Deep in the Amazon rainforest, there are mysterious canines with short ears, pointy noses, and bushy tails that roam the undergrowth. The creatures, which are one of the least studied variety of dogs on the planet, are rarely seen even by scientists who have spent years studying the region.
Officially, they’re called short-eared dogs, but they’re so elusive that they’re often referred to by the much cooler moniker of “ghost dogs.” As scientists have attempted to better understand these elusive creatures, one of the most significant findings about them has been about the size of their balls — seriously.
Veterinary physician Renata Leite Pitman, an affiliated scholar at Duke University’s Nicholas School of Environment, has devoted years of her life to studying ghost dogs. Twenty years ago, she was set to join a Masters program at Duke University, looking to launch a career in veterinary research in the U.S. But an advisor told Pitman about his research project on the ghost dogs of the Peruvian Amazon. At the biological research station where he worked, his team had 10 encounters with the mysterious creatures in as many years.
“That’s a lot,” she told Gizmodo. “There were almost no records of them at the time … only two studies with records of encountering them. I thought, I need to … get over to this place.”
In July 2000, Pitman headed for the Peruvian Amazon. She planned to stay at the research site for two months, but ended up staying for three years, and the ghost dogs ended up being a major focal point in her career.
When Pitman first arrived at the research site, she began learning everything she could about the ghost dogs. Scientists were aware that they’re shy, and unlike many other canines, they hunt solo or in groups of two or three rather than in large packs. Pitman aimed to unravel their mystery even further, though, poring over the footage the research team had captured. She began following the animals’ tracks along the forest floor to learn about where they live and examining the ghost dog poop she found along the way to learn about their diets (a gross job, but someone has to do it). All of this new information helped Pitman track the animals down in the forest.
After just a month at the site, she encountered her first living ghost dogs. She’d followed the animals’ pawprints into an isolated part of the rainforest, about 16 km north of her research base camp.
“I was just in awe,” she said. “I was following the tracks of the animal, when suddenly I saw a couple of them creep forward… But before I knew it, they were gone. I didn’t even have time to pull out my camera.”
In the years following the ethereal encounter, Pitman’s curiosity only grew. She became the first scientist to ever put a tag on a short-eared dog for study, and encountered many of them in the wild. But since they’re so shy, those encounters were cut short much like her first one as the animals disappeared back into the forest.
In late 2006, an opportunity arose to get super up close and personal with a ghost dog. By then, Pitman had relocated to another research site in the Peruvian Amazon, and she heard about a man who had bought a ghost dog from a hunter who found it in the rainforest. The man had named him Oso, the Spanish word for bear. When she went to visit Oso at the man’s house, she found that he was being terrorised by other domestic dogs living there.
“They would eat all the [food] and leave him with nothing,” she said. “These animals aren’t supposed to be pets!”
After a year of trying to convince the man to let her reintegrate Oso into the wild, the man agreed to do so in exchange for a fee. Pitman was delighted — she’d see to it that the animal was re-acclimated to the forest, and along the way, would have an ideal research subject.
When she obtained the animal in 2007 to begin the rewilding process, one of the first things she noticed when she saw a short-eared dog in person was, weirdly, how small it’s testicles were. Bizarrely, that fact would turn out to be important for her research.
“I always make a joke that these dogs are known for having small ears, but I said, they should be known for having small balls,” she said. “I said, we should change the name to small-balled dog.”
Because the docile, domesticated animal would have had trouble fending for himself in the wild, Pitman and her research assistant kept Oso in a crate. They began weaning him off the human food his owner had been feeding him and took him on long, daily walks through the Amazon where they could study his behaviour and see how he acclimated.
At first he behaved like the domesticated animal he was, but after a year, now two-year-old Oso toughened up. He seemed less intimidated by other ghost dogs in the wild, and Pitman determined that he was ready to live on his own.
But by chance, she had trouble obtaining the necessary permits from the Peruvian government to reintegrate him. That turned out to be a blessing. She ended up having to keep Oso at the research site for another year.
Around the time he turned three, his balls dropped — a weird thing to notice for most people, but a key piece of information for a scientist. This suggested that a major reason that the dogs are so rarely spotted is that they don’t reach sexual maturity until they’re three years old, which is really late for canines. Most dogs can reproduce at just one year old. This puts ghost dogs at a huge disadvantage for survival because many of them die before they are old enough to reproduce.
Short thereafter, Pitman finally obtained the permits to reintegrate Oso and began the process. She got a grant to attach a small “crittercam” video camera to his harness to film his behaviour for a year. Over that year, she found he was re-acclimating well and was even popular with female ghost dogs. A real stud.
A year passed, and Pitman recaptured Oso and put a collar outfitted with a VHF tracker around his neck. The tracker’s battery would last only three years, but she planned to go back out into the forest and replace them.
“I was hoping to study him his entire life,” she said.
In 2013, Pitman boarded a small plane to use the tracker signal to find Oso and replace the batteries. She found him before long. But the area he’d moved into was an area where a protected Indigenous tribe lived, so she wasn’t allowed in to recapture him.
“The last time I saw him, I didn’t know it would even be the last time,” she said. “But I wasn’t frustrated or sad at all. I just felt so much joy knowing he was doing well in the wild.”
Pitman has continued to study the rare species. Scientists don’t have exact population estimates, but she thinks there’s fewer than 15,000 of them left. In addition to the challenges they face due to reaching sexual maturity at a relatively late age, the animals are also put at risk by hunters’ domestic dogs, which can spread deadly viruses the ghost dogs have no natural defences against.
In the future, they’ll face even more danger. This year, Pitman coauthored a study that found 30% of the area they inhabit is threatened by deforestation for farming, logging, and mining. Further ecosystem destruction and fragmentation could lead ghost dogs to extinction. Since they’re still not widely studied or understood, it’s hard to know what effect their extinction could have on other species in their ecosystems. But honestly, it’s probably best to not find out.
To protect these good boys, we need to protect the Amazon. That might give the ghost dogs a chance so they don’t become extinct, becoming actual ghosts that haunt the forest.