Eating the fruit of passion: bird functional traits and geography explains fruit removal by frugivorous birds in Blue Passionflower (Passiflora caerulea)

PALACIO, FACUNDO X.; CATAUDELA, J. FRANCISCO; ORDANO, MARIANO; MONTALTI, DIEGO

New Jersey

Congreso; Joint Meeting of the Wilson Ornithological Society and the Association of Field Ornithologists; 2019

Wilson Ornithological Society and the Association of Field Ornithologists

Geographic variation in bird-fruit interactions represents a complex ecological scenario which determinesa mosaic of selection pressures between interactors. This mosaic may partly the result from geographicvariation in bird assemblages, in which birds are expected to fulfil different ecological functions withstrong consequences for seed dispersal patterns. However, the drivers of fruit removal by birds at ageographical scale are not fully understood. We described geographic variation in fruit removal andfunctional diversity (FD) of frugivorous bird assemblages among Blue Passionflower (Passifloracaerulea) populations, a bird-dispersed vine. We observed bird fruit consumption and frugivorous birdabundance in nine plant populations from northern and central Argentina (spanning 10° of latitude, 0-1250 masl, three biogeographical provinces). We quantified FD of frugivorous bird assemblages on thebasis of body mass, fruit-handling behavior (gulper, pulp consumer or seed predator), and degree offrugivory. We recorded 14 bird species consuming passionflower fruits and detected a non-linear trend ofhigher frugivorous bird FD towards lower latitudes. Also, the number of birds consuming fruits (visits)per plant was negatively related to latitude, the proportion of gulper species, the degree of frugivory, andmean body mass. The Blue Passionflower shows functionally diverse frugivorous bird assemblagesthroughout its distribution range, which seems mainly driven by biogeographical factors at thegeographical scale. At the population level, seed dispersal is presumably enhanced by small-sizedgeneralist pulp consumers, whereas large birds may compensate lower visitation rates by increased fruitconsumption.