科学美国人60秒:Urbanization Alters Bird Behavior

Two centuries ago, blackbirds typically lived out their lives in forest habitats. Today, the birds are one of the most common avian urban species. Researchers have shown that urban and rural blackbirds already differ from one another in their songs, the timing of reproduction and their risk of diseases. But could the country blackbird and its city cousin now have different personalities?

Scientists in Germany collected and hand-raised 28 urban birds and 25 from the country nearby. The researchers tested the birds to determine whether they approached or avoided new objects in a familiar environment. They performed the study three times over a year to see if the traits persisted.

And the urban birds avoided new objects near their feeders for significantly longer than did their rural relatives. The study appears in the journal Global Change Biology. [Ana Catarina Miranda et al., Urbanization and its effects on personality traits: a result of microevolution or phenotypic plasticity?]

The researchers say these personality differences may be related to genetic micro-evolutionary changes. And that the findings demonstrate two things. One is that urban and rural differences can be tested in a controlled experiment. The second is that blackbirds and many other species may be quickly evolving new behaviors in response to our rapidly urbanizing world.

—Cynthia Graber