Seasonal Variation in Selected Reproductive Characteristics of Male Common Pheasants (Phasianus colchicus) Throughout the Annual Cycle

Breeding in bird species inhabiting the temperate climate zone is strongly seasonally regulated. One such species is the common pheasant (Phasianus colchicus), widely maintained in aviary systems and of considerable importance in game management. The aim of this study was to determine seasonal variability in selected morphological traits of male common pheasants and to assess their relationship with vocalisation parameters during the annual cycle. The study was conducted on males kept under aviary conditions. Traits related to reproductive condition were analysed, including testicular mass and facial wattle height, together with mating vocalisations. The results revealed clear seasonal variation in the analysed traits. A gradual increase in body mass and spur length was observed from summer to winter, reflecting the maturation of young males and accumulation of energy reserves before the breeding season. The highest values of reproductive parameters, particularly testicular mass and wattle height, were recorded in spring, indicating peak hormonal activity and full sexual maturity. In June, a marked regression of these traits and a decline in the somatic condition traits were observed, corresponding to the end of the breeding season. Changes in vocal activity followed a similar pattern, suggesting a link between acoustic parameters and seasonal reproductive dynamics.