Seasonal feeding habits of the Iberian bullfinch Pyrrhula pyrrhula iberiae in northwestern Spain

Abstract

The first comprehensive approach to the feeding ecology of Iberian bullfinches Pyrrhula pyrrhula iberiae is presented here. The target population inhabited hedgerows in northwestern Spain. Throughout a 6-year main period, the bullfinches were directly observed while searching for and consuming food. Interannual variation in diet was irrelevant, so data from all years were pooled. Availability of plant species and their selection as food resource was assessed. The general categories of food consumed varied significantly between seasons, with a high contribution of fleshy fruits in autumn–winter, tree buds in spring, and herb seeds in summer. The breeding season diet included a considerable proportion of invertebrates. Generally, sex- and age-related variations in diet were not significant throughout the seasons. Bullfinches preferred specific plant species as a food resource in each season and ignored others. The selected fleshy fruit seeds were small in size, in particular thickness, which probably made handling easier. The most consumed buds were numerous per cm of twig and were flower buds, which presumably provided, comparatively, high energy gain per unit time. Generally, favourite herb seeds were contained in small achenes, easy to handle and dehusk. Invertebrate prey identified was small insects and spiders. Bullfinches obtained most of their food while perching, regardless of sex or age, but some important fruits, and the arthropods, were frequently obtained in flight. The high diversity of woody plants and food sources found in hedgerows surely protected fruit trees from the detrimental effect of bullfinches and provided this passerine species with a wide range of habitat resources.