Sailors (birds)
| Sailors | ||||||||
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White-throated needletail ( Hirundapus caudacutus ) |
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Apodidae | ||||||||
| Hartert , 1897 |
The glider (Apodidae) are a bird family of the order of apodiformes (Apodiformes). Sailors resemble swallows in shape and way of life , but are not closely related to them; it is convergent evolution.
No other bird family is as consistently adapted to life in the air as the sailors. All species are fast, long-term fliers; the larger species reach speeds of over 150 km / h in horizontal flight. The birds feed on insects and arachnids that are caught in the air. Even the nesting material is almost exclusively collected in flight; some species also spend the night in the air. Most species live in the tropics , outside of the tropics, sailors are mainly long-distance migrants and cross the equator during the migration.
The family with its slightly more than 90 species is divided into two subfamilies, the larger of the two again into three tribes , so that four main groups result: The subfamily Cypseloidinae (original, American sailors) and the tribe Collocaliini ( salangans ), Chaeturini ( Spiny-tailed swifts) and apodini (typical sailors).
The common swift ( Apus apus ) is the best known and by far the best researched sailor. It is the only species that is widely distributed in Europe. In Central Europe nowadays it almost exclusively uses man-made nesting sites, mostly breeding in multi-storey stone buildings. In midsummer the sociable swifts, like many other sailors, are very noticeable in the air above the cities with their shrill calls.
Some species of salangan in Southeast Asia have the extraordinary ability of birds to echolocate . They use these to find their way in widely ramified cave systems in which their nesting sites are. The nests of some of these species are used for " swallow's nest soup ", a delicacy of Chinese cuisine , which requires protective measures to prevent further decline in the population.
features
Morphology and anatomy
The most striking feature of sailors is their apparently suitable shape for flying at high speeds. This impression is created by their elongated, streamlined body with a short neck, the forward stretched head and, above all, by the long, slender, sickle-shaped wings in most species. The beak is short and wide, useful when hunting small animals in the air. The relatively large eyes of all species are protected by a fine, brush-like row of feathers protruding above the eye.
The plumage is mostly dark, often black, but in many species it is also dark gray or brown. Often there are lighter or white plumage parts, in particular many species have a light throat spot or rump . None of the species shows a variegated plumage, only the reddish throats of the Red-necked and Phelpssegler - two closely related South American sailors of the genus Streptoprocne - show a tendency to conspicuous coloring. Many species have very shiny plumage, some with a bluish or greenish tinge. The function of this plumage luster, which is present in all sailors at least in freshly molted plumage, is unclear; the increased albedo (reflectivity) that results in protecting the plumage may be advantageous because the birds, as airhunters, are exposed to the sun for a relatively long time - most swallow species also show this Shine.
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The short, strong clamp foot with its sharp claws and the very short barrel are ideal for clinging to vertical surfaces, which is supported by the stiff tail feathers. On the other hand, the feet of sailors are hardly suitable for moving on the ground - they cannot sit on branches, only hang from them. Almost all sailors have four toes, with the exception of the Papuan langan ( Aerodramus papuensis ), which lacks the first toe. In many species, some of the toes can be turned; on smooth surfaces, all four toes can be pointed forward. This position of the toes can be observed especially in museum specimens - therefore the sailors were assumed to have a pamprodactyl toe arrangement, but functionally it is actually more heterodactyl .
The shape of the comparatively short tail is quite different for the different types of sailor. A forked tail is particularly widespread among the typical sailors (Apodini), while the salangans only have a slightly notched tail. In the spiny-tailed swifts (Chaeturini), on the other hand, the quills of the control feathers protrude over the flags. These "tail thorns", which protrude beyond the end of the rather short, straight cut or rounded tails, support the birds in locomotion on smooth surfaces. Both the forked tails and the tail spines are aerodynamically advantageous because they reduce air turbulence . Sailors usually have ten rudder springs, a prominent exception is the common swift with twelve.
The size differences within the family are clear, the smallest species weigh just under 8 grams, the largest species exceed blackbirds and weigh up to 180 grams.
flight
The long and slender shape of the wing, which is unique in birds, generates strong lift and propulsion , especially during the frequently observed flapping flight. In this respect, the term “ glider ” may be a bit exaggerated, but gliding is also highly effective, as shown by a comparison of metabolic rates during the flight with other bird species. The wings have nine or ten hand wings and eight to eleven closely arranged, quite short arm wings . The bones of the hand make a disproportionate contribution to the length of the wing in sailors, which is also reflected in the significant difference in length between the hand and arm swing. The longest swing arm can be three times as long as the shortest arm swing - compared to only twice the length of the swallows, which occupy a similar ecological niche.
The wing shape enables sailors to fly at high speeds. The fastest sailor is the spiny-tailed sailor ( Hirunsapus caudacutus ) with 170 km / h in horizontal flapping flight , according to the current state of knowledge it is even the fastest bird in the world in this discipline. Compared to other similarly air-hunting birds like the swallows, however, the sailors lack maneuverability, they are not able to fly at low speed.
