High Flyers

BBC Wales carried an interesting story about a Bangor University-led study on the ability of the Bar-headed goose (Anser indicus) to fly over the Himalayas on its annual migration (http://www.bbc.co.uk/news/science-environment-30799436). This was done by attaching tracking devices to the geese in Mongolia that measured acceleration, heart-rate etc, etc. The main focus of interest was how the geese were able to fly (an energetically demanding activity) under conditions where there was very little oxygen. It appears that the geese try to limit the time they spend at the highest altitudes by following an 'up-and-down' trajectory. They also appeared to favour a night crossing when the air is colder and denser. The oxygen-carrying myoglobin in their red flight muscle may also help. Tracking devices are getting both lighter and more powerful but any such item is still a penalty for the carrying bird.