Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 590:211-226 (2018) - DOI: https://doi.org/10.3354/meps12500 Variable utilization of shelf break-associated habitats by chick-brooding rhinoceros auklets in the California Current System Bradley P. Wilkinson1,3,*, Jaime Jahncke2, Pete Warzybok2, Russell W. Bradley2, Scott A. Shaffer1 1Department of Biological Sciences, San José State University, San Jose, California 95192, USA 2Point Blue Conservation Science, Petaluma, California 94954, USA 3Present address: Department of Forestry and Environmental Conservation, and South Carolina Cooperative Fish and Wildlife Research Unit, Clemson University, Clemson, South Carolina 29634, USA *Corresponding author: bpwilki@g.clemson.edu ABSTRACT: Identifying frequently complex and dynamic spatial distributions of marine predators via the modeling of at-sea observations can be inherently challenging, especially when attempting to predict habitats of specific populations. Remotely-sensed tracking devices provide a viable alternative way to gather this information. We collected fine-scale spatiotemporal movement data for a small seabird, the rhinoceros auklet Cerorhinca monocerata, in the California Current System. Chick-brooding adults nesting on Southeast Farallon Island were outfitted with GPS loggers during the 2015 and 2016 breeding seasons (n = 15). Along with basic movement parameters, kernel density and residence time analyses were conducted to characterize at-sea distribution and identify areas of intensive use. Binomial generalized linear mixed modeling (GLMM) was used to assess foraging habitat. We found a greater utilization of areas beyond the shelf break than predicted by previous distributional models based on at-sea censuses. Interannual variation was evident, with relatively more outer break foraging in 2015 and relatively more shelf and inner break exploitation in 2016, although birds likely use the same habitat intrannually for self- and chick-provisioning. Prey availability and local oceanographic conditions may have influenced foraging decisions, with rockfish Sebastes spp. abundances and sub-mesoscale sea surface temperature (SST) fronts potentially acting as mediating factors. Results of mixed modeling highlighted a composite 3-way interaction between environmental variables facilitating auklet behavioral state switching, with an additional non-linear SST term being significant. Overall, foraging effort within the regional shelf break system appears to be variable at fine spatial scales depending on concomitant oceanographic conditions and related resource dynamics. KEY WORDS: Shelf break · Rhinoceros auklet · Cerorhinca monocerata · Spatial ecology · Foraging behavior · Residence time Full text in pdf format PreviousNextCite this article as: Wilkinson BP, Jahncke J, Warzybok P, Bradley RW, Shaffer SA (2018) Variable utilization of shelf break-associated habitats by chick-brooding rhinoceros auklets in the California Current System. Mar Ecol Prog Ser 590:211-226. https://doi.org/10.3354/meps12500 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 590. Online publication date: March 12, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.
Highlights
Assessing distributional trends and spatial use patterns is fundamental for uncovering many key aspects of population ecology and conservation
We evaluated the coverage by regional marine sanctuaries of the spatial extent of auklet foraging distributions using estimates of home and core ranges, Wilkinson et al.: Variable auklet habitat utilization with the prediction that these areas are spatially adequate to encompass the majority of auklet distribution
Auklets dispersed from and returned to a central place (SEFI) daily, with a majority of trips focusing on areas to the southwest of the colony
Summary
Assessing distributional trends and spatial use patterns is fundamental for uncovering many key aspects of population ecology and conservation. Spatial analytics can inform predictors of habitat selection (Shaffer et al 2009, Louzao et al 2011, Shaver et al.2017), foraging strategies (Weimerskirch et al 1997, Phalan et al 2007, Rodríguez et al 2017), and areas of significant biological importance across trophic guilds (Bost et al 2009, Block et al 2011). This is useful in complex environments with heterogeneously available resources. Incorporating distributional information across a wide range of predator guilds will help build knowledge of drivers of movement at the ecosystem level and aid in identifying broad-scale management solutions (Block et al 2016)
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