Sulidae
Encyclopedia
The bird
family
Sulidae comprises the gannet
s and boobies
. Collectively called sulidas, they are medium-large coastal seabird
s that plunge-dive for fish
and similar prey. The ten species
in this family are often considered congener
ic in older sources, placing all in the genus
Sula. However, Sula (true boobies) and Morus (gannets) can be readily distinguished by morphological
and 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.
Sulids measure about 60 to 85 cm (23.6 to 33.5 in) in length and have a wingspan of about 140 to 175 cm (4.6 to 5.7 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, and thus their wing loading
is high. 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 display
s. 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 darter
s and cormorant
s), 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 feather
s 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.
regions too. These birds are not truly pelagic seabird
s 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 storm
s, 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
invertebrate
s (e.g. cephalopod
s). 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.
s. Males then advertise to females by a special display and call. The display behaviour is characteristic, though not as diverse as the numerous variations found among the cormorant
s; 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 2 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 patch
es, but their feet become vascular
ized 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 regurgitate
d 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.
birds which all lack external nostril
s 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 seabird
s, 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.
The Sulae were traditionally included in the "Pelecaniformes
" in its obsolete paraphyletic circumscription. But pelican
s, the namesake family of the Pelecaniformes, are actually closer related to heron
s, 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 frigatebird
s (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.
There are three living genera
. One is monotypic
, another has but a few species, while the third contains about 65% of all living sulids:
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 evolve
d (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 America
n deposits.
Prehistoric sulids (or suloids) only known from fossil
s 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.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Sulidae comprises the gannet
Gannet
Gannets are seabirds comprising the genus Morus, in the family Sulidae, closely related to the boobies.The gannets are large black and white birds with yellow heads. They have long pointed wings and long bills. Northern gannets are the largest seabirds in the North Atlantic, with a wingspan of up...
s and boobies
Booby
A booby is a seabird in the genus Sula, part of the Sulidae family. Boobies are closely related to the gannets , which were formerly included in Sula.-Description:...
. Collectively called sulidas, they are medium-large coastal seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s that plunge-dive for fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
and similar prey. The ten species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in this family are often considered congener
Congener
Congener has several different meanings depending on the field in which it is used. Colloquially, it is used to mean a person or thing like another, in character or action.-Biology:In biology, congeners are organisms within the same genus...
ic in older sources, placing all in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Sula. However, Sula (true boobies) and Morus (gannets) can be readily distinguished by morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and behavioral
Ethology
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....
and DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
characters. Abbott's Booby
Abbott's Booby
Abbott’s Booby is a large endangered seabird of the gannet family, Sulidae. Found normally only on and around Christmas Island Abbott’s Booby (Papasula abbotti) is a large endangered seabird of the gannet family, Sulidae. Found normally only on and around Christmas Island Abbott’s Booby (Papasula...
(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.
Description
Lozenge
A lozenge , often referred to as a diamond, is a form of rhombus. The definition of lozenge is not strictly fixed, and it is sometimes used simply as a synonym for rhombus. Most often, though, lozenge refers to a thin rhombus—a rhombus with acute angles of 45°...
-shaped tail whose outer feathers are shorter than the central ones. Their flight muscles are rather small to allow for the small cross section
Cross section (geometry)
In geometry, a cross-section is the intersection of a figure in 2-dimensional space with a line, or of a body in 3-dimensional space with a plane, etc...
required for plunge-diving, and thus their wing loading
Wing loading
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing. The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading. Correspondingly,...
is high. Consequently, they are very streamlined
Streamliner
A streamliner is a vehicle incorporating streamlining in a shape providing reduced air resistance. The term is applied to high-speed railway trainsets of the 1930s to 1950s, and to their successor "bullet trains". Less commonly, the term is applied to fully faired recumbent bicycles...
, reducing drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
, so their bodies are "torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...
-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 display
Courtship display
Courtship display is a special, sometimes ritualised, set of behaviours which some animals perform as part of courtship. Courtship behaviours can include special calls, postures, and movements, and may involve special plumage, bright colours or other ornamentation. A good example is the 'dancing'...
s. 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
Binocular vision
Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...
than in most other birds.
The plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
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 darter
Darter
The darters or snakebirds are mainly tropical waterbirds in the family Anhingidae. 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...
s and cormorant
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
s), sulids have a well-developed preen gland whose waxy secretions they spread on their feathers for waterproofing and pest control. They moult
Moult
In biology, moulting or molting , also known as sloughing, shedding, or for some species, ecdysis, is the manner in which an animal routinely casts off a part of its body , either at specific times of year, or at specific points in its life cycle.Moulting can involve the epidermis , pelage...
their tail feathers irregularly and the flight feather
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...
s 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
Stress (biology)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
has been recorded.
