Bird feeders have caused a dramatic evolution of California hummingbirds
https://www.science.org/content/article/bird-feeders-have-caused-dramatic-evolution-california-hummingbirds?et_rid=41105309&et_cid=5644195
According to research published this week in Global Change Biology , artificial feeders have allowed the birds to expand their range out of Southern California up to the state’s northern end. They have also driven a transformation of the birds themselves. Over just a few generations, their beaks have dramatically changed in size and shape…
The researchers’ findings suggest eucalyptus trees—which were planted en masse in California in the late 1800s—might have served as the first steppingstone for some populations of Anna’s hummingbirds to expand their ranges. But hummingbird feeders played the biggest role in driving the hummingbird’s northward population growth. “The feeders are what really make the difference here,” says senior author Alejandro Rico-Guevara, an evolutionary biologist at the University of Washington…
The researchers also found that as feeders proliferated, Anna’s hummingbird beaks got longer and larger, which may reflect an adaptation to slurp up far more nectar than flowers can naturally provide…In areas where feeders are dense, male hummingbirds have also developed beaks that are pointier and sharper than usual. Pointy beaks in hummingbird species often indicate aggressiveness, and the researchers think male skirmishes over feeder control may have made these birds feistier…
The most surprising finding, though, was how quickly these changes took place. By the 1950s, hummingbirds were noticeably different from those of the 1930s: a time span of only about 10 generations of birds, Alexandre says.
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