Organochlorine residues, eggshell thickness, and nest success in barn owls from the Chesapeake Bay

Estuaries
By: , and 

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Abstract

Eggs of barn owls (Tyto alba) were collected from 18 nests in offshore duck blinds on the Maryland side of the lower Potomac River estuary in 1972 and 1973 and analyzed for organochlorine residues. DDE was found in 100% of the clutches, PCBs in 89%, and dieldrin in 78%. Eggshell thickness was inversely correlated with concentrations of DDE, DDD, and dieldrin residues. Six of the 18 clutches had mean DDE residues above 5 ppm, and eggshell thickness in these six clutches was significantly less (P<0.001) than in the other 12 clutches. The owls produced 1.7 young per active nest in 1973. This rate is slightly below the reproductive rate needed to maintain a stable population. An estimated 15% of the population carried concentrations of organochlorine residues that may have been detrimental to their reproduction. Passerine birds, taken extensively as food by a small proportion of the population, are believed to have been the source of elevated concentrations of organochlorines in these barn owls.

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Publication type Article
Publication Subtype Journal Article
Title Organochlorine residues, eggshell thickness, and nest success in barn owls from the Chesapeake Bay
Series title Estuaries
DOI 10.2307/1351649
Volume 1
Issue 1
Year Published 1978
Language English
Publisher Springer
Contributing office(s) Patuxent Wildlife Research Center
Description 8 p.
First page 46
Last page 53
Country United States
State Maryland, Virginia
Other Geospatial Chesapeake Bay
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