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 ten 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.
|Brown booby, Sula leucogaster|
Sulids measure about 60 to 85 cm (24 to 33 in) in length and have a wingspan of about 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" as well as somewhat flat.
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.
The 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 the head. 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.
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.
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 mid-air, taking the bird a meter or two under water. If prey manages to escape the diving birds at first, they may give chase using their legs and wings for underwater swimming.
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 will point the bill upwards (gannets) or forward (boobies). After landing again, they point downwards with the bill. And in response to a threat, they will not attack but shake their heads and point the bill towards the intruder.
All sulids breed in colonies. Males examine the colony area in flight and then pick a nest site, which they defend by fighting and by territorial displays. Males then advertise to females by a special display and call. The display behavior is characteristic, though not as diverse as the numerous variations found among the cormorants; it typically includes the male shaking its 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.
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. Their weight ranges from 3.3 percent to 8 percent of the female's. 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.
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 to 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.
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.
|Cladogram showing the family Sulidae.|
The Sulae were traditionally included in the Pelecaniformes in its obsolete paraphyletic circumscription. But pelicans, the namesake family of the Pelecaniformes, are actually closer 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. The IOC World Bird List uses Suliformes as the proposed order name.
Within the family itself, three living genera—Sula (boobies, 6 species), Papasula (Abbott's booby), Morus (gannets, 3 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.
|Species of Booby|
|Common and binomial names||Image||Range|
|Western Europe and North America|
|West to Southwest African coast.|
(Morus serrator or Sula bassana)
|Australia and New Zealand|
|eastern Pacific Ocean from California to the Galápagos Islands down into Peru|
|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|
|eastern Pacific from the islands in Baja California to the Galápagos Islands and the Isla de la Plata in Ecuador and Malpelo in Colombia|
|pantropical areas of the Atlantic and Pacific oceans|
|Christmas and Galápagos Islands|
|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 (Ma), perhaps a bit earlier. The initial evolutionary radiation formed a number of genera which 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 Ma. 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.
Prehistoric sulids (or suloids) only known from fossils are:
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.
Abbott's booby (Papasula abbotti) is an endangered seabird of the sulid family, which includes gannets and boobies. It is a large booby, smaller than gannets, and is placed within its own monotypic genus. It was first identified from a specimen collected by William Louis Abbott, who discovered it on Assumption Island in 1892.
Abbott's booby breeds only in a few spots on the Australian territory of Christmas Island in the eastern Indian Ocean, although it formerly had a much wider range. It has white plumage with black markings, and is adapted for long-distance flight. It forages around Christmas Island, often around nutrient-rich oceanic upwellings, although individuals can travel for thousands of kilometres. Pairs mate for life and raise one chick every two or three years, nesting near the top of emergent trees in the rainforest canopy.
The population is decreasing. Historically much of its former habitat was logged to make way for phosphate mining. Some logging continues, and the effects of the former logging continue to adversely affect the current population. Another threat has been caused by the introduction of yellow crazy ants, which decrease habitat quality. Minimal habitat declines have a significant effect on the bird population. All nesting areas have been included in a national park.Australasian gannet
The Australasian gannet (Morus serrator), also known as Australian gannet and 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 pale blue-grey bill edged in 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 species range over water above the continental shelf along the southern and eastern Australian coastline, from Steep Point in Western Australia to Rockhampton, Queensland, as well as the North and South Islands of New Zealand, Lord Howe and Norfolk Islands. Nesting takes place in colonies along the coastlines of New Zealand, Victoria and Tasmania—mostly on offshore islands, although there are several mainland colonies in both countries. Highly territorial when breeding, the Australasian gannet performs agonistic displays to defend its nest. Potential and mated pairs engage in courtship and greeting displays. The nest is a cup-shaped mound composed of seaweed, earth, and other debris, built by the female from material mainly gathered by the male. A single pale blue egg is laid yearly, though lost eggs may be replaced. The chick is born featherless but is soon covered in white down. Fed regurgitated fish by its parents, it grows rapidly and outweighs the average adult when it fledges.
