Amazing stuff! Co-evolution of animals and humans! Keep humming!
I bet, the same is also happening in the Phoenix metro area of Arizona given the fact that so many homes have hummingbird feeders.
"... But hummingbird feeders are more than just a beloved hobby and a convenient avian dining spot. They’re also a major evolutionary force. According to research published today in Global Change Biology, artificial feeders have allowed the Anna’s hummingbird, a common species in the western United States, to expand its range out of southern California and up to the state’s northern edge. They have also driven a transformation of the birds themselves: Over just a few generations, their beaks have changed in size and shape.
Records of hummingbird feeders occasionally pop up in the early 20th century, but they really took off after World War II, after the first one was patented in the United States in 1947. To see what most influenced the spread of Anna’s hummingbirds since the 1930s, a team of researchers pulled together a huge amount of data—everything from annual bird surveys to measurements of museum specimens—to create a model of the hummingbird’s range expansion. The results: Feeders played the biggest role in driving the bird’s northward expansion , with old newspaper ads for feeders serving as a proxy for their density.
Feeders directly placed selective pressures on wild hummingbird populations, too. As feeders proliferated, the birds’ beaks got longer and larger, all the better to slurp up artificially bottomless nectar. In areas where feeders are dense, male Anna’s hummingbirds have also developed beaks that are pointier and sharper than usual, a sign of aggressiveness. The researchers think male skirmishes over feeder control may have made these birds feistier. The most surprising finding? How quickly these changes took place. By the 1950s, Anna’s hummingbirds were noticeably different from those of the 1930s: a time span of only about 10 generations of birds."
From the abstract:
"Bird beaks are highly adaptable, with the potential to undergo rapid morphological shifts in response to environmental change such as climatic variation or food availability.
Anna's Hummingbirds (Calypte anna) have undergone dramatic population range expansions over the last 160 years into novel climatic regimes, where supplemental feeders and introduced plant species are frequented.
We used museum specimens to measure and characterize the shape of Anna's Hummingbird bills, hypothesizing that the introduction of novel food sources and the colonization of colder climates were associated with distinct dimensions of beak morphology.
We estimated feeder and Eucalyptus availability using data from archived newspaper databases and found that these two abundances are linked to population increases in Anna's Hummingbirds, while feeders were associated with changes to beak morphology. We found that bill size and shape changed with feeder use, exhibiting a more tapered and longer bill and a distinct maxillary constriction. In males, dorsal bill shape increased in pointedness, which may have provided an advantage with increased agonistic encounters at feeders. In contrast, bill size decreased in association with lower temperatures at higher latitudes. Our data document rapid morphological changes in the Anna's Hummingbird's bill induced by human-caused environmental changes over the last century."
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