Pictured at left is a female broad-tailed hummingbird (Selasphorus platycercus) visiting the flowers of tall larkspur (Delphinium barbeyi). Larkspur is one of several wildflowers that are important nectar resources for migratory hummingbirds to reproduce successfully during the summer. In a research study funded by the National Science Foundation's Division of Environmental Biology, David Inouye and Amy McKinney of the University of Maryland and colleagues found that the lilies are blooming some 17 days earlier than they did in the 1970s. This means that their blooming is no longer in sync with the arrival of the hummingbirds that rely on the nectar. By the time the hummingbirds arrive, many of the flowers have withered away along with their nectar-filled blooms. Each spring, the broad-tailed hummingbirds fly north from Central America to the Western U.S. Here in these high-mountain breeding grounds they will raise their young over the short mountain summer. Males actually arrive before the flowers bloom to scout for territory. But, says Inouye and McKinney, the time between the arrival of the first hummingbird and the first bloom has collapsed by 13 days over the past four decades. "In some years," says McKinney, "the lilies have already bloomed by the time the first hummingbird lands."
Visit Website | Image credit: David W. Inouye, Department of Biology, University of Maryland