The age ratio in the early winter in Argentina is about 2 to 1 in favor of immature birds (Bump and Bump 1969).
Gomes, V. (2014). Spotted Nothura (Nothura maculosa), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.sponot1.01