Growth Curves of Ryukyu Scops Owl Nestlings, an Owl Species with Asynchronous Hatching and Reversed Sexual Dimorphism

factors. For example, the organism’s own sex (Záryb nická et al. 2015, Loonstra et al. 2018, Nogueira et al. 2019), the amount of parental investment (Eising et al. 2001, Hsu et al. 2019), food abundance (Zárybnická et al. 2015) and sibling competition (Nilsson & Svensson 1996, Royle et al. 1999) have all been shown to affect growth. Because body size is a major determinant of individual fitness (Peters 1983), how it develops and what factors influence it are important questions in evolutionary ecology. Sibling rivalry is an important factor to consider when discussing growth patterns in most avian species. Hatching order often shapes competitive hierarchies between nestlings (Lack 1947, Mock & Parker 1998), as later-hatched chicks are usually allocated less food, which results in poor growth or death. Furthermore, hormone levels may also alter the hierarchy, as androgens are related to the intensity of nestling behaviours such as begging and aggressiveness (Groothuis & Schwabl 2008). It is important to note that a relative power balance Growth curves of Ryukyu Scops Owl nestlings, an owl species with asynchronous hatching and reversed sexual dimorphism