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Younger species cope better with changing land

The Blue-crowned Motmot (Momotus momota) is an evolutionarily distinct bird that can be found in the rainforest and in diversified agricultural landscapes.
[Credit: Daniel Karp]

Researchers studying birds in Costa Rica have made an interesting discovery: Older species, which have been evolving for a long time, go extinct much quicker than newer species, which haven't had as long to evolve, when forests are converted to farmland. This discovery shows how changing a landscape can actually change the tree of life by favoring certain species over others--and it may help with conservation efforts in the future.

Luke Frishkoff and colleagues spent 12 years counting birds in Costa Rica and recording their locations to reach this conclusion. The researchers studied forest reserves, where there is no farming; diversified agricultures, where many different crops are grown; and intensive monocultures, where only one kind of crop is grown. They saw 487 different species of birds on 118,127 different occasions, and they created a model to estimate the birds' comings and goings.

Their results show that older bird species with long evolutionary histories do the best in forest reserves—-- that they disappear quickly on farmland where multiple crops are going, but even quicker on farmland where only one crop is growing. In general, birds living in diversified agricultures represent about 600 million more years of evolution than birds in intensive monocultures, according to the researchers.

These findings make it clear that forests are essential for bird diversity--but that farmland with multiple crops still allows a wider range of species to thrive than farmland with only one crop.