Pilfering rodents help trees survive

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RALEIGH, N.C., July 17 (UPI) -- Rodents resorting to stealing food from their neighbor's caches may be responsible for the 10,000-year survival of a tropical tree species, researcher say.

Scientists at North Carolina State University think the thieving rodents known as agoutis helped the black palm tree survive by taking over the seed-spreading role once performed by the mighty mastodon and other extinct elephant-like creatures that are thought to have eaten and then distributed the tree's large seeds.

"The question is how this tree managed to survive for 10,000 years if its seed dispersers are extinct," N.C. State zoologist Roland Kays, said. "There's always been this mystery of how does this tree survive, and now we have a possible answer for it."

The researchers said the agoutis, rainforest rodents that hoard seeds like squirrels, repeatedly stole from their neighbors' underground seed caches, and all that thieving moved some black palm seeds far enough from the mother tree to create favorable conditions for germination.

"We knew that these rodents would bury the seeds but we had no idea that there would be this constant digging up of the seed, moving it and burying it, over and over again," Kays said. "As rodents steal the same seed many, many times, it adds up to a long-distance movement of the seed that one animal by itself could have never done."

One seed was moved and buried 36 times before an agouti dug it up for the last time and ate it, researchers said, and about 14 percent of the seeds survive such treatment until the following year.

"When you think about global climate change and habitats shifting, for a forest to move into new areas, trees need to have their seeds moved into new areas," Kays said. "This opens up a route to study how animals can help trees adjust to climate change through seed dispersal."