Earth is facing a sixth mass extinction. Jaguars, tapirs and giant anteaters may soon join woolly mammoths as examples of the beasts that once roamed our planet. Humans are the primary cause of this biodiversity crises.

There is an urgent need for conservation strategies to turn the tide against the global decline of biodiversity. Yet, conservation interventions can only be effective if we know the extent of the problem. A recent study by wildlife ecologist Ninon Meyer from the Smithsonian Tropical Research Institute in Panama, estimated how connected medium- and large-sized mammals are in Panama. Meyer and her team wanted to know whether the ‘natural bridge’ that historically allowed these species to move between habitats was still being used by them. Meyer explains that “species may no longer be able to move and disperse due to habitat fragmentation” because “deforestation, human encroachment and barriers such as roads … are … separating forest patches from each other, sometimes with a distance that is too great for animals to traverse”. Without the ability to move around these small populations stare extinction in the face.

NATURAL ‘BRIDGES’

Biological corridors are areas of wilderness found alongside or between highways, agricultural land and urban areas. These corridors allow individuals to move or disperse between different habitats. This, in turn, helps species to maintain, or increase, their genetic diversity, and therefore their ability to adapt to changing environmental conditions.

In Central America, the Mesoamerican Biological Corridor (MBC), makes up one of the largest biological passageways in the world. It is this natural causeway that connects protected regions of south-eastern Mexico to that of Panama, a region that harbours exceptionally high biological diversity and some of the world’s rarest and most unique species. However, Meyer points out that “the combination of hunting, habitat loss and fragmentation has resulted in the decline of many of the terrestrial mammal species across Mesoamerica”.

For this reason, she and her team wanted to monitor medium to large mammals to better understand whether the MBC still serves its purpose. They studied nine mammals, including iconic species like the white-lipped peccary (Tayassu pecari), jaguar (Panthera onca), giant anteater (Myrmecophaga tridactyla), white-tailed deer (Odocoileus virginianus) and tapir (Tapirus bairdii). These large animals are good ‘bio- indicators’ – species that are sensitive to, and can indicate the occurrence of, rapid environmental change. This is because these forest specialists typically require large home ranges.

CALL IN THE PAPARAZZI!

Using camera traps to monitor wildlife has changed the way we understand animal behaviour and ecological phenomena like biological corridors. This is exactly what Meyer and her co-workers did.

“Camera trapping has critically advanced the way we monitor wildlife.”

However, camera trapping alone cannot provide the amount of data required to determine large-scale animal movements and connectivity. Many species are nocturnal, shy, or simply good at hiding. This is where the concept of detection probability comes in, whereby the occupancy (an alternative state to abundance) of animals can be modelled without photographing all individuals. Meyer explains: “We used the camera trap data (presence-absence) to develop an occupancy-weighted connectivity metric”. In short, this metric describes the best-case scenario of occupancy and dispersal of species obtained by camera traps and allows for robust estimates of connectivity.

SO, WHAT DOES THIS MEAN FOR THE MAMMALS IN PANAMA? 

There is some good news. Meyer says their findings show “…that the largest remote forests (Darien and La Amistad) are those that still harbor …[the most]… mammals. Not only [how many] in terms of species numbers but also their abundances, including endangered ones such as tapirs, white-lipped peccary and jaguar.” Darien and La Amistad are approximately 500 kilometres apart and despite the agricultural land and human settlements that separate them, small pockets of forest still allow animals to move between them. However, these corridors are under direct threat from imposing fires, logging, mining, poaching, and the proposed completion of the Pan-American Highway, and must therefore be protected at all cost.

“We need to make sure these regions remain conserved because they act as a source area for charismatic yet imperilled species”

WORKING TOWARDS A BETTER TOMORROW

The research by Meyer and her colleagues shows that humans and nature can co-exist. Conserving remnant patches of natural vegetation connecting larger intact wilderness areas is crucial for conserving the remainder of Earth’s biodiversity. Protecting and managing these important corridors require ongoing critical partnerships with private landowners, corporations and local communities.