Recent research has shown that hummingbird feeders can affect the bill size of Anna’s hummingbirds (Calypte anna), a western species. Anna’s hummingbirds have surged northward as far as southeast Alaska over the past 150 years. For years, scientists believed Anna’s hummingbirds expanded their range thanks to the introduction of eucalyptus plantations in the 1930s, which provided winter blooms in an otherwise food-scarce season and urbanization.
However, new research reveals more to the story. By tracing the rise of hummingbird feeders, urban development, and eucalyptus plantations, the researchers at the University of California at Berkley uncovered a more complex story behind the bird’s dramatic expansion and its changing physical form.
Like many birds, the hummingbird took eons to adapt to the changing ecosystem, specifically matching to the flower species that it fed on. Anna’s hummingbirds are now adapting differently, not for the flower shape, but to manmade birdfeeders. This new change has led to male Anna’s hummingbirds developing sharper and smaller beaks, giving them a leg up on their competition at sugar-filled feeders where their main goal is to slurp up as much sugar as fast as possible. This shift in beak size is not consistent with the geographical location. In their northern range, their beaks remain smaller and have a shorter appearance than those in their southern range. Researchers theorize that the shorter bills help to limit heat loss, which is beneficial for their survival in colder climates.
The findings document rapid, measurable changes in bill shape over the last century, providing a striking example of evolution in action and revealing how human choices can impact wildlife.
Source: https://wildlife.org/backyard-feeders-are-reshaping-hummingbirds/
Thanks to VFAS intern Bethany Slagle for assisting with this blog post.
