How to find out what gorillas eat? Easy, rummage through their ‘leavings’

Posted: December 11, 2012 at 2:52 pm

— Are you what you eat Mr Gorilla?

It reminds me a little of a certain TV ‘Dr’ obsessed with poo, but US scientists have been busy analysing the faeces of mountain gorillas. So have the gorilla’s been following a healthy diet, are they what they eat and why oh why would you be rummaging around in gorilla poo for your day job?

Well it turns out that tracking and understanding the diets of wild animals can be tricky. You can observe them eating, or rummage around in their poo for what remains, but that will only give you a snap shot: larger trends can be difficult to spot. Scott Blumenthal at the University of New York and his colleagues used isotope ratios to track how the diet of mountain gorilla’s shifts with the seasons. Using the change in ¹³C values the group showed that while gorilla’s usually eat foliage, when fruit is available gorilla’s prefer it and so change their diet. By increasing the amount of fruit they eat the gorillas also increase the amount of ¹³C they ingest because of the fruit’s position in the canopy of the forest. Plants down towards the ground tend to rely on carbon that has been taken up from the soil and has already been metabolised and so lost much of its ¹³C.

So, it turns out that Ugandan mountain gorillas are seasonal eaters, very trendy. And, perhaps, not that surprising. However, methods of analysing diet that don’t require around the clock observation are sure to be useful, even if it does require a strong stomach for sample collection.

Laura Howes