Condition bias of hunter-shot ring-necked ducks exposed to lead

Kevin G. McCracken, Alan D. Afton, Michael S. Peters

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

We evaluated the condition bias hypothesis for ring-necked ducks (Aythya collaris) exposed to lead by testing the null hypothesis that ducks shot by hunters do not differ in physiological condition from those collected randomly from the same location. After adjusting for structural body size and log(e) concentration of blood lead, we found that overall body condition differed significantly between collection types and age classes, and marginally between sexes. Ingesta-free body mass of ring-necked ducks sampled randomly averaged 8.8% greater than those shot over decoys, and 99% of this difference was accounted for by lipid reserves. Ingesta, ash, and protein did not differ between collection types; however, after-hatching-year (AHY) birds had 5.1% more ash and 4.8% more protein than did hatching-year (HY) birds. The only sex difference was that males had 4.1% more protein than did females. Ingesta-free body mass, lipids, and protein were negatively related to concentration of blood lead. Collection type-by-concentration of blood lead and age-by-sex-by-concentration of blood lead interactions were not significant. To the extent that lead pellets persist as a cause of disease or mortality, waterfowl biologists should account for lead exposure as a possible source of condition bias when estimating population parameters and modeling survival of ring-necked ducks and other waterfowl species prone to ingest lead. These findings further underscore the problem that ingested lead shotgun pellets pose for waterfowl.

Original languageEnglish (US)
Pages (from-to)584-590
Number of pages7
JournalJournal of Wildlife Management
Volume64
Issue number2
DOIs
StatePublished - Apr 2000
Externally publishedYes

Keywords

  • Ash
  • Aythya collaris
  • Blood lead concentration
  • Body composition
  • Body size
  • Condition bias hypothesis
  • Hunting mortality
  • Ingesta
  • Lipid
  • Protein

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Nature and Landscape Conservation

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