I observed birds forage for flowers and fruits for six consecutive years in a North Island forest to compare patterns in insectivory and frugivory in plants that rely on birds for both mutualistic services. Birds visited fewer flowering plant species (n 9) than fleshy fruited plant species (n 23). Four ‘bird plant’ species were identified (i.e., plant species that are co-dependent on birds for both pollination and seed dispersal). Visitation rates to flowers produced by bird plants were correlated with visitation rates to fruits, indicating that if a bird plant relied heavily on a particular bird species to visit its flowers, it tended to rely on the same bird species to visit its fruits. Coupled rates of insectivory and frugivory raise a significant conservation concern, as it indicates that the loss of specific bird species may have a two-fold, negative effect on the reproductive fitness of plants that rely on birds for both pollination and seed dispersal.
Comparative ecology of bird-pollinated and bird dispersed New Zealand plants
Year: 2013