On Dry Land

Yards with gravel and desert plants might provide higher-quality habitat for Arizona birds than lushly-landscaped lawns, researchers report in PLoS ONE.

Cities generally support fewer bird species than the countryside. But residents can boost diversity by maintaining native plants in their yards. To find out whether landscaping could also influence the birds’ feeding patterns, a research team studied 20 yards in the Phoenix area. Half the yards had turf and exotic plants, while the other half were more desert-like.

The team put trays of seeds in each yard and used videocameras to monitor birds that arrived. After a day, the researchers took away the trays and measured the amount of seed remaining in each one. Using the videos of birds pecking at the trays, they also estimated how much seed each bird probably left behind.

Birds that visited the lusher yards tended to eat more of the seeds in the trays, the authors found. The result suggests that the birds in the desert-like yards stopped feeding at trays sooner because other food options were available or because it took less energy to forage in those areas. In other words, the drier yards appeared to offer “a superior habitat,” the team writes.

The researchers also tested whether birds preferred trays in the open or near bushes. Shrubs might provide cover from flying predators but could also conceal hidden cats. The birds didn’t show a preference, so perhaps they considered one location just as dangerous as the other — or are enjoying the benefits of lower predation in cities. Roberta Kwok | 23 August 2012

Source: Lerman, S.B. et al. 2012. Linking foraging decisions to residential yard bird composition. PLoS ONE doi: 10.1371/journal.pone.0043497.

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