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Seed-eating birds play a critical role in maintaining forests in the Serengeti by keeping seed-killing beetles in check, report researchers writing in the journal Science. The finding is another example of ecological interdependency between species.
Gregory J. Sharam, A. R. E. Sinclair, and Roy Turkington used a 40-year data set from Tanzania to study the relationships between the birds, beetles, and trees in riverine forests in the Serengeti ecosystem. They found that beetles only feed on fallen seeds that birds had not yet eaten, not on seeds that had already been eaten by, and passed through, birds. Thus the birds provide a vital ecosystem service: they protect the forest through their feeding.
 Close canopy forest. Courtesy of Science |
When birds are removed from the ecosystem, as is the case when fires open up the forest canopy, the forest loses its regenerative capacity and does not recover to its original density.
“The frugivorous birds are necessary for the maintenance of forests, and their absence could result in the continued disappearance of forests,” write the auhors. “In general, this study illustrates, first, how a stable community is maintained and, second, how it can unravel by a single disturbance. This causes a positive feedback loop of processes that, over decades, changes the ecosystem into a different state, despite the removal of the original disturbance. This unravelling has been widely observed … and also measured at one site for 40 years (1966 to 2006).”
Gregory J. Sharam, A. R. E. Sinclair, Roy Turkington. Serengeti Birds Maintain Forests by Inhibiting Seed Predators. Science 2 July 2009