Environmental Monitoring and Assessment

, Volume 15, Issue 1, pp 83–89

Within-and among-clutch variation of organochlorine residues in eggs of black-crowned night-herons


  • Thomas W. Custer
    • Patuxent Wildlife Research Center, Gulf Coast Research StationU.S. Fish and Wildlife Service
  • Grey Pendleton
    • Patuxent Wildlife Research CenterU.S. Fish and Wildlife Service
  • Harry M. Ohlendorf
    • Patuxent Wildlife Research Center, Pacific Coast Research StationU.S. Fish and Wildlife Service
    • c/o Department of Wildlife and Fisheries BiologyUniversity of California

DOI: 10.1007/BF00454750

Cite this article as:
Custer, T.W., Pendleton, G. & Ohlendorf, H.M. Environ Monit Assess (1990) 15: 83. doi:10.1007/BF00454750


Within-clutch variability of DDE and PCB residues in eggs from 62 clutches of black-crowned night-herons (Nycticorax nycticorax) was small (12% and 17%) compared to among-clutch variability (88% and 83%). Significant correlations between concentrations of DDE (median r=0.8885) and of PCBs (median r=0.8244) occurred when 501 correlations were run on two randomly selected eggs from within the same clutch; no significant correlation occurred for either concentrations of DDE (median r=0.0353) or PCBs (median r=−0.0843) when eggs were not restricted to the same clutch but were restricted to the same colony. The probability of finding infrequently detected organochlorine contaminants (e.g., DDT, cis-chlordane) in eggs from the same clutch varied from 43–96% and increased as the chemical became more prevalent and the number of eggs per clutch became smaller. These results further support one of the basic assumptions of the sample egg technique, that the chemical residues in one egg in a clutch accurately reflect residues in the remaining eggs of the clutch.

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© Kluwer Academic Publishers 1990