A rare species of monkey could become extinct because they are too stressed, scientists revealed today.
Endangered Mexican howler monkeys are finding it increasingly difficult to find food as a result of deforestation.
Cambridge University boffins have found that howler monkeys are taking longer to find fruit to eat, leading to an increase in stress levels which reduces their chances of reproduction.
Dr Jacob Dunn, a biological anthropologist who carried out the research, said: “As forests are fragmented the howlers become cut off and isolated on forest islands that increasingly lack the fruit which provide an important component of their natural diet.
“This has led to the monkeys expending ever more time and effort foraging for food, often increasing leaf consumption when their search is, quite literally, fruitless.
“The traditional view was that the leaves exploited by howler monkeys were an abundant food source – but this is not the case.
“The monkeys rely much more heavily on fruit than previously believed, and when turning to foliage for food they have to be highly selective in the leaves they consume, visiting lots of different trees.
“This leads to the increased ‘travel time’ and consequent high levels of stress we are seeing in these primates as their habitats disintegrate.”
Fruit occurs in natural cycles and the monkeys will naturally revert to “fallback” foods like leaves when fruit is scarce.
The monkeys are consuming more leaves and less fruit as a result of the deforestation of the tropical rainforests where they live.
Many of these leaves are difficult to digest and can be filled with toxins, forcing the monkeys to spend more time seeking out the right foliage to eat.
It is the time spent foraging – and the stress that it causes the animals – that could potentially lead to the Mexican Howler monkey becoming extinct.
The research, published today in the International Journal of Primatology, took place in the tropical rainforests of the Mexican state of Veracruz – which are being deforested and fragmented by human activity.
Researchers believe the study could serve as a general model for behavioural change in primates living in habitats disturbed by human activities – such as deforestation.
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