NEWS RELEASE: For Rufous Hummingbirds, migration looks different depending on age and sex
CORVALLIS, Ore. – Plucky, beautiful and declining in numbers at about a 2% annual rate, the Rufous Hummingbird makes its long annual migration in different timing and route patterns based the birds’ age and sex, new research by Oregon State University shows. The findings, published in the journal Avian Conservation & Ecology, are important because the more that is known about how Rufous Hummingbirds migrate, the more that can be done to ensure birds of each age and sex category have the resources they need each year on their journey up and down the western part of North America.
With a reputation as one of the continent’s most determined and assertive birds, the Rufous Hummingbird, scientifically known as Selasphorus rufus, weighs less than a nickel and tops out at about 3 inches long. Based on its body length, its migratory journey is one of the world’s longest – the hummingbirds that travel the full extent of the range, from Alaska to Mexico, migrate almost 80 million body lengths, or 3,900 miles.
By comparison, an Arctic Tern covers about 51 million body lengths on the 13-inch bird’s one-way flight of 11,000 miles.
Rufous Hummingbirds live in open woodlands, nest in trees and eat nectar. A common visitor to bird feeders, the extremely territorial Rufous Hummingbird will chase away much larger species of hummingbirds, and they’ll even drive squirrels away from their nesting areas.
Equipped with excellent memories, Rufous Hummingbirds will visit the same feeders multiple years, even looking for food at former locations of feeders that have been moved.
The study by scientists in the Oregon State University College of Forestry and at the Klamath Bird Observatory in Ashland looked at 15 years’ worth of fall migration banding data involving nearly 30,000 captures at more than 450 locations.
The research showed that adult females tended to have a southbound migration route that was parallel to and between those of young and adult males, said the study’s corresponding author, Josée Rousseau, a Ph.D. candidate in the College of Forestry.
“Also, a greater number of young birds migrated south through California in comparison to adult females and adult males,” she said. “Our results suggest that the migration of each age-sex category is separated by about two weeks, with adult males migrating first, followed by adult females, and then the young of both sexes. Interestingly, though, migration speed was not statistically different among the categories.”
The adult males were captured within a smaller geographic distribution during any given week of migration compared with adult females and young birds, she added.
“Different age-sex categories of rufous hummingbirds use alternative routes and differ in migration distributions,” she said. “Our results seem to indicate that the age-sex categories could be affected in different ways by habitat loss and climate during migration. Keeping that in mind, we can guide conservation efforts to make sure all hummingbirds have the resources they need during their migration across the landscape.”
Collaborating with Rousseau on the study were Matt Betts of the OSU College of Forestry and John Alexander of the Klamath Bird Observatory.
The Natural Sciences and Engineering Research Council, the National Science Foundation, the Western Hummingbird Partnership, the U.S. Forest Service and the OSU Richardson Family Graduate Fellowship supported the research.
Written by Steven Lundeberg, Oregon State University
To view the original press release and press materials, click here.
Full Citation:
Rousseau, J. S., J. D. Alexander and M. G. Betts. 2020. Using continental-scale bird banding data to estimate demographic migratory patterns for Rufous Hummingbird (Selasphorus rufus). Avian Conservation and Ecology 15 (2):2. [online] URL: http://www.ace-eco.org/vol15/iss2/art2/
The Department of Forest Ecosystems and Society at Oregon State is world renowned for its education, outreach, and research in the areas of forest science, natural resources, and tourism, recreation and adventure leadership. Students and faculty study and work in Corvallis, at OSU-Cascades in Bend and around the state, nation and world. The Department’s research impacts policy and land management decisions worldwide and outreach programs benefit communities throughout Oregon.
The Klamath Bird Observatory (KBO) is a non-profit organization that advance bird and habitat conservation through science, education, and partnerships. Working in the Pacific Northwest and throughout the ranges of migratory birds KBO emphasizes high-caliber science and the role of birds as indicators to inform and improve natural resource management. KBO also nurtures an environmental ethic through community outreach and education.
