‘Shocking’ Mortality of Infant Macaques Points to Dangers of Oil Palm Plantations

Picture: Anna Holzner.

In an article by Mongabay, Spoorthy Raman reports the finding from a new study which identifies the link between exposure to oil plantation in Segari, Peninsular Malaysia and the risk of death among infant southern pig-tailed macaques.

Between January 2014 and February 2023, the researchers noticed 52 of the 92 infants disappeared from the two groups of macaques they studied. Statistical analysis revealed that when infant macaques spent more than three hours each day in the plantations, they were three times more likely to die. The whopping 57% death rate, much higher than is common among wild primates, can jeopardize the already-endangered macaque’s future, they say.

The high death rate among infants correlated with the time they spent in oil palm plantations, where they not only face threats from predators and humans but are also exposed to toxic pesticides like rat poison and the herbicides glyphosate and paraquat. Previous studies in humans and other mammals have shown these chemicals reduce fertility in females, lead to the accumulation of toxins in the food chain, wreck children’s health, and are possibly fatal.

Researchers also noticed that baby macaques born to first-time mothers and those giving birth after a long period were more likely to die than those born to mothers with a short interval between births. A one-year increase in the birth interval led to a twofold increase in the likelihood of the infant dying. This is counterintuitive because longer birth intervals generally lead to healthier mothers giving birth to healthier babies.