Mauser
For many migrating species, the annual moult begins when they arrive in their winter quarters. With other sailors, moulting can already begin in the breeding area and is then interrupted during the migration and completed in the winter quarters. Other species, especially those of the genus Chaetura , change their plumage during the breeding season.
The common swift is known to have a peculiarity that presumably also applies to other species of swift that breed in temperate latitudes: after they have fled out, the young birds only partially change their plumage, so that the flight feathers are only renewed after a year and a half when they spend the second time in their winter quarters. Since the outermost hand wings are not changed every time they moult , it is possible that these feathers will only be moulted after two and a half years.
Exact knowledge of the moulting cycles is not absolutely necessary to determine the species of sailor, but the resulting change in the shape of the wings can certainly cause confusion. Representatives of the genus Apus can, for example, show a wing shape during the moult, reminiscent of the spiny-tailed swift (Chaeturini).
Vocalizations
Sailors are very shouting, especially during the breeding season. The warm summer evenings of many Central European cities include the high-pitched, shrill screams of the swifts , which can even drown out the traffic noise. The calls of most types of sailor sound quite similar, but make it possible - at least for common swifts - to differentiate between the sexes. Erich Kaiser found out in 1997 that during so-called “dueting” at the breeding site, where a couple jointly utters a “swii-rii”, the lighter “swii” comes from the female and the slightly deeper “rii” from the male. Sailors who are looking for a partner and fly to the entrance of a breeding cave are also shown by means of this duet whether they are a potential candidate for starting a family. Erich Kaiser suspects that the other of the many sailor species that do not show any external sexual dimorphism and prefer dark nesting places also identify their gender acoustically in this way.
Another very unusual adaptation of the sailors are the clicking sounds for echolocation , which can be heard especially with many species of salangan . In birds, this ability is otherwise only known from the South American fat swallow ( Steatornis caripensis ). The clicking sounds of the sailors are in the audible frequency range of humans, they have been compared to the noise when you run your finger over the teeth of a comb. Echolocation enables sailors to find their way in deep, widely ramified cave systems. Because of the lower frequency compared to bats using ultrasound , the resolution is not sufficient to hunt insects in the dark. However, this may allow the sailors to stay active longer than other air fighters in the twilight before they go to their breeding and sleeping places in the caves.
The click sounds, like the other sounds made by birds, are generated by the syrinx (vocal head) and cover a large frequency range , the maximum intensity is between 2 and 8 kilohertz . The duration of a click is between one and around three milliseconds. With the exception of two types, all salangans make not just one, but two sounds in quick succession, typically around 17 milliseconds apart, the second being louder. Species-specific differences can be seen in the length of the breaks, but there are also large intraspecific deviations.
Distribution, migrations and habitat
distribution
Sailors occur worldwide with the exception of the polar regions and the high latitudes. Most of the species are native to the tropics . With the exception of a few archipelagos, all areas of the world that offer suitable habitats for sailors are also populated by them.
In the Western Palearctic , which includes Europe, the swift is widespread almost everywhere. Furthermore, there are six species of sailors in this fauna region, all of which belong to the Apodini tribe : The alpine sailor ( Tachymarptis melba ) mainly inhabits a belt between the Alps and the Mediterranean Sea and is common in certain areas. The pale swift ( Apus pallidus ) can be observed around the Mediterranean, especially in North Africa . The Alexander and monochrome sailors ( Apus alexandri and Apus unicolor ) have isolated occurrences on individual islands . The house sailor ( Apus affinis ), which breeds mainly south of the Sahara, comes mainly as a summer visitor to North Africa and also to Turkey and, more recently, southern Spain. The Cape Swift ( Apus caffer ) in North Africa and on the Iberian Peninsula is also mainly a summer visitor - sometimes also a breeding bird .
hikes
The highly seasonal frequency of insects in the temperate latitudes makes most of the sailors breeding outside the tropics long-distance migrants . Within the tropics, post-breeding season dispersion and seasonal migration to neighboring areas can often be observed, especially to other altitudes. Furthermore, daily hikes in search of food are typical for this family, the range of distances covered is quite large.
All species that migrate over long distances usually form swarms. Long distances can be covered in a short time, an alpine sailor was encountered at two locations 1620 kilometers apart every three days. The move takes place across the board and also at night. There are hardly any draft funnels in straits; on the contrary, it is even assumed that black swifts ( Cypseloides niger ) breeding in western North America, for example, shorten their way to South America across the Pacific .
Hikes over long distances do not only take place in an annual, seasonal rhythm. So-called weather escapes are known in particular from common swifts and black swifts . When passing through a low pressure area , the animals use the zones with the best availability of food and fly through areas with very bad weather conditions in the shortest possible time. During these hikes, the sailors can move up to 2000 kilometers from their breeding grounds. Mainly non-breeders participate in these weather escapes, but breeding birds also leave their brood depending on the weather conditions; the young birds fall into a kind of starvation during this time .
