Toads in the UK are unexpectedly climbing trees

Volunteers have made an unexpected discovery of tree climbing by over 50 common toads in nest boxes and tree cavities at least 1.5 meters high. Until now, common toads were thought to be terrestrial. 

New research led by the University of Cambridge and Froglife, and supported by wildlife charity People’s Trust for Endangered Species (PTES), is the first to study the tree climbing potential of amphibians at a national scale. 

The researchers found toads as high as three meters up a tree, and scientists say these toads could be venturing even higher. The surprising discovery was made during a survey for hazel dormice and bats as part of the National Dormouse Monitoring Programme and the Bat Tree Habitat Key project.

“This is a really exciting finding, and significant for our understanding of the ecology and conservation of common toads – one of the most widespread and abundant European amphibians,” said study first author Dr. Silviu Petrovan.

“We know common toads favour woodlands as foraging and wintering habitat, but it appears their association with trees is much more complex than we had previously thought.”

Common toads are terrestrial amphibians, spending their time on land and in water during breeding. There have only been a handful of documented sightings of common toads in trees in the United Kingdom.

Over 50 common toads were found during surveys of hazel dormouse nest boxes and tree cavities usually used by bats. This suggests that toads spend more time in trees than previously thought. 

Given the small sizes of tree cavities, it is unclear how toads are finding them, and how difficult it is for toads to climb particular trees.

“We couldn’t believe what we found. We’re used to discovering woodland birds and other small mammals in nest boxes but we hadn’t considered finding amphibians in them,” said Nida Al-Fulaij, Conservation Research Manager at PTES.

The findings highlight the ecological importance of tree cavities and protecting natural woodland habitats and ancient trees for all wildlife. In 2016, common toad populations declined by 68 percent in the last 30 years across the UK.

It is not currently known why toads are climbing trees and using nest boxes. Factors could include searching for food, avoiding predators or evading parasites such as toad fly. Future research will support a better understanding of tree climbing behaviour, and how conservation efforts can best support the species. The study demonstrates how much there is still to learn about species believed to be well known. 

Froglife is calling on members of the public to record any sightings they have of amphibians in trees on their Dragon Finder App, or to contact them directly. 

—

By Katherine Bucko, Earth.com Staff Writer