Climate Change Could Alter Spidey Love

Summary

Short Wave: Climate Change Could Alter Spidey Love
Hosted by Emily Kwong and Regina Barber
Release Date: August 6, 2025

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Introduction to the Tarantula Migration

In the episode titled “Climate Change Could Alter Spidey Love,” NPR’s Short Wave takes listeners on a captivating journey to the Comanche National Grasslands in southeastern Colorado. Host Emily Kwong introduces the phenomenon of tarantula migrations, a yearly event where thousands of male Colorado brown tarantulas emerge from their burrows in search of mates.

Emily Kwong sets the scene:
"You're listening to Short Wave from npr. Hey shortwavers. Emily Kwong here. And today we're going on a road trip to the Comanche National Grasslands of southeastern Colorado near Lahon..." [00:17]

The Spectacle of Migrating Tarantulas

As drivers traverse dusty roads during early fall, shadows resembling rocks begin to traverse the asphalt. These shadows are, in fact, tarantulas making their slow journey across highways. Ecologist Dallas Haselhun elaborates on this mesmerizing display:

"They are tarantulas, slowly meandering their way across the asphalt as you're driving at highway speeds, trying your best, hopefully to avoid them." [00:51]

Tarantulas, though intimidating to some, are described by Haselhun as fascinating creatures. Each year, from mid-September to mid-October, sexually mature male tarantulas undertake this perilous quest to find a mate, often facing dangers from speeding cars and predators.

Personal Encounters and Community Impact

Dallas Haselhun shares a personal anecdote from their time as a tarantula researcher:

"And I was like a kid in the candy shop. The second I saw one, I pulled over immediately and I jumped out and I just ran straight to it." [01:37]

This passion for tarantulas extends beyond research. The local community in La Junta celebrates the migration with Tarantula Fest, a beloved annual event where Haselhun serves as a parade judge:

"It was hard not to continually get choked up given the reputations of tarantulas and seeing a whole community come around to celebrate them." [02:21]

The Mystery Behind the Migration

Despite the public fascination, the triggers for this massive tarantula migration remain largely unknown. Haselhun discusses the challenges in understanding what incites thousands of males to leave their burrows simultaneously:

"We lack such basic knowledge of their life history. No one had gotten out and done the gritty dirty fieldwork to actually see. Is there something that's triggering these males to go and mate seek?" [02:32]

Investigating the Triggers

To uncover the mysteries of tarantula behavior, Haselhun conducted extensive fieldwork. They monitored tarantula activity by counting spiders at various times of the day. A significant observation was the correlation between sudden cold snaps and increased tarantula activity:

"There was this cold snap where the temperature dropped significantly. And then all of a sudden, I saw 20 to 30 tarantulas after seeing none for weeks." [06:38]

Haselhun hypothesizes that abrupt temperature changes may compel the tarantulas to emerge:

"They're sitting in there in the sweltering heat... then it gets really cold very quickly. And it's making them go, oh no, I gotta go find a mate." [08:00]

Life Cycle and Challenges of Male Tarantulas

The episode delves into the life cycle of male tarantulas, highlighting their brief adult phase and the perilous quest for mating:

"Male tarantulas actually die after they've sexually matured within about a year. So this is quite literally their last hurrah." [08:39]

After mating, males often face the risk of being eaten by females, a behavior observed through tracking with radio transmitters:

"We quickly found that it was pretty hard to track them down because they would be half eaten inside the female's burrow." [09:48]

Ecological Importance and Knowledge Gaps

Haselhun emphasizes the gaps in our understanding of tarantulas’ ecological roles:

"These tarantulas could be contributing quite a lot to their ecosystems, but we don't even know what's triggering their mating season." [10:12]

Referencing a 1950s book titled The Tarantula, Haselhun points out that over six decades later, many fundamental aspects of tarantula biology remain unexplored.

