Crag Martin
Encyclopedia
The Eurasian Crag Martin or just Crag Martin (Ptyonoprogne rupestris) is a small passerine
bird
in the swallow
family. It is about 14 cm (5.5 in) long with ash-brown upperparts and paler underparts, and a short, square tail that has distinctive white patches on most of its feathers. It breeds in the mountains of southern Europe, northwestern Africa and southern Asia. It can be confused with the other two species in its genus, but is larger than both, with brighter tail spots and different plumage tone. Many European birds are resident, but some northern populations and most Asian breeders are migratory
, wintering in northern Africa, the Middle East
or India
.
The Eurasian Crag Martin builds a nest adherent to the rock under a cliff overhang or increasingly onto a man-made structure. It makes a neat half-cup mud nest with an inner soft lining of feathers and dry grass. Nests are often solitary, although a few pairs may breed relativity close together at good locations. Two to five brown-blotched white eggs are incubated mainly by the female, and both parents feed the chicks. This species does not form large breeding colonies, but is gregarious
outside the breeding season. It feeds on a wide variety of insects that are caught in its beak as the martin flies near to cliff faces or over streams and alpine meadows. Adults and young may be hunted and eaten by birds of prey
or corvid
s, and this species is a host of blood-sucking mites. With its very large and expanding range and large population there are no significant conservation concerns.
This bird is closely related to the other two crag martins which share its genus, and has sometimes been considered to be the same species as one or both, although it appears that there are areas where two species' ranges overlap without hybridisation occurring. All three Ptyonoprogne crag martins are quite similar in behaviour to other Old World
swallows that build mud nests, and are sometimes subsumed into the larger genus Hirundo
, but this approach leads to inconsistencies in classifying other genera, particularly the house martins
.
in 1769 and was moved to the new genus Ptyonoprogne
by German ornithologist Heinrich Gustav Reichenbach
in 1850. Its nearest relatives are the two other members of the genus, the Rock Martin, P. fuligula, and the Dusky Crag Martin
, P. concolor. The genus name is derived from the Greek ptuon (φτυον), "a fan", referring to the shape of the opened tail, and Procne (Πρόκνη), a mythological girl who was turned into a swallow. The specific rupestris means "of rocks", from the Latin rupes "rock". There are no generally recognised subspecies. Two races, Central Asian P. r. centralasica and P. r. theresae in the Atlas Mountains
of Morocco, have been proposed, but the slight differences in size and colour show no consistent geographical pattern. Fossils of this species have been found in Late Pleistocene
deposits in Bulgaria, and in central France in layers dated at 242,000 to 301,000 years ago.
The three Ptyonoprogne species are members of the swallow family of birds, and are placed in the Hirundininae subfamily, which comprises all swallows and martins except the very distinctive river martin
s. DNA
studies suggest that there are three major groupings within the Hirundininae, broadly correlating with the type of nest built. The groups are the "core martins" including burrowing species like the Sand Martin
, the "nest-adopters", which are birds like the Tree Swallow
that utilise natural cavities, and the "mud nest builders". The Ptyonoprogne species construct an open mud nest and therefore belong to the last group; Hirundo
species also build open nests, Delichon
house martins have a closed nest, and the Cecropis
and Petrochelidon
swallows have retort-like
closed nests with an entrance tunnel.
Ptyonoprogne is closely related to the larger swallow genus Hirundo into which it is often subsumed, but a DNA analysis showed that an enlarged Hirundo genus should logically contain all the mud-builder genera, including the Delichon
house martins, a practice which few authorities follow. Although the nests of the Ptyonoprogne crag martins resembles those of typical Hirundo species like the Barn Swallow
, the research showed that if Delichon, Cecropis
and Petrochelidon
are split from Hirundo, Ptyonoprogne should also be treated as a separate genus.
are blackish, the eyes are brown, the small bill is mainly black, and the legs are brownish-pink. The sexes are alike, but juveniles have buff-brown tips to the plumage of the head, upperparts and wing coverts. This species can be distinguished from the Sand Martin
by its larger size, the white patches on the tail, and its lack of a brown breast band. Where the range overlaps with that of another Ptyonoprogne species, the Eurasian Crag Martin is darker, browner and 15% larger than the Rock Martin, and larger and paler, particularly on its underparts than the Dusky Crag Martin. The white tail spots of the Eurasian Crag Martin are significantly larger than those of both its relatives.
