MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 336:291-303 (2007) - doi:10.3354/meps336291 Diving behavior of blue-footed boobies Sula nebouxii in northern Peru in relation to sex, body size and prey type Carlos B. Zavalaga1,*, Silvano Benvenuti2, Luigi DallAntonia2, Steven D. Emslie1 1Department of Biology and Marine Biology, University of North Carolina, 601 South College Road, Wilmington, North Carolina 28403-5915, USA 2Dipartimento di Biologia, University of Pisa, Via Volta 6, 56126, Pisa, Italy *Email: cbz3724@uncw.edu ABSTRACT: We studied the diving behavior and diet of the sexually size-dimorphic blue-footed booby Sula nebouxii (BFB) breeding on Isla Lobos de Tierra, Peru, to evaluate whether sexual dimorphism is associated with feeding niche divergence between the sexes. We also discuss the foraging behavior of BFBs in relation to what is known about the vertical distribution of their main prey, and compare the BFBs foraging behavior with that of other tropical and temperate Sulidae. After analyzing data on 23 females and 28 males, we found no sexual differences in diet composition, crop mass, trip length, number of trips per day, proportion of time in flight and on the water, and number of dives per hour. We argue that this is because males and females were foraging in the same areas close to their colony. Conversely, females dived significantly deeper and longer, and consumed larger prey than males indicating that segregation may occur underwater. Body size (regardless of sex) was positively correlated to dive depth and prey size, suggesting that feeding niche separation is mediated by size dimorphism. However, the effects of body size and sex on foraging behavior could not be separated. BFBs and larger temperate gannets attained similar depths, but BFBs dived much deeper than did tropical boobies. The Peruvian anchovy Engraulis ringens was the most important prey consumed by BFBs, accounting over 79 to 97% of the total mass of the regurgitations. The temporal distribution of dives and dive profiles seems to be linked to the behavior and vertical distribution of anchovies. KEY WORDS: Foraging niche segregation · Blue-footed boobies · Sula nebouxii · Sexual dimorphism · Diving behavior · Peruvian anchovies Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 336. Online publication date: April 27, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.