Sulidae | |
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Brown booby, Sula leucogaster | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Suliformes |
Family: | Sulidae Reichenbach, 1849 |
Genera | |
Synonyms | |
Enkurosulidae Kashin, 1977 Contents |
The bird family Sulidae comprises the gannets and boobies. Collectively called sulids, they are medium-large coastal seabirds that plunge-dive for fish and similar prey. The 10 species in this family are often considered congeneric in older sources, placing all in the genus Sula. However, Sula (true boobies) and Morus (gannets) can be readily distinguished by morphological, behavioral, and DNA sequence characters. Abbott's booby (Papasula) is given its own genus, as it stands apart from both in these respects. It appears to be a distinct and ancient lineage, maybe closer to the gannets than to the true boobies. [3] [4]
Sulids measure about 60 to 85 cm (24 to 33 in) in length and have a wingspan around 140 to 175 cm (4.59 to 5.74 ft). They have long, narrow, and pointed wings, and a quite long, graduated, and rather lozenge-shaped tail whose outer feathers are shorter than the central ones. Their flight muscles are rather small to allow for the small cross-section required for plunge-diving, as an adaptive trade-off relative to some sacrifice in flight performance. Consequently, they are very streamlined, reducing drag, so their bodies are "torpedo-shaped" and somewhat flat. [5]
They have stout legs and webbed feet, with the web connecting all four toes. In some species, the webs are brightly colored and used in courtship displays. The bill is usually conspicuously colored, long, deep at the base, and pointed, with saw-like edges. The upper mandible curves down slightly at the tip and can be moved upward to accept large prey. To keep water out during plunges, the nostrils enter into the bill rather than opening to the outside directly. The eyes are angled forward, and provide a wider field of binocular vision than in most other birds. [5]
Their plumage is either all-white (or light brownish or greyish) with dark wingtips and (usually) tail, or at least some dark brown or black above with white underparts; gannets have a yellowish hue to their heads. The face usually has some sort of black markings, typically on the lores. Unlike their relatives (the darters and cormorants), sulids have a well-developed preen gland whose waxy secretions they spread on their feathers for waterproofing and pest control. They moult their tail feathers irregularly and the flight feathers of their wings in stages, so that starting at the first moult, they always have some old feathers, some new ones, and some partly grown ones. Moult as a response to periods of stress has been recorded. [5]
The sulids are distributed mainly in tropical and subtropical waters, but they, particularly gannets, are found in temperate regions, too. These birds are not truly pelagic seabirds like the related Procellariiformes, and usually stay rather close to the coasts, but the abundant colonies of sulids that exist on many Pacific islands suggest that they are not infrequently blown away from their home range by storms, and can wander for long distances in search of a safe place to land if need be. [5]
All species feed entirely at sea, mostly on mid-sized fish and similarly sized marine invertebrates (e.g. cephalopods). Many species feed communally, and some species follow fishing boats to scavenge discarded bycatch and chum. The typical hunting behavior is a dive from midair, taking the bird a 1–2 m under water. If prey manages to escape the diving birds at first, they may give chase using their legs and wings for underwater swimming. [5]
As noted above, the behavioral traits of gannets and boobies differ considerably, but the Sulidae as a whole are characterized by several behavioral synapomorphies: Before taking off, they point their bills upwards (gannets) or forward (boobies). After landing again, they point downwards with their bills. In response to a threat, they do not attack, but shake their heads and point their bills towards the intruders. [3]
All sulids breed in colonies. Males examine the colony area in flight and then pick a nest site, which they defend by fighting and territorial displays. Males then advertise to females by a special display and call. Their display behavior is characteristic, though not as diverse as the numerous variations found among the cormorants; it typically includes the male shaking his head. Females search the colony in flight and on foot for a mate. Once they select males, pairs maintain their bonds by preening each other and by frequent copulation. [3] [5]
The clutch is typically two eggs. The eggs are unmarked (but may become stained by debris in the nest), whitish, pale blue, green, or pink, and have a coating that resembles lime. Egg[ verification needed ] weight ranges from 3.3 to 8.0% of the female's weight. Incubation lasts 42 to 55 days, depending on the species. Both sexes incubate; like their relatives, they do not have brood patches, but their feet become vascularized and hot, and the birds place the eggs under the webs. Eggs lost during the first half of incubation are replaced. [5]
