MEXICO CITY (AP) — Heat-related howler monkeys deaths have now been reported in two more states in southern Mexico, after two other states reported die-offs earlier this month, environmental authorities said.

Mexico's Environment Department said late Tuesday that monkey deaths have now been reported in Chiapas and three states on the Gulf of Mexico: Tabasco, Campeche and Veracruz.

The department also said tests indicated the primates died of heat stroke, but that the country’s current drought and the "lack of water in the streams and springs in the areas where the monkeys live” appeared to also have played a role.

The department did not give the latest estimate on the number of deaths, but earlier said at least 157 monkeys had perished since the die-off began in early May.

The deaths were first reported by a wildlife biologist and a veterinarian in Tabasco two weeks ago. Howler monkeys — mid-sized primates that live in trees — were literally falling dead to the ground from tree limbs.

The environment department had originally speculated that an unidentified disease or chemical could have caused the deaths, but said tests have since ruled that out.

A relatively small number of monkeys have been rescued alive, treated and released back into the wild. Experts have warned residents of the four southern states not to try to adopt or house the monkeys, since they are wild animals and are vulnerable to diseases carried by cats and dogs.

An animal park in northern Mexico also reported last week that at least a hundred parrots, bats and other animals have died, apparently of dehydration.

A heat dome — an area of strong high pressure centered over the southern Gulf of Mexico and northern Central America — has blocked clouds from forming and caused extensive sunshine and hot temperatures all across Mexico.

For much of this month, a large part of the country has seen high temperatures of 45 degrees Celsius (113 degrees Fahrenheit).

The department said authorities have started putting out water supplies for the howler monkeys and set up a mobile veterinary facility that is treating seven baby monkeys and five adults. A few others have already been released back into the wild.

But with heat, fires, and deforestation hitting the trees where the howler monkeys live, it was unclear whether even releasing them could ensure their survival.

Normally quite intimidating, howler monkeys are muscular and some can be as tall as 90 centimeters (3 feet), with tails just as long. Some males weigh more than 13.5 kilograms (30 pounds) and can live up to 20 years. They are equipped with big jaws and a fearsome set of teeth and fangs. But mostly they’re known for their lion-like roars, which bely their size.

With below-average rainfall throughout almost all the country so far this year, lakes and dams are drying up, and water supplies are running out. Authorities have had to truck in water for everything from hospitals to fire-fighting teams. Low levels at hydroelectric dams have contributed to power blackouts in some parts of the country.

___

Follow AP’s coverage of Latin America and the Caribbean at https://apnews.com/hub/latin-america

Copyright 2024 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.