Relative influence of static and dynamic features on black‐footed albatross (Phoebastria nigripes) habitat use in central California Sanctuaries

Abstract

Effective conservation of highly mobile species requires an understanding of the factors that influence their habitat use patterns, locally and within a large‐scale oceanographic context. We characterized the seasonal (chick‐rearing, post‐breeding) and inter‐annual (2004–2008) distribution and abundance of black‐footed albatross (Phoebastria nigripes; BFAL) along the central California continental shelf/slope using standardized vessel‐based surveys. We used a hypothesis‐based information‐theoretic approach to quantify the relative influence of environmental conditions on BFAL occurrence and abundance by assessing their association with: (i) local static bathymetric features, (ii) local and regional dynamic oceanographic processes, and (iii) seasonal and inter‐annual basin‐wide variability. While the presence/absence models yielded stronger results than the abundance models, both revealed that static and dynamic features influence BFAL habitat use. Specifically, occurrence was greatest near the shelf‐break, particularly in months with strong upwelling. High BFAL densities were associated with Rittenburg Bank, especially during the chick‐rearing season, periods of positive North Pacific Gyre Oscillation index and large northern monthly upwelling, evidenced by cool, salty waters in the study area. BFAL aggregation intensity was greatest onshore of the shelf‐break (200 m isobath). Behavioral observations reinforced the notion that transiting BFAL are widely dispersed near the shelf‐break and concentrate in large flocks of birds sitting on the water farther onshore. These results underscore the need to consider oceanographic processes at multiple spatial scales when interpreting changes in BFAL dispersion within marine sanctuaries, and highlight the feasibility of implementing bathymetrically defined protected areas targeting predictable BFAL aggregations within these larger management jurisdictions.

Topographic determinants of mobile vertebrate predator hotspots: current knowledge and future directions

“…(5) In particular, current contentions over the effectiveness of protected areas for mobile taxa have made ocean zoning a topical issue in the marine arena (Agardy et al ., ; Williams, ReVelle & Levin, ). Despite the fact that oceanic reserves may need to be framed around adaptive dynamic boundaries (Hooker et al ., ), we claim that large bathymetric features should still provide a robust initial foundation for delineating potentially important marine predator habitats, a view shared by an increasing number of authors (Hyrenbach, Forney & Dayton, ; Michael, Jahncke & Hyrenbach, ). This may be especially relevant in the remote and relatively inaccessible high seas, where biological data remain sparse and ephemeral drivers of wildlife dynamics, like prey availability, are hard or impossible to assess (Grémillet et al ., ).…”

“…Jahncke & Hyrenbach, 2014). This may be especially relevant in the remote and relatively inaccessible high seas, where biological data remain sparse and ephemeral Biological Reviews 90 (2015) 699-728 © 2014 The Authors.…”

Continental‐scale hotspots of pelagic fish abundance inferred from commercial catch records

“…Sparse ecological data in remote offshore waters [i.e., beyond the territorial sea baseline, both within exclusive economic zones (EEZs) and beyond; Webb, Vanden Berghe, & O'Dor, ] make the direct identification of critical habitat difficult and call for robust surrogates of biological diversity to predict, delineate and prioritize candidate sites for zoning (McArthur et al, ). Complex topography has been recognized as a determinant of wildlife dynamics across numerous taxa (Bouchet, Meeuwig, Salgado Kent, Letessier, & Jenner, ), which suggests that locating protected areas over sites of rugged terrain could yield a range of conservation gains (Harris & Whiteway, ; Michael, Jahncke, & Hyrenbach, ). Morato et al (), Morato, Hoyle, Allain, and Nicol () and Worm, Lotze, and Myers () illustrated this possibility in the open ocean by showing that North Atlantic and Pacific seamounts were important centres of taxonomic richness of special interest for the management of threatened vertebrates.…”

Scale of inference: on the sensitivity of habitat models for wide‐ranging marine predators to the resolution of environmental data

“…depth) and dynamic (e.g. sea surface temperature, SST) environmental variables are widely used in model construction (Michael et al ). Remotely‐sensed data fields are most often used as dynamic variables (Block et al , Nur et al , Becker et al , Pikesley et al ), although oceanographic models (e.g.…”