Seed Dispersal ofAmyema preissiiandLysiana exocarpiby Mistletoebirds and Spiny-cheeked Honeyeaters

Abstract

This study examines the role of two species of bird, the Mistletoebird Dicaeurn hirundinaceurn and the Spiny-cheeked Honeyeater Acanthagenys rufogularis, in dispersing seeds of two mistletoe species, Arnyerna preissii and Lysiana exocarpi, in arid South Australia. For both mistletoe species, fruiting peaked around May and lasted until late winter. Spiny-cheeked Honeyeaters and Mistletoebirds were the two most important consumers of mistletoe fruit, accounting for more than 99% of observed feeding visits. For both bird species, the number of feeding visits per hour decreased from peak fruiting season to post-peak fruiting season. Similarly, the number of fruits eaten per feeding visit by Spiny-cheeked Honeyeaters declined from peak fruiting season to late season. In contrast, the number of fruits consumed per visit by Mistletoebirds remained relatively constant over the fruiting seasons. Seeds defecated by the two bird species had high germination rates, suggesting both Spiny-cheeked Honeyeaters and Mistletoebirds are seed dispersers of the two mistletoe species.