Generally, elevated yolk testosterone increases nestling growth, competitive behaviors, and bold behavioral traits.
Testosterone (T) is a key hormone regulating behavioral trade-offs in male birds, shifting investment towards sexual and competitive behaviors.
Our results conform to the competitive model for behavioral selection originating in the ethological literature [ 2, 3] and provide an interneuronal mechanism for it.
The observation that social presence in a competitive setting resulted in behavioral change is consistent with previously conducted research.
Additional behavioral [sorting, rumination, competitive interactions (replacements), lying time] and production (milk yield and components) data were collected.
In one of the first studies reporting behavioral evidence of competitive interactions, Bahcall and Kowler [8] utilized a divided attention task in which they asked observers to report the identities of two spatially cued letters from a circular array.
23 Indeed, social value orientations, such as prosocial, individualistic, and competitive, are largely predictive of behavioral tendencies on task performance, and influence one's intrinsic and extrinsic motivations related to exercise.
In contrast, females and males may rely on different traits and different behavioral strategies for competitive success (e.g., Draud et al. 2004; Arnott and Elwood 2009; Milner et al. 2010), and territorial competition would not select for the same traits in males and females.
In animals, competitive interactions between species are often behaviorally mediated, and behavioral syndromes (correlations between different behaviors, also known as animal personalities) may lead to trade-offs between the behavioral suites favored in interspecific versus intraspecific competition.
Behavioral manifestations of these competitive interactions have been observed in a number of different experimental paradigms [3] [7].
