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Ecology Letters (2012) 15: 347-356 Abstract Food webs are comprised of a network of trophic interactions and are essential to elucidating ecosystem processes and functions. However, the presence of unknown, but critical networks hampers understanding of complex and dynamic food webs in nature. Here, we empirically demonstrate a missing link, both critical and variable, by revealing that direct predator-prey relationships between shorebirds and biofilm are widespread and mediated by multiple ecological and evolutionary determinants. Food source mixing models and energy budget estimates indicate that the strength of the missing linkage is dependent on predator traits (body mass and foraging action rate) and the environment that determines food density. Morphological analyses, showing that smaller bodied species possess more developed feeding apparatus to consume biofilm, suggest that the linkage is also phylogenetically dependent and affords a compelling re-interpretation of niche differentiation. We contend that exploring missing links is a necessity for revealing true network structure and dynamics. [ABSTRACT FROM AUTHOR]

To elucidate the effects of light, site, temperature, time after emersion, and wind speed on foraging attempt rate (FAR) (attempts/unit time) and feeding success (FS) (captures/attempts) in the obligate visual foraging shorebird, Kentish plovers Charadrius alexandrinus, field observations were performed at a sandflat in Tokyo Bay, using a visible-light telescope camcorder during the day and a thermal infrared telescope camcorder at night. The re-analysis capability and frame-step replay of highly magnified video-images can contribute to accurate measurement of feeding behaviour over conventional focal observation techniques. Kentish plovers increased both FAR and FS in areas of high prey (polychaetes and crabs) density, resulting in a synergistic increase in feeding rate (captures/unit time). In areas of high prey abundance, FAR was higher at lower wind speed. FS increased with increasing time after emersion. Increasing temperatures induced a positive effect on FAR but a negative effect on FS. The effect of light on FAR was not observed; however, time-to-defecation occurrence was 2.2-fold shorter at night than during the day, indicating that feeding rate and FS are higher at night. These results are attributable to an increase in availability of cues due to higher nocturnal activity in polychaetes. Since available foraging time (emersion time) at night was 1.7-fold longer than during the day in the present study period, Kentish plovers could capture 3.7-fold (2.2 × 1.7) more prey at night than during the day. Results from this study indicate that nocturnal feeding in overwintering plovers is not a compensation but a major foraging activity to meet their energy requirements. [ABSTRACT FROM AUTHOR]