This great mobility of sailors certainly contributes to their almost worldwide spread. In this context, the phenomenon of the stray guests is important, for which there are some sensational cases among sailors. For example, there are often wanderers who cross the Atlantic , and this - in contrast to almost all other bird families - in both directions: Several Alpine swifts have been observed in the Caribbean ; the chimney sailor often gets lost in Europe.
habitat
The diet of sailors is highly specialized, they need areas in which there are usable insects or arachnids in the air in sufficient density. On the other hand, sailors also prefer species-specific, well-protected nesting sites; these two needs can often not be met in one place and force sailors to go on daily hikes. The distance varies considerably, with smaller species and species with large clutch sizes depending on a shorter distance between the breeding site and the areas with a sufficient density of “ aerial plankton ”. Since water is of particular importance in the life cycle of many insects, the habitats of sailors are also located near bodies of water. This is particularly clear with the species that use dry habitats inland - such as the pale swift , which can be found in the Sahara in the vicinity of oases.
The common swift is considered to be a universal sailor in terms of the diversity of habitats. In its vast breeding area, which encompasses much of the Palearctic , it is found in various habitats such as deserts , thorny savannas , steppes , agricultural areas, suburbs, and the centers of large cities. During the summer in sub-Saharan Africa, it can be found in the airspace of every biotope , including over forests, which are avoided by many species of sailors. The habitat requirements of some other types of sailors are much more specific; for example, the species of the genera Cypsiurus and Tachornis are almost always found in the vicinity of palm trees .
Food and subsistence
All sailors feed exclusively on insects and arachnids , almost all of which are caught in the air. Various studies consistently count bees , wasps , flying ant stages , two-winged animals , beaked beetles and beetles among the most important prey animals. Some species avoid stinging insects and eat insects that imitate their warning color . A study also showed that swifts hunting near beehives almost exclusively used non-stinging drones .
The sailors show opportunistic behavior when they acquire food, for example collar swifts in South America deliberately use insects startled by bushfires . Sailors do not seem to be choosy, as evidenced by the number of 500 different species of prey found in Europe for common swifts, the actual number is likely to be much higher. There should be even more different prey for sailors in the tropics. Such a range has not yet been found in any other comparable bird. On the other hand, the metaphor of the “flying vacuum cleaner” used by sailors is surely exaggerated, there are also studies that show a clear discrepancy between the usable supply and the prey actually found in the stomachs or ball of feces of the birds. Larger birds are better able to exploit temporary mass reproductions of insects due to their larger radius of action . As a result, the variety of recovered prey in larger species can be less than that of smaller species.
Larger species tend to hunt in higher air layers than smaller ones, especially when hunting in the same area. The birds are usually at a considerable height above the ground, even if the height of a hundred meters is usually an upper limit due to the decreasing density of prey, at least outside the tropics. Although sailors do not have the maneuverability of the swallows, there are some species that search for food directly above the treetops. In a few species - for example the chimney-swift - the reading of the food from the leaves of the trees, which is quite unusual for sailors, was observed. The delimitation of the ecological niche in the acquisition of food by sympatric sailor species or swallows settled in the same area is done either by the height range or, in the case of communal hunting at the same height, by the size of the prey, which is determined by the size and shape of the beak.
For most species, the acquisition of food is tied to certain times of the day; many species mainly forage in the evening hours. Only the Alpine Swift and the Malabars Salad were seen hunting at night, both in the vicinity of artificial lighting. One suspects that the alpine sailor searches for food in total darkness, possibly this is not as unusual with the sailors as previously assumed.
Sailors drink regularly by flying low over a surface of water and submerging their lower beak. Surprisingly, they prefer smaller areas of water, and insects are occasionally read from the surface of the water.
Reproduction
In all sailors there is a dependency between the breeding season and the availability of insects. In the tropics this usually leads to breeding during the rainy season , in the temperate latitudes the young are reared during the summer months. The shorter period of sufficient food availability in the higher latitudes allows only one annual brood there, while in the climatic zones with longer insect abundance, second broods are the rule. Both sexes participate equally in raising the young in all sailors.
Nest location and nest
Sailors prefer nesting places that are particularly inaccessible for nest robbers, as they can hardly defend themselves against enemies. Most species prefer dark places. This is particularly evident in the salangans capable of echolocation , which often cover long distances in caves in total darkness. Despite the wide range of nesting sites used within the family, most species have very specific requirements. For many, a great height above the ground and the possibility of flying in and out freely from the entrance of the breeding cave is a decisive factor. Many species of sailors breed in colonies that can be large and densely packed. Some species also or exclusively use man-made nesting sites, i.e. suitable areas or cavities on structures.
Some species of sailors also adopt other species' nests; The Horus swift ( Apus horus ) is particularly flexible and mainly takes over nests from bee-eaters , kingfishers or swallows. Sometimes there are also violent takeovers; The Cape Swift ( Apus caffer ) should be emphasized here , which has tempted the Red-breasted Swallows to prefer nesting sites less than a meter above the ground. This also shows that this brood parasitism must be older in evolutionary terms.
The typical sailor's nest is a flat, self-supporting bowl, often attached to a vertical surface. The nesting material - mainly plant components and feathers - is usually collected in flight with the beak, which is why nest building is often quite inconsistent; Progress is greatest in windy conditions. Most sailors use saliva to glue the nesting material together, which is why the birds' salivary glands are enlarged during the breeding season. The use of saliva reaches its extreme with the salangans, especially with the white nest salangans ( Aerodramus fuciphagus ), whose nest consists exclusively of saliva. The palm swift ( Cypsiurus parvus ) also uses saliva to stick the eggs, which are laid in a relatively exposed place, to the nest.
