Birds and guelder rose Viburnum opulus: selective consumption and dispersal via regurgitation of small-sized fruits and seeds

摘要: The evolution of fleshy fruit size, in particular bird-dispersed plants, is believed to be influenced by the size seed-dispersing vertebrates through gape limitation. Also, it has been demonstrated that seed correlates positively with especially single- or few-seeded fruits. However, there little evidence current selection pressure disperser birds on and within populations a plant species. In present study, this aspect was investigated guelder rose Viburnum opulus (Caprifoliaceae) consumption an area NW Spain. Guelder fruits are sub-globose drupes can exceed 11 mm width, single hard up 8.5 width. Most seeds were dispersed robin Erithacus rubecula (gape width < 8 mm) small thrush, song thrush Turdus philomelos mm), which swallowed whole, some destroyed bullfinch Pyrrhula pyrrhula. regurgitated rather than defecated birds, probably because limited gut processing. mean ingested smaller diameter droppings, turn available plants. As winter progressed, only larger remained plants (seed correlated), increased. Thus, largest consumed less exposed seed-predators (bullfinches climbing rodents) for longer. Selection must therefore effective dispersal stage study area.