Linking frugivore behaviour to plant population dynamics: thrushes and fleshy-fruited trees in the Cantabrian range

MORALES, JUAN MANUEL; GARCIA, D.; MARTÍNEZ, D.; HERRERA, J. M.; SASAL, YAMILA

Le Corum, Montpellier

Simposio; 5th International Symposium-Workshop on Frugivores and Seed Dispersal; 2010

Centre d'Ecologie Fonctionnelle et Evolutive

We present results from simulations of frugivore-dispersed plant dynamics and observational studies of Turdus spp foraging for fruits to show that frugivore behaviour can have an important role in determining plant spatial distribution and abundance. Simulated plant dynamics showed increased clustering and smaller population sizes as dispersing agents were less willing to move larger distances while foraging. This tendency was further modulated by how selective animals were. Field work was conducted in a 400 x 440m plot in Sierra de Peña Mayor (Asturias, N Spain) during three fall-winter seasons (2007 to 2010). The plot was divided into 20x20m cells where we estimated forest cover and fruit abundance. We followed individual birds, recording their position and time spent on different perches and the species and number of fruits eaten on fleshy-fruited trees. Birds where highly mobile, but net travel distances from source plants were short, as birds frequently returned to the same feeding patches. Turdus merula and T. philomelos moved shorter distances and were more selective for fruit abundance than T. iliacus and T. viscivorus. Furthermore, T. iliacus was more associated to forest cover than T. viscivorus. Overall these movement behaviours would result in highly aggregated seed dispersal but with seeds deposited in open areas occasionally. However, in order to fully link seed dispersal patterns to plant demography, studies of plant establishment and survival are required.