In some species there are clear deviations from the classic sailor's nest. The representatives of the subfamily Cypseloidinae and possibly also the spiny-tailed swifts (Chaturini) do not use saliva when building their nests. Some of these species, which are native to the tropics, can do without building a nest and use a hollow in the underground of the nesting site. The nests of the two panyptila species native to tropical South America, for example, also differ significantly from the typical sailor's nest : Their nests hang down from the underside of a branch or an overhanging rock and consist of a tube that can be up to 60 centimeters long, whereby each other the entrance hole is at the lower end. The eggs lie in a kind of compartment in the upper part of this building.
Courtship and mating
The couple bond among sailors is generally very strong and the monogamous partner relationships last for more than one season in almost all cases examined. To a certain extent, this is probably due to the sailors' loyalty to their nesting sites. In the case of migratory birds, the breeding partners from the previous year do not arrive at the nesting site together, and the pair bonds must be renewed at the beginning of the season. The behavior shown by the partners initially resembles the threatening gestures that they also show when a strange bird enters the nesting cavity.
The various flying games of the sailors have been examined several times, their function is often unclear and also to what extent they serve to find partners. In particular with chimney swifts , immediately after arriving in the breeding area, one can often observe how pairs break away from a larger swarm and continue to fly together, following each other. Later on, three groups often form in which two birds, presumably males, chase after a female. During these courtship flights, the birds often show a V-position of the wings, in which the wing tips can touch over the back, which can sometimes also be heard.
At least for the common swift, it has been proven that copulations take place in the air. The male lands on the back of the pursued female, which typically only succeeds after a few unsuccessful attempts, which may be part of the ritual. During the contact, which lasts only a few seconds, the pair quickly loses altitude while gliding, sometimes one or both birds flap their wings. Similar, but also different processes are described by other types of sailors, which are also interpreted as pairings in the air. Mating at the nesting site has also been observed with many sailors, with salangans this is believed to be the only possibility. It has also been proven that swifts mate in the breeding cave. The evolutionary meaning of the air equations is unclear.
Clutch and brood
The eggs of all sailors are consistently white and matt. They are small in relation to the size of the birds, but have a high proportion of yolk . The dimensions of the eggs range from approximately 15.5 x 10 millimeters for the fork-tailed sailor to 43 x 28.5 millimeters for the collar swift . The clutch size is very different: For example, some salangans lay only one egg, the clutches of some Chaetura or Hirundapus species comprise up to seven or more .
In many species there is a strong dependency between clutch size and weather conditions and thus the food supply. The different breeding times for the various genera also show such a dependency. It is extremely variable in some sailors breeding in temperate latitudes, such as common swifts . The eggs are resistant to chilling during break due to the weather.
In various investigations it was found that broods which were placed under additional eggs did not achieve greater breeding success. This shows that the clutch size is well matched to the respective circumstances, and also that rearing the brood is a considerable effort for the adult birds. The Australian Queensland Alangans ( Aerodramus terraereginae ) have developed a special strategy that is considered to be an adaptation to highly incalculable food availability and extreme food shortages. The species has two annual broods with one egg each. The second egg, which is laid 50 days after the first, is mainly incubated by the nestling of the first brood. It may also breed during the night while the adult birds are present. After it flies out, the adult birds take over the rest of the incubation.
The American Chimney Swift are breeding helpers not uncommon. In 21 percent of the broods examined, three birds took part in the rearing of the young, in 6 percent four birds. The brood helpers are often not yet breeding annuals, but also very old birds.
Development of the young birds
Hatched sailors spend a relatively long time in the nest before they fly out, compared to other birds of comparable size. This fact is attributed to the fact that the flying birds must be completely independent. The nestling time within the sailor family shows no relation to size. The longest known among sailors fledging period is that of the diadem sailors ( Cypseloides cherriei ); the young of this species spend between 65 and 70 days in the nest.
The adult birds collect the food in the throat pouch. Such a ball of food sticky with saliva is choked out and can be fed directly to a single nestling or distributed to several. Both adult and young birds do their part to keep the nest clean. Bales of excrement are either eaten or carried out by the adult birds. The offspring of the white- rump salangans ( Aerodramus spodiopygius ) excrement over the edge of the nest on the first day after hatching, the nestlings of other species behave in a similar way, but only when they are a little older.
The nestling time can also vary significantly depending on the weather conditions. The nestlings of the species that breed in areas with fluctuating food supply can store the most fat and survive for up to a week if there is a lack of food, whereby their weight can be halved. Since sailors immediately need full flight ability when going out and fat reserves have to be broken down by this time, well-nourished nestlings of some species have to switch from one extreme to the other before going out; and they have an amazing sense of when to stop eating in order to have the optimal flight weight at the right time.
Various flying exercises have been observed in nestlings of many species of sailors. One exercise is reminiscent of the push-up : The body is lifted from the ground with outstretched wings pointing downwards. At first the young birds can only hold their bodies in the raised position for a short time, later much longer and it is assumed that this exercise is also used to determine the time of flight.
