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Contaminants in the marine environment are widespread, but ship-based sampling routines are much narrower. We evaluated the utility of seabirds, highly-mobile marine predators, as broad samplers of contaminants throughout three tropical ocean regions. Our aim was to fill a knowledge gap in the distributions of, and processes that contribute to, tropical marine contaminants; and explore how species-specific foraging ecologies could inform or bias our understanding of contaminant distributions. Mercury and persistent organic pollutant (POPs) concentrations were measured in adults of five seabird species from four colonies in the central Pacific (Laysan and Tern Islands, Hawaii; Palmyra Atoll) and the eastern Caribbean (Barbuda). Blood-based total mercury (THg) and 89 POPs were measured in two seabird families: surface-foraging frigatebirds (Fregata spp.) and plunge-diving boobies (Sula spp.). Overall, largescale contaminant differences between colonies were more informative of contaminant distributions than inter-specific foraging ecology. Model selection results indicated that proximity to human populations was the best predictor of THg and POPs. Regional differences in contaminants were distinct: Barbudan Magnificent Frigatebirds had more compounds (n = 52/89 POP detected) and higher concentrations (geometric mean THg = 0.97 μg g−1; mean ΣPOP 53 = 26.6 ng mL−1) than the remote colonies (34–42/89 POP detected; range of THg geometric means = 0.33–0.93 μg g−1; range of mean ΣPOP 53 :7.3–17.0 ng mL−1) and had the most recently-synthesized POPs. Moderate differences in foraging ecologies were somewhat informative of inter-specific differences in contaminant types and concentrations between nearshore and offshore foragers. Across species, contaminant concentrations were higher in frigatebirds (THg = 0.87 μg g−1; ΣPOP 53 = 17.5 ng mL−1) compared to boobies (THg = 0.48 μg g−1; ΣPOP 53 = 9.8). Ocean currents and contaminants' physiochemical properties provided additional insight into the scales of spatial and temporal contaminant exposure. Seabirds are excellent, broad samplers with which we can understand contaminant distributions in the marine environment. This is especially important for tropical remote regions that are under-sampled. Unlabelled Image • Seabirds are excellent samplers of broadscale marine contaminant patterns. • Contaminants and foraging ecology assessed in 5 seabird species in Pacific, Caribbean. • Mercury and persistent organic pollutants (POP) were detected in all samples. • Proximity to human populations was the best predictor of contaminant concentrations. [ABSTRACT FROM AUTHOR]

Oceanic seabirds are generally thought to avoid overland flight, perhaps limiting larger-scale distribution, but examples exist to the contrary. We asked whether Blue-Footed Boobies Sula nebouxii, Brown Pelicans Pelecanus occidentalis, or frigatebirds Fregata spp. crossed the Perry Isthmus (width 12.25 km, minimum height 23 m), a low point in the wasp-waist shape of Isla Isabela, Galapagos. Except for the Perry Isthmus, Isla Isabela presents an elongated, high-elevation challenge to movement between the central and western waters of Galapagos. Daytime observations over 3.5 d in June 2012 revealed ≥48 crossings by boobies and more than two crossings by frigatebirds. Overland crossing of a terrestrial barrier of this size may be facilitated by the seabirds' ability to see water across the Perry Isthmus from an altitude of 42 m looking west and 43 m looking east, altitudes that both the boobies and frigatebirds attain during foraging. [ABSTRACT FROM AUTHOR]

O habito da fregata (Fregata magnificiens) de roubar peixes do atobã marrom (Sula lecogaster) é bem conhecido na literatura, comportamento este que tem nos levado a classificar a primeira espécie como sendo cleptoparasita da segunda. Este trabalho, no entanto, mostra que a relação entre estas duas espécies é mais complexa e que o comportamento cleptoparasitãrio pode ser interpretado como sendo apenas parte de todo um processo de exploração mutua. Quando estas aves voam no encalço de embarcações pesqueiras, as fregatas localizam a fonte de alimento, sendo então seguidas pelos atobas que aparecem logo apos, apanhando os peixes mortos com muito mais eficiencia, de tal maneira que as fregatas não conseguem mais pescar, tendo que abandonar a atividade, Quando os atobas terminam sua atividade pesqueira, ou mesmo apos um numero deste ciclo, sugere-se que a fregata venha a procurar os atobas, roubando-lhes parte do pescado, fenomeno este bem descrito na literatura. Esta observação conduz a uma revisão da interpretação acerca da relação entre estas espécies, até então, considerada como cleptoparasitismo para a de exploração mutua.The frigatebird (Fregata magnificiens) often is referred to as a kleptoparasite of the brown booby (Sula lecogaster). This paper however, shows that the relationship between these species is more complex and that kleptoparasitism can be interpreted as just a part of a whole process of mutual exploration. When these birds fly behind fishing boats, F. magnificens locates the food source first and S. lecogaster then moves in and catches fish more efficiently in such a way that the frigatebird can no longer fish and has to fly away. When the fishing period is over then the frigatebird is thought to approach the brown boobies in order to get fish from them, as described in the literature, This leads to a revision on the interpretation about the relation between these species, from that of kleptoparasitism to this of mutual exploration.