Screaming Cowbird Molothrus rufoaxillaris

  • Order: Passeriformes
  • Family: Icteridae
  • Monotypic
  • Authors: Peter E. Lowther

Demography and Populations


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.

Recommended Citation

Lowther, P. E. (2011). Screaming Cowbird (Molothrus rufoaxillaris), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.