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RESEARCH ARTICLE

Time within reproductive season, but not age or inbreeding coefficient, affects seminal and sperm quality in the whooping crane (Grus americana)

M. E. Brown A B , S. J. Converse C , J. N. Chandler C , A. L. Crosier B , W. Lynch B , D. E. Wildt B , C. L. Keefer A and N. Songsasen B D
+ Author Affiliations
- Author Affiliations

A Department of Animal and Avian Sciences, 1413 Animal Sciences Center, University of Maryland, College Park, MD 20742, USA.

B Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA 22630, USA.

C United States Geological Survey, Patuxent Wildlife Research Center, 12100 Beech Forest Road, Laurel, MD 2078, USA.

D Corresponding author. Email: songsasenn@si.edu

Reproduction, Fertility and Development 29(2) 294-306 https://doi.org/10.1071/RD15251
Submitted: 31 May 2014  Accepted: 27 June 2015   Published: 11 August 2015

Abstract

All 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 AI is commonly used in the management of the captive population of this species, little is known about seminal traits or factors affecting sperm quality in the whooping crane. In the present study, semen samples were collected from 29 adult males (age 3–27 years) during the early (March), mid (April) and late (May) breeding season over 2 consecutive years. The effects of donor age, time within reproductive season and level of inbreeding on seminal characteristics were analysed using regression and information–theoretic model selection. Only time within reproductive season significantly affected seminal traits, with total numbers of spermatozoa and proportions of pleiomorphisms increasing across the season. 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, similar to values reported for the greater sandhill crane (Grus canadensis tabida).

Additional keywords: avian, male reproduction, seasonality, spermatozoa.


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