Distribution and ecology
The sulids are distributed mainly in tropical and subtropical waters. Particularly gannets, however, are found in temperateTemperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions too. These birds are not truly pelagic seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s like the related Procellariiformes
Procellariiformes
Procellariiformes is an order of seabirds that comprises four families: the albatrosses, petrels and shearwaters, storm petrels, and diving petrels...
, 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 storm
Storm
A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather...
s, and can wander for long distances in search of a safe place to land if need be.
All species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
feed entirely at sea, mostly on mid-sized fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
and similarly-sized marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s (e.g. cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s). Many species feed communally, and some species follow fishing boats to scavenge discarded bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
and chum
Chumming
Chumming is the practice of luring animals, usually fish or sharks, by throwing "chum" into the water. Chum often consists of fish parts and blood, which attract fish, particularly sharks due to their keen sense of smell....
. 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
Ethology
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....
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.
Reproduction
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 displayDisplay (zoology)
Display is a form of animal behaviour, linked to survival of the species in various ways. One example of display used by some species can be found in the form of courtship, with the male usually having a striking feature that is distinguished by colour, shape or size, used to attract a female...
s. Males then advertise to females by a special display and call. The display behaviour is characteristic, though not as diverse as the numerous variations found among the cormorant
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
s; 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
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
is typically 2 eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
. The eggs are unmarked (but may become stained by debris
Debris
Debris is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, in geology, large rock fragments left by a melting glacier etc. The singular form of debris is debris...
in the nest), whitish, pale blue, green or pink, and have a coating that resembles lime
Lime (mineral)
Lime is a general term for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide. It is also the name for a single mineral of the CaO composition, occurring very rarely...
. 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
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
; like their relatives they do not have brood patch
Brood patch
thumb|250px|Brood patch of [[Sand Martin]]A brood patch is a patch of featherless skin that is visible on the underside of birds during the nesting season. This patch of skin is well supplied with blood vessels at the surface making it possible for the birds to transfer heat to their eggs when...
es, but their feet become vascular
Vascular
Vascular in zoology and medicine means "related to blood vessels", which are part of the circulatory system. An organ or tissue that is vascularized is heavily endowed with blood vessels and thus richly supplied with blood....
ized 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 regurgitate
Regurgitation (digestion)
Regurgitation is the expulsion of material from the mouth, pharynx, or esophagus, usually characterized by the presence of undigested food or blood.Regurgitation is used by a number of species to feed their young...
d food straight from its gape
Gape
In bird anatomy, the gape is the interior of the open mouth of a bird and the gape flange is the region where the two mandibles join together, at the base of the beak...
. At first at least one parent is always in attendance of the altricial
Altricial
Altricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born...
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
Peruvian Booby
The Peruvian Booby, Sula variegata, is an endemic bird of the Peruvian current whose distribution is restricted to the west coast of South America from Punta Pariñas in Peru to Concepción in Chile . It is the second most abundant seabird species that inhabits the Peruvian Coast and the second...
(Sula variegata) – which has the biggest clutch (two to four eggs) –, and less often in the Blue-footed Booby
Blue-footed Booby
The Blue-footed Booby is a bird in the Sulidae family which comprises ten species of long-winged seabirds. The natural breeding habitat of the Blue-footed Booby is tropical and subtropical islands off the Pacific Ocean, most famously, the Galápagos Islands, Ecuador.- Etymology :The name booby...
(S. nebouxii) . Siblicide
Siblicide
Siblicide is the killing of an infant individual by its close relatives . It may occur directly between siblings or be mediated by the parents. The evolutionary drivers may be either indirect benefits for the genetic viability of a population or direct benefits for the perpetrators...
by the stronger of two chicks is frequent.
Systematics and evolution
Sulids are related to a number of other aquaticAquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
birds which all lack external nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s and a brood patch
Brood patch
thumb|250px|Brood patch of [[Sand Martin]]A brood patch is a patch of featherless skin that is visible on the underside of birds during the nesting season. This patch of skin is well supplied with blood vessels at the surface making it possible for the birds to transfer heat to their eggs when...
, 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
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
birds in a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
containing otherwise seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s, 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
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
; 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.
