Meet the Mysterious Fossa

BY Karyl Carmignani

Photography by Ken Bohn
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Fossas estimated
to remain on Madagascar

Fast, svelte, dexterous, and unbelievably agile are just a few adjectives fitting the fossa (pronounced “FOO-sah”) family dashing, drowsing, or dining throughout their new habitat in Conrad Prebys Africa Rocks. Last June, Miles, a 15-pound female fossa, gave birth to 4 tiny, altricial pups, which stayed tucked away in the nest box for about the first 6 weeks. “We had been weighing Miles, and we knew she had bred,” explained Lacy Pearson, mammal keeper at the San Diego Zoo. “Then one morning, we could hear mewls and squeaky noises coming from the nest box.

We didn’t actually see them for several more weeks, when two of them finally peeked out.” The male, Gandalf, is currently off exhibit, but visitors can see mom and pups enjoying their varied vertical space, which was created especially for this species. Lacy said the pups hit milestones quickly, but grow slowly. “It’s incredible to watch the pups develop. They are wobbling one day and leaping the next!”

PRECIOUS PUP
At birth, fossa pups are kitten-sized and mom keeps them safely stowed in the den for several weeks. With age, their appetite grows along with their curiosity and agility.

Fossa life span in years in zoos

Who’s a Fossa?

Most people have never seen a fossa up close, much less realized what it is. Resembling a long-bodied, catlike dog with a hint of weasel, this carnivorous mammal endemic to Madagascar would stop anyone in their tracks, if they could see it. As a crafty apex predator, the fossa hunts by day or night, often high in the trees in search of its favorite prey: lemurs. But they also take down rodents, birds, fish, and even wild pigs. An ambush hunter, the stealthy fossa can outmaneuver the most nimble arboreal creatures using its long tail for balance, strong claws and forelimbs to capture prey, and its sharp teeth to finish the job. It can reach 6 feet in length—with half of that being its tail—and weigh over 20 pounds.

UP HIGH THERE!
Like all baby animals, fossa pups eagerly explore their environment, testing boundaries and honing their skills.

While little is known about the fossa, largely due to their sparse numbers—they are listed as Vulnerable by the International Union for Conservation of Nature and continue to decline—and remote forest habitat, what is known about them is exceptional. Once classified as a type of cat, we now know that the fossa is related to the mongoose. These intelligent, solitary animals were once thought to be nocturnal, but it has since been revealed that they are flexible in habit, napping and hunting when they choose. They can travel up to 16 miles a day. Fossas favor forested landscapes and, in fact, they can scamper down a tree trunk headfirst! They walk flat-footed, like a bear or a human, a form of locomotion called “plantigrade.” Mothers with pups, and brief breeding encounters in September and October are the only exceptions to their solitary existence. However, in 2009, scientists observed three male fossas cooperatively hunting a sifaka for 45 minutes. That could have been residual behavior from millions of years ago, when now-extinct lemurs were as big as horses, and cooperation was required to hunt them successfully.

 

 

CARNIVORE KING  
The fossa is critical to the ecosystems of Madagascar, keeping prey species in check.

Fossa pups born at the Zoo over
the years

Unique among carnivores, female fossas in heat establish a site high in a tree as male fossas clamor below for mating rights. She may pick and choose among her suitors, and mating can last for several hours. Once she is satisfied, she will leave the tree and another female will take over the mating site. The same “mating trees” may be used each year. Another quirky female fossa characteristic (last one, I promise!) is the “masculinization” phase of an adolescent female, when the clitoris becomes spiny and enlarged, resembling the male fossa penis; and she develops an orange secretion on her underbelly, which is a mature male characteristic. But soon, she reverts back to her femaleness. Even the fossa’s scientific name Cryptoprocta ferox reflects its secretive nature: the first part means “hidden anus,” referring to a pouch that conceals its privates, while ferox signifies its reputation for ferocity.

MOTHER KNOWS BEST
Talking back to mom is never a good idea.

 

San Diego Zoo’s fossas are part of the Association of Zoos and Aquariums’ Species Survival Plan (SSP).

Zoo Pups

At the Zoo, keepers go to great lengths to keep the fossas engaged and on their game. “We provide them a varied diet of rabbits, mice, meat, and bones, which we disperse throughout their exhibit at different times of the day throughout the week,” said Lacy. She explained how they save up some daily calories for enrichment items like squid, trout, or chicken baby food. “The pups love smelt, but mom not so much. For Miles, baby food is a high-value item, and we use it when training her.” At around four months of age, one of the pups finally took food through the mesh from Lacy. “It was very exciting!” she said, adding that it is always surprising what they like and how they behave. For instance, a hollowed-out log in the exhibit near Zoo guests? No problem, they love it, despite the proximity to people. Palm fronds provide hours of fun, with the pups climbing and sliding on them.

FROLICKING FUN
Pups must learn early the vital skill of tree climbing—and hanging.

Fossa pups currently at the Zoo

The exhibit was built with fossa behaviors in mind, so there’s plenty of vertical space and trees from which to leap. “There are niches and caves in the rockwork, where we hide treats, and the fossas enjoy exploring,” said Lacy. Next door to the fossas is the ratel, or honey badger. The exhibits are connected in the bedroom areas with a chute, so the animals can occasionally be swapped. “That will be mind-boggling enrichment for them!” exclaimed Lacy. It’s a challenge keeping the fossas challenged, and the new species-specific exhibit is providing layers of nuanced excitement to the animals…and visitors. “These apex predators of Madagascar are dwindling,” said Lacy. “If they disappear in the wild, it would have a devastating effect on the entire ecosystem. We hope people will learn about them here at the Zoo and understand that they are not good pets, nor are they ‘bad luck.’ They serve a better purpose in the wild—even to the lemurs—than they would in your house.”

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