This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.
Time within reproductive season, but not age or inbreeding coefficient, influences seminal and sperm quality in the whooping crane (Grus americana)
All existing, living whooping cranes (Grus americana) are descended from 16 or fewer birds that remained alive in the early 1940s, a bottleneck that puts the species at potential risk for inbreeding depression. Although artificial insemination is used commonly to ensure breeding between unrelated, genetically valuable birds, little is known about seminal traits or factors influencing sperm quality in the whooping crane. In this study, semen samples were collected from 29 adult males (age, 3-27 yr) during early (March), mid- (April), and late (May) breeding season over 2 consecutive years. The influence of donor age, time of reproductive season, and levels of inbreeding on seminal characteristics was analyzed using multi-model selection theory and longitudinal regression. Only time within the reproductive season significantly affected seminal traits, with total numbers of spermatozoa and proportions of pleiomorphisms increasing throughout this interval. We conclude that, even with a highly restricted number of founders, there is no discernible influence of inbreeding (at the levels described) on sperm output or quality. Furthermore, although there is variance in seminal quality, the whooping crane produces significant numbers of motile spermatozoa throughout the breeding season, and similar to values reported for the greater sandhill crane.
RD14181 Accepted 19 January 2015
© CSIRO 2015