The influence of oceanographic and terrestrial attributes on marbled murrelet (Brachyramphus marmoratus) marine habitat selection during the breeding season.

We examined how oceanographic and terrestrial features influence marine habitat selection by radio-tagged marbled murrelets (Brachyramphus marmoratus), and how selection varies temporally, geographically and with respect to reproductive status. Murrelet marine habitat selection was simultaneously affected by sea surface temperature and nearshore environment characteristics, as well as distance to nest site for breeders, with lesser influence by physical oceanographic features. Marbled murrelets were generally associated with areas characterized by higher relative tidal speeds, greater depths, steeper ocean floor slopes, less freshwater inflow and proximity to sandy beaches, though the strength of these relationships varied. Breeding murrelets were also associated with proximity to nest sites. We observed within-season and between-site variability in murrelet-SST associations, suggesting that murrelets change their foraging tactics as their needs and/or local oceanographic conditions change. We suggest that availability of suitable nesting habitat within proximity of profitable marine foraging areas is critical for recovery of this species.