It’s tarantula mating season. This is the best place to watch.
A town in southeastern Colorado hosts a yearly tarantula festival, attracting both tourists and scientists studying tarantula mysteries.
Just before sunset, as baseball-sized tarantulas cross the road at Colorado’s Southern Plains Land Trust, two biologists quietly exit their car to scoop up a few of these eight-legged pedestrians. Graduate student Spencer Poscente and his advisor Cara Shillington have traveled from their lab at Eastern Michigan University to do science, but also to take part in a one-of-a-kind festival that celebrates all things tarantulas.
On September 26 and 27, the neighboring town of La Junta, Colorado, featured its annual Tarantula Fest, a two-day celebration of everything arachnid. The festival included public science talks, tours of the local grassland where scores of tarantulas make their homes, a showing of the 1990 film Arachnophobia, and even a parade where everyone dresses up as a spider.
The festival started with a glimmer of an idea in 2018 of how to promote tarantula tourism, says Pamela Denahy, who directs tourism for the city of La Junta. “We were able to identify the perfect time of day, the perfect time of year, and the perfect location where we can almost guarantee you see a tarantula. September is the ideal time.”
Mysteries of mating season
When Shillington started coming out to southeastern Colorado, she was awed. Though she has studied tarantulas for years, she had never so many skittering across the undeveloped prairie. “It’s absolutely astounding,” she says. “That’s one of the reasons that we are establishing a long-term focus on the tarantulas here.”
Tarantulas are typically solitary creatures who only crawl above ground to grab prey, such as crickets, mealworms, roaches and even lizards. Females can live in the same burrow for decades.
But for males, their time to shine comes when they reach sexual maturity at around 8 to 10 years old. That’s when they leave their homes, en masse, and travel up to a mile across grassland areas like the one in Colorado to find a mate. The animals can sense light and dark, are very tactile, and have chemosensory hairs for detecting vibrations and chemical cues. When the males find a female burrow, they will perform a courtship dance – tapping or drumming to indicate interest.
Sometimes the males are successful, but even if they’re not, their end is in sight. Males typically die after mating season – killed by a car, or a predator, or even starvation after they have spent their energy mating. Females, which are usually larger and can live twice as long, may even devour them after mating.
There are still many questions about the mating season, which goes from August to October, which is why Shillington and Poscente are spending time in the grasslands. The researchers are weighing and measuring the spiders, and running them through a “racetrack” – a half a gutterpipe covered with plexiglass. The goal isn’t to see who wins, but instead to monitor the body composition and mobility. That’s because as the mating season goes on, the males get weaker, slower and more senescent – closer to death.
(These tarantulas may have evolved huge genitalia to fend off bloodthirsty females)
For an animal that’s common to see in the southwestern U.S., the spiders still guard many secrets. That’s partly because they live underground, so much of their lifespan is hidden from human research. Scientists don’t even have an easy way to tell a male from a female until the male develops grasping appendages at sexual maturity, or unless the female looks “poochy” with eggs, Shillington says.
And for the males, the mysteries go even deeper. “They have that one brief, intense season, and they change their lifestyles, and they expend a lot more energy than they really ever have,” Poscente says. He’s interested in how they deteriorate over the mating season, literally falling apart at the seams.
Another question is how far the spiders travel over a day, or over as season. Shillington has started using radio tags and video tracking to gauge their behavior and physiology. It’s also not clear how they choose which burrows to knock at. “Sometimes, the males appear to be bumbling around, and walk right by a burrow,” Shillington says. “Is that because it’s a juvenile inside, or another reason? This is a huge animal that everybody knows, and we know very, very little about its natural history.”
Investigating arachnids
One reason that tarantulas have been so under-studied: Simple human fear, the researchers say, along with a bias towards mammals. Shillington pointed out that there are far more people studying vertebrates than invertebrates like tarantulas and other spiders. That’s another thing that makes this weekend so special. Hundreds of people came out to observe, celebrate and revel in the special world of the tarantulas. “This festival is just so great,” she says. “To see so many people who are enthusiastic and who come to see the tarantulas and celebrate the tarantulas is just wonderful.”
(Finding a forever home for trafficked tarantulas)
In a town where city buses are adorned with tarantulas, almost everyone has a story about interacting with the hairy creatures. But Denahy says the city is all-in on responsible tarantula tourism. The ideal time for viewing is about an hour before sunset, and they prefer undisturbed grasslands, which is why the festival has set up tours to see them. The biggest risks for people are cars stopping quickly to avoid or view a crossing spider.
The town also benefits from its close association with the hairy arachnids: Denahy says local hotels are booked solid, and the waitlist for the tarantula tours is as long as the tours themselves.
For Poscente, going out every evening is an awe-inspiring experience, for the simplicity of its humble lifestyle. “You’ve got your little tarantula just out there, looking for a female,” he says. “This animal has been living in this burrow for eight years. Then here’s its chance: and here it comes.”