The escape rates determined, i.e. the ratio of the number of birds flown out to the number of hatched birds, ranged between 26 percent for the palm-swift - whose nest is comparatively easily accessible to nest-robbers - and 96.1 percent for the chimney-swift .
Other behavior
Social behavior
Almost all species of sailor are very gregarious, both when breeding together and in the air. The formation of larger swarms enables sailors to better utilize the local, short-term high availability of food. Often mixed swarms with other types of sailors and also swallows are formed. Although sailors, as fast fliers, do not belong to the main prey of birds of prey , protection from them is another function of flocking. Smaller birds of prey are often hated collectively by sailors .
A very conspicuous behavior of the sailors, especially on warm summer evenings, are the so-called "screaming parties". This especially when swifts observed flight games do not serve food intake and obviously have nothing to do with courtship. The birds of one or more breeding colonies can be animated to participate by the loudly calling, flying past. Breeding birds also take part. It is believed that these flying games promote the cohesion of the group. They could also serve to prepare for the departure, although the move does not take place in such large groups.
Overnight and rest
Most sailors rest at night, although in large breeding colonies of some species chatter can be heard throughout the night. Non-migrating birds usually sleep in or near the nest all year round.
The much-discussed overnight stay in the air by sailors is only definitely proven for swifts. It is assumed, however, that pale and alpine swifts sometimes spend the night in the air, as they also have an exceptionally effective oxygen uptake , which leads to an increased concentration of hemoglobin in the blood, such as is only found in hummingbirds or in mountainous regions living bird species. The birds typically spend the night at an altitude of between 1000 and 2000 meters, but overnight stays at altitudes of up to 3000 meters have also been observed. Often the night in the air takes place after the "screaming parties", mainly non-breeding annuals spend the night in the air, but also breeding birds. Swifts that fly out also spend their first night in the air outside the nest.
In particularly cold weather, sailors have various strategies to keep themselves warm and to reduce energy losses. In many species of yachtsmen, densely packed birds have been observed clinging to walls or trees in the form of grapes, even during the day. It has been proven for many types of sailors that they can become torpid , i.e. fall into a kind of starvation sleep.
Parasites, Enemies, and Life Expectancy
Parasites
Sailors are heavily infested with parasites , especially in the nesting areas. This is mainly to louse flies , bird lice , feather mites or ticks . Some species of these parasites specialize in a single species of sailor. The reason for the unusually high exposure to ectoparasites could be due to the imperfect plumage care, which is difficult for the sailors due to anatomical properties. Some of these ectoparasites also act as vectors of various endoparasites , the infestation of which often affects the birds more.
The more nests there are in a confined space, the greater the parasite infestation. In an investigation in England, the connections in swifts were examined in a very differentiated manner and the infestation by swift fly and another parasite artificially increased. There was no connection between the intensity of the infestation and the success of breeding. This is attributed to the fact that the parasites are transmitted to new breeding colonies via the offspring - a so-called vertical transmission - and therefore excessive impairment of the host would be disadvantageous for the parasite itself. Nevertheless, the exposure can be life-threatening for individual individuals, especially with exhausted birds on or after the migration.
Enemies
Because of their airborne lifestyle and speed, sailors have few natural enemies . Nevertheless, there are some species of birds of prey and owls that sailors occasionally or more often prey ; Special mention should be made of the Eleonora's falcon and other larger species of falcon . The bat pair is a threat to some species of salangan , which it ambushes at the entrance to their cave.
The preference for sheltered nesting sites high above the ground does not make it easy for nest robbers living on the ground, so that rats or snakes, for example, hardly get a chance. An exception is the nest of the palm swift ( Cypsiurus parvus ), which is comparatively accessible - eggs, nestlings and adult birds are captured by different bird species at the nesting site. In the extensive caves in northern Borneo , a species of insect has specialized in eating the eggs and nestlings of the salangans that nest there, namely the wingless cave shrimp Rhaphidophora oophaga .
Life expectancy
Sailors have low death rates; the common swift has an annual survival rate of 81 to 85 percent, and the chimney swift was 71 to 81 percent. When you consider that these species travel long distances on the train each year and cross the equator twice, these rates are astonishingly high. In all studies, the birds have the highest death rates in the first year of life, 29 percent of common swifts and 67 percent of white swifts . The ascertained maximum age of ringed sailors was 26 years for alpine swifts , 21 years for common swifts and 14 years for chimney swifts.
Systematics and evolution
Alpine swift ( Tachymarptis melba )
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Tree Swift ( Hemiprocne comata )
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The scientific name of the family is derived from the genus Apus ( ancient Greek ἄπους ápous here in the sense of "not using the feet, walking poorly"). Aristotle used the term in his Historia animalium ; There he mentions in 9.30 "the [birds] with stunted feet, some of which call themselves kypselous , insofar as they are similar to the swallows [...]." Apus is the type genus of the subfamily Apodinae, which in turn is the nominate form of the family.
