Sex and occupation time influence niche space of a recovering keystone predator

Predators exert strong effects on ecological communities, particularly when they re-occupy areas after decades of extirpation. Within species, such effects can vary over time and by sex, and cascade across trophic levels. We used a space-for-time substitution to make foraging observations of sea otters (Enhydra lutris) across a gradient of re-occupation (1–30 yrs), and nMDS analysis to ask if 1) sea otter niche space varies as a function of occupation time, and 2) if niche space varies by sex. We found that niche space varied among areas of different occupation times. Dietary niches at short occupation times were dominated by urchins (Mesocentrotus and Strongylocentrotus spp; > 60 % of diets) in open habitats at 10–40 m depths. At longer occupation times niches were dominated by small clams (Veneroida; > 30% diet), mussels (Mytilus spp; > 20% diet), and crab (Decapoda; > 10% diet) in shallow (< 10 m) kelp habitats. Diet diversity was lowest (H’ = 1.46) but energy-rich (~3...