Changing Perceptions and the Impact of Climate Change

The cultural perception of tarantulas is shifting, influenced by increased scientific interest and public education:

"It’s this push a lot more recently, I think, where people are starting to love... the creepy crawlies, the outcasts... are getting a lot more popular." [11:10]

Addressing the implications of climate change, Haselhun discusses how rising temperatures and altered weather patterns could affect tarantula populations, particularly those at the northern edge of their range:

"As climate change starts warming these areas up, or we start just seeing much different climactic variation, I would expect that this group of tarantulas actually ends up being able to be that stronghold for the species because they're used to such swings in temperature." [12:35]

Conclusion: The Future of Tarantulas

As the episode concludes, Haselhun reflects on the importance of understanding tarantulas not just for scientific knowledge, but also for appreciating their role in the ecosystem and the broader implications of environmental changes.

Emily Kwong wraps up by highlighting the dedication of scientists like Haselhun in unraveling the complexities of these elusive spiders, leaving listeners with a deeper appreciation for tarantulas and the mysteries they present.

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Notable Quotes

• Dallas Haselhun on first encountering wild tarantulas:
  "And I was like a kid in the candy shop. The second I saw one, I pulled over immediately and I jumped out and I just ran straight to it." [01:37]

• Dallas Haselhun on tarantulas’ survival strategies:
  "Male tarantulas actually die after they've sexually matured within about a year. So this is quite literally their last hurrah." [08:39]

• Dallas Haselhun on climate change impact:
  "I would expect that this group of tarantulas actually ends up being able to be that stronghold for the species because they're used to such swings in temperature." [12:35]

Key Takeaways

• Tarantula Migration: An annual event where male tarantulas emerge to mate, a behavior influenced by environmental triggers like temperature changes.

• Research Gaps: Despite their prominence, fundamental aspects of tarantula biology and ecology remain underexplored.

• Cultural Shift: Perceptions of tarantulas are improving, fostering greater public interest and appreciation.

• Climate Change Concerns: Altered climatic conditions could significantly impact tarantula populations and their migratory behaviors.

This episode of Short Wave not only sheds light on the intricate lives of tarantulas but also underscores the broader implications of environmental changes on lesser-known species. Through engaging storytelling and expert insights, listeners gain a comprehensive understanding of the delicate balance within ecosystems and the factors that influence it.

Transcript

[Sponsor Voice]

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[Emily Kwong]

You're listening to Short Wave from npr. Hey shortwavers. Emily Kwong here. And today we're going on a road trip to the Comanche National Grasslands of southeastern Colorado near Lahon, where if you drive down a dusty road in early.

[Dallas Haselhun]

Fall, usually right around sunrise or sunset, you'll start seeing these little shadows that look like rocks crossing the road.

[Emily Kwong]

More and more will appear and ecologist Dallas Haselhun says pretty soon you realize these moving shadows are not rocks.

[Dallas Haselhun]

They are tarantulas, slowly meandering their way across the asphalt as you're driving at highway speeds, trying your best, hopefully to avoid them.

[Emily Kwong]

Tarantulas are a group of large hairy spiders that I think are quite cute up close, but feel free to debate me on that. These tarantulas in Colorado are on a mission. Once a year, from mid September to mid October, Colorado brown tarantulas leave their burrows en masse to find a mate. These wanderers are sexually mature males crossing the road as the cars try to dodge them. When Dallas was a tarantula researcher at Eastern Michigan University's Shillington Arachnid Laboratory, they remember the first time they saw these arachnids in the wild.

[Dallas Haselhun]

And I was like a kid in the candy shop. The second I saw one, I pulled over immediately and I jumped out and I just ran straight to it.

[Emily Kwong]

Time stopped like a slow motion love scene with the tarantulas running to find a mate and Dallas running to find them.

[Dallas Haselhun]

It felt like I was running through the wildflowers in the grasslands, finally seeing something. Because I had only worked with tarantulas in a lab setting, this was my first time seeing wild ones and it was beautiful. It was everything you could imagine.

