This kind of bird has a distinctive call and lays its eggs in the nests of other birds. What is it?

That iconic two-note call, famously replicated in clocks, gives this bird its name. The sound is a clear giveaway, but the bird's most fascinating trait is its unusual parenting strategy, or rather, its lack thereof. This bird is the world's most well-known "brood parasite (Review)," a term for animals that trick others into raising their young. Instead of building her own nest, a female will find the nest of another, often smaller, bird species and stealthily lay one of her eggs inside it.

The unsuspecting host bird, such as a reed warbler or meadow pipit, then incubates the foreign egg along with its own clutch. The cuckoo egg is adapted to hatch quickly, and the newborn chick has a ruthless instinct. Shortly after hatching, it will maneuver to push the host's own eggs or young out of the nest, eliminating all competition for food.

The foster parents, driven by instinct, work tirelessly to feed the single, rapidly growing chick, which soon dwarfs them in size. This clever and somewhat sinister survival strategy ensures the cuckoo's offspring gets a dedicated, private food supply without the parent bird needing to invest any energy in raising it. While this behavior is what they are most famous for, not all species in this bird's family are brood parasites; many build nests and raise their own young.