Spatial and temporal variation in the avian-frugivore assemblage of Prunus mahaleb: patterns and consequences

摘要

The patterns of spatial and temporal sariatton in the species richness and relative abundance of frtigivorous birds that consume truits and disperse seeds of Pntoms otoltaleb (Rosaceae) were studied in two Southeastern Spain populations and compared svilh previous information from 4 sites. 3 of them iii Northwestern Spain. Data for S study years iii one population are usenl to assess temporal variation in tins trugivore assemblage. Species richness of local bird assemblages ranged between 6 and 26 species. Thrushes. redstarts, and warhlers were the main seed dispersers among a total of 31 species recorded for all sites pooled, and together account for 82% of the feeding records. Chaffinches and tits. acting as pulp consumers, were also important in at least tsvo highland assemblages. The propoi tional similarities for pai ‘wise compansoits among assemblages averaeed 0.3 I ± 1). 16. indicative of significant local s ariatioii iii assemblage eooipositiimn. Hoss ever, most differences ss crc bets ecu assemblages from the two geographic regions, with pairsvi se si nO larities between assernbl ages within a gis en region being significant. The relative importance of legitimate seed dispersers. pulp consumers, and seed predators varied significantly among sites, this variation being more pronounced than variability amoni! years ss ithin a site. The matrix of proptir i on il 5 iii I an ty among sites showed t. structured pat tern and w as strong1 correlated ss t th a matrix ol geographic di stance anioug them, The frugi vorous bt ml isiting P. oinlioleb show cr1 significant sintilarit and constancy among sites within a region and ataong ‘ears within a site. bitt subtle sat iations in the relative importance ud legitimate seed dispersers versus non-disperser species had meastirable effects on seed dispersal Average fruit removal and seed dispersal efficiency for oidis idual trees increased in sites or years is ith greater relative importance of legitimate seed dispersers in the frugivore assemblages. These variations and their potential effects could be very difficult to detect in short term studies hut mas has e demographic and es olutionary implications in this plant—frugivore interaction