The fate of seeds dispersed by monkeys was evaluated to determine which seeds germinate and if seedlings grown from fecal samples are later re-ingested by monkeys. For the past 30 years, two naturalized monkey species, Macaca mulatta and Erythrocebus patas, have formed permanent colonies on and around the slopes of the Sierra Bermeja in the southwest of Puerto Rico.  Fifteen fecal samples were collected per month for a period of six months.  Each month, seeds were dissected from 10 of the fecal samples and identified by comparing the seeds found in fecal samples to the seeds of plants fruiting in the study area.  The remaining five fecal samples were planted in pots with potting soil and monitored for seed germination.  Seedlings grown from fecal samples were returned to the study site and monitored 24 hours per day with an automatic infrared camera.    

Results/Conclusions

We have identified four native: Lantana sp., Pilosocereus royenii, Capparis cynophallophora, and Coccoloba venosa and three non-native plant species: Solanum americanum, Tamarindus indica, Panicum maximum  in dissections of 46 of the fecal samples. Experiments of planting fecal samples in pots revealed that an assortment of seeds:  Lantana sp., Ipomea sp., and Tamarindus indicus successfully survive the digestive tract of monkeys.  Field photos of potted plants have captured M. mulatta visiting and defoliating seedlings.  These preliminary results indicate that:  1) monkeys are consuming the fruits of both native and non-native plants, 2) the seeds of some fruit ingested by monkeys remain viable, and 3) monkeys may negatively affect seedlings, post dispersal, by consuming their leaves.  This study, while inconclusive, underscores the importance of considering the fate of seedlings especially in research where the agent of dispersal is being evaluated as beneficial or not.