The Crag Martin's flight appears relatively slow for a swallow. Rapid wing beats are interspersed with flat-winged glides, and its long flexible primaries give it the agility to manoeuvre near cliff faces. The average migration flight speed has been measured at 9.9 m/s (32.5 ft/s), less than the roughly 11 m/s (36 ft/s) typical for hirundines, but the data is limited. The bird often flies high, and shows the white spots as it spreads its tail. The vocalisations include short high pli, and piieh and tshir calls resembling those of the Linnet
and the House Martin respectively.
The Eurasian Crag Martin breeds in mountains from Iberia
and northwesternmost Africa through southern Europe, the Persian Gulf
and the Himalayas
to southwestern and northeastern China. Northern populations are migratory
, with European birds wintering in north Africa, Senegal, Ethiopia and the Nile Valley
, and Asian breeders going to southern China, the Indian subcontinent and the Middle East
. Some European birds stay north of the Mediterranean, and, like martins in warmer areas such as India, Turkey and Cyprus, just move to lower ground after breeding. The breeding range is bounded by the 20 °C (68 °F) July isotherm, and wintering areas need a temperature of about 15 °C (58 °F) for enough insect food to be available. This is a rare species any distance north of its breeding areas. For example, there are only eight records from the UK, none from Ireland, and the first record for Sweden was reported as recently as 1996. South of its normal wintering range, it has occurred as a vagrant in The Gambia.
Crag Martins breed on dry, warm and sheltered cliffs in mountainous areas with crags and gorges. The typical altitude is 2,000–2,700 m (6,600–8,900 ft) but breeding occurs up to 5,000 m (16,500 ft) in Central Asia. The Eurasian Crag Martin's choice of nest sites is very similar to that of Savi's Pipistrelle
, Hypsugo savii; the bird and the bat often breed in the same locations and have almost identical ranges in Europe. In South Asia, migrant Eurasian birds sometimes join with flocks of the Dusky Crag Martin and roost communally on ledges of cliffs or buildings.
, usually containing fewer than ten nests. Nests are on average 30 m (100 ft) apart and each pair aggressively defends its breeding territory against other Crag Martins and most other bird species. Nesting takes place from May to August, and usually two broods are raised. The nest, built by both adults, is an open half cup made of mud and lined with soft material such as feathers or dry grass. It is constructed under an overhang on a rock cliff face, in a crevice or cave, or on a man-made structure. It takes one to three weeks to build and is re-used for the second brood and in subsequent years. The clutch is two to five eggs with an average of three. The eggs are white with brownish blotches particularly at the wide end, and average 20.2 x 14.0 mm (0.80 x 0.55 in) with a weight of 2.08 g (0.073 oz). The eggs are incubated mainly by the female for 13–17 days to hatching, and the chicks take another 24–27 days to fledge. Both parents feed the chicks bringing food every two to five minutes, and the young are fed for 14–21 days after fledging. With such frequent feeding rates the adults mainly forage in the best hunting zones in the immediate vicinity of the nest, since the further they fly to forage the longer it would take to bring food to the chicks in the nest. In an Italian study, the hatching rate was 80.2 percent, and the average number of fledged young was 3.1.
The Crag Martin has over the last few decades increasingly used houses and other man-made sites to nest. This greater availability of breeding sites has enabled the species to expand its range, but it is possible that this will lead to competition with other hirundines, such as the Barn Swallow and Common House Martin, which also use artificial nest sites.
An Italian study showed that, as with other aerial feeders, the start of breeding was delayed by cold or wet weather, but this had no influence on the clutch size nor on the number of fledged young. Unexpectedly, it was found that once the eggs had hatched there was a negative relationship between temperature and the number of fledged young. The authors suggested that hot weather dried up the small rivers where the parents found food. Colony size did not influence the laying date, the clutch size or the number of successfully fledged young, but this species does not form large colonies anyway.
, ants, aerial spiders, and beetle
s. Aquatic species such as stoneflies
, caddisflies and pond skaters appear to be important in at least Spain and Italy. Unlike other hirundines, these birds feed close to their breeding sites, and may be locally vulnerable to fluctuations in insect availability. This martin is gregarious outside the breeding season, and may form sizeable flocks where food is abundant. Cliff faces generate standing wave
s in the airflow which concentrate insects near vertical areas. The Crag Martin exploits the area close to the cliff when it hunts, relying on its high manoeuvrability and ability to perform tight turns.
