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Mystery surrounds death of 44 howler monkeys in Ecuador wildlife reserve

  • In some areas in Ecuador, howler monkeys are affected by habitat loss due to forest fragmentation and illegal hunting.
  • Ecuador’s Health Ministry has ruled out the theory that the primates’ deaths have something to do with dengue, chikungunya, yellow fever, or zika.
  • While the local authorities look for the culprit, the 44 monkeys that were found dead have been buried in an isolated area within the Pacoche Reserve, to avoid any type of contamination of the surrounding areas.
Photo courtesy of Reserva Pacoche.

The Pacoche Reserve in Ecuador’s Manabí department, is located in one of the few areas with a standing native semi-arid tropical forest on the country’s Pacific coast.

Within its 13 hectares is the habitat of around 400 howler monkeys (Alouatta palliata aequatorialis) which can often be heard, especially around dawn, from as far as a half a mile away –their howls are believed to be the loudest sounds emitted by a primate. They can also easily be seen from the observation decks throughout the reserve as they jump about on the tree canopies. The area is also home to ocelots and pacas, and more than 200 species of birds.

However, in early February, the refuge’s neighbors in La Solita said they had noticed that the local howler monkeys were barely heard anymore.

“We used to hear them all the time,” said Rolando Sánchez, a community leader in La Solita, to the newspaper El Comercio. “All of a sudden, we started to hear them less and then we began to find their bodies.”

The Environment Ministry confirms they have found 44 bodies in the areas surrounding the Reserva Pacoche; there are up to 600 monkeys in the entire area.

Wherever they call home, from southern Mexico to Argentina’s Atlantic coast, howler monkeys do not face any serious threats. In some areas in Ecuador, however, they are affected by habitat loss due to forest fragmentation and illegal hunting.

Now, there is a widespread fear that an illness may be to blame for the loss of the 44 monkeys. Ecuador’s Health Ministry has ruled out the theory that the primates’ deaths have something to do with dengue, chikungunya, yellow fever, or zika. This last virus is being investigated after a case in Nicaragua, where an infectious illness was found to have been connected with a possible zika infection in some howler monkeys.

“So far, and according to the results sent by the National Institute of Public Health Research (Instituto Nacional de Investigación de Salud Pública or INSPI), they have also dismissed the Angiostrongylus cantonensi parasite, which tends to cause meningitis,”, said a statement published by the Health Ministry.

In 2008, a yellow fever outbreak showed up in Misiones province in Argentina’s Atlantic Forest, and eliminated approximately 200 howler monkeys. In an article for Tropical Conservation Science, researcher Ilaria Agostini explained that howler monkeys there found themselves especially vulnerable to the infection, adding that the loss in their population was largely due to the outbreak of the disease. It was such a bad case, according to Agostini, that she feared yellow fever could ultimately be responsible for causing the extinction of the species (Alouatta guariba clamitans) in that region.

On the other hand, most researchers believe that the majority of howler monkey subspecies in Latin America are highly adaptable, since they can tolerate the fragmentation of their habitats and they have such a diverse diet.

For now, while the local authorities look for the culprit, the 44 monkeys that were found dead have been buried in an isolated area within the Pacoche Reserve, to avoid any type of contamination of the surrounding areas.