Sept. 6 (UPI) -- According to a new study, bird feeders trigger the formation of interspecies hierarchies. These localized hierarchies, the new research confirmed, are dominated by the biggest birds.
The presence of a consistent, concentrated source of food, like a bird feeder, naturally attracts a range of species -- species that may not ordinarily compete for the same resources.
To better understand how this act of charity effects bird communities, scientists at the University of Exeter and the British Trust for Ornithology monitored the feeding patterns of birds near bird feeders placed near hedges and woodlands.
"Our findings show that larger, heavier species get better access to food -- so if the aim of bird feeders is to benefit all species, we need to investigate ways to achieve this, such as different mixes of foods and feeder designs," Exeter ecologist Jon Blount said in a news release.
Blount and his colleagues measured dominance by observing interspecies interactions and noting which of the two species retreated, ceding access to the food. Dozens of interactions left researchers with a list of "winners" and "losers."
Researchers found a species' dominance was closely correlated with the species' weight.
Smaller birds like blue tits and coal tits spent shorter stints at the feeder, pecking faster at lower quality food. Larger species like house sparrows and greenfinches spent longer periods of time, pecking slower at higher quality food.
"We know that during harsh weather the foods put out by homeowners can offer a lifeline but beyond this the benefits might be more subtle, so it is interesting that our findings are less straightforward and that more work needs to be done to fully understand garden bird feeding," BTO researcher Kate Plummer said.
Researchers published their findings this week in the journal PLOS One.