External system
The sister group of sailors are the tree swifts (Hemiprocnidae). The four species of this small family are not to be confused with any kind of sailor. In contrast to sailors, they have colorful plumage and the anatomy of their legs and feet allows them to sit on branches and twigs. The hummingbirds (Trochilidae) are also closely related to the sailors, the greatest commonality is the construction of the wing with very short upper and lower arm and long hand.
Tree swifts, sailors and hummingbirds, which have been grouped together to form the order of the sailor birds (Apodiformes), form a monophylum , that is, they have a common stem form and include all subgroups that are derived from this stem form. However, the order established in this way made the swallow-like (Caprimulgiformes) paraphyletic , as phylogenetic studies showed, since the cave swallows (Aegothelidae) form a sister group of the group previously known as sailor birds, but were counted among the swallow-like. As a solution to this dilemma, the sailing birds were often subordinated to the swallow-like. In 2005 it was proposed to introduce the designation “Daedalornithes” for the clade resulting from the previous sailing birds and the cave swallows.
Lately, the cave dwarves have simply been placed with the sailing birds.
The resulting family relationships are illustrated by the following cladogram :
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Internal system
The family of sailors (Apodidae) is divided into the subfamilies Cypseloidinae and Apodinae. The subfamily Cypseloidinae consists of two purely American genera , while the other subfamily is distributed almost worldwide and is only absent in the high latitudes. The larger subfamily Apodinae is also divided by three tribes . Some authors see one of these tribes, the spiny-tailed swifts (Chaturini), also as a third subfamily.
The representatives of the subfamily Cypseloidinae are considered to be the most primitive sailors living today. This point of view is justified, among other things, with the presence of two carotid arteries and the lack of saliva use when building nests in these species. In the three tribes of the subfamily Apodinae, the salangans (Collocaliini) are considered to be the original form and the spiny-tailed swifts (Chaturini) as a further development due to their tail spines and more specialized nesting sites. The most modern form are the typical sailors (Apodini) with their pamprodactyl toe arrangement and the more elaborate nests.
The often difficult delineation of genera and species in this family is most evident in the salangans. Originally all salangans were assigned to a single genus, the genus Collocalia . Subsequently, divisions to several genera were discussed, and the species were rearranged several times based on external characteristics and differences in breeding biology, until in 1970 a division of the salangans into three genera by RK Brooke found relatively broad recognition. An essential criterion was the ability to echolocation . Species that have this ability have been assigned to the genus Aerodramus .
This division was and is not recognized by some authors , although it has been confirmed by molecular genetic studies. Was noted in particular since that due to their brilliant plumage to the genus Collocalia scoring Zwergsalangane ( C. troglodytes ) also has the ability to echolocation, the genre division is again controversial.
The following classes belong to the sailors:
- Subfamily: Cypseloidinae
- Genus: Cypseloides with 8 species
- Genus: Streptoprocne with 5 species
- Subfamily: Apodinae
- Tribus: Salangans (Collocaliini)
- Genus: Collocalia with 3 species
- Genus: Aerodramus with 22 species, including white and black nest salangans ( A. fuciphagus and A. maximus )
- Genus: Hydrochous with the only species of giant salangan ( H. gigas )
- Genus: Schoutedenapus with 2 species
- Tribus: spiny-tailed swift (Chaeturini)
- Genus: Mearnsia with 2 species
- Genus: Zoonavena with 3 species
- Genus: Telacanthura with 2 species
- Genus: Rhaphidura with 2 species
- Genus: Neafrapus with 2 species
- Genus: Hirundapus with 4 species, including spiny-tailed swift ( H. caudacutus )
- Genus: Chaetura with 9 species, including chimney swifts ( C. pelagica )
- Tribus: Typical sailors (Apodini)
- Genus: Aeronautes with 3 species
- Genus: Tachornis with 3 kinds
- Genus: Panyptila with 2 species
- Genus: Cypsiurus with 2 species, including palm swift ( C. parvus )
- Genus: Tachymarptis with 2 species, including Alpine swift ( T. melba )
- Genus: Apus with 15 species, including common swift ( A. apus ) and pale swift ( A. pallidus )
- Tribus: Salangans (Collocaliini)
Fossil sailors
A well-known fossil of a sailor-like bird comes from the London Basin and is dated to the early Eocene . The species was named Primapus lacki in honor of David Lacks , an English ornithologist who devoted himself extensively to sailors. Known only through a humerus, the fossil suggests that the sailor-like birds were much smaller at the time than today's sailors.
The earliest known fossil, the core group is attributed to the sailor, the found in Denmark wardi Scaniacypselus . The fossil is also dated to the early Eocene . Scaniacypselus szarski is also assigned to the extinct genus Scaniacypselus , of which several skeletons were found in the Messel Pit , which are dated to the middle Eocene. The proportions of the wing bones with shortened upper and lower arms already correspond strongly to today's sailors. In some specimens the feathers are very well preserved and give a clear impression of the appearance of these birds.
In the Australian Riversleigh area, a fossil belonging to the Salangan genus Collocalia was found ( C. buday ). This fossil find, consisting of various wing bones, comes from the late Oligocene or the early Miocene and would be included in the crown group of today's sailors, if the assignment to the salangans is correct.
