Sulidae: Boobies
Boobies and gannets are goose-sized seabirds that have the general appearance of gulls, but with long, thin wings, long necks, and large, conical bills. They are popularly known for the clownish mating rituals of some species—most famously the Blue-footed Booby (Sula nebouxii) on the Galápagos—and for their dramatic, plunging dives into schools of fish.
The family is exclusively marine, foraging in both coastal and offshore waters, although some species are mainly pelagic and rarely seen near land except at their breeding colonies. Most boobies are tropical, but the three species known as “gannets” (genus Morus) favor cold temperate waters.
Identification
Boobies present a slew of difficult identification challenges. Some have light and dark morphs, some have juvenile or subadult plumages that strongly resemble one another or adults of other species. Leg and bill coloration are distinctive in many cases but also change with age. The legs of most species are gray at first, then develop into the distinctive adult colors.
To identify individuals encountered in transitional stages, it is often important to notice details of wing coloration, above and below. These patterns are often diagnostic and, compared to leg and bill color, are less dependent on lighting because they are delineations of the contrast between light and dark feathers.
Taxonomy
The internal systematics of the Sulidae have been reexamined in recent decades. This has resulted in one form—the Nazca Booby (S. granti)—being shown to qualify as a separate species from the nearly identical, pantropical Masked Booby (S. dactylatra). Pending further study of the “Tasman Booby” (S. d. tasmani) and a possible subdivision of the Brown Booby (S. leucogaster), the family comprises somewhere from 10 to 13 species.
Abbott’s Booby (Papasula abbotti)
Northern Gannet (Morus bassanus)
Cape Gannet (Morus capensis)
Australasian Gannet (Morus serrator)
Brown Booby (Sula leucogaster)
“Atlantic Booby” (S. l. leucogaster)
“Forster’s Booby” (S. l. plotus)
“Brewster’s Booby” (S. l. brewsteri)
Masked Booby (Sula dactylatra)
“Masked Booby” (S. d. dactylatra)
“Tasman Booby” (S. d. tasmani)
Blue-footed Booby (Sula nebouxii)
Peruvian Booby (Sula variegata)
References
Boyd, J.H., 2019. Taxonomy in Flux: Ardeae II: Aequornithes II. http://jboyd.net/Taxo/List8a.html. (Posted August 6, 2019. Accessed February 18, 2021.)
Howard, L. 2003. Sulidae: gannets and boobies. Animal Diversity Web. http://animaldiversity.org/accounts/Sulidae/. (Accessed November 18, 2017.)
Nelson, J.B. 2005. Pelicans, Cormorants and Their Relatives. Oxford University Press.
Patterson, S.A., J.A. Morris-Pocock, and V.L. Friesen. 2011. A multilocus phylogeny of the Sulidae (Aves: Pelecaniformes). Molecular Phylogenetics and Evolution 58:181-191.
Roberson, D. 2000. Bird Families of the World: Boobies, Sulidae, http://creagrus.home.montereybay.com/boobies.html. (Posted May 19, 2000. Accessed November 18, 2017.)