At hatching, parents move the eggs and then the hatchlings to the tops of their webs. The young hatch naked, but soon develop white down. They beg by touching the parent's bill and take regurgitated food straight from its gape. At first, at least one parent is always in attendance of the altricial young; after two weeks, both parents leave the nest unguarded at times while they go fishing. The times for the chicks to fledge and become independent of their parents depend greatly on the food supply. Rarely does more than one chick survive to maturity, except in the Peruvian booby (Sula variegata), which has the biggest clutch (two to four eggs), and less often in the blue-footed booby (S. nebouxii). Siblicide by the stronger of two chicks is frequent. [5]
Sulids are related to a number of other aquatic birds, which all lack external nostrils and a brood patch, but have all four toes webbed and a gular sac. The closest living relatives of the Sulidae are the Phalacrocoracidae (cormorants and shags) and the Anhingidae (darters). The latter are somewhat intermediate between sulids and cormorants, but (like many cormorants) they are freshwater birds in a clade containing otherwise seabirds, and also symplesiomorphic with sulids but synapomorphic with cormorants in some other respects. Thus, the Sulidae seem to be the oldest and most distinct lineage of those three, which are united in a suborder Sulae. Therein, the Sulidae are typically placed simply as a family; sometimes, a superfamily Suloidea is recognized, wherein some of the primitive prehistoric forms (e.g. Empheresula , Eostega , and Masillastega ) are placed as basal lineages distinct from the living Sulidae. However, the proposed family Pseudosulidae (or Enkurosulidae) is almost certainly invalid. [2] [6] [7] [8]
Sulid phylogeny | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Cladogram showing the family Sulidae. [9] |
The Sulae were traditionally included in the Pelecaniformes in its obsolete paraphyletic circumscription, but pelicans, the namesake family of the Pelecaniformes, are actually more closely related to herons, ibises and spoonbills, the hamerkop, and the shoebill than to the sulids and allies. In recognition of this, the Sulae have been proposed for separation in a new order Phalacrocoraciformes, which also includes the frigatebirds (Fregatidae), as well as one or more prehistoric lineages that are entirely extinct today. [7] The IOC World Bird List uses Suliformes as the proposed order name. [10]
Within the family itself, three living genera— Sula (boobies, six species), Papasula (Abbott's booby), and Morus (gannets, three species)—are recognized. A 2011 study of multiple genes found Abbott's booby to be basal to all other gannets and boobies, and likely to have diverged from them around 22 million years ago, and the ancestors of the gannets and remaining boobies split around 17 million years ago. The most recent common ancestor of all boobies lived in the late Miocene around 6 million years ago, after which time the boobies steadily diverged. The gannets split more recently, only around 2.5 million years ago. [9]
Species of boobies | ||
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Common and binomial names | Image | Range |
Northern gannet (Morus bassanus) | ![]() | Western Europe and North America |
Cape gannet (Morus capensis) | | West to Southwest African coast |
Australasian gannet (Morus serrator or Sula bassana) | ![]() | Australia and New Zealand |
Abbott's booby (Papasula abbotti) | ![]() | Christmas Island |
Blue-footed booby (Sula nebouxii) | ![]() | Eastern Pacific Ocean from California to the Galápagos Islands south into Peru |
Masked booby (Sula dactylatra) | | Tropical oceans between the 30th parallel north and 30th parallel south. In the Indian Ocean it ranges from the coastlines of the Arabian Peninsula and East Africa across to Sumatra and Western Australia |
Nazca booby (Sula granti) | ![]() | Eastern Pacific from the islands in Baja California to the Galápagos Islands and the Isla de la Plata in Ecuador and Malpelo in Colombia |
Brown booby (Sula leucogaster) | ![]() | Pantropical areas of the Atlantic and Pacific Oceans |
Red-footed booby (Sula sula) | ![]() | Most tropical areas of oceans, main exceptions being tropical areas of E Atlantic and SE Pacific, breeding on islands |
Peruvian booby (Sula variegata) | ![]() | Coast of South America from Peru to Chile |
The fossil record of sulids is quite extensive due to the many Miocene/Pliocene forms that have been recovered, but the lineage of sulids extends back to the Eocene, and all things (such as the Early Eocene frigatebird Limnofregata ) considered, the sulids seem to have diverged from the lineage leading to cormorants and darters around 50 million years ago (Mya), perhaps a bit earlier. The initial evolutionary radiation formed a number of genera that are now completely extinct, such as the freshwater Masillastega (which, as noted above, might not have been a modern-type sulid) or the bizarre Rhamphastosula (which had a bill shaped like an aracari's). The modern genera evolved (like many other living genera of birds) around the Oligocene-Miocene boundary about 23 Mya. Microsula , which lived during that time, seems to have been a primitive booby that still had many symplesiomorphies with gannets. Like the other Phalacrocoraciformes, the sulids originated probably in the general region of the Atlantic or western Tethys Sea – probably the latter rather than the former, given that their earliest fossils are abundant in Europe, but absent from the well-studied contemporary American deposits. [6] [8]
Prehistoric sulids (or suloids) only known from fossils are:
For prehistoric species of the extant genera, see the genus articles.
