In moments of danger, intruder chick releases slime that may foil attackers
Courtesy of Vittorio Baglione
A parasitic cuckoo chick foisted upon other birds can turn out to be luck in disguise, saving the nest with a disgusting defense.
About 1 percent of bird species, including cuckoos, outsource their childcare by sneaking into other birds’ nests and leaving an egg.
The intruder chick often kills or outcompetes the rightful offspring of a nest. Defense by cuckoo chicks of carrion crow nests at high risk of predator attack could be the first example of a parasitic bird’s benefit to its host, says ecologist Daniela Canestrari of the University of Oviedo in Mieres, Spain.