ABSTRACT
The ecology of seed dispersal by vertebrates has been investigated extensively over
recent decades, yet only limited research has been conducted on how suites of
invasive plants and frugivorous birds interact. In this review, we examine how plant
fruit traits (morphology, colour and display, nutritional quality, accessibility and
phenology), avian traits (fruit handling techniques, gut passage time and effect, bird
movements and social behaviour and dietary composition) and landscape structure
(fruit neighbourhood, habitat loss and fragmentation and perch tree effects) affect
frugivory and seed dispersal in invasive plants. This functional approach could be
used to develop generic models of seed dispersal distributions for suites of invasive
plant species and improve management efficiencies. Four broad research approaches
are described that could direct management of bird-dispersed invasive plants at the
landscape scale, by manipulating dispersal. First, research is needed to quantify the
effect of biological control agents on dispersal, particularly how changes in fruit
production and/or quality affect fruit choice by frugivores, dispersal distributions of
seed and post-dispersal processes. Second, we explore how seed dispersal could be
directed, such as by manipulating perch structures and/or vegetation density to
attract frugivorous birds after they have been foraging on invasive plant fruits. Third,
the major sources of seed spread could be identified and removed (i.e. targeting core
or satellite infestations, particular habitats and creating barrier zones). Fourth, alternative
food resources could be provided for frugivores, to replace fruits of invasive
plants, and their use quantified.
Keywords
Biological invasions, exotic species, frugivore, fruit, landscape, mutualism, plant
invasions, seed dispersal.