Pesticide Analysis, Egg and Eggshell Characteristics of Red-Tailed Hawk Eggs
Creators:Springer, Mark Andrew
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Citation:The Ohio Journal of Science. v80, n5 (September, 1980), 206-210
In this study, addled and viable Red-tailed Hawk eggs were compared in terms of pesticide levels, egg and eggshell parameters, and shell ultrastructure as determined by scanning electron microscopy. These values were then used to compare actual measurements against egg and eggshell indices commonly reported in the literature. Addled eggs of Red-tailed Hawks were of greater length, weight and volume than viable eggs, while viable eggs showed greater shell weights and thickness than addled eggs. The general structure of the eggshell consisted of 3 layers: shell membrane, mammillary layer and palisade layer. No cuticle was present. No differences in thickness of the shell membrane or mammillary layer were detected between addled and viable eggs; however, the palisade layer was found to be 24% thicker (X2, P<0.05) in viable eggs than in addled eggs (0.11 ±0.03 mm and 0.08±0.01 mm, respectively). The thicker palisade layer resulted in an overall thicker eggshell in viable compared to addled eggs (0.28±0.02 mm and 0.25±0.03 mm, respectively). Extensive areas of cavitation in the mammillary layer were found in many addled eggs, but never in viable eggs. Pore channels originating at the membrane layer could be seen extending to the outer surface of the egg. All egg samples analyzed for pesticide residues bore measureable amounts of PCB and DDE, while some samples contained dieldrin and heptochlor epoxide.
Author Institution: Department of Anatomy, Wright State University
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