The abundance of essential vitamins in food chains and its impacton avian reproduction

Birds produce fewer or less viable eggs if the micro-nutrient requirements for reproduction cannot be met. Forexample, embryos from failed eggs of European sparrowhawks Accipiter nisus often show anomalies that indicate vitamin B2deficiency. B2 is only produced by plants and is propagated through the food chain. Here, egg B2 concentrations werecompared between habitats (great tit, Parus major), food chain levels (great tit and sparrowhawk), and within clutches (greattit). Invertebrates were sampled to detect food chain differences between habitats. The range of B2 concentrations was narrowand three times lower in sparrowhawks than in great tits. Repeatability of vitamin concentration within great tit clutches waslow. In poor habitat, there was a skew towards low vitamin levels. Because there were differences between habitats in invertebratedensity and composition, the question remains whether habitat differences in vitamin concentrations occur due todifferences in food abundance or its vitamin load.

Arnold B. van den Burg, Acta Zoologica Sinica 52(Supplement): 276-279, 2006