Abstract
BackgroundAlthough assessing temporal dynamics of populations is crucial for understanding metacommunities, empirical studies have primarily analyzed only static snapshots of communities. Here, we present a holistic view of how species traits and habitat characteristics relate to metacommunity dynamics and use it to test for differences in the spatiotemporal distribution of seasonal bird assemblages.MethodsWe surveyed forest birds in breeding and winter seasons within 36 islands for 9 years. We then grouped birds into four landbird assemblages, selected on the basis of published differences in biology or ecology: winter residents, migratory winter visitors, breeding summer residents, and migratory summer visitors. We estimated dynamic species colonization and extirpation through the 9-year period, and evaluated the associations among island attributes, species attributes and community composition.ResultsOverall, winter and summer residents showed strong associations between composition and habitat structure of the islands. In addition, winter and summer residents on large islands had lower extirpation and turnover than winter and summer visitors. Visitor assemblages showed no significant habitat associations, and in winter had high extirpation rates and small body sizes. By contrast, local extirpation of summer visitors was correlated with local species richness, indicating a likely effect of competition on extirpation.ConclusionsOur results demonstrated repeated patterns among species composition, bird traits, habitat/island characteristics and observed metacommunity dynamics. Winter and summer residents best matched species sorting and patch dynamics, respectively, due to differences in resource availability and requirements of overwinter survival versus breeding. Summer visitors were consistent with species sorting and winter visitors were randomly distributed, likely because of interactions with resident competitors. Our results highlight that coexisting seasonal migrant and resident assemblages differ in their spatial dynamics, with consequences for relevant conservation and management strategies.
Highlights
Assessing temporal dynamics of populations is crucial for understanding metacommunities, empirical studies have primarily analyzed only static snapshots of communities
Patch dynamics assume that patches are identical and that species richness and composition are determined by species competitive ability and colonization ability (Leibold et al 2004)
As predicted by Hypotheses 1 and 3, average extirpation and island turnover rates were higher for winter visitors than for winter or summer residents, and lowest for summer visitors (Fig. 2d, f )
Summary
Assessing temporal dynamics of populations is crucial for understanding metacommunities, empirical studies have primarily analyzed only static snapshots of communities. Species sorting emphasizes environmental gradients (or habitat or patch types) causing species to have habitat-specific demography. In such a system, species are regulated by traits related to habitat-related niches, and dispersal is not sufficient to alter their distribution (Logue et al 2011). Mass effects assume that habitat-specific demography (e.g. along environmental gradients) and dispersal both affect species richness and composition (Leibold et al 2004). Neutral dynamics would be reflected by weak associations between community composition, species traits and environmental characteristics, and create high extirpation, colonization and turnover (Chave 2004)
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