Richard Collins: Bird migration is dangerous and demanding — why do it?

Scientists fitted data-logging devices to 120 birds to measure their heart-rate and body-tempearture every half hour throughout winter. Picture: iStock
‘The ouzel cock so black of hue With orange tawny bill...’ – Bottom in
Some of us are stay-at-home birds, while others are restless souls not content to remain in one place for long. There’s a motor vehicle for every two people in Ireland and more than a million passengers are airborne, worldwide, at any given time. How odd!