AVIS-IBIS

Birds of Indian Subcontinent

Tracing Nutrient Allocation to Reproduction with Stable Isotopes: A Preliminary Investigation Using Colonial Waterbirds of Great Slave Lake

Publication Type:Journal Article
Year of Publication:2000
Authors:Hobson, KA, Sirois, J, GLOUTNEY, MARKL
Journal:The Auk
Volume:117
Issue:3
Date Published:2000
ISBN Number:00048038
Keywords:Chlidonias, Chlidonias niger, Chlidonias nigra, Hirundo, Hydroprogne, Hydroprogne caspia, Hydroprogne tschegrava, Laridae, Larus, Larus argentatus, Larus cachinnans, Larus canus, Larus vegae, Niger, Paradisaea, Stercorariidae, Stercorarius, Stercorarius parasiticus, Sterna, Sterna caspia, Sterna hirundo, Sterna nigra
Abstract:We investigated the use of stable-isotope analysis as a direct means of tracing allocation of endogenous protein and lipid reserves to reproduction in five gulls (Larus canus, L. delawarensis, L. californicus, L. argentatus, L. philadelphia), four terns (Sterna caspia, S. hirundo, S. paradisaea, Chlidonias niger), and one jaeger (Stercorarius parasiticus) breeding on Great Slave Lake (GSL) in the Northwest Territories. Our approach was based on assumptions that (1) body tissues of birds just arriving at GSL from their assumed marine-associated wintering habitats would have stable-isotope ratios more enriched than those of birds in equilibrium with the local GSL foodweb, and (2) mobilization of these reserves to reproduction could be traced by the isotopic measurement of egg macronutrients. As predicted, the pectoral muscle of six species of arriving birds was more enriched in 13 C (x̄ = -21.5‰) and 15 N (x̄ = 12.7‰) than was that of postbreeding birds (13 C, x̄ = -23.5‰; 15 N, x̄ = 9.9‰) or hatching-year birds raised at GSL (13 C, x̄ = -24.3‰; 15 N, x̄ = 9.0‰). Abdominal fat of arriving Herring Gulls and Mew Gulls was more enriched in 13 C (x̄ = -19.7‰) than the fat of other species (x̄ = -23.4‰), indicating lipids of marine origin. We compared isotope values of the local GSL foodweb with dietary values predicted from isotope measurements of egg macronutrients if diets were entirely derived at GSL. Isotopic analysis of lipid-free egg yolk, yolk lipid, and shell carbonate suggested that for most species, little if any endogenous protein reserves were used for reproduction, with the possible exception of Caspian Terns, whose egg protein and egg lipid values, and Common Terns, whose egg protein values, were more enriched in 13 C than those of the other species. Although endogenous nutrient reserves likely were important to birds during migration and the initial settling period at GSL, local food supplies were adequate to provide nutrients for reproduction.
URL:http://www.jstor.org/stable/4089600
Short Title:The Auk
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith