The forgotten fauna: Native vertebrate seed predators on islands

Human colonization of islands has resulted in the reduction or loss of many native species, and the introduction of non‐native species, producing novel ecosystems. The impacts of these changes on mutualistic plant–animal interactions have received considerable attention, but the potential effects on...

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Bibliographic Details
Published in:Functional ecology Vol. 34; no. 9; pp. 1802 - 1813
Main Authors: Carpenter, Joanna K., Wilmshurst, Janet M., McConkey, Kim R., Hume, Julian P., Wotton, Debra M., Shiels, Aaron B., Burge, Olivia R., Drake, Donald R., Barton, Kasey
Format: Journal Article
Language:English
Published: London Wiley Subscription Services, Inc 01.09.2020
Subjects:
antagonism
Archipelagoes
Birds
Cluster analysis
Clustering
Colonization
Dispersal
Ecosystems
Endangered & extinct species
Environmental changes
Environmental impact
Extinct species
Extinction
fauna
functional diversity
granivores
Granivory
habitats
Herbivores
humans
Indigenous plants
Indigenous species
information
Introduced species
Islands
Native species
non‐native species
omnivores
Parrots
Passeriformes
Plant populations
plant–animal interactions
Pollination
population
Predation
Predators
Restoration
rodents
Seed dispersal
Seed predation
Seeds
Teeth
Vertebrates
ISSN:0269-8463, 1365-2435
Online Access:Get full text
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Summary:Human colonization of islands has resulted in the reduction or loss of many native species, and the introduction of non‐native species, producing novel ecosystems. The impacts of these changes on mutualistic plant–animal interactions have received considerable attention, but the potential effects on some antagonistic interactions, such as seed predation, are less thoroughly understood, and often overlooked. Using three archetypal island groups—New Zealand, the Mascarenes and Hawaiʻi—we compare the taxonomic richness and functional diversity of vertebrate seed predators from prehuman and contemporary ecosystems. We scored species on several traits relevant to seed predation, then clustered species into functionally similar groups using hierarchical clustering. These archipelagos once supported between 19 and 24 species of exclusively avian seed predators (representing two to four orders) ranging from large, flightless herbivores to small, volant finches and parrots. Following human arrival, 63%–89% of these species went extinct, and between 12 and 23 non‐native seed predators were introduced. Contemporary seed predator faunas consist of between 14 and 26 species (representing six to seven orders), dominated by non‐native granivorous birds and omnivorous mammals. Our results reveal several examples in which non‐native species may be functionally similar to extinct seed predators, but most non‐native species are functionally different from extinct species, and therefore may be introducing novel seed predation pressures for insular ecosystems. Mammalian seed predators are especially functionally different from the native avian seed predators, as their teeth and widespread habitat distribution allow them to destroy a more diverse range of seeds, including the largest seeds. We highlight the need to understand how these altered seed predator communities are affecting native plant populations, particularly in the context of reduced pollination and seed dispersal. More broadly, we argue that antagonistic interactions are an integral part of any ecosystem, and therefore must be understood if we are to achieve more holistic restoration frameworks for insular ecosystems. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.
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ISSN:0269-8463
1365-2435
DOI:10.1111/1365-2435.13629