Bar-headed geese exhibit an interesting roller coaster flight pattern, according to a new study published in the journal Science. These birds annually migrate from breeding grounds in Mongolia to southern Tibet or India and have a little fun in the Himalayas, which they use as a giant roller coaster. For the purpose of research, 30 geese were implanted with monitors by an international team of researchers. This was done before their annual flight in 2011 and the monitors were used for measuring their body movement, heart rate and altitude.
Only seven of them got wounded and provided unstable data. However, the data obtained from the rest of them were contradictory to the long accepted notion about the behavior of these migratory birds. University of Bangor lead researcher Charles Bishop said “At the beginning we were just puzzled that there were so few reports of very high flight over the last 60 years.” Bishop added “We knew that these birds were especially well-adapted to fly in air containing very low oxygen, so we certainly expected to record some high flights. The question was how high did they normally fly? For how long? And how difficult were such flights? How close to the limit did they have to go?”
Previously it was thought that bar-headed geese mainly migrate at high altitudes. However, this study unveiled that while flying over the Himalayas, the birds come closer to the mountainous terrain and fly with a roller coaster-like pattern. Biologists believe that the efficient respiratory systems and massive wing strength of bar-headed geese allow them to endure long high-altitude flights.
As per the new study, during their flight the geese search for low altitudes where oxygen is present in abundance. Bishop explained “I think it is the most economical way to travel through the mountains.” He also stated “However, it appears that the winds were seldom blowing in the right direction to help the geese with their migrations, so the best thing to do is stay as low as possible and keep in the most dense air available.”
On hitting a mountain ridge, some of the wind gets deflected upwards, creating an updraft. This helps the birds to increase their rate of climb, with reduced energy required to climb. Bishop elaborated “It’s a spectacular migration through 500 kilometers of the highest mountain area in the world.” Scientists are now hoping to unveil the genetics of these birds due to which they are capable of performing energetic feats at such great heights.