The Early Oligocene Prophalacrocorax ronzoni of Ronzon, France, was variously placed in the seaduck genus Mergus , in Sula, and after a distinct genus was established for it, in the Phalacrocoracidae. While it is quite likely to belong in the Sulae and may have been an ancient sulid (or suloid), of the three placements explicitly proposed, none seems to be correct. [6] [2] [16] [8]
The darters, anhingas, or snakebirds are mainly tropical waterbirds in the family Anhingidae, which contains a single genus, Anhinga. There are four living species, three of which are very common and widespread while the fourth is rarer and classified as near-threatened by the IUCN. The term snakebird is usually used without any additions to signify whichever of the completely allopatric species occurs in any one region. It refers to their long thin neck, which has a snake-like appearance when they swim with their bodies submerged, or when mated pairs twist it during their bonding displays. "Darter" is used with a geographical term when referring to particular species. It alludes to their manner of procuring food, as they impale fishes with their thin, pointed beak. The American darter is more commonly known as the anhinga. It is sometimes called "water turkey" in the southern United States; though the anhinga is quite unrelated to the wild turkey, they are both large, blackish birds with long tails that are sometimes hunted for food.
The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, floating on the water surface, and in some cases diving in at least shallow water. The family contains around 174 species in 43 genera.
The Pelecaniformes are an order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes. Most have a bare throat patch, and the nostrils have evolved into dysfunctional slits, forcing them to breathe through their mouths. They also have a pectinate nail on their longest toe. This is shaped like a comb and is used to brush out and separate their feathers. They feed on fish, squid, or similar marine life. Nesting is colonial, but individual birds are monogamous. The young are altricial, hatching from the egg helpless and naked in most. They lack a brood patch.
Rails are a large, cosmopolitan family of small- to medium-sized terrestrial and/or semi-amphibious birds. The family exhibits considerable diversity in its forms, and includes such ubiquitous species as the crakes, coots, and gallinule; other rail species are extremely rare or endangered. Many are associated with wetland habitats, some being semi-aquatic like waterfowl, but many more are wading birds or shorebirds. The ideal rail habitats are marsh areas, including rice paddies, and flooded fields or open forest. They are especially fond of dense vegetation for nesting. The rail family is found in every terrestrial habitat with the exception of dry desert, polar or freezing regions, and alpine areas. Members of Rallidae occur on every continent except Antarctica. Numerous unique island species are known.
Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the International Ornithologists' Union (IOU) adopted a consensus taxonomy of seven genera. The great cormorant and the common shag are the only two species of the family commonly encountered in Britain and Ireland and "cormorant" and "shag" appellations have been later assigned to different species in the family somewhat haphazardly.
Gannets are seabirds comprising the genus Morus in the family Sulidae, closely related to boobies.
A booby is a seabird in the genus Sula, part of the family Sulidae. Boobies are closely related to the gannets (Morus), which were formerly included in Sula.
