Quantifying the seed shadow generated by a disperser, which is the way seeds are
distributed as a function of both the time seeds are retained in its digestive tract and of
its ranging patterns through the habitat, is a key step to assess the impact of the seed
disperser on structuring and functioning of plant populations and communities. This is
the first study concerning the primate S. bicolor as a seed disperser and aimed to
investigate the formation pattern of seed shadow in relation to the ranging patterns of
the species. The moving of four groups of S. bicolor was monitored in three forest
fragments in Manaus, Central Amazonia. The position of the animals in a trail grid was
registered at five minutes intervals over the whole period of activity for five days a
month over at least 15 months each group. The seed retention time were estimated by
records of the time of ingestion, defecation and number of seeds of five species of
cultivated fruits offered to four captive tamarins. Seed shadows were estimated by
combining ranging patterns data with the seed retention time data. To each group, mean
dispersal distance and the proportion of the home range used were obtained on a
monthly basis, and their relation was accessed by a simple linear regression. The seed
retention time ranged from 27 to 295 minutes (N = 394), with more than half of the
seeds being retained up to two hours in the gut, and average number of seeds per
defecation was 3,5 (± 3,7; N = 111). Probabilities of seed dispersal out of the vicinity of
the parent plant are greater than 80% besides including distances greater than 1 km. For
only two groups was verified a relation between the proportion of home range used and
the dispersal distance, on a monthly basis, and one of them the explanatory power of
the model reached less than 20%. The results indicate that S. bicolor disperses seeds
effectively and, like other callitrichines, may contribute to the structuring and
regeneration of forest ecosystems.
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