A survey to log animals in shrinking forest

A new comprehensive survey of the mammals of South America’s second-largest rainforest will aid efforts to preserve the many threatened species that live there.

The enormous dataset published in the journal Ecology describes the physical form and life history of 39,850 animals from 279 species found in the Atlantic Forest, which stretches across 1.3 million square kilometres of Brazil, Paraguay and Argentina. It represents the most detailed examination yet of the animals of this region.

While land clearing over the past 500 years has diminished the Atlantic Forest to just 8-to–12% of its former size, the area still boasts rich biodiversity. Remaining pockets of habitat support 60% of Brazil’s threatened animal species, including jaguars, woolly spider-monkeys, lowland tapirs and giant anteaters.

“Most ecologists know a lot about the Amazon Forest but virtually nothing from the Atlantic Forest,” says Fernando Gonçalves of São Paulo State University in Brazil, who led the study.

The research focuses on physical traits that allow mammals to perform unique ecosystem functions, such as seed dispersal, pollination, predation or grazing.

Ecologists value studies of such functional traits of different species for their ability to explain large-scale ecological patterns.

“They look at the underlying patterns and potential mechanisms for why species are where they are, and possible causes of increases or decline,” according to ecologist Mathew Crowther from the University of Sydney, who was not involved in the study. In the fight against extinction, it helps to know “what combination of traits are more important than others for threats to species’ conservation.”

In Australia, similar studies have looked at combinations of traits associated with extinction risk. “Such analyses have revealed the importance of body size, and the role dingoes have in conserving the Australian fauna,” says Crowther.

However, functional traits also vary between individuals within a species, and limitations on available data can make this variation hard to study.

The Atlantic Forest project is one of the first of its kind to try to understand trait variation at the level of individuals.

Putting together the data wasn’t easy. Gonçalves sent out a call to his fellow ecologists. He asked them to give him “as much information on mammal morphological traits at individual level as they could.”

Some 96 answered the call, providing data on the age, sex, reproductive stage, body mass and geographic location of all mammals sampled, as well as some other specifics, such as the forearm length of bats, and body and tail length of rodents and marsupials.

This study and others like it will enhance our understanding of questions that relate biology and geography with ecology, according to Noé U. De La Sancha, an ecologist from Chicago State University and co-author of the study, “especially in the face of the sixth mass extinction”.

Gonçalves believes group studies such as this one can be extended further into citizen science projects to gather data over long periods that may aid understanding of how species may adapt to climate change.

“Every day millions of mammals are road killed and we lose not only individuals but valuable ecological information,” he says. “If citizen scientists also collect and make this information available, we can have long term data on mammal evolution.”