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

Estuaries

2078_Klaas.pdf
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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.

Additional Publication Details

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
Volume
1
Issue:
1
Year Published:
1978
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
46-53
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Estuaries
First page:
46
Last page:
53