Endangered Old Whooping Cranes Keep Young Ones on Track in Migration

Bird migration is one of the most fascinating behaviors in the natural world. Yet how these feathered creatures accomplish this type of navigation has baffled scientists for centuries. Is their migration route encoded in their genes, or is it learned? Now, scientists have discovered that whooping cranes may actualyl learn their routes from older birds rather than possessing some type of innate sense.

Whooping cranes are critically endangered, which means that understanding their migration patterns is crucial when it comes to reintroducing them into the wild. The largest birds in North America, whooping cranes stand at a massive five feet tall and are some of the longest-lived birds in the U.S.---they survive 30 years or more in the wild. Each year, these birds fly between Wisconsin and Florida, breeding in colder climes before wintering in the more-tropical environment.

In order to understand these long-distance flights a bit better, the researchers examined records from a long-term effort to reintroduce these birds in the Eastern U.S. They found that whooping crane groups that included a seven-year-old adult deviated 38 percent less from a migratory straight-like path between their migratory sites. One-year-old birds that did not follow older birds, though, tended to veer an average of 60 miles from a straight flight path. When they followed older birds, the deviation was less than 40 miles.

That's not all they found, though. The researchers also discovered that the cranes became better at navigation with age. Individual cranes' ability to stick to the route increased steadily each year up to about the age of five. Then, it remained roughly constant from that point on.

"Here we could look over the course of the individual animals' lifetimes, and show that learning takes place over many years," said Thomas Mueller, one of the researchers, in a news release.

These findings are especially important for making sure that these cranes make their 1,300-mile trek. Each summer, experts train a group of captive-raised chicks to follow an ultralight aircraft to lead them on their migration. From then, the birds usually travel on their own. Yet learning that these birds benefit from experience is huge when it comes to learning how to better assist this species.

"We need to take into consideration that these birds may also reproduce more successfully as they age," said Mueller in a news release.

The findings are published in the journal Science.