Laurent Tillon, wildlife and biodiversity officer at the National Forestry Office, has never seen this. Standing in the middle of a dry pond, he carries out his surveys, which will enrich the database of the ONF, manager of the 11 million hectares of French public forests.

"For 25 years, we had not experienced any major difficulties, even during the drought of 2003. There, I start to be really worried, "blows the forest ecologist.

The walk resumes through the forest. Head to one of its "reference" ponds in the 150 hectares of forest that it crisscrosses all year round in search of the living.

All that remains of this aquatic refuge of 20 meters in diameter where it usually has "water up to the waist" is a muddy gap, "probably dug by a wild boar".

"This pond has been dry since July 2022. This means that it has been two years since the reproduction cycle of amphibians could not be completed," says Laurent Tillon.

Newts, toads and frogs lay eggs between February and April depending on the species, then the larval cycle lasts three to four months. It is at the earliest in June that the small amphibians, whose gills have atrophied to make way for lungs, come out of the water to reach the undergrowth.

Adult amphibians can survive one or two years without a pond: they look for other waterholes a few hundred meters around. But the drying up of ponds directly threatens their reproduction.

In this area, if it does not rain heavily within 15 days, thousands of eggs will not even reach the larval stage. For Laurent Tillon, "the future of amphibian populations will be decided next year", because even adults would not survive a third year without water.

Deer, heron and agile frog

The drought threatens all the biodiversity of Rambouillet: 22,000 hectares of a green border between Paris and the cereal plain of Beauce.

This massif, which would have sheltered the forest of Carnutes where the Gallic druids met, was considered as "the water tower" of Yvelines because of the density of its network of rivers, ponds and marshes. The Palace of Versailles drew its water from it in the seventeenth century.

At the crossroads of Atlantic and continental influences, very dry and humid environments, sandy soils and peat bogs coexist. Dozens of protected species are sheltered there, from salamanders to bats or woodpeckers, which are fond of old oaks.

In this area of the west of the massif, only two of the 40 ponds monitored by Laurent Tillon remain. Aquatic plants can produce seeds that "will remain dormant for years, buried in the ground. Plants know how to do that, animals don't," he said.

A wild boar in the forest of Rambouillet, in the Yvelines, September 12, 2012 © KENZO TRIBOUILLARD / AFP/Archives

A few hundred meters further, finally, a pond resisted. The ecologist smiles, notes piles of clutches of "agile frog", small clusters of black eggs in a feeding gangue that emerge on the surface of the water.

Dried up last year, this water point, fed by nearby springs, is a refuge for many animals.

Full of hope, Laurent Tillon walks to the large nearby pond, where deer and wild boar met last spring. "A heron came fishing, there was an incredible life."

Suddenly, he comes to a standstill. Another big empty hole. On the wet earth lie hundreds of eggs. "Everything will burst."

"Here, most of the ponds are + groundwater ponds +, fed by groundwater" whose very low level this year explains the disappearance.

Laurent Tillon knows that the face of his forest will change. Even the oaks are suffering. "We see it in the absence of buds at the end of the branches of the top."

In April, a hydrologist will come to study the ponds and see how to maintain them as long as possible.

© 2023 AFP