Slate-coloured Seedeater (Sporophila schistacea) Science Article 1
The idea of constant density and stable territoriality found in some tropical birds (Greenberg & Gradwohl1986) does not lend itse1f to species that rely on a short-term, unpredictable resource. One such resource is mast-seeding plants. Mast seeding is the synchronized production of seed at long intervals by a population of plants (Janzen 1976). This behavior is thought to be a reproductive strategy whereby plants satiate seed predators. The long or irregular periods between seed crops reduce predation by specialized seed predators only if the period between seeding is longer than the predator can endure (Janzen 1971, 1976j Willson 1983). This large quantity of synchronously produced seed attracts many predators, both local and nomadic. Because of its irregularity in space and time, mast is not a dependable food resource, and species that specialize on seeds from these plants must wander widely every year (Smith & Scarlett 1987).
Diane L Neudorf & Paul J. Blanchfield, ORNITOLOGIA NEOTROPICAL 5: 129-132