Each patch consisted of five artificial plants with three "flowers" each microcentrifuge tubes wrapped in red electrical tape which were filled with a fixed amount of sugar water for nectar. To help in estimating pollen transfer within and between the patches, the researchers also dusted the flowers of one plant per patch with artificial pollen, using a different color for each patch.
Din levels at noisy patches were similar to a highway heard from 500 meters away, Francis explained. When the researchers compared the number of pollinator visits at noisy and quiet sites, they found that one bird species in particular the black-chinned hummingbird (Archilochus alexandri) made five times more visits to noisy sites than quiet ones.
"Black-chinned hummingbirds may prefer noisy sites because another bird species that preys on their nestlings, the western scrub jay, tends to avoid those areas," Francis said.
Pollen transfer was also more common in the noisy sites. If more hummingbird visits and greater pollen transfer translate to higher seed production for the plants, the results suggest that "hummingbird-pollinated plants such as scarlet gilia may indirectly benefit from noise," Francis explained.
Another set of experiments revealed that noise may indirectly benefit some plants, but is bad news for others.
In a second series of experiments at the same study site, the researchers set out to find out what noise might mean for tree seeds and seedlings, using one of the dominant trees in the area the pion pine (Pinus edulis).
Pion pine seeds that aren't plucked from their cones fall to the ground and are eaten by birds and other animals. To find out if noise affected the number of pion pine seeds that animals ate, the researchers scattered pion pine seeds
|Contact: Robin Ann Smith|
National Evolutionary Synthesis Center (NESCent)