The Pacific Banyan in the Cook Islands: have its pollination and seed dispersal mutualisms been disrupted, and does it matter?

Abstract

Fig trees (Ficus spp., Moraceae) are pollinated by species-specific fig wasps and have seeds that are mainly dispersed by fruit bats and birds. Consequently, they should be strongly dependent on mutualisms with animals for their reproductive success. As elsewhere in the Pacific, extinctions of potential seed dispersers have occurred on the islands in the southern Cook Islands archipelago. The abundance of the Pacific Banyan, Ficus prolixa, was found to be unrelated to the extent of potential seed disperser extinctions on different islands. There was no evidence of recruitment on Rarotonga, which has the most diverse bird and bat assemblage, and healthy populations on Mangaia, where all the native avian frugivores are extinct. Despite its very small population sizes on some of the islands, the trees pollinators are still present, showing that this mutualism has not yet been disrupted. Habitat loss, rather than a loss of mutualists, appears to be the main problem facing this species.