Specializing in order to generalize: fidelity to foraging areas is modulated by flexible fine-scale habitat use in Hudsonian Whimbrel (Numenius hudsonicus)

Many mobile organisms exhibit fidelity to specific foraging areas across seasons and years. Those that are both site faithful and habitat specialists may be particularly vulnerable to habitat loss and disturbance, as they may be less able to adjust their habitat use in response to environmental change. However, site fidelity can sometimes be a strategy to maximize efficiency via site familiarity rather than specialization, enabling more flexible habitat use at finer spatial scales. We used high-resolution GPS tracking data, remote sensing imagery, and focal foraging observations to measure individual habitat specialization and its potential tradeoffs in Hudsonian Whimbrel (Numenius hudsonicus), a species that exhibits high individual foraging site fidelity in a spatiotemporally patchy intertidal environment during a month-long migratory stopover. We found that Whimbrel show low levels of habitat specialization and instead select habitat in proportion to its availability within their home range and its accessibility based on tidal inundation. Each habitat type, however, has associated tradeoffs between accessibility, foraging reward, and predation risk. Flexible habitat use is therefore likely a means to balance these tradeoffs. We posit that fidelity at the home range scale allows individuals to develop familiarity with how to balance habitat quality tradeoffs in a dynamic environment. While this inherent behavioral flexibility could buffer Hudsonian Whimbrel from the risks of environmental change, their reliance on low-lying intertidal habitats raises concerns as sea-level rise increasingly restricts the availability of their preferred foraging habitats. More broadly, investigating the interplay between fidelity and flexibility is critical for assessing how site-faithful species might cope with rapidly changing environments.