For many visitors to big cities like New York or London, one of the first things they notice is how quickly the locals walk. It’s not just their imagination, either; scientists who study cities have confirmed that tourists’ intuitions are correct—the bigger the city, the faster the pace. In fact, as cities have grown in the last few decades, walking speeds have risen, too. Human dominated environments, it appears, have a way of quickening the pace of life.
Now we can say the same thing about birds in human landscapes, or at least one species, the Mauritius kestrel, a regal member of the falcon family. The raptor is native to the remote island of Mauritius, an isolated speck in the Indian Ocean some some 680 miles off the coast of Madagascar. The bird was common in the tropical forests that once covered the island, though since sugar cane’s introduction as a cash crop in the 18th century, plantations have replaced trees in most places.
Things got so bad that in 1974, there were only four Mauritius kestrels left. Fortunately, their numbers have rebounded since then, and that may be partially due to the birds’ adaptability—many now live amidst the sugar cane. But while the move may have saved their species, it has also changed their lifestyles.
Sindya Bhanoo, reporting for the New York Times:
Kestrels living in agricultural areas have more offspring earlier in life and also die earlier — “a sort of speeding-up of the pace of life,” said Samantha J. Cartwright, an ecologist at the University of Reading in England and an author of a new study about the birds in the journal Current Biology.
Birds in both forested and agricultural areas “ultimately produce the same number of offspring in life,” she added.
Cartwright and her colleagues write that the kestrels’ change in life history appears to be adaptive—the birds are coping with the altered landscape by becoming more precocious. It’s possible that other birds could do the same, they say, though not all species may be able to cope in the same way.