ECOLOGICAL CORRELATES OF RESIDENCE AND NON-RESIDENCE IN A MEDITERRANEAN PASSERINE BIRD COMMUNITY

(1) A southern Spanish passerine bird community was studied throughout a year, collecting information on species composition and abundance, as wellas foraging beha-viour and feeding site utilization of component species. In this paper, comparisons of behavioural, morphological and feeding site niche characteristics between resident and non-resident species are made. (2) For all species, within-species foraging diversity is significantly greater for non-resi-dent than for resident species, indicating that individual resident species have a narrower repertoire of foraging tactics than non-resident ones. On a seasonal basis, between-species foraging diversity for non-residents is higher than that for residents during spring and early summer, but it falls well below the figures for resident species in winter. (3) Resident species are morphologically more diversified and less densely packed in the morphological space than non-resident ones. Resident species tend to show a wider range of bill length, and to be long-billed, with respect to non-residents. (4) Resident species exhibited feeding site niche shifts in response to its own population density, higher densities promoting wider niches as theoretically expected. Non-resident