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| camera trap photo showing macaws gathering palm seeds |
Blue Macaws are not only beautiful residents of the Amazon rain forest, but they help it grow by dispersing 18 species of seeds a new study has found. Blue or hyacinth macaws
(Anodorhynchus hyacinthinus) and Lear’s macaw
(Anodorhynchus leari) were observed in 1700 seeding events by camera traps and direct observation. The study conducted by researchers from five institutions and
published jointly, disputes the previously held view that only extinct Pleistocene megafauna dispersed large seeds in the forest. Other macaw species only eat the outer pulp of fruits and discard the seed. But the macaws studied
[photo credit: Doñana Biological Station] are capable of extracting palm seeds from their hard, protective shells and ingesting them. Both species have the strongest beaks in the
Psittacidae family of true parrots.
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| Lear's macaws; credit S. Brooks |
Macaws were observed carrying seeds up to a mile away from were they gathered the fruit, an important factor for the dispersed plant's genetic health. This includes large fruits previously thought to be dispersed only by Pleistocene herbivores; 98% of the fruits gathered were from 6 large palm species. The birds also engaged in what is known as tertiary dispersal, where macaws picked up fruit previously regurgitated by cattle. Even though the parrots eat the seeds, enough of the seed survives their digestive systems to germinate.
Extinction of these parrots would also endanger the tree species that depend on their dispersal activity. Currently the hyacinth is listed by the ICUN as vulnerable and Lear's as endangered. There are an estimated 6,500 hyacinth macaws surviving in scattered pockets of habitat in the Pantanal, Cerrado, and Amazon regions. About 1,200 Lear's macaws live in the Caatinga region in isolated forest fragments. The region has been heavily deforested by clearance for cattle pasture. The licuri palm,
(Syagrus coronata), is considered the Lear's main food source. Macaws can survive in disturbed forests, but without the symbiotic relationship of parrot and plants, a forest's ecological functioning is disrupted beyond recovery.
