The term "cuckoo bird" often refers to the cuckoo species known for their unique reproductive strategy. Female cuckoos lay their eggs in the nests of other bird species, leaving the unsuspecting host to raise their young. This behavior is known as brood parasitism and allows cuckoo chicks to benefit from the care provided by other birds. In psychology, "cuckoo" can describe someone perceived as insane or eccentric. This usage stems from the cuckoo bird's unusual nesting habits, which can symbolize unpredictability or irrational behavior. The term is often used informally and can carry a negative connotation when referring to mental health.