USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

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Albany, CA 94710-0011
(510) 883-8830
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Publications and Products

Title: Bottom-up processes influence the demography and life-cycle phenology of Hawaiian bird communities

Authors: Wolfe, Jared D.; Ralph, C. John; Wiegardt, Andrew

Date: 2017

Source Ecology. 98(11): 2885-2894


Changes in climate can indirectly regulate populations at higher trophic levels by influencing the availability of food resources in the lower reaches of the food web. As such, species that rely on fruit and nectar food resources may be particularly sensitive to these bottom-up perturbations due to the strength of their trophic linkages with climatically-influenced plants. To measure the influence of climatically-mediated, bottom-up processes, we used climate, bird capture, bird count, and plant phenology data from the Big Island of Hawaii to construct a series of structural equation and abundance models. Our results suggest that fruit and nectar-eating birds arrange life cycle events around climatically-influenced food resources, while some of these same food resources also influence seasonal patterns of abundance. This trend was particularly strong for two native nectarivores, ‘I'iwi and ‘Apapane, where we found that the dissimilar timing of molting and breeding activity was associated with peak abundance of the two most common flowers at our study site which, in turn, were each driven by dissimilar climatic cues. Given the rapidly changing Hawaiian climate, we suggest that determining behavioral plasticity, or evolutionary capacity of birds to mitigate changes in climatically-influenced food resources, should be recognized as a future research priority.

Keywords: bottom-up, climate, community ecology, food web, Hawaiian birds, plant phenology, structural equation models

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    Wolfe, Jared D.; Ralph, C. John; Wiegardt, Andrew. 2017. Bottom-up processes influence the demography and life-cycle phenology of Hawaiian bird communities. Ecology. 98(11): 2885-2894.
Last Modified: November 7, 2017