Nine families of largely arboreal birds make up the order Piciformes, the best-known of them being the Picidae, which includes the woodpeckers and close relatives. The Piciformes contain about 71 living genera with a little over 450 species, of which the Picidae make up about half.
The mousebirds are birds in the order Coliiformes. They are the sister group to the clade Cavitaves, which includes the Leptosomiformes, Trogoniformes (trogons), Bucerotiformes, Piciformes and Coraciformes. This group is now confined to sub-Saharan Africa, and it is the only bird order confined entirely to that continent, with the possible exception of turacos which are considered by some as the distinct order Musophagiformes, and the cuckoo roller, which is the only member of the order Leptosomiformes, and which is found in Madagascar but not mainland Africa. Mousebirds had a wider range in the Paleogene, with a widespread distribution in Europe and North America during the Paleocene.
The Australasian gannet, also known as the Australian gannet or tākapu, is a large seabird of the booby and gannet family, Sulidae. Adults are mostly white, with black flight feathers at the wingtips and lining the trailing edge of the wing. The central tail feathers are also black. The head is tinged buff-yellow, with a pearly grey bill edged in dark grey or black, and blue-rimmed eyes. Young birds have mottled plumage in their first year, dark above and light below. The head is an intermediate mottled grey, with a dark bill. The birds gradually acquire more white in subsequent seasons until they reach maturity after five years.
The Cape gannet is a large seabird of the gannet family, Sulidae.
The Pelagornithidae, commonly called pelagornithids, pseudodontorns, bony-toothed birds, false-toothed birds or pseudotooth birds, are a prehistoric family of large seabirds. Their fossil remains have been found all over the world in rocks dating between the Early Paleocene and the Pliocene-Pleistocene boundary.
Odontopteryx is a genus of the extinct pseudotooth birds or pelagornithids. These were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty.
Dasornis is a genus of prehistoric pseudotooth birds. These were probably close relatives of either pelicans and storks or waterfowl; they are placed in the order Odontopterygiformes to account for this uncertainty.
Pelagornis is a widespread genus of prehistoric pseudotooth birds. These were probably rather close relatives of either pelicans and storks, or waterfowl, and are placed here in the order Odontopterygiformes to account for this uncertainty.
Pseudodontornis is a rather disputed genus of the prehistoric pseudotooth birds. The pseudotooth birds or pelagornithids were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty. Up to five species are commonly recognized in this genus.
The order Suliformes is an order recognised by the International Ornithologist's Union. In regard to the recent evidence that the traditional Pelecaniformes is polyphyletic, it has been suggested that the group be divided to reflect the true evolutionary relationships; a 2017 study indicated that they are most closely related to Otidiformes (bustards) and Ciconiiformes (storks).
Bimbisula is an extinct genus of sulid bird known from fossils discovered in Pliocene rocks of South Carolina, United States. The type and only named species is B. melanodactylos. The genus name is a combination of the Gullah name "Bimbi", meaning dawn, with "sula", an Icelandic word for "fool" that has been used to describe boobies in general. The species name is Greek for "black-fingered", referring to the iron staining that darkened the bones of the type specimen. Bimbisula melanodactylos is based on Charleston Museum PV2818, a partial skeleton including fragments of the skull, shoulder girdle, left upper arm, right hand, and fused hip vertebrae, and much of the right leg. It was collected in 1980 by James Malcolm from a locality along the Seaboard Coast Line Railroad in Charleston County in the vicinity of the Dorchester Road overpass. A second specimen assigned to the species, Science Museum of Minnesota P90.38.8, consists of a cranium discovered in October 1990 by Bruce Erickson near the Wando Terminal. Both specimens were found in the Goose Creek Limestone, of middle Pliocene age. The type specimen comes from the upper part of the formation, which is approximately 3.6 to 3.5 million years old. The exact stratigraphy of the second specimen is uncertain, and it may be anywhere from 3.9 to 3.5 million years old. Bimbisula was a large sulid, comparable in size to smaller species of gannets, and its skeleton shows a combination of booby-like and gannet-like characteristics.
Tonsala is an extinct genus of Plotopteridae, a family of flightless seabird similar in biology with penguins, but more closely related to modern cormorants. The genus is known from terrains dated from the Late Oligocene of the State of Washington and Japan.
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