Zoologger: The bird with a password-protected nest
Michael Slezak for New Scientist:
Most parents are security conscious but Australian superb fairy-wrens take it to another level. They have no choice: fairy-wren mothers often have their nests hijacked by Horsfield’s bronze cuckoos (Chalcites basalis).
The cuckoo egg looks like the wren eggs but hatches earlier, at which point the cuckoo chick ejects the wren eggs. Unless the mother wren realises an intruder is in the nest, she raises the cuckoo as her own, wasting time and food.
But the cuckoo only gets away with it 60 per cent of the time. In the other 40 per cent of cases, the wren detects the cuckoo within days, abandons it, and starts another nest. That’s because the mother teaches her chicks a password while they are still inside their eggs. Once hatched, the mother abandons the nest if they can’t give the password.
Nature is both weird and awesome at the same time.