[Emily Kwong]

The tarantula migration is so beloved in the local community that every year Tarantula fest takes over downtown La Junta. Dallas has been a parade judge and loves it.

[Dallas Haselhun]

It was hard not to continually get choked up given the reputations of tarantulas and seeing a whole community come around to celebrate them.

[Emily Kwong]

But despite the public embrace of tarantulas, very little is known about what triggers this massive migration like event.

[Dallas Haselhun]

We lack such basic knowledge of their life history. No one had gotten out and done the gritty dirty fieldwork to actually see. Is there something that's triggering these males to go and mate seek.

[Emily Kwong]

So Dallas did what scientists do and got dirty. Today on the show, a tarantula migration mystery. What causes thousands of male tarantulas to leave their cozy burrows after years of being homebodies? And how is public opinion about tarantulas changing? I'm Emily Kwong and you're listening to Short Wave, the science podcast from npr.

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[Emily Kwong]

Okay Dallas, so we're talking today about tarantulas and they have a pretty interesting life cycle. Can you just explain how male tarantulas are hanging out in the years prior to this this big day that they go on this quest?

[Dallas Haselhun]

Yeah, absolutely. So males will hatch out of their mom's egg sac and then all baby tarantulas, when they're ready to leave their mom's burrow, they'll leave in a single file line and then one will break off from that line and a handful will follow and then one will break off from that line and they do this weird fractal pattern. We still have no idea what they're doing that for. It might be A dispersal mechanism. And then the tarantulas do the most boring thing in the world, right as they're babies, they dig a hole and then they sit there from anywhere between three to 10 years before they sexually mature. The other fun fact that I love to share is tarantulas are very cleanly. When they eat, they'll have to liquefy their prey. You know, they make a protein shake out of their food and they slurp em up. And then all tarantulas have these little mustaches, kind of like baleen in a whale. And what they'll do is, once they're done eating, they will sit there and meticulously clean that, make sure there's no food crumbs left in their mustache. And then whatever leftovers they have, they'll wrap up in their silk.

[Emily Kwong]

They're really model citizens.

[Dallas Haselhun]

They are. They are.

[Emily Kwong]

All right, so you encountered these tarantulas at the moment that the male tarantulas emerge from their burrows to. To make this mass journey. What did you find in your research?

[Dallas Haselhun]

Yeah, so I went out there a couple of weeks before. I had kind of a hunch the males would start coming out. Uh, and I went out to the grassland every day, four times a day. I went out there right before sunrise, sometime in the morning, at the exact heat of the day. And then I went back out right around dusk. Uh, and I just counted tarantulas.

[Sponsor Voice]

Mm.

[Dallas Haselhun]

But I didn't see any males until early September. There was this cold snap where the temperature dropped significantly. And then all of a sudden, I saw 20 to 30 tarantulas after seeing none for weeks. And then fewer and fewer and fewer over the next couple of days. And then there was another cold snap in late September. And all of a sudden, I saw around 50 to 60 tarantulas in a day. And it also happened to be a really, really hot day. So it was a. It was a whiplash as far as temperatures are concerned.

[Sponsor Voice]

Hmm.

[Dallas Haselhun]

And then over the course of the next couple of weeks, all through October, less and less tarantulas until I was literally out there finding frozen tarantulas on the ground in the mornings.

[Emily Kwong]

What is the leading reason you think that the cold is correlated to this movement?

[Dallas Haselhun]

Yeah. What I think is happening, if I wanted to kind of anthropomorphize them a little bit, is that they're sitting in there in the sweltering heat going, I do not want to come out of this burrow so hot. And then it gets really cold very quickly. And it's making them go, oh no, I gotta go find a mate. I'm sexually mature, this is my last hurrah. Male tarantulas actually die after they've sexually matured within about a year. So this is quite literally their last hurrah. And that cold snap is getting, you know, kicking them in the butts.

[Emily Kwong]

Yeah, just to close out the life cycles of tarantula a little bit. Once these males find their lady and they mate, what happens to them?

