MEASURES OF BREEDING ACTIVITY
Age at first breeding; intervals between breeding. Age at first breeding presumably 1 year and breeds annually thereafter.
Clutch. Clutch size unknown.
Annual and lifetime reproductive success. No information. Some collective (host plus parasite) data given by Fraga (1983): of total of 549 eggs in 80 Bay-winged Cowbird nests, 137 hatched (comprising 88 Bay-winged Cowbirds, 44 Screaming Cowbirds and 5 Shiny Cowbirds). In Argentina, observations on 39 eggs in Brown-and-yellow Marshbird nests, daily survival 0.93 ± 0.01 SE; for 9 nestlings, daily survival 0.92 ± 0.04 SE (Mermoz and Fernández 2003).
Number of broods normally reared per season. No information.