Meteorological Dependencies in Ducks: Influence of Weather on Sex Ratio Bias and Hatchability.

The feasibility of altering the sex ratio of hatching ducklings artificially can be an important economic factor in reducing production costs. As a preliminary investigation, associations between seasonal and weather factors and the secondary sex ratio in domestic ducks were examined to establish mechanisms that may determine the sex ratio of offspring. Over several years, a predominance of male hatchlings was observed, with an average bias of 51%-52%. There was no significant relationship found between the sex ratio shift and a particular meteorological season. A greater robustness was achieved by separately considering the time cycles of growth and decline in oviposition. Examining weather factors, i.e., average temperature, wind speed, and sea level pressure, we found significant relationships between these parameters and the sex ratio of hatching ducklings during periods of increasing egg production of their mothers. Wind force had the greatest influence on hatchability, to a greater extent during periods of decline in egg production. The decrease in hatchability of the duck flock was associated with increased wind speed. Our findings are crucial for further experimental evaluation of the sex ratio under controlled ambient temperature and wind strength.