Biology
The Chemical Ecology of Brood Parasitism in Cuckoos and Host Counter-Adaptations
Quick fact
Some cuckoo species produce eggs that chemically mimic the host’s own eggs, reducing the chance of rejection; host birds can use olfactory cues to detect foreign eggs, leading to a chemical arms race.
Why this is interesting
You’ve probably seen a cuckoo chick being fed by a much smaller foster parent, but how does the cuckoo trick its host into accepting an egg that isn’t its own—especially when the host can smell and see?