| 'natural experiment' demonstrates top-down control of spiders by birds on a landscape level. | the combination of small-scale manipulative experiments and large-scale natural experiments provides a powerful approach for demonstrating the importance of top-down trophic control on the ecosystem scale. the most compelling natural experiments have come from studies examining the landscape-scale loss of apex predators like sea otters, wolves, fish and land crabs. birds are dominant apex predators in terrestrial systems around the world, yet all studies on their role as predators have come from ... | 2012 | 22970126 |