[Dallas Haselhun]

So if you're a male tarantula, ideally what you want to happen is you mate and then you're able to skedaddle, get out of there as quick as possible and go find another female. Unfortunately, as the mating season goes on, the males are using more and more of their reserve energy. Typically during a mating season, males aren't really eating or even drinking, and they get weaker and weaker. And eventually, if they are mating pretty regularly and successfully, they're a little too slow on the draw. And the female decides that she wants a nice dinner to go along with the date, and she clamps down on the male. We also tracked males. You put this little tiny radio transmitter on their backs. And we quickly found that it was pretty hard to track them down because they would be half eaten inside the female's burrow. And we'd have to dig up the burrow to get our. Yeah, we'd have to dig up their burrows to get the transmitter back and then, you know, make it a little bit nice for the female again so we're not destroying her home.

[Emily Kwong]

Okay, so after doing your master's thesis, I imagine your appreciation of tarantulas has only deepened and I want to pass that along to our listeners. What role do torrentials play in their ecosystems?

[Dallas Haselhun]

Yeah, so we don't know what we don't know. These tarantulas could be contributing quite a lot to their ecosystems, but we don't even know what's triggering their mating season. As soon as you start bringing up tarantulas, the question then becomes, well, what do we really care about them? What are they actually doing? And the answer is, we really don't know. There's a book written in the 1950s called the Tarantula that points out this lack of information. And it is a wonderful little read. It is full, full of old timey science lingo. And since then we still lack the majority of that information.

[Emily Kwong]

You know, the. I'm struck by the date of this book too, because the movie, the horror movie tarantula came out in 1955. And I'm just wondering, why do you think we know so little about tarantulas? Because some of this stuff does seem very basic.

[Dallas Haselhun]

Yeah. And I think what. What it is, if you'll allow me to get on a slight soapbox here, I think what it is is just cultural ideas of tarantulas and their importance. You know, people love birding in their backyards. We set up bird feeders and things like that. People love hearing about, you know, any. Anything that's big and fuzzy. Tarantulas have this scare factor. And I just like to point out that tarantulas are little and fuzzy, you know, but because there's been this push a lot more recently, I think, where people are starting to love whether it's ironic or not. You know, the creepy crawlies, the outcasts, you know, the roly polys, are getting a lot more popular. Things like bats. Bats have had a huge cultural shift over the past two decades. They went from being the scary creatures of the night that Dracula called to being people affectionately calling them sky puppies and things like that. And I think we're seeing that with a lot of other creepy crawlies like tarantulas.

[Emily Kwong]

There clearly has been a major shift. Yeah. And it's in no doubt because of scientists like yourself providing this information. So now that we know that these tarantulas need a cold snap to trigger their mating behavior, how are you feeling about climate change?

[Dallas Haselhun]

Yeah. And so one of the aspects of my research that I deliberately chose was the population that I looked at near La Junta, Colorado, is on the northernmost edge of this species range. And we often find that these edge populations act as like a stronghold for that species because they're subject to more climatic. Climatic variations. And so as climate change starts warming these areas up, or we start just seeing much different climactic variation, I would expect that this group of tarantulas actually ends up being able to be that stronghold for the species because they're used to such swings in temperature. That's my speculation. Without more so knowing basic life history about them.

[Emily Kwong]

Dallas, thank you so much for coming on the show.

[Dallas Haselhun]

Thank you very much for having me. I appreciate it.

[Emily Kwong]

Short Wavers, myself and the team have been creating episodes for you for almost six years. And now we have a small but important favor to ask. Can you share your favorite episode of Short Wave with a friend or a coworker or a lover or a frenemy? We really just want to grow the show. And the thing that will help us do that is word of mouth. Tell them to follow us on their favorite podcasting platform and you should do the same. This episode was Produced by Burleigh McCoy. It was edited by our showrunner, Rebecca Ramirez, and fact checked by Tyler Jung. Robert Rodriguez was the audio engineer, Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Emily Kwong. Thank you for listening to short wave from NPR.

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