COMALCALCO, Mexico — Threatened howler monkeys have been dropping dead from trees in Mexico’s southeastern tropical forests in recent weeks amid a nationwide drought and heat waves that have sent temperatures soaring across much of the country.

In the state of Tabasco, where temperatures are forecast this week to surpass 45 degrees Celsius (113 degrees Fahrenheit), local media have reported up to 85 deaths, while local authorities have confirmed the trend without providing a death toll.

In a statement over the weekend, Tabasco’s Civil Protection agency attributed the deaths to dehydration.

A source from the agency told Reuters on Monday that monkeys have been confirmed dead in three municipalities of the state.

In a forest outside Camalcalco, Tabasco, volunteers collected the corpses of mantled howler monkeys (alouatta palliata) that died from high temperatures, before placing buckets of water and fruit to try to stave off more deaths.

The mantled howler monkey is classified as vulnerable on the International Union for Conservation of Nature (IUCN) Red List.

“It is because the heat is so strong. I’ve been visiting the states for a long time and I have never felt it as much as now,” Mexican President Andres Manuel Lopez Obrador, who hails from Tabasco, said on Monday when asked about the monkey deaths.

“So, yes, we have to care for the animals and yes we are going to do it,” he said in his regular news conference.

Later on Monday, Mexico’s environment ministry said in a statement that it was coordinating efforts to address the monkeys’ deaths, which it attributed to several possible reasons, including “heat stroke, dehydration, malnutrition or the spraying of crops with toxic agro-chemicals.”

Mexico is also home to the Yucatan howler monkey, which because of deforestation is classified as endangered on the IUCN Red List.

Mexico’s health ministry reported a preliminary count of 26 people who have died from heat-related causes between the start of Mexico’s heat season on March 17 and May 11.