Agelaius

: Born altricial (naked and helpless), they possess one of the fastest avian growth rates , increasing their body mass by 9–10 times within the first few days.

: They undergo a "thermoregulatory metamorphosis" over approximately 12 days , transitioning from an ectothermic-like state to being able to maintain their own body heat.

: Young typically leave the nest 10–14 days after hatching. They are fed by parents for another 2–3 weeks before becoming independent. agelaius

: A single male often defends a territory containing a "harem" of up to 15 nesting females .

: Unlike many other birds, male Red-winged Blackbirds do not acquire their full adult plumage (glossy black with intense red/yellow patches) until their second year . In their first year, they often have an orange or streaked appearance. Breeding and Social Behavior : Born altricial (naked and helpless), they possess

: They typically breed in marshlands, wetlands, or grassy areas near water, with females building deep cup-shaped nests lashed to reeds like cattails. Species Profiles yellow-souldered blackbird revised recovery plan - FWS ECOS

: Males are aggressively defensive, famously attacking much larger animals, including hawks, horses, and humans, if they approach the nesting site. They are fed by parents for another 2–3

The genus includes several species of New World blackbirds, most notably the widespread Red-winged Blackbird ( Agelaius phoeniceus ). These birds are known for their rapid development and highly territorial breeding habits. Developmental Stages