IN PHOTOS: See images from the camera-trap study
We all love mammals — from furry pandas to wise old elephants — yet even we ecologists who dedicate our lives to their study still know so little about them. That’s why our newly-published camera trap study — with almost 52,000 images of elusive animals from seven sites across the globe — holds so much potential.
Here’s what we do know: even though mammals live nearly everywhere on the planet, most species live in tropical areas — especially tropical forests, where they play key roles dispersing seeds, pollinating trees and keeping tabs on other species so they don’t become pests.
Because many tropical mammals disperse seeds, and the plant species they disperse have dense wood with lots of carbon, these mammals may play an important role in climate change mitigation. Forests with fewer mammals might have less of these high wood-density trees, therefore mammal-depleted forests might not be able to sequester carbon as effectively as forests with healthy mammal populations.
Although conservationists are concerned about tropical forest mammals, there is very little information on what is actually happening to most of these mammal communities as the threats of climate change and deforestation loom over them. But now we have system to gather it: the Tropical Ecology Assessment and Monitoring (TEAM) Network.
TEAM has the largest monitoring system for terrestrial vertebrates on the planet. Instead of having people walking around the forest looking for mammals — which is very inefficient, as these animals are usually rare and hard to spot — TEAM deploys camera traps over large areas of forest all over the tropics (eight monitoring sites in Latin America, five in Africa and Madagascar and four in Southeast Asia).
At each monitoring site, these camera traps work 24/7 for one month, taking pictures of everything that crosses their path — including hunters. These hunter images could potentially be used by park authorities to help control poaching in these areas. On average we obtain 7,500 images from each site every year, which provide important information about the conservation status of many of the species living there.
This all sounds great until you find yourself with 10,000–20,000 pictures from one site and try to make sense of what is happening with the species there. These images have most of the information we need (location, time, date, temperature, etc.) except one crucial element: the name of the species captured on film. Manually assigning species names for tens of thousands of images is a daunting task and could take months. To help us do this, TEAM has created revolutionary software that allows scientists to process large amounts of images quickly by intelligently grouping them based on time and date and lighting features. This cuts down our processing time to a matter of days.
We have just published an important paper that compiles this information and shows the impacts of reserve size and landscape fragmentation on these mammal communities. We found a significant decline in several measures of diversity as our monitoring sites vary from continuous intact forests to highly fragmented landscapes. As the sites shrink and become more and more fragmented, species richness, species diversity (which measures also the relative abundance of species), the diversity of animal body sizes and their diversity in the food web all declined. This pattern persists across sites, despite their differences in rainfall patterns, soil and location.
Perhaps more importantly, TEAM is providing a baseline against which we can measure our success as conservationists. By collecting data on these tropical forests year after year, we will be able to understand how different conservation strategies might work — and better inform decision-makers.
It is not enough to love mammals; if we really want to save them and the forests they live in, we need to roll up our sleeves and see how well we’re doing.