Nebraskaland

16 Nebraskaland • April 2026 IN THE FIELD A juvenile brown-headed cowbird clings to the branch of a ponderosa pine tree at Ponderosa Wildlife Management Area. This bird species relies solely on other birds incubating and feeding their young; this is called brood parasitism. JUSTIN HAAG, NEBRASKALAND Cuckoos gained their name from the sound of the Eurasian common cuckoo's call. But the term "cuckoo" has now grown to be synonymous with brood parasitism, an evolutionary strategy for outsourcing the rearing of young. Let's begin with avian brood parasitism. Avian Brood Parasites Avian brood parasites are birds that lay their eggs in other birds' nests. In Nebraska, birds that exhibit brood parasitism include cliff swallows, goldeneye and of course, our cuckoos. We have two kinds of cuckoos in Nebraska: the black- billed cuckoo and the yellow-billed cuckoo. Both species are migratory, with the black-billed being the rarer of the two. Our native cuckoos differ from their Eurasian namesake in many ways, including not having the classic cuckoo call and not being obligate brood parasites — species that depend on a host to complete its life cycle, as it cannot survive or reproduce on its own. In contrast, a non-obligate parasite can live and reproduce both with and without a host. All these birds mentioned also rear their own young, an example of non-obligate brood parasites. There is a benefit to having this two-pronged reproductive strategy — it increases the chances that at least some of their young will survive. However, Nebraska and the greater United States is home to one avian obligate brood parasite, the brown-headed cowbird. These incredible birds rely solely on other birds incubating and feeding their young but still provide vital parenting to their young. In a study published by ecologist Matthew Louder, cowbird females continue to keep tabs on their young and even use the failure or success of different nests to decide where to lay future broods. Cuckoos — More Than Just Birds Birds are not the only group of animals that rely on parasitic reproductive strategies. In Nebraska, we have two kinds of cuckoo bumble bees that have been found in recent years. Although rare, both the indiscriminate and the lemon cuckoo bumble bee have been recorded. Like cowbirds, cuckoo bumble bees are obligate brood parasites. Cuckoo bumble bees don't just lay eggs in the host's nest, they also take over. Female cuckoo bumble bees will invade the host's nest and replace the current queen. This allows them to take over a fully functional nest with plenty of worker bees to take care of both the false queen and their young. Nomad cuckoo bees are a kind of bee in Nebraska that utilizes brood parasitism. These bees are wasp-like in appearance. They lay their eggs in the nest of ground- nesting bees. The larvae hatch with impressive mouthparts that enable them to kill the host larvae and utilize the food left by the host mother. These evolutionary strategies have allowed these species to thrive in our complicated natural world. By Alie Mayes, Assistant Division Administrator – Fish & Wildlife Education BROOD PARASITES

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