Macronutrient selection of free-ranging urban Australian white ibis (Threskiornis moluccus)

Anthropogenic habitats often provide urban wildlife the opportunity to feed on a range of nutritionally diverse foods, which may ultimately lead to human-wildlife conflict. The Australian white ibis (Threskiornis moluccus) provides an exemplar model for examining the nutritional priorities and constraints of a native vertebrate that is successfully transitioning to an urban specialist. Here, we used field-based feeding trials to investigate the macronutrient preferences of free-ranging ibis in Sydney, Australia. Feeding trials (n = 61) offering three experimental feeds showed that ibis selected significantly more high-carbohydrate (HC) than high-protein (HP) and high-lipid (HL) foods (95% CIHP-HC = −1.115 to −0.709; CIHL-HC = −1.874 to −1.468), and significantly more HP than HL (CIHL-HP = −0.962 to −0.556). The average proportion of macronutrient-derived energy selected by ibis was 25% protein (P; ± 1.1 SE): 23% lipid (L; ± 1.1): 52% carbohydrate (C; ± 1.8). Nutritional geometry suggest...