More than fifty common toads have been discovered in nests and tree cavities at least 1.5 meters highin a citizen collaboration study led by Cambridge in the United Kingdom.
Until now, common toads – one of the most widespread and abundant European amphibians – were thought to be exclusively terrestrial. The tallest toad in this study was found three meters up a tree, and scientists say there is a chance the toads will venture even higher.
The surprising discovery was made during a survey to look for dormouse and bats as part of the National Dormouse Monitoring Program and the Key Tree Bat Habitat project.
The research was led by the University of Cambridge and Froglife, and supported by the wildlife charity People’s Trust for Endangered Species (PTES). It is published in the magazine PLOS ONE.
Dr Silviu Petrovan, Principal Investigator at the University of Cambridge and Trustee of Froglife, and first author of the study, said: "This is a really exciting and significant finding for our understanding of the ecology and conservation of common toads, one of the most widespread and abundant European amphibians.".
He added: "We know that common toads prefer forests for feeding and wintering habitat, but it seems that its association with trees is much more complex than we had previously thought".
Common toads are considered typical terrestrial amphibians, spending their time both on land and in water during breeding. To date, there have only been a handful of documented sightings of common toads in trees in the UK.
Consequently, UK toads and amphibians in general have never been censused in trees, unlike censuses of bats and dormice, which focus specifically on this habitat. The study highlights the importance of sharing data between conservation organizations representing different species and shows that there is much to learn about wildlife in the UK, even about species that are thought to be well known.
Nida Al-Fulaij, Conservation Research Manager at PTES said in a statement: "We couldn’t believe what we found. We are used to finding forest birds and other small mammals in holes, but we had not considered finding amphibians in them".
Were found over 50 common toads during dormouse nest surveys (located 1.5 m above the ground) and tree cavities often used by bats.
Many of the cavities were small or not visible from the ground, so it is unclear how the toads find them and what it takes for them to climb trees in particular.
The toads were not found in boxes or tree holes with other species, however, they were found using old nests made by dormouse and even birds.
While 50 records is not a large number, it is comparable to the records of other animals known to use trees regularly, such as blue tits. This suggests that toads spend more time in trees than previously thought. If this is true, it means that common toads can be found on one in a hundred trees in the UK in particularly favorable areas, such as near large ponds or lakes.
The discovery suggests that tree cavities could represent an even more important ecological feature than conservationists previously thought. It highlights the importance of protect our remaining natural forest habitats, especially ancient trees with ancient characteristics (such as holes, cracks and other natural cavities) for all wildlife.
Froglife research in 2016 showed that common toads have declined by 68% on average over the last 30 years across the UK.
It is currently not known why toads climb trees and use nests. Factors could include foraging for food, avoiding predators, or evading parasites such as toad flies.
"Future targeted research will allow scientists to better understand the reasons for this tree-climbing behavior in toads, and how forest management should take it into account."Petrovan said.
