Andean Bears - The Stalking of Stalk

When one thinks of studying the diets of large, charismatic predators such as bears and big cats, one cannot help but get carried away with the notion that the research must be like a David Attenborough documentary: carefully studying the most exciting moments of the hunt – the stalk; the chase; the kill.

Yet often, the science itself is not like that. As it was for my PhD research on polar bears, the most effective (and safest) study comes after the kill is made, and the scene is pieced back together like a CSI investigation. Or, in the case of some species of bears with more vegetarian tendencies, it’s because the food they seek doesn’t run or hide.

For Andean bears, very little is understood about their diet. We assume that they fill a similar ecological role to the omnivorous North American black bear, but direct dietary studies have been rare. So, over the last year, we have set out to learn more about the culinary predilections of Andean bears in SE Peru, specifically in the high elevation grasslands.

The scenes of carnage we are looking for are often a strewn mess of plant bits, not unlike when Xiao Liwu tears into his bamboo at the Zoo. Bears forage in concentrated patches, whether it’s grizzlies digging up sweet vetch roots or pandas shearing through bamboo. A bear is a bear, the signs of foraging are similar, and Andean bears are no different.

Andean bears predominantly inhabit the cloud forests, but will transit across the grasslands above to get from one patch of forest to another, and sometimes even spend extended periods in the grasslands. While in the grasslands, they often find one of their favorite snacks: bromeliads. Bromeliads are a large family of plants, and include species that most people are very familiar with, such as pineapple (although pineapple itself is not available to the bears).

When Andean bears eat bromeliads, they are very precise about what they want: the stalk of each leaf where it attaches to the base of the plant. The leaves themselves are covered in sharp spines, whereas the base of the leaf is the most tender. Andean bears also prefer bromeliads of a certain age. As it is for pineapples, some species of bromeliad are biennial: they grow in the first year, flower and die the next year. So far, we’ve noticed that Andean bears seem to prefer non-flowering bromeliads early in their growth cycle, potentially because the plant is sweeter prior to investing in growing a flower.

By understanding where and when Andean bears eat bromeliads, we can identify important habitats and seasons of use. While the stalk and chase of bromeliads may not be the fodder of popcorn-crunching predator-prey documentaries, the science is critical to the conservation of Andean bears.

Add new comment