It has been, say scientists, "a mammoth journey". The satellite-tagged common cuckoo (Cuculus canorus), named Onon after a Mongolian river, set off from its winter home in Zambia on 20 March.
This story appears in the January 2018 issue of National Geographic magazine. For the care and feeding of its offspring, the common cuckoo outsources. When she’s ready to lay an egg, a female ...