandua, a type of anteater with a vestlike patch of black fur. Also spotted was a white-faced capuchin monkey, a reputed seed-pooper, and two similar-looking cousins of raccoons—a kinkajou and a northern olingo, both limber, springy, and sharp-clawed.

Round one of elimination was easy. Three of the candidates—the dwarf squirrel, the tamandua, and the Robinson’s mouse opossum—made mere cameos, flashing across the screen without interacting with the pseudoparasitica cones. Of the remaining four, Monteza spied one character who seemed like an obvious suspect: the capuchin, a species that’s been documented nibbling on other forest seeds, then redistributing them through its other end. “As soon as I saw the first photo, I was like, Yes, that makes total sense,” he told me. But the footage kept rolling, and he quickly saw that the capuchin cared … not at all for Zamia pseudoparasitica. It inspected the cone briefly, lost interest, then peaced out. “It was just one individual, doing nothing,” Monteza said. “I was like, You are disappointing me.” The Central American woolly opossum and the kinkajou, too, were a bit blasé. Both prodded the cone, flicked their tongues around its base—and left without lifting any seeds.

And then there was one: the northern olingo, a nocturnal, stern-faced tree-climber known for its intense yen for fruit. It blew into Monteza’s data set and suddenly, spectacularly, began implicating itself. The team’s traps, he realized, had captured dozens of instances of olingos patronizing the plants at all three study sites. Unlike the other creatures, who showed little enthusiasm for the cones, the olingos strutted up as if greeting old friends, and diligently sniffed, rubbed, nibbled, and poked. Early in Panama’s dry season, when the cones were still young and sealed shut, the animals seemed to be scouting their prospects, yanking unsuccessfully at the seeds before flitting away, as if “waiting for those suckers to ripen,” says Roland Kays, an olingo expert at North Carolina State University who watched the team’s footage. In January, the cones began to crack, allowing the olingos to excavate the now-mature, rank-smelling seeds with their teeth and claws. They stuffed their winnings into their mouth, two or four or even eight at a time, and leaped away into the dark.

Credit: Courtesy of Claudio Monteza, Max Planck Institute of Animal Behavior

Clearly, the olingos looked to be the guiltiest members of the camera-trap lineup—“they were the only ones that came back repeatedly, the only ones seen going in and taking seeds out,” says Kristin Saltonstall, of the Smithsonian Tropical Research Institute, who helped supervise the team’s work. The olingo’s culpability “seems pretty solid to me,” says Calonje, who wasn’t involved in the study.

But no one is quite ready to call the case closed. The olingos captured on film didn’t seem to be immediately consuming the seeds they pilfered—they just jammed them into their cheeks like hamsters and ran. “We don’t know where the olingo goes next,” says Ann Marie Gawel, a seed-dispersal researcher at Iowa State University who wasn’t involved with the STRI project. Maybe the seeds get swallowed whole, then serendipitously pooped out to germinate in the trees. Or maybe they’re chewed up and irreparably damaged, making the olingo a predator, rather than a reproductive ally in arms. Even if the seeds survive the sojourn, that doesn’t mean olingos get to take all the credit; other animals may still be involved. (During the study, a researcher on the forest floor managed to snap a non-trap photo of a yellow-eared toucanet harvesting a pseudoparasitica seed—but it appeared to destroy its prize shortly thereafter.)

To really clinch the story, Rodríguez Castro told me, “we would have to track the animal and track the seeds,” maybe with some sort of collar for the olingo, and luminescent paint for the plant. It also wouldn’t hurt, Gawel says, to sift through some olingo scat, to see if any gulped-down seeds emerge out the other end.

For now, Monteza is keen on another explanation that doesn’t necessarily require a trip through a digestive tract. Perhaps the olingos are absentmindedly caching seeds in tree nooks and crannies; the ones the animals forget to collect then get the chance to grow. The olingos, after all, weren’t feasting on the cones at their source, but amassing facefuls and skedaddling, as if scared they would be detained and frisked. If that’s the case, Kays, the olingo expert, wouldn’t be surprised. Olingos must share their habitat with their bigger, buffer kinkajou cousins, which will sometimes bully smaller mammals out of their meals. Hastily hoarding food for later might be olingos’ best bet at outsmarting their rivals. Kays also notes that a collect-and-hide seed-dispersal strategy might be more sensible than a feces-based one, considering where a lot of olingo waste ends up. “I’ve sat under them, while they do that,” he told me, referring to the act of defecating. The scat, like seeds, cannot defy gravity: “It lands on my head.”

I asked Kays, who has respectfully chased many northern olingos through the tropics, if “pseudoparasitica-seed disperser” might be a title befitting of the species and its antics. “Who the hell knows,” he said. (Though he does find the STRI team’s data compelling.) “We don’t know much about what olingos do.” But should the dynamics of this duo be cemented in the future, it’ll be a neat narrative—the teaming-up of a “rare animal and a rare plant,” Saltonstall says. The perfect partners in arboreal crime.