Change is difficult for the best of us. And you’d think a move from temperate southern England to the hot and cold extremes of New York would be especially difficult for our feathered friends. But not so for the European starling. Not only did the birds survive while other species did not—after being introduced in 1890 by Shakespeare enthusiast and German immigrant Eugene Schieffelin of the American Acclimatization Society—they thrived. The birds now call the majority of North America home, adapting to both the harsh winters of the Canadian prairies and the arid Arizona climate.
According to Natalie Hofmeister, a doctoral student at the Cornell Lab of Ornithology and first author of the recently-published “Environmental correlates of genetic variation in the invasive European starling in North America,” the key to the birds’ success was that their genomes—their molecular set of operating instructions—have a variation which allowed them to adapt to change at, in evolutionary terms, the lightning speed of about 130 years, as opposed to the millions previously thought necessary.
“My results show genetic signature variations that specifically affect their ability to adapt to differences in temperature and rainfall,” says Hofmeister. “And those unique variations matched really nicely onto the environmental conditions they encountered in North America.”
Exactly what those adaptations are—whether the birds’ feathers are different, if they’ve changed to better retain water, or if they’ve adjusted their behaviours to handle the Canadian winters—is yet to be determined.
Even if those founding flocks of starlings were equipped with a genetic adaptive leg-up to acclimate at the speed of flight, they couldn’t have adapted in one or two years. So how did they initially survive in New York, and then, at their peak, number about 200 million birds, with such a vast range?
Hofmeister doesn’t know for sure, but has drawn speculations from previous research. “It could be that when Eugene Schieffelin introduced them during spring, when it was warmer, the city may have provided ‘heat islands’ with good roosting locations,” she says. “Although it’s highly unlikely, it’s also possible they met up with other released populations, such as another group in Portland, Oregon.” But the birds also had another characteristic that likely helped them flourish: their inclination to travel.
Over an unbelievably short span of around 70 years, the birds gradually shifted from New York to Arizona. “We’ve followed historical sightings over time from the east and as far north as the Canadian plains, to the middle of the U.S., and then to the Rocky Mountains,” says Hofmeister. “They spent a lot of time there, and then to the southwest. The birds’ have stronger adaptation in the southwest, and, once there, moved a lot less. Although this paper doesn’t prove it—more research is necessary—it seems their mutation wasn’t that useful in the U.K., but was very helpful here.”
Although in today’s world, the ability to adapt quickly to climate differences seems like a super power, it hasn’t helped the birds adjust to a different sort of change: human urbanization. Starling numbers have declined almost 50 per cent over the past 40 years. Hofmeister suspects it’s because of a reduction in farmland and, consequently, access to insects and other food sources.
Still, it’s hard not to take away a hopeful message from the birds’ success. If they can genetically adapt to extreme geographical change in as little as 130 years, what can we learn from them to help other species? Perhaps ones threatened with extinction? What are we capable of?
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