Studies in birds show that testosterone (T) concentrations vary over the annual cycle depending on mating system and life history traits. Socially monogamous species show pairing behavior throughout the year and low levels of male-male aggression and are underrepresented in these studies, yet the function of testosterone could be particularly important for sexual and social interactions occurri...

The basic unit of temporal organization in long-lived animals is the annual cycle, In birds this includes most prominently the periods of winter maintenance, reproduction, molt, and migration or dispersal. To attain maximal, or at least adequate, fitness, all of these essential processes must occur and be timed in individuals and populations so that conflicting demands for time and energy are m...

The structure of ocean-atmosphere annual-cycle variability across the global tropics is extracted from the Comprehensive Ocean-Atmosphere Data Set (COADS) surface winds and SSTS, and oceanic heat-content simulation from a nonlinear shallow water model (forced by COADS wind stress) using the co-variance based rotated principal component analysis technique. ‘l’he coupled annual-cycle variability ...