Combined usage of stable isotopes and GPS-based telemetry to understand the feeding ecology of an omnivorous bird, the Ring-billed Gull (Larus delawarensis)

The aim of the present study was to investigate the feeding ecology of an omnivorous bird, the Ring-billed Gull (Larus delawarensis Ord, 1815), breeding in a highly urbanized and heterogeneous landscape (Montréal area, Quebec, Canada). We used gastrointestinal (G.I.) tract content analysis, GPS-based tracking information, and stable isotope profiles of carbon (δ 13 C) and nitrogen (δ 15 N) in selected tissues and major food items. Based on GPS...