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Stable Isotopes (δD, δ 13 C, δ 15 N) Reveal Associations Among Geographic Location and Condition of Alaskan Northern Pintails
Author(s) -
YERKES TINA,
HOBSON KEITH A.,
WASSENAAR LEONARD I.,
MACLEOD ROBB,
COLUCCY JOHN M.
Publication year - 2008
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.2193/2007-115
Subject(s) - feather , anas , boreal , habitat , taiga , ecology , geography , stable isotope ratio , isotope analysis , philopatry , δ13c , physical geography , biology , biological dispersal , demography , population , sociology , physics , quantum mechanics
Information on spring migration routes, geographic linkages among winter, spring, and breeding locations, and potential geographic effects on arrival body condition of northern pintails ( Anas acuta ) are currently unknown. Through a combination of stable‐isotope measurements of tissues representing different periods of dietary integration and body composition analyses, we examined these linkages for pintails breeding in Alaska, USA. We collected 77 females at 4 locations upon spring arrival. We performed carbon (δ 13 C), nitrogen (δ 15 N), and hydrogen (δD) isotope measurements on flight feathers, breast feathers, and whole blood, and we conducted body composition analyses. Inference based on stable‐isotope values in pintail tissues suggests that philopatry to Alaska was strong, as most of the collected females had stable‐isotope values consistent with the boreal forest of Canada or western Alaska and most spring migrating females had whole‐blood values indicating use of a food web in the boreal forest before collection. These patterns highlight the importance of the boreal forest for production and staging of pintails. Breast feather isotope values grown during prealternate molt were variable and covered the currently documented distribution of wintering pintails. Our results indicate associations among specific geographic areas, habitat use, and arrival condition of female pintails settling in Alaska. Females that wintered or staged in coastal habitat (as indicated by elevated δ 13 C values) arrived with less body fat compared to those that we inferred to have wintered or staged on inland freshwater habitat. Those females we inferred to use coastal areas appeared to rely more heavily on agricultural fields for nutrient acquisition (as indicated by elevated δ 15 N but low δ 13 C values). Our results provide the first link between low‐condition females and inferred use of specific geographic areas before arrival. Conservation on wintering grounds should focus on restoration and protection of wetland complexes that provide adequate natural food resources in proximity to coastal systems that are heavily used by wintering pintails. Conservation efforts should also focus on the boreal forest, not only for pintail, but for other boreal‐dependent species such as lesser scaup ( Aythya affinis ) (JOURNAL OF WILDLIFE MANAGEMENT 72(3):715–725; 2008)