Researchers at the University of Southern Mississippi have discovered that Ruby-throated hummingbird flies more than 1,200 miles without stopping, which is an incredible migration feat for such a tiny creature weighing only 0.12 ounces. The study is the first to shed new light on this tiny bird's annual fall journey from the eastern U.S. to Central America.
After gathering data on Ruby-throated hummingbirds traveling through southern Alabama, researchers led by Theodore Zenzal found that the birds moved through the area between late August and late October, peaking in September.
Subsequent computer models used to estimate the birds' flight range based on their body mass and wingspan revealed that older hummingbirds and males are able to travel farther at a time than younger birds and females. Older individuals also arrived at their winter sites earlier than younger birds and did so in better condition.
"The most interesting thing, in my opinion, is how some of these birds effectively double their body mass during migration and are still able to perform migratory flights, especially given some of the heftier birds seem to barely make it to a nearby branch after being released," Zenzal said.
Based on their findings, older birds are believed to be more experienced and socially dominant. However, researchers are still unsure whether Ruby-throated hummingbirds migrate across the Gulf of Mexico or around it. Their estimated flight range of about 1,200 miles suggests that most of the birds would be able to make it across if weather conditions were favorable.
"Patterns we previously had hints of from small, anecdotal observations are documented here with a very large sample size. It's interesting that the young of the year migrate after adults and are quite different in their stopover phenology. This suggests there are substantial differences between flying south for the first time, as opposed to flying somewhere again as an adult," said Chris Clark, an expert on hummingbird behavior from the University of California, Riverside. "I think that further research on how young hummingbirds migrate, and the decisions they make, would be really interesting."
Mist nets were set up in Alabama's Bon Secour National Wildlife Refuge to capture hummingbirds during their fall migrations of 2010 through 2014. A total of 2,729 individual hummingbirds were banded and examined.
The study, largely funded by the National Geographic Society, was documented by a film crew, who seemed to be charmed by the hummingbirds, too.
"All but one person on the crew was from Europe and most had never seen a hummingbird in real life, so you can imagine how fascinating these birds must have seemed," Zenzal added. "During the course of filming, members of the crew would regularly ask me to place a hummingbird in their hand so they could release it."
The study were recently published in the journal The Auk: Ornithological Advances.
