We're excited to share our Low-Impact Bat Survey Protocol for Sea Caves, designed especially for eco-visitors, researchers, and citizen scientists!

This easy-to-follow guide helps ensure that our visits to these fragile habitats are safe for bats and meaningful for conservation. With small group sizes, limited lighting, and a focus on silent observation, we aim to protect sensitive roosting colonies while still learning from them.

What it includes:
✔️ Max visit time of 30 mins
✔️ Group size of 4 or fewer
✔️ One red/amber light only
✔️ No flash photography
✔️ No touching or disturbing bats
✔️ Slow, silent entry and exit
✔️ Emphasis on education and ethics

​We've also created a beautiful A3 poster version for field use and education, available to download and print!
Let’s explore respectfully and protect these nighttime navigators
#Bats #SeaCaves #Conservation #CitizenScience #WildlifeEthics #FieldProtocol #Ecotourism #MermanConservation

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.

On July 20th, 2024, a team of the project participants embarked on a significant wildlife recovery survey at the picturesque Radakia beach, located in the southeast region of Pelion, Greece. This survey was part of a larger initiative, the Wildlife Recovery Survey: After the September 2023 Floods in Pelion, aiming to assess and document the impact of the catastrophic floods on the local fauna.

Survey Location: Radakia Beach Sea Cave

Radakia beach is renowned for its natural beauty, featuring stunning sea caves that provide a unique habitat for various species, including bats. These caves, carved by the relentless waves of the Aegean Sea, offer a sanctuary for chiropteran species, making them an ideal location for this survey. In Greek Mythology, Radakia is known for the cave of Thetis.

Bats in Focus: Miniopterus schreibersii and Rhinolophus euryale

During the survey, the team recorded two primary species of bats inhabiting the sea cave: Miniopterus schreibersii and Rhinolophus euryale.

Miniopterus schreibersii, commonly known as Schreiber's bat, was found to be the predominant species in the cave. These bats are characterized by their long wings and swift, agile flight, which enable them to navigate the narrow and twisting passages of the cave with ease. They are a key species in the region, contributing to the ecological balance by controlling insect populations.

Alongside Schreiber's bats, Rhinolophus euryale, also known as the Mediterranean horseshoe bat, was observed. This species is distinguishable by its unique horseshoe-shaped noseleaf, which aids in its sophisticated echolocation abilities. Rhinolophus euryale is particularly sensitive to environmental changes, making its presence a critical indicator of the cave's ecological health post-floods.