Poachers Also Disrupt Plants

"Poachers are nearly ubiquitous in the Neotropics," says Joseph Wright of the Smithsonian Tropical Research Institute in Balboa, Panama. "They are reducing the abundance of forest mammals virtually everywhere." Wright and his colleagues reasoned that poachers are probably also affecting forest plants, in part because many of the seeds are dispersed by mammals.

Wright's colleagues are: Roberto Ibanez, also of the Smithsonian Tropical Research Institute in Balboa, Panama; Horacio Zeballos of the Prodefensa de la Naturaleza-Arequipa in Miraflores, Peru; and Ivan Dominguez, Marina Gallardo and Marta Moreno of the Autoridad Nacional del Ambiente in Panama.

The researchers studied how poaching affects regeneration of two palm species in central Panama. They studied eight sites with different levels of poaching. They measured seedling abundance, and seed dispersal and predation.

Wright and his colleagues found that poaching reduced the abundance of five of the 12 mammal species encountered regularly at the study sites, including agouti, collared peccari and coati. Overall, the researchers found that poaching increased palm regeneration: seedling density was up to five times higher at heavily poached sites.

However, the effects of poaching on seed dispersal and predation did not uniformly favor palm regeneration. Specifically, poaching reduced seed dispersal: up to 99% of seeds were dispersed from protected sites but only 3% were dispersed from heavily poached sites. Poaching increased beetle predation of dispersed seeds: beetles ate up to 10% of seeds at protected sites and about 40% at poached sites. Poaching decreased rodent predation of dispersed seeds: rodents ate up to 99% at protected sites and only 4% at heavily poached sites.

What does it all mean? "There is no single relation between the reduction of mammal communities and plant regeneration," says Wright. "We can only be certain that poachers will alter the natural pattern of regeneration for many plant species." In other words, there's no easy fix.