Open AccessVariation in isotopic niche, digestive tract morphology, and mercury concentrations in two sympatric waterfowl species wintering in Atlantic Canada
Author(s) -
Matthew D. English,
Gregory J. Robertson,
Nelson J. O’Driscoll,
Sara J. Klapstein,
Liam E. Peck,
Mark L. Mallory
Publication year - 2020
Publication title -
facets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 9
ISSN - 2371-1671
DOI - 10.1139/facets-2019-0056
Subject(s) - anas , niche , ecological niche , sympatric speciation , waterfowl , biology , ecology , niche segregation , interspecific competition , competition (biology) , niche differentiation , habitat , zoology
Sympatric communities of organisms may exploit different ecological niches to avoid intra- and interspecific competition. We examined the isotopic niches of American black ducks ( Anas rubripes) and mallards ( A. platyrhynchos) wintering in coastal and urban areas of Atlantic Canada and compared isotopic niche with digestive tract morphologies and blood mercury (Hg) concentrations. Isotopic niche width (for δ 13 C and δ 15 N) varied between the three groups of ducks studied, with coastally foraging black ducks exhibiting the widest isotopic niche, followed by coastal mallards, while urban feeding black ducks had a narrow isotopic niche. These niche differences had physical and chemical consequences: coastal black ducks had longer digestive tracts, a larger range in gizzard sizes, and higher and more variable Hg concentrations than urban black ducks and coastal mallards. This plasticity in ecological niche may reduce competition among and within species, and subsequently explain why winter numbers of black ducks and mallards have increased in Atlantic Canada.