Agelaius

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

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

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

: 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

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