Effects of changes in bird community composition and species abundance on plant reproduction, through pollination and seed dispersal

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dc.contributor.author Anderson, Sandra H
dc.contributor.author Ladley, Jenny J
dc.contributor.author Robertson, Alastair W
dc.contributor.author Kelly, Dave
dc.date.accessioned 2021-11-11T04:46:38Z
dc.date.available 2021-11-11T04:46:38Z
dc.date.issued 2021-4-12
dc.identifier.issn 0019-1019
dc.identifier.uri https://hdl.handle.net/2292/57384
dc.description.abstract The consequences of global bird declines on ecosystem function are gaining increasing attention. Here we consider the effects of changes in bird community composition and species abundance on reproduction for two endemic plant species in New Zealand. Birds service a relatively high proportion of the New Zealand flora as both pollinators and seed dispersers, and bird losses have been extensive during the 700 years since human colonization. We compare fruit set and seed removal for plants in reserves free of introduced predators, where seven endemic flower and fruit visiting bird species were present and relatively abundant, with plants outside these reserves where endemic bird species were absent or at lower abundance. The study plants, Dysoxylum spectabile and Pittosporum crassifolium, have both flowers and fruit visited by birds. Both species are also dioecious (a characteristic that has not been commonly associated with bird-pollinated plants) and despite having mixed pollination systems, bird visits are essential for successful seed production. Outside introduced predator-free reserves, the winter-flowering D. spectabile was still visited by endemic pollinators and maintained pollination levels, despite a 59% decrease in endemic bird abundance. However, reduced endemic bird abundance was associated with a halving of pollination levels in P. crassifolium, which flowers in spring, as do other native and introduced flowering plants attractive to birds. The effect of altered bird species composition and abundance on seed dispersal was associated with a 74% reduction in seed dispersal for P. crassifolium. Additionally, undispersed seeds of P. crassifolium had lower germination, and higher pre-dispersal seed predation, compared with dispersed seeds. We stress three important aspects of these results: (1) for some plant species, the same bird species perform both pollination and seed dispersal, (2) dispersal reduces pre-dispersal seed predation, so that dispersal failure secondarily increases losses to seed predators, and (3) the effects of mutualism loss are not even across all species. Our results highlight that introduced species do not adequately replace endemic mutualists, which may be a particular problem for plant species with both bird-visited flowers and fruit.
dc.language en
dc.publisher Wiley
dc.relation.ispartofseries Ibis
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm
dc.subject 0602 Ecology
dc.subject 0608 Zoology
dc.title Effects of changes in bird community composition and species abundance on plant reproduction, through pollination and seed dispersal
dc.type Journal Article
dc.identifier.doi 10.1111/ibi.12938
pubs.issue 3
pubs.begin-page 875
pubs.volume 163
dc.date.updated 2021-10-01T03:29:26Z
dc.rights.holder Copyright: The author en
pubs.end-page 889
pubs.publication-status Published
dc.rights.accessrights http://purl.org/eprint/accessRights/RetrictedAccess en
pubs.subtype Journal Article
pubs.elements-id 849348
dc.identifier.eissn 1474-919X
pubs.online-publication-date 2021-4-12

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