Many mountain lakes and ponds are teeming with Rana temporaria tadpoles, but just a few days ago, we encountered some truly special ones! They are seven tadpoles observed at Lake Leità, within the Gran Paradiso National Park. Their presence indicates that Rana temporaria has successfully reproduced in the lake, and since one of the tadpoles already had four legs and a resorbing tail, it is likely they will complete metamorphosis.

Nothing exceptional so far—except that these might be the first Rana temporaria tadpoles to complete metamorphosis in Lake Leità in many decades!

Since the 1960s, the lake had been colonized by an introduced population of brook trout, a salmonid native to North America, introduced into several park lakes at a time when the devastating effects of fish introduction into these ecosystems were still unknown. Among these effects, the presence of fish tends to prevent Rana temporaria from reproducing in the same environments due to predation on both tadpoles and adults.

However, since 2023, an ecological restoration action has been underway at Lake Leità as part of the LIFE RESQUE ALPYR project, aiming to return the lake to its natural, fish-free condition. This year, the project team is working to remove the last remaining brook trout individuals, but the first positive effects of the eradication are already becoming visible. As early as 2024, unusual movements of frogs had been observed around the lake… these few tadpoles might be the first of many new generations of Rana temporaria in this lake!

Image of Lac Leità, in Parco Nazionale del Gran Paradiso