Abstract
The biodiversity hotspot of New Caledonia hosts high levels of endemism (74% of flora) that is threatened increasingly by climate change, habitat reduction, and invasive species. The fruit‐eating red‐vented bulbul (Pycnonotus cafer) is currently invading the main island of the archipelago, and its recent dispersal out of urbanized habitats raises questions about its potential to disperse noxious plant seeds along urban corridors and beyond. Indeed, the red‐vented bulbul is considered a vector of several introduced plant species in its alien range including Miconia calvescens, Lantana camara, and Schinus terebinthifolius. We conducted a quantitative assessment of the bulbul's fruits consumption by analyzing the gut contents of shot birds. We estimated gut passage times for four species of fruit found in gut contents (S. terebinthifolius, Myrtastrum rufopunctatum, Passiflora suberosa, and Ficus prolixa) and tested the effects of bird digestion on seed germination rates for two species. Finally, we monitored the movements of individual VHF radio‐tagged red‐vented bulbuls. All of the consumed fruit species we identified here have red fleshy diaspore, including fruit of the shrub M. rufopunctatum that occurred frequently (9.6%) in bulbul gut samples. Median gut passage times were short (15–41 min), corresponding to short‐distance seed transportation (77–92 m). The effect of gut passage was positive for the germination of the invasive S. terebinthifolius and negative for the endemic M. rufopunctatum, suggesting a potential bias in the contribution to the dispersal toward alien species. This study provides the first integrated assessment of mechanisms involved in the seed dispersal effectiveness of this high‐concern invasive bird species that is expected to face similar plant communities in most of its alien range in tropical islands. More generally, our results enhance knowledge of synergies between non‐native frugivores and plant species dispersal.
Highlights
| INTRODUCTIONConstruction, transportation, trade, and other human activities modify landscape structure, change plant and animal communities, drive changes in distribution patterns, and accelerate the rate of non-native species dispersal leading to increasing biological invasions (Gosper, Stansbury, & Vivian-Smith, 2005; Haddad et al, 2015; Hulme, 2009; Kokko & López-Sepulcre, 2006; McConkey et al, 2012; Ramaswami, Kaushik, Prasad, Sukumar, & Westcott, 2016; Richardson et al, 2000; Smart et al, 2006)
Thereby, dispersal has been explored from a variety of perspectives including its relevance to conservation biology (Levey, Silva, & Galetti, 2002; Primack & Miao, 1992; Trakhtenbrot, Nathan, Perry, & Richardson, 2005), restoration ecology (Bakker, Poschlod, Strykstra, Bekker, & Thompson, 1996; Ribeiro da Silva et al, 2015) and landscape ecology (Bacles, Lowe, & Ennos, 2006; Carlo & Morales, 2008)
The impact of passage through the gut of a red-vented bulbul on germination rates differed between the two fruit species we tested, with germination success of M. rufopunctatum seeds being significantly lower when they were collected from bulbul droppings compared with control seeds that had been extracted from their fruits, but the reverse was true for S. terebinthifolius
Summary
Construction, transportation, trade, and other human activities modify landscape structure, change plant and animal communities, drive changes in distribution patterns, and accelerate the rate of non-native species dispersal leading to increasing biological invasions (Gosper, Stansbury, & Vivian-Smith, 2005; Haddad et al, 2015; Hulme, 2009; Kokko & López-Sepulcre, 2006; McConkey et al, 2012; Ramaswami, Kaushik, Prasad, Sukumar, & Westcott, 2016; Richardson et al, 2000; Smart et al, 2006). Interactions between non-native and native species are complex, but so are interactions among introduced species (Parker, Burkepile, & Hay, 2006; Relva, Nunez, & Simberloff, 2010) This is encapsulated in Simberloff and Von Holle’s (1999) “invasional meltdown” hypothesis that postulates that mutualistic interactions between invaders can facilitate secondary invasions (Green et al, 2011). Concerns about the range expansion of this species derive from its ability to disperse non-native plant seeds more than native ones It feeds predominantly on fruits (Brooks, 2013; Islam & Williams, 2000) and can consume leaves, flowers, and fruits of a large variety of species (Thibault, Vidal, Potter, Dyer, & Brescia, 2018), leading to significant impacts on agriculture and horticulture (Cummings, Mason, Otis, Davis, & Ohashi, 1994; Vander Velde, 2002; Walker, 2008). Results are discussed with regard to the current range expansion of the red-vented bulbul, and their relevance to a broader understanding of the mechanisms and impacts of seed dispersal by non-native avian frugivores
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