These birds are plunge divers and spectacular fishers, plunging into the ocean at high speed. They eat mainly squid and forage fish that school near the surface. The species faces few natural or man-made threats, and since its population is growing it is considered to be a least-concern species by the International Union for Conservation of Nature (IUCN).Bimbisula
Bimbisula ("big booby") 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 (Sulidae, Sula) 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.Birds of Ashmore Reef
The Birds of Ashmore Reef comprise three main groups:
Seabirds, including at least five species of breeding terns, with several other seabirds, including petrels, recorded in the surrounding waters
Migratory shorebirds en route from northern Asia to Australia
Landbirds, only three breeding species (two herons and a rail) but several others, including passerines, visit, either on migration to northern Australia or as vagrantsBooby
A booby is a seabird in the genus Sula, part of the Sulidae family. Boobies are closely related to the gannets (Morus), which were formerly included in Sula.Brown booby
The brown booby (Sula leucogaster) is a large seabird of the booby family, Sulidae, of which it is perhaps the most common and widespread species. It has a pantropical range, which overlaps with that of other booby species. The gregarious brown booby commutes and forages at low height over inshore waters. Flocks plunge-dive to take small fish, especially when these are driven near the surface by their predators. They only nest on the ground, and roost on solid objects rather than the water surface.Cape gannet
The Cape gannet (Morus capensis) originally Sula capensis, is a large seabird of the gannet family, Sulidae.
They are easily identified by their large size, black and white plumage and distinctive yellow crown and hindneck. The pale blue bill is pointed with fine serrations near the tip; perhaps because of the depth and speed of the gannet's dive when fishing (depending on altitude, gannets hit the water at speeds of between 40 and 120 km/h (25 and 75 mph), its beak has no external nostrils into which the water might be forced.Gannet
Gannets are seabirds comprising the genus Morus, in the family Sulidae, closely related to boobies. "Gannet" is derived from Old English ganot "strong or masculine", ultimately from the same Old Germanic root as "gander". Morus is derived from Ancient Greek moros, "foolish", due to the lack of fear shown by breeding gannets and boobies allowing them to be easily killed.The gannets are large white birds with yellowish heads; black-tipped wings; and long bills. Northern gannets are the largest seabirds in the North Atlantic, having a wingspan of up to 2 metres (6.6 ft). The other two species occur in the temperate seas around southern Africa, southern Australia and New Zealand.
Gannets hunt fish by diving into the sea from a height and pursuing their prey underwater. Gannets have a number of adaptations which enable them to do this:
no external nostrils, they are located inside the mouth instead;
air sacs in the face and chest under the skin which act like bubble wrapping, cushioning the impact with the water;
positioning of the eyes far enough forward on the face for binocular vision, allowing them to judge distances accurately.Gannets can dive from a height of 30 metres (98 ft), achieving speeds of 100 kilometres per hour (62 mph) as they strike the water, enabling them to catch fish much deeper than most airborne birds.
The gannet's supposed capacity for eating large quantities of fish has led to "gannet" becoming a description of somebody with a voracious appetite.List of birds of Christmas Island
The Birds of Christmas Island form a heterogeneous group of over 100 species. There is a core group of ten endemics that have evolved on the remote island in the eastern Indian Ocean for thousands of years, attended by a suite of regular migrants, opportunists and occasional visitors. Some 200 km from the nearest land, Java, Christmas Island was not occupied by humans until the late 19th century. It is now an Australian territory. The natural vegetation of most of the 140 km² island is rainforest, to which the endemic landbirds are adapted, while the seabirds have taken advantage of a breeding location which had no major natural predators.
After over a century of human exploitation of the phosphate deposits covering much of the island, two thirds of the rainforest cover remains and is now protected as a national park. However, gaps where the forest has been cleared, and the introduction of exotic fauna, continue to destabilise the island’s biological diversity. The endemic Abbott's booby is threatened when nesting by wind turbulence caused by past forest clearance. However, the biggest immediate threat is the introduction and spread of yellow crazy ants, through both direct predation and ecosystem collapse. This has led to all the island’s endemic bird species and subspecies being classified as Critically Endangered.
Meanwhile, the number of species recorded from Christmas Island continues to increase as birders, especially from Australia, attracted by the island’s endemics, record a variety of vagrants previously unnoticed. Some of these may in time, as with the white-breasted waterhen, establish breeding populations. Christmas Island is now seen as a birding ‘hot spot’, not only for its endemics but also for the chance of recording new species for the Australian bird list, something reflected in the frequency of submissions of sightings to the Birds Australia Rarities Committee.Masillastega
Masillastega ("Messel roof") is an extinct aquatic bird from the Eocene of Germany. It is related to modern gannets and boobies, but unlike these birds it occurred in freshwater environments. It was found in the lake that would become the Messel Pit.Nazca booby
The Nazca booby (Sula granti) is a large seabird of the booby family, Sulidae, native to the eastern Pacific. First described by Walter Rothschild in 1902, it was long considered a subspecies of the masked booby until recognised as distinct genetically and behaviorally in 2002. It has a typical sulid body shape, with a long pointed orange-yellow bill, long neck, aerodynamic body, long slender wings and pointed tail. The adult is bright white with black and white wings, a black tail and a dark face mask.Northern gannet
The northern gannet (Morus bassanus) is a seabird, the largest species of the gannet family, Sulidae. It is native to the coasts of the Atlantic Ocean, breeding in Western Europe and North America. The sexes are similar in appearance. The adult northern gannet has a mainly white streamlined body with a long neck, long and slender wings. It is 87–100 cm (34–39 in) long with a 170–180 cm (67–71 in) wingspan. The head and nape have a buff tinge that is more prominent in breeding season, and the wings are edged with dark brown-black feathers. The long pointed bill is blue-grey, contrasting with black bare skin around the mouth and eyes. Juveniles are mostly grey-brown, becoming increasingly white in the five years it takes them to reach maturity.
