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Placing local aggregations in a larger-scale context: hierarchical modeling of black-footed albatross dispersion

Citation

Michael, PE and Jahncke, J and Hyrenbach, KD, Placing local aggregations in a larger-scale context: hierarchical modeling of black-footed albatross dispersion, PLoS One, 11, (4) Article e0153783. ISSN 1932-6203 (2016) [Refereed Article]


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Copyright Statement

Copyright: © 2016 Michael et al. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.1371/journal.pone.0153783

Abstract

At-sea surveys facilitate the study of the distribution and abundance of marine birds along standardized transects, in relation to changes in the local environmental conditions and large-scale oceanographic forcing. We analyzed the form and the intensity of black-footed albatross (Phoebastria nigripes: BFAL) spatial dispersion off central California, using five years (2004–2008) of vessel-based surveys of seven replicated survey lines. We related BFAL patchiness to local, regional and basin-wide oceanographic variability using two complementary approaches: a hypothesis-based model and an exploratory analysis. The former tested the strength and sign of hypothesized BFAL responses to environmental variability, within a hierarchical atmosphere—ocean context. The latter explored BFAL cross-correlations with atmospheric / oceanographic variables. While albatross dispersion was not significantly explained by the hierarchical model, the exploratory analysis revealed that aggregations were influenced by static (latitude, depth) and dynamic (wind speed, upwelling) environmental variables. Moreover, the largest BFAL patches occurred along the survey lines with the highest densities, and in association with shallow banks. In turn, the highest BFAL densities occurred during periods of negative Pacific Decadal Oscillation index values and low atmospheric pressure. The exploratory analyses suggest that BFAL dispersion is influenced by basin-wide, regional-scale and local environmental variability. Furthermore, the hypothesis-based model highlights that BFAL do not respond to oceanographic variability in a hierarchical fashion. Instead, their distributions shift more strongly in response to large-scale ocean—atmosphere forcing. Thus, interpreting local changes in BFAL abundance and dispersion requires considering diverse environmental forcing operating at multiple scales.

Item Details

Item Type:Refereed Article
Keywords:black-footed albatross, dispersion, modeling, distribution
Research Division:Environmental Sciences
Research Group:Environmental Science and Management
Research Field:Environmental Management
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Environmental Sciences
Author:Michael, PE (Ms Pamela Michael)
ID Code:114484
Year Published:2016
Deposited By:Centre for Ecology and Biodiversity
Deposited On:2017-02-16
Last Modified:2017-03-31
Downloads:18 View Download Statistics

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