London, England (CNN) -- A new picture index is helping scientists monitor long-term trends in rare animal species around the world using strategically placed remote cameras.
Although camera traps are nothing new -- conservationists have been using them for years -- they have mostly been placed on a small-scale, and predominately in protected areas, says the Wildlife Conservation Society (WCS).
The WPI is the first time species have been monitored on a "landscape-wide scale," according to the WCS.
"Landscape-wide scale refers to sampling at the scale of movement of the most wide-ranging animals in the ecosystem," Tim O'Brien of WCS told CNN via email.
Previously, scientists "needed an airplane and complicated sampling methods" to measure animals over a vast area, according to O'Brien.
"Now we can use camera traps set up over hundreds or thousands of square kilometers to sample entire communities, both day and night," he said.
Approximately 100 camera traps are placed for every two square kilometers of land.
This new methodology, O'Brien says, will help conservationists work out where to focus their efforts to help stem biodiversity loss.
"All photographs are examined by the field team and identified to species. Experts are consulted for unusual or blurry photos," O'Brien said.
Scientists have already been able to track changes in wildlife diversity over a 10-year period in Bukit Barisan Selatan National Park in southwest Sumatra in Indonesia.
The 1,300 square-mile park is home to some of the most endangered plant and animal species on the planet, struggling to survive the threats of poaching, illegal logging and agriculture.
The cameras allowed researchers to "re-discover" the Sumatran short-eared rabbit which hadn't been seen in the park for more than 80 years.
It was one of 25 different species of mammals and one bird species recorded.
After running statistical analysis of over 5,000 images the WPI showed a net decline in biodiversity of 36 percent.
Data also showed that wildlife loss was outpacing deforestation rates in Indonesia as well as revealing larger mammals like tigers, rhinos and elephants were at greater risk of extinction than smaller ones, like species of primates and deer.
O'Brien says that other WPI projects are being rolled out in Liberia and Mongolia as well as on sites in South America, Africa and Asia.
WPI was designed to meet the future needs of the Convention of Biological Diversity (CBD) -- a treaty signed by 188 countries to reduce the rate of biodiversity loss.
WCS hopes to make WPI images available to the public on the Internet in the future.