Asian Tapirs Are No Elephants When It Comes To Seed Dispersal

The elimination of the largest herbivores (elephants and rhinoceroses) from many forests in tropical East Asia may have severe consequences for plant species that depend on them for seed dispersal. We assessed the capacity of Malayan tapirs Tapirus indicusthe next largest nonruminant herbivore in the regionas a substitute for the lost megafauna in this role by studying their ability to disperse the seeds of nine fleshy-fruited plants with seeds 597 mm in length. We combined information from feeding trials, germination tests, and field telemetry to assess the effect of tapir consumption on seed viability and to estimate how far the seeds would be dispersed. The tapirs (N=8) ingested few seeds. Seed survival through gut passage was moderately high for small-seeded plants (e.g., 36.9% for Dillenia indica) but very low for medium- (e.g., 7.6% for Tamarindus indica) and large-seeded (e.g., 2.8% for Artocarpus integer) plants. Mean seed gut passage times were long (63236 h) and only the smallest seeds germinated afterwards. Using movement data from four wild tapirs in Peninsular Malaysia we estimated mean dispersal distances of 9171287 m (range=223289 m) for small-seeded plants. Malayan tapirs effectively dispersed small-seeded plants but acted as seed predators for the large-seeded plants included in our study, suggesting that they cannot replace larger herbivores in seed dispersal. With the absence of elephants and rhinos many megafaunal-syndrome plants in tropical East Asia are expected to face severe dispersal limitation problems.