Migration Hotspots, by Tim Harris – review

Consider for a moment the plight of the willow warbler. Russian birds of this species fly between eastern Siberia and southern Africa and back every year of their short lives, a distance of nearly 7,500 miles in each direction. Each weighs roughly as little as two teaspoons-full of sugar.

But at least these tiny birds can refuel on their journey. Southern bar-tailed godwits are unluckier. These fly the 7,000 or so miles between New Zealand and Alaska over the immense Pacific Ocean — hence non-stop — twice each year. Moreover, Arctic terns migrate from the Antarctic to the Arctic and back again: a fledgling of this species, born on the Farne islands off the Northumberland coast, was recorded only three months later near Melbourne, Australia. And some shear-water have been tracked flying up to 46,000 miles per year, so that a 30-year-old bird could have flown the equivalent of 50 circuits around planet Earth.