Snakes aren’t all cold-blooded loners, ASU researcher says

Melissa Amarello has always loved snakes. As a graduate student at Arizona State University in 2009, she dedicated three years of study to the often-maligned creatures.

Rattlesnakes, in particular, are often thought of as cold, solitary creatures, but Amarello’s thesis offered a new take: Snakes, like people, prefer to hang out together, rather than be alone. In other words, snakes have friends, too.

“In my thesis, the word ‘friend’ does not appear,” Amarello said in a recent phone interview. “I got lots of eye rolling from my committee for using it at all.

But that’s how you describe your human relationships that you spend a lot of time with.”

In animal behavior literature, relationships outside mating are called “special bonds.”

“So, what we would call friends,” Amarello said.

Amarello looked to methods that scientists use to study other animals that are more traditionally thought of as social, like elephants or baboons. Through camera trap footage and a rigorous system of identifying the snakes by their patterns, which act something like a fingerprint, Amarello analyzed the interactions between pairs of non-mating individuals.

“If they were within a body length of each other, we knew based on other work that they would know the other snake is there by smelling and seeing, and that they have the ability to recognize individuals,” Amarello said. “And at that distance, if they were going to make a choice about hanging out together or avoiding within that distance, they would be able to do so.”

Through modeling and observation, she found that some snakes actively chose to associate with certain individuals, while avoiding others. She observed some pairs of snakes that spent more time with each other than average and even “hung out” together well past midMay, beyond when they would need additional winter warmth or outside of mating season.

“They’re definitely making choices about who they’re hanging out with,” Amarello said. “When they come out on the surface after wintering in the den and have the freedom to move around, they’re still like, well, I’m going to bask with him, but I’m not going to bask with her.”

Snakes like to interact

To test the theories, Amarello set camera traps outside a den near Prescott where Arizona black rattlesnakes nest for the winter. It had largely been thought that snakes only den together during the winter because it’s so cold they can’t get enough heat from anything other than each other’s bodies. Communal denning of the cold-blooded reptiles is most common in the north. When they come out in the spring, they usually hang out long enough to mate, then go their separate ways.

“That’s an easy evolutionary explanation for why they would hang out like that,” Amarello said. “But with Arizona black rattlesnakes, number one, this is Arizona, so even where we were working at a mile in elevation approximately just outside of Prescott, it’s not that cold.”

Furthermore, Arizona black rattlesnakes mate during the monsoon, not in early spring.

“So no combat, no courtship. Just kind of hanging out,” Amarello said. “We were like, what’s going on there?”

An increasing amount of studies support Amarello’s conclusions. Most recently, a study that assessed the personalities and sociability of eastern garter snakes found that they seek out social contacts and are picky about whom they “hang out” with.

Scientists still have no idea what’s motivating the friendships, though they do know it’s not related to reproduction or mating: The study said snakes did not prefer the opposite sex as friends.

“All animals — even snakes — need to interact with others,” Morgan Skinner, a doctoral candidate in behavioral ecology at Wilfrid Laurier University in Canada, told National Geographic.

Snakes need saving, too

For Amarello, the new studies and widening acceptance of snakes as social creatures are vital to her work to help conserve the reptiles. In 2014, she launched a nonprofit, Advocates for Snake Preservation, dedicated to changing the way people view and treat snakes.

The idea spawned from an “aha” moment Amarello had while listening to a radio report about the threats whales face.

“I just had this idea in general, when we talk about saving whales and a lot of other charismatic animals, it gets a bare mention of how important they are in the ecosystem, whether they eat animals that we find to be pests or that spread disease,” Amarello said.

“It’s always like ‘whales have families, and they’re social and they’re just cool’ — all these nice things that make an emotional appeal,” she said. “And I realized with snakes, a lot of their troubles come from or are amplified by the negative attitudes that a lot of people have.”

If people say they’re scared of snakes or hate them, “I just don’t think that feeding them numbers about how many mice a snake might eat in a year is really going to do it.”

Her work started to encompass the idea of “critical anthropomorphism,” a phrase coined by Gordon Burghardt, an evolutionary biologist at the University of Tennessee.

“The idea is basically, we’re humans, we can’t help but talk about things from a human perspective and in a human way,” Amarello said. “In the same way that being totally unbiased is not really possible, you have to recognize your biases as a human scientist and be critical of that.”

For example, she said, people will talk about animals feeling fear or being angry, “but talking about them having friends or loving their babies that they’re taking care of? No way.”

‘Every native animal has a place’

Amarello has gone on to capture how snake mothers care for their young, with moms even “babysitting” for one another, or watching the babies that are not their own while other mothers hunt or go about other “snake business.”

Not only do they seem to have rich family lives, snakes are vital to the ecosystems in which they exist. Because they’re not territorial and are able to fast for long periods of times, vipers (rattlesnakes, copperheads, cottonmouths) are more effective at controlling rodent populations than bird or mammal predators. Additionally, they eat vectors and carriers of many diseases, including the plague and Lyme disease.

“Every native animal has a place. Animals, plants, don’t tend to stick around if they don’t have a role to play,” Amarello said. “Rattlesnakes are the subject of kind of the most hate and persecution because their bites are painful and expensive and, very rarely, deadly to people. And people in the United States don’t like things that compete or threaten us in any way. Our historical way of dealing with things is that we get rid of them.”

For her, focusing her scientific research on the sociability of snakes is a way to get people to confront their internal biases towards the creatures. In turn, she hopes to help build a world that is safer for both snakes and humans.

Early on in her work, Amarello talked to a group of Boy Scouts about the social lives of snakes. She told them how mother rattlesnakes keep their babies warm at night by letting them all pile on top of her and how they selflessly protect them from predators.

“The troop leader came back and he said, ‘You know, I have definitely taken the shovel to every rattlesnake that has ever shown up in my yard. I can’t say that I will never do that again, but I’m going to think twice about it,’” Amarello said.

“He had never really thought about them having families. So sometimes just talking about them in a positive way, in a different way than people have heard before, makes people reconsider treating them like these evil, coldblooded killers.”

Living with snakes

Worried about a rattlesnake in your yard? Here are some ways to make sure you and the snakes stay safe:

Don’t feed or water pets or wildlife on the ground outside.

Eliminate debris piles and other shelters for snakes or their prey.

Reduce water and lush or overgrown vegetation that attract snakes and their prey.

Horse hair ropes, mothballs, and other commercial repellents don’t work.

How you can create a safe, wildlifefriendly yard i Use lights when walking at night. i Create clear, wide paths for safe walking.

Look before placing your hands and feet.

If you can’t see, use a long stick to disturb vegetation and hidden animals.

Don’t use bird netting or glue traps (it is difficult to safely extract trapped animals).

Keep pets indoors or under control. You can fence snakes out

The most effective fences to keep snakes out should:

Be 4 feet high with solid, buried footing.

Be made of smooth, solid material or one-quarter inch or finer hardware cloth or wire mesh.

Have their drainage areas covered with one-quarter inch or finer hardware cloth or wire mesh.

Trim trees and shrubs that give climbers a way in (all snakes can climb).

If you find a venomous snake in your house or on the patio:

Wait for it to move.

Use a long-handled broom to gently encourage it to move.

Call a wildlife professional. Let them know you don’t want him moved far because this is his home too.