bird dispersal

The New Zealand mountain flora is rich in fleshy-fruited species but many terrestrial frugivorous birds are extinct or declining, potentially putting seed dispersal mutualisms at risk. To determine whether fruits are currently being removed by animals, we measured removal rates of eight fleshy-fruited mountain plant species from five families over two fruiting seasons, at two sites in inland Canterbury. We compared fruit removal rates within cages (no animal access to fruits), on unmanipulated plants (open-access to fruits by all animals), and within lizard-only cages (large mesh).

The dispersal, germination and establishment of the New Zealand Loranthaceae (Alepis flavida, Peraxilla colensoi, P. tetrapetala, Ileostylus micranthus and Tupeia antarctica) were investigated. The most important bird dispersers were tui, bellbirds and silvereyes. These birds appear to provide reasonably good quality dispersal: fruits were swallowed whole and the seeds later defecated in germinable condition; birds tended to visit plants for only 1-2 minutes and eat a few mistletoe fruits each time.