Hidden wings in the cave of Thetis – why a tiny bat discovery matters?

In July 2024, during a field visit to the remote and stunning Cave of Thetis at Radakia Beach in South Pelion, We spotted something new—something small, winged, and easy to miss. It was Rhinolophus euryale, the Mediterranean Horseshoe Bat. This was the first time this elusive species had ever been recorded in the cave.

But this wasn’t just a “tick the box” kind of observation. It was part of something much bigger.

Citation of the published article: Taklis Christos. Updated bat (chiroptera) records from the cave of thetis, south pelion, greece. Acta Entomol Zool 2025;6(1):189-191. DOI: 10.33545/27080013.2025.v6.i1c.205​

Why this research matters?

This latest discovery adds a new species to the known bat community of the Cave of Thetis, which had previously only included Miniopterus schreibersii (Schreibers’ Long-fingered Bat), first documented there in 2019. In 2021, Christos Taklis observed juveniles of that species inside the cave, confirming that the site is more than just a temporary roost—it's a breeding ground.

This means the Cave of Thetis isn’t just a cool place to explore—it’s an important home to species that are considered Vulnerable on the IUCN Red List.

And what makes this even more significant is that the 2024 survey was conducted as part of the Wildlife Recovery Survey: After the September 2023 Floods in Pelion. We were looking to see what had survived, what habitats were damaged, and how resilient the wildlife of the region really is.

The presence of both species—especially a new one—after such a major environmental disruption is a hopeful sign.

What do the results tell us?

• Long-Term Roosting: Miniopterus schreibersii has used the cave consistently for over five years, even raising young there. That’s long-term commitment in bat years.
  
  
• New Presence of Rhinolophus euryale: The discovery suggests that the cave may support more biodiversity than previously thought—or that species are shifting their roosts in response to environmental pressures.
  
  
• Resilience Post-Disaster: Even after catastrophic flooding in 2023, bats are returning to their roosts (or they never left). That tells us something about the ecological value and stability of this site.
  
  

Why we should care?

Bats might not get the spotlight that dolphins or bears do, but they are absolutely crucial to ecosystems. They eat insects (many of which are pests), pollinate plants, and disperse seeds. A single roosting site like the cave of Thetis can be the lifeline for entire local populations.

When we lose caves like this—or when they're disturbed by noise, tourism, or development—we risk losing more than just a handful of bats. We chip away at a fragile, interconnected ecosystem.

That’s why this research matters. That’s why we need to keep exploring, documenting, and protecting places like the Cave of Thetis.

Curious to see the cave or learn more about the species?
📸 Check out photos and observations on iNaturalist.
🦇 Follow updates from my conservation work at Merman Conservation Expeditions.