Labor division in parental care and reduction of inter-sex competition by division of the foraging niche have been suggested as part of the evolutionary basis for reversed sexual size dimorphism in boobies (Sulidae). To test the potential viability of both hypotheses for the maintenance of dimorphism, we studied parental care and foraging behavior of the Blue-footed Booby (Sula nebouxii) in two colonies in the Gulf of California, Mexico. Proportion of time spent at the nest, feeding frequency, and time devoted to nest defense were used as indicators of parental care. Foraging ecology was evaluated through the number and duration of foraging trips, proportion of time dedicated to flight and to active feeding, rate and depth of diving, and diet. We found some inter-sex differences in foraging only under high demand conditions, such as food shortage or large broods. Inconsistent inter-sex differences seem to be part of a strategy to maximize chick rearing under a variable environmental regime.

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â€" We evaluated maximum diving depth and time spent at the nest of fledging Blue-footed Boobies ( Sula nebouxii) at Isla El Rancho, Sinaloa, in the Gulf of California, Mexico. Within three consecutive 10day post-fledging intervals, maximum diving depth was highly variable, but was not affected by sex, weight, or body condition. During the first days of post-fledging flight, maximum diving depth increased rapidly. By the second week after first flight, the plunge-dives of juveniles were almost as deep as those of adults. Parental care and attachment to the nest lasted several additional weeks (up to 40 days after first flight). Although their diving capacity rapidly reached a level similar to that of the adults, it appeared that juvenile boobies took much longer in acquiring other foraging skills.

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Due to rapidly changing global environmental conditions, many animals are now experiencing concurrent changes in both resource availability and the foraging cues associated with finding those resources. By employing flexible, plastic foraging strategies that use different types of environmental foraging cues, animals could adapt to these novel future environments. To evaluate the extent to which such flexibility and plasticity exist, we analyzed a large dataset of a clade (Sulidae; the boobies) of widespread aerial tropical predators that feed in highly variable marine habitats. These surface foragers are typical of many ocean predators that face dynamic and patchy foraging environments and use a combination of static and ephemeral oceanographic features to locate prey. We compared foraging habitats and behaviors of four species at seven colonies in the eastern and central Pacific Ocean that varied greatly in depth, topography, and primary productivity. Foraging behaviors, recorded by GPS‐tracking tags, were compared to remotely sensed environmental features, to characterize habitat‐behavior interactions. K‐means clustering grouped environmental characteristics into five habitat clusters across the seven sites. We found that boobies relied on a combination of static and ephemeral cues, especially depth, chlorophyll‐a concentrations, and sea surface height (ocean surface topography). Notably, foraging behaviors were strongly predicted by local oceanographic habitats across species and sites, suggesting a high degree of behavioral plasticity in use of different foraging cues. Flexibility allows these top predators to adapt to, and exploit, static and ephemeral oceanic features. Plasticity may well facilitate these species, and other similarly dynamic foragers, to cope with increasingly changing environmental conditions.

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