Screaming Cowbird

Primarily diurnal, Screaming Cowbirds are commonly observed in pairs or small flocks foraging on the ground in open grasslands, pastures, savannas, and agricultural edges. They move with deliberate hops and short flights, scanning for seeds, insects, and small invertebrates. As obligate brood parasites, adults do not build nests but follow potential host species, such as the Bay-winged Cowbird and other icterids, persistently approaching host nests to deposit eggs. Screaming Cowbirds are non-territorial and roam widely in search of hosts, exhibiting gregarious and opportunistic behavior. They communicate with loud, piercing calls used in display and alarm. Outside the breeding season, flocks may mix with other cowbird species and exploit livestock gatherings for insect prey disturbed by grazing animals. Their adaptable nature allows thriving in modified landscapes.

The diet of the Screaming Cowbird consists primarily of grass seeds, grains, and small invertebrates such as grasshoppers, beetles, and caterpillars. They forage by pecking and probing disturbed soil, leaf litter, and pasture ground, often following large mammals or farm machinery to catch flushed prey. Adults also consume a variety of weed seeds and occasionally take fallen fruits. During the breeding season, nutritional demands rise, and individuals increase insect consumption to meet protein needs for egg production. The combination of carbohydrate-rich seeds and protein-rich invertebrates supports energy-intensive behaviors such as brood parasitism and vocal displays. Chicks reared by host parents initially subsist on regurgitated insects and seeds provided by the foster parents. Dietary flexibility enables Screaming Cowbirds to occupy diverse habitats and cope with seasonal fluctuations in food availability.

Reproductive behavior centers on obligate brood parasitism, with females laying two to three eggs in the nests of host species. They engage in rapid, surreptitious visits to host nests, often removing a host egg before depositing their own. Males display to females with fluttering flights and vocal calls, but no pair bonds form. Adults do not provide parental care; hatchlings are raised entirely by unwitting foster parents.

Population estimates for Screaming Cowbirds are not precisely known, but the species maintains widespread and stable numbers across its eastern South American range. Local declines may occur where preferred host species are rare or habitats are heavily altered. Brood parasitism strategies and dietary adaptability contribute to resilience in fragmented landscapes. Ongoing monitoring indicates no significant population decreases at a continental scale, and the species remains common within suitable habitats.