Conservation Genetics

, Volume 12, Issue 1, pp 257–268 | Cite as

Genetic consequences of trumpeter swan (Cygnus buccinator) reintroductions

  • Findley A. RanslerEmail author
  • Thomas W. Quinn
  • Sara J. Oyler-McCance
Research Article


Relocation programs are often initiated to restore threatened species to previously occupied portions of their range. A primary challenge of restoration efforts is to translocate individuals in a way that prevents loss of genetic diversity and decreases differentiation relative to source populations—a challenge that becomes increasingly difficult when remnant populations of the species are already genetically depauperate. Trumpeter swans were previously extirpated in the entire eastern half of their range. Physical translocations of birds over the last 70 years have restored the species to portions of its historical range. Despite the long history of management, there has been little monitoring of the genetic outcomes of these restoration attempts. We assessed the consequences of this reintroduction program by comparing patterns of genetic variation at 17 microsatellite loci across four restoration flocks (three wild-released, one captive) and their source populations. We found that a wild-released population established from a single source displayed a trend toward reduced genetic diversity relative to and significant genetic differentiation from its source population, though small founder population effects may also explain this pattern. Wild-released flocks restored from multiple populations maintained source levels of genetic variation and lacked significant differentiation from at least one of their sources. Further, the flock originating from a single source revealed significantly lower levels of genetic variation than those established from multiple sources. The distribution of genetic variation in the captive flock was similar to its source. While the case of trumpeter swans provides evidence that restorations from multiple versus single source populations may better preserve natural levels of genetic diversity, more studies are needed to understand the general applicability of this management strategy.


Translocation Reintroduction Trumpeter swan Microsatellite Conservation genetics Genetic diversity 



Pacific Population


Rocky Mountain Population



We would like to thank the volunteers and staff from many state and federal agencies who helped collect both natural and reintroduced trumpeter swan samples with special thanks to W. Long, from the Wildlife Wetlands Society, and the late J. Johnson, from the Kellogg Bird Sanctuary. We thank J. St. John, J. Cornely, J. Dubovsky, P. Llambias, G. Ransler, P. Stevens, and the Harrison lab at Cornell for thoughtful comments on the manuscript. J. St. John also provided invaluable lab expertise. A. Coulon and R. Vallender gave helpful advice with some of the analysis programs. Funding for this project was provided by the U.S. Fish and Wildlife Service Migratory Bird Program and the U.S. Geological Survey through its Science Support Program. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.


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Copyright information

© Springer Science+Business Media B.V. (outside the USA) 2010

Authors and Affiliations

  • Findley A. Ransler
    • 1
    • 2
    Email author
  • Thomas W. Quinn
    • 1
  • Sara J. Oyler-McCance
    • 1
    • 3
  1. 1.Department of Biological Sciences, Rocky Mountain Center for Conservation Genetics and SystematicsUniversity of DenverDenverUSA
  2. 2.Department of Ecology and Evolutionary BiologyCornell UniversityIthacaUSA
  3. 3.U.S. Geological Survey, Fort Collins Science CenterFort CollinsUSA

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