Reassessing the importance of granivorous pigeons as massive, long-distance seed dispersers.

Long-distance dispersal (LDD) of plants remains as a little-understood, key ecological process. We present evidence indicating that granivorous pigeons may disperse large amounts of viable seeds when they die with seeds in their crops at long distance from the parent plant. Research was conducted in Eared Dove (Zenaida auriculata) breeding colonies in central Argentina where breeding populations may reach over 8000 doves/ha. We measured (a) crop seed viability and germination rate from dead doves and (b) daily travel distance from the breeding colonies to the feeding grounds. Seed viability was over 50% in fresh adult and nestling samples. Seed-germination rate ranged between 35% and 65%, even in corpses left on the ground for 30 days. Maximum doves' daily flight distance from the breeding colonies was 117 km. The estimated annual seed deposition per hectare resulting from crop spillage in two breeding colonies was 10.95 and 9.66 Mg, respectively. Significant ecological implications of dove-crop spillage include seed dispersal among fragments, rapid colonization of new habitats including islands, and dispersal of large volumes of weed and transgenic material. A preliminary assessment of dispersal kernel generated by crop spillage in colonial Eared Doves is included.