Andean Condors Can Stay Aloft For Hours Without Flapping Wings

Andean Condors, which weigh between 20 to 30 pounds (9 to 13 kilograms) and boast a wingspan of more than 10 feet, are one of the world's heaviest and largest flying birds. Yet the majestic vultures, which spend their days circling the Andes mountains and nearby Pacific coasts of western South America in search of carcasses, manage to stay afloat for hours.

Though researchers have long suspected that the massive creatures conserved energy by using rising air currents to surf the skies, nobody had ever documented how infrequently the birds used their wings. Now, a new study has found that the incredibly energy-efficient condors use their wings just 1 percent of their time aloft – mostly during takeoff and landing. In comparison, ospreys and storks flap their wings 25 percent and 17 percent of the time, respectively, during their overland migratory flights.

"Condors are expert pilots, but we just had not expected they would be quite so expert," said study co-author Professor Emily Shepard, a biologist at Swansea University in Wales.

The extensive research, conducted in Patagonia — a semi-arid plateau on the southernmost tip of South America — from 2013 to 2018, entailed attaching high-tech flight recorders to the birds' wings. Shepard and her team, in collaboration with Sergio Lambertucci, a biologist at the National University of Comahue in Argentina, often spent hours waiting for the magnificent animals to be lured in by strategically placed sheep carcasses and bones.

The information collected — 320 different data points per second — was too much to send back via the phone or satellite network. Hence, the researchers had to physically retrieve the devices, which were designed to fall off the birds after a week. While an embedded GPS tracker allowed the scientists to ascertain the recorders' exact locations, getting to them was no easy task given Patagonia's rough terrain and minimal infrastructure.

After losing seven recorders for every one they retrieved, the team shifted their focus to younger condors, who tend to hover over the communal roosts, which are located on gently rolling hills rather than the cliff tops frequented by adults. The 250 hours of flight data collected from eight juvenile condors revealed that the birds flew for an average of three hours but flapped their wings for less than two minutes of the time. One efficient aviator managed to cover 106 miles (172 kilometers) over five hours without a single flap!

The researchers, who published their findings in the journal PNAS on July 28, 2020, say the large fliers expend the most energy during takeoff. However, once in the air, they can soar for long periods of time without turning on their "engines." The scientists speculate that adult condors may demonstrate an even more impressive flight record than their younger counterparts.

Resources: theconversation.com, theguardian.com