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We describe a new disjunct population of Blue-footed Booby Sula nebouxii at Islote González in the Islas Desventuradas archipelago. Though likely much larger, the population size at the time of our survey was a minimum of 16 breeding pairs. On 14-15 December 2020, two pairs of boobies with nestlings and four pairs with empty nests were found. Likely the species is a recent arrival to the archipelago, perhaps during one of the strong El Niño events between 1970 and 2001 (especially 1982/83, when the species was first recorded in Chile). Blue-footed Booby might also nest on different areas at San Félix Island and some smaller islets around the archipelago, where they would have no nesting-site competition from the larger Masked Booby S. dactylatra. [ABSTRACT FROM AUTHOR]

The article presents the study conducted regarding the species-specific and sex-specific differences in the foraging behaviour and zones of the two sympatric seabirds in the Gulf of California, Mexico. The study will examine the diving behavior, movement and activity of brown boobies and blue-footed boobies rearing young chicks using the highly accurate data loggers. The scheme also aims to disentangle the respective impact of species and sex on the observed foraging behaviour of the boobies. The result shows that the sex-specific differences of the seabirds which totally determined by their body size and mass are affected by the biomechanical constraints.

The temporal, inter-site, and sex-based variation of 19 organochlorine pesticides (OCPs) in blood plasma samples collected from blue-footed boobies of two islands in Sinaloa, Mexico, was evaluated. The effect of OCPs was evaluated with the heterophil/lymphocyte ratio, micronucleated erythrocyte frequency, and scaled mass index. The OCP-group levels decreased as the breeding season progressed, and interannual (but not inter-colony) differences were detected. Intra-annual variation in OCP levels seemed to reflect run-off inputs, although other environmental processes may better explain the variation between years. Sex-based differences in OCP levels were likely related to ecological and physiological processes linked to breeding (e.g., egg-laying and use of lipid reserves). No correlations between OCP-group levels and biomarkers were detected. Small pelagic fishes are the main prey sources of blue-footed boobies and the targets of regional industrial fisheries, and thus blue-footed booby OCP levels could reflect ecosystem health and indicate potential risks for human consumers. Unlabelled Image • Sex-based differences in OCP levels are likely related to breeding physiology. • OCP levels decreased as the breeding season progressed • Interannual but not intercolony differences in OCP levels were detected. • Blue-footed booby OCP levels likely reflect ecosystem health. [ABSTRACT FROM AUTHOR]