Milne-Edwards, Alphonse (1882). "Recherches sur la faune des régions Australes: Chapitre VII - Totipalmes". Annales des sciences naturelles, Zoologie. 6 (in French). 13 (4). p. 37, plate 14. a b Drummond, Hugh; Chavelas, Cecilia Garcia (1989). "Food shortage influences sibling aggression in the Blue-footed Booby". Animal Behaviour. 37: 806–819. doi: 10.1016/0003-3472(89)90065-1. S2CID 53165189. a b Díaz, Hernández; José Alfredo; Erika Nathalia Salazar Gómez. "Blue-footed Booby ( Sula nebouxii)". Neotropical Birds Online . Retrieved 9 December 2012. The blue-footed booby is monogamous, although it has the potential to be bigamous. [16] It is an opportunistic breeder, with the breeding cycle occurring every 8 to 9 months. [23] The courtship of the blue-footed booby consists of the male flaunting his blue feet and dancing to impress the female. The male begins by showing his feet, strutting in front of the female. Then, he presents nest materials and finishes the mating ritual with a final display of his feet. [24] The dance also includes "sky-pointing", which involves the male pointing his head and bill up to the sky while keeping the wings and tail raised. [25] Morales, Judith; Torres, Roxana; Velando, Alberto (2012). "Safe betting: males help dull females only when they raise high-quality offspring". Behavioral Ecology and Sociobiology. 66 (1): 135–143. doi: 10.1007/s00265-011-1261-8. S2CID 14882787.

BirdLife International (2018). " Sula nebouxii". IUCN Red List of Threatened Species. 2018: e.T22696683A132588719. doi: 10.2305/IUCN.UK.2018-2.RLTS.T22696683A132588719.en . Retrieved 11 November 2021. Gill, Frank; Donsker, David, eds. (2016). "Hamerkop, Shoebill, pelicans, boobies & cormorants". World Bird List Version 6.3. International Ornithologists' Union . Retrieved 31 July 2016. Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London, United Kingdom: Christopher Helm. p. 266. ISBN 978-1-4081-2501-4. Dentressangle, F.; Aubin, T.; Mathevon, N. (2012). "Males use time whereas females prefer harmony: individual call recognition in the dimorphic Blue-footed Booby". Animal Behaviour. 84 (2): 413–420. doi: 10.1016/j.anbehav.2012.05.012. S2CID 53159414.Velando, Alberto (2002). "Experimental manipulation of maternal effort produces differential effects in sons and daughters: implications for adaptive sex ratios in the Blue-footed Booby". Behavioral Ecology. 13 (4): 443–449. doi: 10.1093/beheco/13.4.443. Blue-footed Booby Population Analysis". Galapagos Conservancy. Archived from the original on October 22, 2017 . Retrieved January 26, 2016. Blue-footed boobies make raucous or polysyllabic grunts or shouts and thin whistling noises. The males of the species have been known to throw up their heads and whistle at a passing, flying female. These ritual displays are also a form of communication.

a b Harris, M. 2001. "Sula nebouxii" (On-line), Animal Diversity Web. Accessed September 22, 2013 at http://animaldiversity.ummz.umich.edu/accounts/Sula_nebouxii/ a b c Drummond, Hugh; Gonzalez, Edda; Osorno, Jose Luis (1986). "Parent-offspring cooperation in the Blue-footed Booby ( Sula nebouxii): social roles in infanticidal brood reduction". Behavioral Ecology and Sociobiology. 19 (5): 365–372. doi: 10.1007/bf00295710. S2CID 36417383. a b Drummond, Hugh; Gonzalez, Edda; Osorno, Jose Luis (1986). "Parent-Offspring Cooperation in the Blue-footed Booby ( Sula nebouxii): Social Roles in Infanticidal Brood Reduction". Behavioral Ecology and Sociobiology. 19 (5): 365–372. doi: 10.1007/bf00295710. S2CID 36417383.

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Unlike other avenues that offer immediate satisfaction, the creators of this little diversion have programmed it with strict instructions that you cannot skip ahead days. So if you want to see all 50 breasts (25 days X 2 breasts per day), you just have to wait. Drop ’em out, let me see them ti - - ies,” the 2015 country song goes. “Gonna take a long look at those tig ol’ bitties.” The blue color of the blue-footed booby's webbed feet comes from structures of aligned collagens in the skin modified by carotenoid pigments obtained from its diet of fresh fish. The collagens are arranged in a manner that makes the skin appear blue. The underlying color is a "flat, purplish blue". That color is modified by carotenoids to aquamarine in healthy birds. Carotenoids also act as antioxidants and stimulants for the blue-footed booby's immune function, suggesting that carotenoid pigmentation is an indicator of an individual's immunological state. [17] [18] Blue feet also indicate the current health condition of a booby. Boobies that were experimentally food-deprived for 48 hours experienced a decrease in foot brightness due to a reduction in the amount of lipids and lipoproteins that are used to absorb and transport carotenoids. Thus, the feet are rapid and honest indicators of a booby's current level of nourishment. [17] As blue feet are signals that reliably indicate the immunological and health condition of a booby, coloration is favored through sexual selection. Mates can recognize each other by their calls. Although calls differed between sexes, unique individual signatures were present. Both males and females can discriminate the calls of their mates from others. [39] Population decline [ edit ]

Osorio-Beristain, Marcela; Drummond, Hugh (1993). "Natal dispersal and deferred breeding in the Blue-Footed Booby" (PDF). The Auk. 110 (2). Since the blue-footed booby preys on fish by diving headlong into the water, its nostrils are permanently closed, and it has to breathe through the corners of its mouth. Its most notable characteristic is its blue-colored feet, which can range in color from a pale turquoise to a deep aquamarine. Males and younger birds have lighter feet than females. [2] Its blue feet play a key role in courtship rituals and breeding, with the male visually displaying his feet to attract mates during the breeding season.a b Todd, W. E. Clyde (1948). "A new booby and a new Ibis from South America". Proceedings of the Biological Society of Washington. 61: 49. Drummond, Hugh; Rodriguez, Cristina; Schwabl, Hubert (2008). "Do mothers regulate facultative and obligate siblicide by differentially provisioning eggs with hormones?". Journal of Avian Biology. 39 (2): 139–143. doi: 10.1111/j.0908-8857.2008.04365.x. Angier, Natalie (March 6, 2017). "On Galapagos, Revealing the Blue-Footed Booby's True Colors". The New York Times. Archived from the original on June 22, 2022 . Retrieved September 26, 2022. Concerns of a decline in the booby population of the Galápagos Islands prompted a research project in its cause. The project, completed in April 2014, confirmed the population decline. [40] The blue-footed booby population appears to be having trouble breeding, thus is slowly declining. The decline is feared to be long-term, but annual data collection is needed for a firm conclusion that this is not a normal fluctuation.