For rufous hummingbirds, migration looks different depending on age and
sex

Date:
July 28, 2020
Source:
Oregon State University
Summary:
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 shows.



FULL STORY ========================================================================== 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 different ages
and sexes have the resources they need each year on their journey up
and down the western part of North America.

"Different age-sex categories of rufous hummingbirds use alternative
routes and differ in migration cycles and distributions," said the
study's corresponding author, Jose?e Rousseau, a Ph.D. candidate in
the OSU College of Forestry. "Our results seem to indicate that the
age-sex categories could be affected in different ways by things like
habitat loss and climate during migration. If we keep that in mind, we
can make conservation efforts that help these amazingly feisty little
creatures -- and I describe them that way with the utmost respect --
have the resources they need during their migration across the landscape."
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 over 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
hummingbird 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, Rousseau said.

"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.

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.


========================================================================== Story Source: Materials provided by Oregon_State_University. Original
written by Steve Lundeberg. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Jose'e S. Rousseau, John D. Alexander, Matthew G. Betts. Using
continental-scale bird banding data to estimate demographic
migratory patterns for Rufous Hummingbird (Selasphorus rufus). Avian
Conservation and Ecology, 2020; 15 (2) DOI: 10.5751/ACE-01612-150202 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200728150639.htm

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