Sailor and man
The allusions to sailors that may exist in the historical literature that has been handed down are often hidden, since colloquial language does not distinguish so precisely between swallows and sailors. An example can be found in the Book of Jeremiah of the Old Testament ( Jer 8,7 EU ), where the migration of various birds and probably the sailor is mentioned. It became a swallow in most Bible translations , although the word (' sīs ') used in Hebrew is now used in Arabic for sailors.
The situation is similar with the " swallow's nest soup ", a delicacy of Chinese cuisine , since it uses the nests of salangans - that is, sailors - that breed in Southeast Asia . This tradition goes back at least to the late Ming Dynasty . Some assume a much longer tradition and recognize as early as 700 BC. Signs of a trade in salangan nests in Sarawak .
Mainly the nests of the white nest salangans ( Aerodramus fuciphagus ) and the black nest salangans ( Aerodramus maximus ) are used. Those of the white nest salangans consist exclusively of saliva, those of the black nest salangans contain about 10 percent other components, mainly feathers. These nests consist of 50 to 60 percent proteins ; the list of the health-promoting effects they are said to have is long, and in any case they should have an invigorating effect. Other examples include strengthening the immune system , curing excessive phlegm and tuberculosis, or increasing libido . Possible effects have been shown in various scientific studies, but the practical significance of these studies is questionable, as it was often not taken into account that the nests are boiled for a long time before consumption, which changes the chemical composition. The selling price of such nests in 2003 in Hong Kong - the main trading place for these nests - was around 5000 euros per kilogram. The significant increase in trade in recent years has made protective measures necessary for the species concerned.
Status and protection
The effects of human civilization on sailors are ambivalent: On the one hand, habitats are being destroyed and, above all, the use of insecticides adversely affects the food base; on the other hand, the use of man-made nesting sites has enabled many sailors to penetrate new habitats. Some species of sailors now almost exclusively use nesting sites near humans. However, the architectural style that has prevailed since the middle of the 20th century has had a negative impact; Today's buildings and modernized facades offer far fewer niches than older buildings that are suitable for breeding grounds. Several initiatives in different countries are addressing this problem and drawing the attention of builders to possible measures that lead to a more sailor-friendly construction method.
The lucrative exploitation of the nests of various species of salangan for swallow's nest soup has led to a dramatic decline in the populations of the species concerned. For example, the population of black nest salangans in the Niah Caves in the Malaysian state of Sarawak has decreased from over 2 million in 1931 to around 300,000 in 1999. These species and their nests are now under protection in most countries in Southeast Asia, but sometimes only in the national parks . In Indonesia , Thailand and western Malaysia in particular, the production of nests that are used for culinary purposes is also running successfully in special breeding operations that locate salangans in special buildings.
Of the more than 90 species of sailors, five are on the pre-warning list and another five are classified as endangered by the IUCN : The glossy-backed sailor ( Apus acuticauda ), the Seychelles salangans ( Aerodramus elaphrus ), the Polynesian salangans ( Aerodramus leucophaeus ), the Atiusalangans ( Aerodramus ) and the sawtelli Schouteden's sailor ( Schoutedenapus schoutedeni ).
literature
- Josep del Hoyo , Andrew Elliot , Sargatal (Eds.): Handbook of the Birds of the World. Volume 5: Barn-owls to Hummingbirds. Lynx Edicions, 1999, ISBN 84-87334-25-3 .
- Phil Chantler, Gerald Driessens: A Guide to the Swifts and Tree Swifts of the World. Pica Press, Mountfield 2000, ISBN 1-873403-83-6
- UN Glutz von Blotzheim , KM Bauer : Handbook of the birds of Central Europe . Volume 9: Columbiformes - Piciformes. AULA-Verlag, Wiesbaden 1994, ISBN 3-89104-562-X .
- David Lack : Swifts in a Tower. Methuen & Co. Ltd., London 1956
Individual evidence
- ↑ a b c d e f g h del Hoyo et al .: Handbook of the birds of the world. Page 390ff, see literature
- ↑ CT Collins: A reinterpretation of pamprodactyly in swifts: a convergent grasping mechanism in vertebrates. In: The Auk. 100: 735-737, 1983 ( online ; PDF; 261 kB)
- ^ A b Stefan Bosch: Segler am Sommerhimmel Niebühl 2003, ISBN 3-89906-463-1 , pages 17-21
- ↑ a b Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 41, see literature
- ↑ thetravelalmanac.com: The world's fastest birds
- ↑ Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 38ff, see literature
- ↑ a b del Hoyo et al .: Handbook of the birds of the world. Page 398ff, see literature
- ↑ Erich Kaiser: Sexual recognition of Common Swifts . In: British Birds. 90: 167-174, 1997
- ^ Fullard, Barclay: Echolocation in Free Flying Atiu Swiftlet (Aerodramus sawtelli). In: Biotropica. 25: 334–339, 1993 ( online ( memento of the original from December 17, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this note .; PDF ; 766 kB)
- ↑ a b Thomassen et al .: Phylogenetic relationships amongst swifts and swiftlets: A multi locus approach . In: Molecular Phylogenetics and Evolution. 37: 264-277, doi : 10.1016 / j.ympev.2005.05.010 .
