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Investigating Poor Reproduction in Captive Whooping Cranes

  • whooping crane

Scientists at the Center for Species Survival (CSS) are conducting a number of studies to examine management approaches to increase captive reproduction in North American whooping crane populations—the rarest crane worldwide.

By 1941, only 16 or fewer individuals of this species remained in Texas’ Aransas–Wood Buffalo population (AWBP), which is the source of all whooping cranes alive today. Through a combined in situ and ex situ conservation strategy, as well as legal protection under the Endangered Species Act and the Canadian Species at Risk Act, the total population has grown to approximately 600 birds, of which approximately 25 percent reside in captivity. Threats to this species continue to be significant and include habitat conversion and loss, collisions with power lines and wind turbines, illegal hunting and human disturbance in critical habitat areas.

Ex situ conservation breeding has been a major part of efforts to recover whooping cranes. The captive population was established beginning in the late 1960s. However, this population is plagued by numerous reproductive problems including low number of eggs laid, low natural fertility, and delayed onset of egg laying in young females. CSS researchers are working to understand the impact of housing on reproductive hormones, behavior and success. The study includes eight established breeding pairs with lower-than-expected egg production. Four pairs are currently housed in normal dry pens, while the other four have been moved to renovated, wetland pens. Through behavioral recordings and non-invasive hormone monitoring, researchers will examine the effect of captive environment on reproductive function. Additional studies include the effect of captive management on egg fertility and the establishment of cryopreservation protocols for use in the whooping crane.

Collaborators

Sarah Converse, USGS Patuxent Wildlife Research Center
Carol Keefer, University of Maryland

Support

Funding for these projects, past and present, include the Morris Animal Foundation, the Cosmos Club, United States Geological Survey, and the University of Maryland-Animal and Avian Science Department