Sunday, August 18, 2013

Primate diet

Primates can be grouped into categories based on what their diet is primarily composed of. Primates that eat mostly leaves are called folivores. Primates that eat mostly fruit are called frugivores, mostly gums=gumivores, mostly insects=insectivores, and mostly meat=carnivores. There is only one solely carnivorous primate, the tarsier. This small Asian primate eats insects, lizards, and even small mammals. Tarsiers are solitary and nocturnal primates that truly eat nothing but meat.
Crocodile at Berenty  (in enclosure)

Sifakas are folivores. Think about the last time you ate a salad with only lettuce and other leaves. If you’ve ever attempted such a bland meal, was it filling? Probably not. Leaves aren’t exactly the most high-energy food item, so a lot of leaves need to be ingested if that’s going to be your diet. Leaves can also be hard to digest because they contain cellulose (it’s part of the plant cell wall and is what humans call “dietary fiber” in our diets). Some leaves may even harbor toxins that protect the leaves. Sifakas and other folivores have adaptations to handle these difficulties. They have a longer digestive tract than we do and they likely have behavioral adaptations as well. Leaves are low energy, and sifakas are low energy primates. Like many folivores, they do not spend a lot of time engaged in social activities. Rather, sifakas spend significant portions of their day just resting, conserving energy, and digesting their food. (They’re not the most interesting primates to do behavioral observations on, but they’ll suffice for my research questions.)
Sifakas feeding on flower buds

Now, just because we may call a sifaka a folivore does not mean that this species only eats leaves. Many species of primates consume a variety of food items dependant on availability. Gorillas are often classified as folivores for example, but they certainly feast on fruit when it is available. Diet composition can vary within a species too, if the species inhabits multiple habitats with differing food availability.

Critical thinking: Howmight a carnivore’s activity pattern differ from a folivore’s activity pattern? What other variables need to be considered?

Critical thinking: How might introduced plant species or other food sources introduced through humans affect a primate? Think about group size, aggression, infant mortality rates: would these increase or decrease?

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