Custer, T. W., Pendleton, G., and Ohlendorf, H. M., 1990, Within-clutch and
among-clutch variation of organochlorine residues in eggs of black-crowned
night-herons: Environmental Monitoring and Assessment, v. 15, no. 1, p. 83-90.

Abstract:

Within-clutch variability of DDE and PBC 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 = 0.885) 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 egg technique, that the chemical
residues in one egg in a clutch accurately reflect residues in the remaining eggs of the
clutch.

Keywords:

Nycticorax-Nycticorax Cis Chlordane Ddt Dde Insecticide Toxicity Polychlorinated
Biphenyls