Tropical birds are facing an extinction crisis due to forests being converted into farmland, say experts, who warn that more than 650 million years of evolutionary history may be lost.
Scientists found that tropical birds in the Choco-Andes of Colombia fare better when farming practices are combined with protecting large forest blocks—rather than land-sharing with farms. Says David Edwards from the University of Sheffield:
“Our research shows that converting tropical forests into farmland is causing dramatic species loss among tropical birds. The idea behind the land-sharing method of farming is that the biodiversity of birds can be maintained at the same time as producing a low yield. However, what we’ve found in this study is that farming intensively in one area while leaving large natural reserves untouched will save more evolutionary distinct species of bird.”
Researchers sampled birds in three study areas, each containing contiguous forest and cattle farms. While they found many bird species living within low-intensity farmland communities, those areas showed bigger losses when compared to the forest.
Sharing vs. Sparing
The researchers then used landscape simulations to examine the outcomes of land-sharing versus land-sparing practices. Their analyses show that land-sharing becomes increasingly inferior to land-sparing as the distance from the intact forest grows.
(Credit: Bryant Olsen/Flickr)
Isolation from the forest also leads to the loss of more evolutionary distinct species from communities within land-sharing landscapes—something that could be avoided with effective land-sparing.
“The Choco-Andes are a hotspot of endemism and have been widely impacted by low-intensity farming, making this one of the most threatened faunas on Earth,” Edwards says. “It is vital to consider how best to farm here, but also how to use this region as a model for how best to farm in other tropical locations.
Our results underline the critical importance of halting the conversion of contiguous forests to farmland. If we fail to do so then we will see a vast array of the world’s most evolutionary distinct birds become extinct.”
The study predicts that even when significant wildlife-friendly habitat cover is retained, converting forest to low-intensity farmland will still result in a dramatic loss of evolutionary distinct tropical bird species.
Furthermore, pairing spared forests reserves with intensively managed farmland might best serve tropical conservation interests.