The Sulae were traditionally included in the "Pelecaniformes
Pelecaniformes
The Pelecaniformes is a 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...
" in its obsolete paraphyletic circumscription. But pelican
Pelican
A pelican, derived from the Greek word πελεκυς pelekys is a large water bird with a large throat pouch, belonging to the bird family Pelecanidae....
s, the namesake family of the Pelecaniformes, are actually closer related to heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....
s, ibises and spoonbills
Threskiornithidae
The family Threskiornithidae includes 34 species of large terrestrial and wading birds, falling into two subfamilies, the ibises and the spoonbills. It was formerly known as Plataleidae. The spoonbills and ibises were once thought to be related to other groups of long-legged wading birds in the...
, the hamerkop and the shoebill
Shoebill
The Shoebill also known as Whalehead or Shoe-billed Stork, is a very large stork-like bird. It derives its name from its massive shoe-shaped bill. The adult bird is tall, long, across the wingspan and weighs . Their beaks have an average length of length of . The adult is mainly grey while the...
than to the sulids and allies. In recognition of this, the Sulae have been proposed for separation in a new order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Phalacrocoraciformes
Suliformes
The Order Suliformes is a proposed order by the International Ornithologist's Union...
, which also includes the frigatebird
Frigatebird
The frigatebirds are a family, Fregatidae, of seabirds. There are five species in the single genus Fregata. They are also sometimes called Man of War birds or Pirate birds. Since they are related to the pelicans, the term "frigate pelican" is also a name applied to them...
s (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.
There are three living genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
. One is monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
, another has but a few species, while the third contains about 65% of all living sulids:
- Sula (boobies, 6 species)
- Papasula (Abbott's Booby)
- Morus (gannets, 3 species)
Evolution and fossil genera
The fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
record of sulids is quite extensive due to the many Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
/Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
forms that have been recovered. But the lineage of sulids extends back to the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
, and all things (such as the Early Eocene frigatebird
Frigatebird
The frigatebirds are a family, Fregatidae, of seabirds. There are five species in the single genus Fregata. They are also sometimes called Man of War birds or Pirate birds. Since they are related to the pelicans, the term "frigate pelican" is also a name applied to them...
Limnofregata
Limnofregata
Limnofregata is an extinct genus of primitive frigatebird. The two known species were described after fossils from the Early Eocene Green River Formation of Wyoming. A number of good complete and partial skeletons, some with feather impressions, are known of the type species, and L...
) 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
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...
formed a number of genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
which are now completely extinct, such as the freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
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
Aracari
The aracaris are medium-sized toucans in the genus Pteroglossus. As denoted by the presence of the cedilla on the C , the proper pronunciation is "ahr-uh-SAHR-ee" not "ahr-uh-KAR-ee"....
's). The modern genera evolve
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
d (like many other living genera of birds) around the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
-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
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
but absent from the well-studied contemporary America
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
n deposits.
Prehistoric sulids (or suloids) only known from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s are:
- Masillastega (Early Eocene of Messel, Germany) – may belong in Eostega
- Eostega (Late Eocene of Cluj-Manastur, Romania) – may include Masillastega
- Sulidae gen. et sp. indet. (Thalberg Late Oligocene of Germany) – Empheresula?
- Sulidae gen. et sp. indet. (Late Oligocene of South Carolina, USA) – Microsula?
- Empheresula (Late Oligocene of Gannat, France – Middle Miocene of Steinheimer Becken, Germany) – including "Sula" arvernensis, "Parasula"
- Microsula (Late Oligocene of South Carolina, USA – Grund Middle Miocene of Austria) – may belong in Morus or Sula, includes "Sula" avita, "S." pygmaea, Enkurosula, "Pseudosula"
- Sarmatosula (Middle Miocene of Credinţa, Romania)
- Miosula (Late Miocene of California)
- Palaeosula (Early Pliocene? of California)
- Rhamphastosula (Pisco Early Pliocene of SC Peru)
- Sulidae gen. et sp. indet. (Late Pliocene of Valle di Fine, Italy) – Morus?
For prehistoric species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of the extant genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
, see the genus articles.
The Early Oligocene Prophalacrocorax ronzoni of Ronzon (France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
) was variously placed in the seaduck genus Mergus
Mergus
Mergus is the genus of the typical mergansers, fish-eating ducks in the seaduck subfamily . The Hooded Merganser, often termed Mergus cucullatus, is not of this genus but closely related...
, 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.
External links
- Live camera from Eldey Iceland
- Sulidae videos on the Internet Bird Collection