Abstract
Aim: Species distributions across islands are shaped by dispersal limitations, environmental filters and biotic interactions but the relative influence of each of these processes has rarely been assessed. Here, we examine the relative contributions of island characteristics, marine subsidies, species traits, and species interactions on avian community composition. Location: Central Coast region of British Columbia, Canada. Taxon: Terrestrial breeding birds. Methods: We observed 3610 individuals of 32 bird species on 89 islands that spanned multiple orders of magnitude in area (0.0002–3 km2). We fit a spatially explicit joint species distribution model to estimate the relative contributions of island physical characteristics, island-specific inputs of marine subsidies, species' traits, and biotic interactions on species distributions. Biogeographic characteristics included island area, isolation, and habitat heterogeneity, while marine influence was represented by forest-edge soil δ15N, wrack biomass, shoreline substrate, and distance to shore. This approach also allowed us to estimate how much variation in distributions resulted from species' biological traits (i.e. body mass, feeding guild, feeding height, and nesting height). Results: Bird species distributions were determined almost equivalently by island biogeographic characteristics (23.5% of variation explained) and marine influence (24.8%). We detected variation in species-specific responses to both island biogeographic characteristics and marine influence, but no significant effect of any biological trait examined. Additionally, we found evidence that habitat preferences were a more important driver than competitive interactions. Main Conclusions: Although most island biogeographic studies focus only on islands' physical characteristics, we found evidence for an equivalent role of marine subsidy in structuring island bird communities. Our study suggests that for small islands, disentangling the effects of island biogeographic characteristics, marine inputs, and biotic interactions is a useful next step in understanding species distributions.
| Original language | English |
|---|---|
| Pages (from-to) | 40-53 |
| Number of pages | 14 |
| Journal | Journal of Biogeography |
| Volume | 51 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 2024 |
Bibliographical note
Publisher Copyright:© 2023 The Authors. Journal of Biogeography published by John Wiley & Sons Ltd.
Funding
We are grateful to the Haíɫzaqv and Wuikinuxv First Nations for their support in conducting this research. We also thank many field and laboratory technicians for their hard work on the ‘100 Islands’ project, particularly the bird crew: Kate Prince, Ian Thomas, Janine McManus, Rob White, Blair Dudeck and Julian Heavyside. Thank you also to the Hakai Institute staff at the Calvert Island Ecological Field Station for field and laboratory support, and to Carl Humchitt for his guidance and knowledge both on the water and on land. In addition, we thank members of the Reynolds lab and the Earth to Ocean Research Group, as well as Dr. David Green, Dr. Leithen M'Gonigle and Dr. Richard Johnston for their input and statistical advice. This work was supported by the Hakai Institute (Tula Foundation), MITACS, NSERC Discovery Grants to J.D.R., B.M.S. and C.T.D., NSERC CGS-M and CGS-D grants to DSO, and a Fisheries and Oceans Canada Aquatic Science Supplement to DSO. This study was conducted with permission from both Haíɫzaqv (Heiltsuk) and Wuikinuxv governments. It was also conducted in British Columbia Provincial Protected Areas within the Hakai Lúxvbálís Conservancy, the Calvert Island Conservancy, the Outer Central Coast Islands Conservancy, the Penrose Island Marine Provincial Park and the Penrose-Ripon Conservancy under BC Parks Permit no. 107190. Avian point count surveys were conducted under SFU Animal Care Permit no. 1165B-15. This work was supported by the Hakai Institute (Tula Foundation), MITACS, NSERC Discovery Grants to J.D.R., B.M.S. and C.T.D., NSERC CGS‐M and CGS‐D grants to DSO, and a Fisheries and Oceans Canada Aquatic Science Supplement to DSO. This study was conducted with permission from both Haíɫzaqv (Heiltsuk) and Wuikinuxv governments. It was also conducted in British Columbia Provincial Protected Areas within the Hakai Lúxvbálís Conservancy, the Calvert Island Conservancy, the Outer Central Coast Islands Conservancy, the Penrose Island Marine Provincial Park and the Penrose‐Ripon Conservancy under BC Parks Permit no. 107190. Avian point count surveys were conducted under SFU Animal Care Permit no. 1165B‐15.
| Funders | Funder number |
|---|---|
| Fisheries and Oceans Canada Aquatic Science Supplement | |
| Not added | 1165B-15, 107190 |
| Tula Foundation | |
| Natural Sciences and Engineering Research Council of Canada | |
| Mitacs |
Keywords
- avian ecology
- biotic interactions
- community structure
- habitat filter
- island biogeography theory
- joint species distribution model
- marine-derived nutrients
- species composition
- terrestrial birds