Rufous-collared sparrows living farther from the equator grow feathers faster than their relatives near the tropics. Photo by Ryan Terrill
Sept. 5 (UPI) -- According to a new study, birds living at higher latitudes complete the feather molting process faster than their peers living closer to the equator.
Previous studies have shown birds living among northern climates adopt a "live fast, die young" lifestyle. Northern birds mature faster and start reproducing earlier, sacrificing their survival for the chance at more offspring.
Farther from the equator, seasons are shorter and resources are variable. Nature demands a fast-lane approach to life.
And according to the latest research, the fast-lane approach entails shedding and regrowing feathers faster than birds enjoying more tropical environs.
Ryan Terrill, an ornithologist at the Louisiana State University, was able to estimate the growth rates of bird feathers by measuring the light-colored bars found on each. The bars are produced by exposure to sunlight as new feathers grow during day and night. Faster-growing feathers yield larger spaces between the bars.
Using museum specimens, Terrill analyzed the feathers of four bird species with expansive ranges in both the Northern and Southern hemisphere. His analysis -- detailed this week in the journal The Auk: Ornithological Advances -- proved birds living farther from the equator grow feathers faster than their relatives living among the tropics.
Terrill thinks birds molt faster for the same reasons they mature faster. They need the tools to take advantage of resources as quickly as possible -- and also need to mate, as soon as possible.
"It wasn't until recently that many people considered that how feathers grow might be important for birds or realized that you could measure feather growth rates on specimens, and I hope this study will publicize yet another way that museum specimens are useful for understanding birds," Terrill said.