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Reproduction of black-crowned night-herons related to predation and contaminants

Pacific Seabirds

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Abstract

Reproductive characteristics were studied at five colonies of Black-crowned Night-Herons (Nycticorax nycticorax) in south central Washington (4) and north central Oregon (1) in 1991. Predation (primarily avian) was a major factor that adversely affected reproductive success in three colonies and was relatively unimportant in two colonies. The mean number of young surviving to 14 days of age in each colony ranged from 0.47 to 1.94 per nesting female (includes recycling efforts). Unadjusted nest success at each I colony ranged from 31 to 84% (including recycling efforts). Clutch size and incidence of recycling also varied markedly by colony. Residues of DDE, total PCBs, and related compounds were relatively low in most eggs, and mean eggshell thinning by colony ranged from 7 to 11 %. Cytochrome P-450 enzyme (EROD, PROD, and BROD) induction in livers of pipped embryos by colony ranged from low to average in comparison with other colonies throughout the U.S. Residues of dioxins (TCDD) and furans (TCDF) in eggs were generally low and apparently had little influence on reproductive success at any of the colonies.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Reproduction of black-crowned night-herons related to predation and contaminants
Series title:
Pacific Seabirds
Volume
23
Issue:
1
Year Published:
1996
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
24 (abstract)
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
24 (abs)