Comparing dietary preferences of Bufflehead duckli

Authors: J P Hornung A L Foote

Publish Date: 2007/02/21

Volume: 42, Issue: 1, Pages: 61-70

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Abstract

Aquatic invertebrates are essential for duckling growth and development We present results on the trophic status and dietary analysis of Bufflehead Bucephala albeola ducklings from the boreal breeding grounds of western Canada We estimated dietary preference by comparing invertebrates found in Bufflehead diets to those identified in standardized dip net samples at their wetland feeding sites Stable isotope ratios of Bufflehead and their prey were used as a second estimator of trophic position Bufflehead ducklings preferentially foraged for larval Dytiscidae predaceous diving beetles 46 of total dietary biomass Zygoptera larvae damselflies 14 and nonDytiscidae adult Coleoptera 5 mainly Haliplidae Results from stable isotope analyses supported these results the separation between primary and secondary invertebrate consumers and ducklings was significant for all possible contrasts when considering nitrogen isotope ratios Tukey HSD P  0001 We iteratively explored all possible combinations of δ15N and δ13C data to generate a proportional range over which each food source may contribute to Bufflehead stable isotope signatures these results suggested larval Zygoptera and larval Dytiscidae figure prominently in diets when accounting for isotope fractionation The incorporation of prey availability into the metric of dietary preference as opposed to the tabulation of ingested items alone reduces the importance of invertebrate groups such as adult Dytiscidae as highlighted in previous studiesWe acknowledge the diligent work provided by the field workers employed during this study Neil Jeffrey and Christine Hornung and Stephanie Neufeld The manuscript was greatly improved by several anonymous reviewers We thank the members of the Hydrology Ecology and Disturbance HEAD research group at the University of Alberta and Waterloo for their help and guidance Funding and support was provided by Circumpolar/Boreal Alberta Research C/BAR Grants through the Canadian Circumpolar Institute and NSERC Collaborative Research and Development Grant to the HEAD research group

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