Nesting takes place in colonies on both sides of the north Atlantic, the largest of which are at Bass Rock (75,000 pairs as of 2014), St Kilda (60,000 pairs as of 2013) and Ailsa Craig (33,000 pairs as of 2014) in Scotland, Grassholm in Wales, and Bonaventure Island (60,000 pairs in 2009) off the coast of Quebec. Its breeding range has extended northward and eastward, colonies being established on Russia's Kola Peninsula in 1995 and Bear Island, southernmost island of Svalbard, in 2011. Colonies are mostly located on offshore islands with cliffs, from which the birds can more easily launch into the air. The northern gannet undertakes seasonal migrations and hunts for the fish that form the bulk of its diet by high-speed dives into the sea.
The gannet was previously hunted for food in parts of its range, and the traditional practice still continues in the Outer Hebrides of Scotland and the Faroe Islands. It faces few natural or man-made threats, and since its population is growing it is considered to be a least-concern species by the International Union for Conservation of Nature (IUCN). As a conspicuous and common bird, it has been mentioned in several ancient myths and legends.Pelecaniformes
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 (gular 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.
The Fregatidae (frigatebirds), Sulidae (gannets and boobies), Phalacrocoracidae (cormorants and shags), Anhingidae (darters), and Phaethontidae (tropicbirds) were traditionally placed in the Pelecaniformes, but molecular and morphological studies indicate they are not such close relatives. They have been placed in their own orders, Suliformes and Phaethontiformes, respectively.Protopelicanus
Protopelicanus cuvierii is a putative fossil waterbird of uncertain affinities. It was briefly described and figured by Georges Cuvier in 1822 from Late Eocene material from Montmartre, France, though not formally described and named until 1852 by German botanist and ornithologist Ludwig Reichenbach as an early pelecanid. The original material comprised the cranial part of a left scapula and a nearly complete left femur. The lectotype femur was thought by Michel Brunet in 1970 to be typical of a pelican. However, Colin Harrison in 1979 considered that it belonged to the Sulidae, and Storrs Olson in 1995 thought it might be a pelagornithid. The femur is held by the Muséum national d'histoire naturelle in Paris (No.7978); the location of the scapular fragment is unknown.Red-footed booby
The red-footed booby (Sula sula) is a large seabird of the booby family, Sulidae. Adults always have red feet, but the colour of the plumage varies. They are powerful and agile fliers, but they are clumsy in takeoffs and landings. They are found widely in the tropics, and breed colonially in coastal regions, especially islands. The species faces few natural or man-made threats, although its population is declining it is considered to be a least-concern species by the International Union for Conservation of Nature (IUCN).Rhamphastosula
Rhamphastosula ("toucan booby") is an extinct genus of sulid bird known from fossils discovered in early Pliocene rocks of Peru. The type and only named species is R. ramirezi, named for Peruvian vertebrate paleontologist Gregorio Ramirez. The genus name is a combination of "Rhamphastos", "toucan" and "sula", an Icelandic word for "fool" that has been used to describe boobies (Sulidae, Sula) in general.Rhamphastosula is known from a partial skull that has bony characters placing it in the booby family Sulidae. Unlike living boobies, it has a large bill with a convex upper mandible, reminiscent of a toucan. The remains were recovered from the west side of Sud Sacaco Level (4-5 Million year-old) of the Pisco Formation. This area was a sheltered beach with rock platforms.Sibley-Monroe checklist 9
The Sibley-Monroe checklist was a landmark document in the study of birds. It drew on extensive DNA-DNA hybridisation studies to reassess the relationships between modern birds.Suliformes
The order Suliformes (dubbed "Phalacrocoraciformes" by Christidis & Boles 2008) 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 split up to reflect the true evolutionary relationships.White-breasted cormorant
The white-breasted cormorant (Phalacrocorax lucidus) is much like the widespread great cormorant and if not a regional variant of the same species, is at least very closely related. It is distinguished from other forms of the great cormorant by its white breast and by the fact that subpopulations are freshwater birds. Phalacrocorax lucidus is not to be confused with the smaller and very different endemic South Australian black-faced cormorant, which also is sometimes called the white-breasted cormorant.