Image credits: Egor Myznik.

Record temperatures have been causing mass poultry deaths in western France since June 22, Reuters reported.

The heat wave, with temperatures exceeding 40° Celsius (104° Fahrenheit), is also behind the drowning of 40 people. Météo-France, the French national weather service, wrote in a statement that June 24 and 25 were the hottest days recorded in France since records began in 1947.

Yann Nedelec, head of ANVOL, a French poultry-sector organization, estimated that at least several hundred thousand poultry in both indoor and outdoor farms died, though he told Reuters it was too soon for a precise death count.

Chicken farmer Clement Blanchard, based in Saint-Andre-Goule-d’Oie, a commune in Pays de la Loire, told Reuters that around 700 of his chickens had died over the span of a few days, compared to an average death rate of one or two per day.

“We’re faced with the same thing with our animals as we ​are ourselves: they suffer enormously from the heat, and so at times like this there are abnormally high death rates,” he told Reuters.

Stéphane Delapré, a poultry breeder in Beauvoir-sur-Mer in Normandy, northwestern France, told AFP that the heat on June 22 had killed roughly half of his 17,600 chickens. 

“Half of the chickens died, suffocated by the heat: those that were in the buildings and also those that were under the trees,” he said. “In [my] 42-year … career, I have never seen anything like it.”

The Chamber of Agriculture in both Brittany and Pays de Loire, which together make up more than half of France’s poultry flock, recognized the mass mortality events over the last week.

French authorities exceptionally allowed pig and poultry farmers across western France to bury dead animals on location until July 1, pending environmental authorization, as animal collection services were overwhelmed.

“Poultry are animals that do not have a sweat gland, meaning they do not perspire. They therefore dissipate heat by breathing through their beaks,” Dominique Balloy, a veterinarian said in a statement released by ANVOL.

“This is why they are highly sensitive to rising temperatures: the hotter it gets, the faster their breathing rate accelerates,” she added.

This article originally appeared on Mongabay and has been republished.