Annual variation in polychlorinated biphenyl (PCB) exposure in tree swallow (Tachycineta bicolor) eggs and nestlings at Great Lakes Restoration Initiative (GLRI) study sites

  • Christine M. CusterEmail author
  • Thomas W. Custer
  • Paul M. Dummer
  • Diana Goldberg
  • J. Christian Franson


Tree swallow (Tachycineta bicolor) eggs and nestlings were collected from 16 sites across the Great Lakes to quantify normal annual variation in total polychlorinated biphenyl (PCB) exposure and to validate the sample size choice in earlier work. A sample size of five eggs or five nestlings per site was adequate to quantify exposure to PCBs in tree swallows given the current exposure levels and variation. There was no difference in PCB exposure in two randomly selected sets of five eggs collected in the same year, but analyzed in different years. Additionally, there was only modest annual variation in exposure, with between 69% (nestlings) and 73% (eggs) of sites having no differences between years. There was a tendency, both statistically and qualitatively, for there to be less exposure in the second year compared to the first year.


Tree swallows PCBs Annual variation Great Lakes Restoration Initiative GLRI 



This study was funded by the Great Lakes Restoration Initiative and the Environmental Health Mission Area of USGS.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed involving animals were approved by, and in accordance with, the ethical standards of the institution at which the studies were conducted.


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Copyright information

© This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2018

Authors and Affiliations

  • Christine M. Custer
    • 1
    Email author
  • Thomas W. Custer
    • 1
  • Paul M. Dummer
    • 1
  • Diana Goldberg
    • 2
  • J. Christian Franson
    • 2
  1. 1.U.S. Geological SurveyUpper Midwest Environmental Sciences CenterLa CrosseUSA
  2. 2.U.S. Geological SurveyNational Wildlife Health CenterMadisonUSA

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