- ^ Price et al .: The evolution of echolocation in swiftlets. In: Journal of Avian Biology. 35: 135-143, 2004
- ↑ a b Glutz, Bauer: Handbook of the birds of Central Europe. Volume 9, page 669f, see literature
- ↑ a b c d e del Hoyo et al .: Handbook of the birds of the world. Page 411ff, see literature
- ↑ a b del Hoyo et al .: Handbook of the birds of the world. Page 392f, see literature
- ↑ a b c d e f del Hoyo et al .: Handbook of the birds of the world. Page 400ff, see literature
- ↑ a b Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Pages 32–35, see literature
- ↑ Glutz, Bauer: Handbook of the birds of Central Europe. Volume 9, page 709f, see literature
- ↑ a b c d e f g h i j k del Hoyo et al .: Handbook of the birds of the world. Pages 402–410, see literature
- ↑ a b c d e f Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 27ff, see literature
- ↑ a b c d e del Hoyo et al .: Handbook of the birds of the world. Pages 393–398, see literature
- ^ Thais LF Martins: Low incidence of extra-pair paternity in the colonially-nesting swift (Apus apus) revealed by DNA fingerprinting. In: Journal of Avian Biology. 33: 441-446 ( doi : 10.1034 / j.1600-048X.2002.02686.x )
- ↑ Ralph W. Dexter: Extra-parental cooperation in the nesting of Chimney Swifts. In: Wilson Bulletin. 64: 133-139, 1952 ( online ; PDF; 371 kB)
- ^ J. Wright, S. Markman, SM Denney: Facultative adjustment of pre-fledging mass loss by nestling swifts preparing for flight. In: Proceedings. Biological sciences / The Royal Society. Volume 273, Number 1596, August 2006, pp. 1895-1900, ISSN 0962-8452 . doi : 10.1098 / rspb.2006.3533 . PMID 16822749 . PMC 1634777 (free full text).
- ↑ a b Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 30f, see literature
- ↑ Michael K. Tarburton, Erich Kaiser: Do fledgling and pre-breeding Common Swifts Apus apus take part in aerial roosting? An answer from a radiotracking experiment. In: Ibis. 143: 255-263, 2008 ( online )
- ↑ a b Tompkins et al .: Effect of vertically transmitted ectoparasites on the reproductive success of Swifts (Apus apus). In: Functional Ecology. , 10: 733-740, 1996 ( online ; PDF; 283 kB)
- ↑ a b c Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 36f, see literature
- ^ Wilhelm Pape , Max Sengebusch (arrangement): Concise dictionary of the Greek language. 3rd edition, 6th impression, Vieweg & Sohn, Braunschweig 1914. 1914, accessed on October 23, 2017 (word formation Apodidae from the word stem ἄποδ- ápod- recognizable in the genitive ).
- ↑ Aristotle: Historia animalium. In: Wikisource. Retrieved April 24, 2015 .
- ^ The Taxonomicon: Taxon: Subfamily Apodinae
- ↑ a b c Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 19ff, see literature
- ↑ Gerald Mayr: Osteological evidence for paraphyly of the avian or Caprimulgiformes (nightjars and allies). In: Journal of Ornithology. 143: 82–97, 2002 ( online ; PDF; 470 kB)
- ↑ Hackett et al .: A Phylogenomic Study of Birds Reveals Their Evolutionary History . In: Science. 320: 1763–1768 ( doi : 10.1126 / science.1157704 )
- ^ George Sangster: A name for the clade formed by owlet-nightjars, swifts and hummingbirds (Aves). In: Zootaxa. 799: 1–6, 2005 ( online ; PDF; 44 kB)
- ^ Frank Gill, Minturn Wright: Birds of the World: Recommended English Names. Princeton University Press, 2006, ISBN 0-7136-7904-2
- ↑ International Ornithological Congress (IOC) note (Family Aegothelidae) ( Memento of the original from October 28, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Thomassen et al .: A new phylogeny of swiftles (Aves: Apodidae) based on cytochrome-b DNA . In: Molecular Phylogenetics and Evolution. 29: 86-93, 2003, doi : 10.1016 / S1055-7903 (03) 00066-6
- ↑ del Hoyo et al .: Handbook of the birds of the world. Page 388ff, see literature
- ↑ a b c Gerald Mayr: Paleogene Fossil Birds. Springer, Berlin 2009, ISBN 3-540-89627-9 , page 132ff
- ↑ Lack: Swifts in a Tower. Page 101, see literature
- ↑ a b del Hoyo et al .: Handbook of the birds of the world. Page 413f, see literature
- ^ A b Amy SM Lau, David S. Melville: International trade in swiftlet nests with special reference to Hong Kong. Traffic International, Cambridge 1994 ( online ; PDF; 1.5 MB)
- ↑ a b c d Joseph J. Hobbs: Problems in the harvest of edible birds' nests in Sarawak and Sabah, Malaysian Borneo. In: Biodiversity and Conservation. 13: 2209–2226, 2004 ( doi: 10.1023 / B: BIOC.0000047905.79709.7f )
- ↑ Apodidae in the IUCN Red List of Threatened Species 2009. Accessed September 16, 2009.
