Black Mantled Howler Monkeys turning blonde due to pesticides

The jet black Howler monkeys, that make up 69% of the primates in Costa Rica have been turning blonde at an alarming rate within the last 5 years.  Science Alert states, “This marks the first time scientists have noticed such a rapid change in the pigmentation of primate fur, or any other mammal for that matter.  We are not aware of similar changes in pigmentation of other primates or other groups of animals.  The patches of yellow fur appear to be growing not only in number but also in size. On some monkeys the yellowish pigmentation even outshines the black.”  Regional Institute of Studies of Toxic Substances (IRET) of the National University (UNA) in Costa Rica, have gathered data showing that Costa Rica uses an average of 18.2 kilograms(40 pounds) of pesticide per hectare of cropland.  


The study is ongoing, but upon closer inspection of the monkeys coat, the tentative conclusion is that the mutations are due to the high pesticide use.  What is being used is mostly sulfur based, and sulfur is exactly what was found to be the cause of the color change.  Pesticides here are used to repel bugs from cash crop foods such as pineapples, bananas, African palm trees and coffee.  That being said, the pesticides are not able to be contained solely to the farm, but also travel to surrounding trees and plants, the common food for many animals of the jungle.


Our vocal primate friends aren’t the only ones being affected by the pesticides.  According to Costa Rican authorities 22 people, the majority being children, have recently become ill due to pesticide poisoning in Alajuela.  A pineapple farm close to La Ceiba School in San Juan de Florencia will be the target of the investigation by the Costa Rican Ministry of Agriculture and Livestock (MAG).  All are in stable condition, but the victims reported symptoms of severe headache, dizziness, nausea, among others.  

*photos by Science Alert Steve Harbula

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