, which shares its mountain habitat, and during its migration over the Himalayas, it is reported to be subject to predation by crows. Common Kestrel
s, Eurasian Sparrowhawks, Eurasian Jay
s and Common Raven
s are also treated as predators and attacked by repeated dives if they approach nesting cliffs. Despite the general aggressiveness of the martin, it tolerates sympatric Common House Martins, perhaps because the large numbers of that highly colonial species provide an early warning of predators.
The Crag Martin is a host of blood-sucking mites of the genus Dermanyssus, including D. chelidonis, and of the nasal mite Ptilonyssus ptyonoprognes. Two new species of parasites were first discovered on this martin, the fly Ornithomya rupes in Gibraltar and the flea Ceratophyllus nanshanensis from China.
on the IUCN Red List
.
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
bird
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...
in the swallow
Swallow
The swallows and martins are a group of passerine birds in the family Hirundinidae which are characterised by their adaptation to aerial feeding...
family. It is about 14 cm (5.5 in) long with ash-brown upperparts and paler underparts, and a short, square tail that has distinctive white patches on most of its feathers. It breeds in the mountains of southern Europe, northwestern Africa and southern Asia. It can be confused with the other two species in its genus, but is larger than both, with brighter tail spots and different plumage tone. Many European birds are resident, but some northern populations and most Asian breeders are migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, wintering in northern Africa, the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
or India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
.
The Eurasian Crag Martin builds a nest adherent to the rock under a cliff overhang or increasingly onto a man-made structure. It makes a neat half-cup mud nest with an inner soft lining of feathers and dry grass. Nests are often solitary, although a few pairs may breed relativity close together at good locations. Two to five brown-blotched white eggs are incubated mainly by the female, and both parents feed the chicks. This species does not form large breeding colonies, but is gregarious
Social
The term social refers to a characteristic of living organisms...
outside the breeding season. It feeds on a wide variety of insects that are caught in its beak as the martin flies near to cliff faces or over streams and alpine meadows. Adults and young may be hunted and eaten by birds of prey
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
or corvid
Corvidae
Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers. The common English names used are corvids or the crow family , and there are over 120 species...
s, and this species is a host of blood-sucking mites. With its very large and expanding range and large population there are no significant conservation concerns.
This bird is closely related to the other two crag martins which share its genus, and has sometimes been considered to be the same species as one or both, although it appears that there are areas where two species' ranges overlap without hybridisation occurring. All three Ptyonoprogne crag martins are quite similar in behaviour to other Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
swallows that build mud nests, and are sometimes subsumed into the larger genus Hirundo
Hirundo
The bird genus Hirundo is a group of passerines in the family Hirundinidae . These are the typical swallows, including the widespread Barn Swallow. Many of this group have blue backs, red on the face and sometimes the rump or nape, and whitish or rufous underparts...
, but this approach leads to inconsistencies in classifying other genera, particularly the house martins
Delichon
Delichon is a small genus of passerine birds that belongs to the swallow family and contains three species named as house martins. These are chunky, bull-headed and short-tailed birds, blackish-blue above with a contrasting white rump, and with white or grey underparts. They have feathering on the...
.
Taxonomy
The Eurasian Crag Martin was formally described as Hirundo rupestris by Italian naturalist Giovanni Antonio ScopoliGiovanni Antonio Scopoli
Giovanni Antonio Scopoli was an Italian physician and naturalist.-Biography:...
in 1769 and was moved to the new genus Ptyonoprogne
Ptyonoprogne
The crag martins are three species of small passerine birds in the genus Ptyonoprogne of the swallow family. They are the Eurasian Crag Martin , the Rock Martin and the Dusky Crag Martin . They are closely related to each other, and have formerly sometimes been considered to be one species...
by German ornithologist Heinrich Gustav Reichenbach
Heinrich Gustav Reichenbach
Heinrich Gustav Reichenbach was an ornithologist, botanist and the foremost German orchidologist of the 19th century...
in 1850. Its nearest relatives are the two other members of the genus, the Rock Martin, P. fuligula, and the Dusky Crag Martin
Dusky Crag Martin
The Dusky Crag Martin is a small passerine bird in the swallow family. It is about 13 cm long with a broad body and wings, and a short square tail that has small white patches near the tips of most of its feathers. This martin has sooty-brown upperparts and slightly paler underparts...
, P. concolor. The genus name is derived from the Greek ptuon (φτυον), "a fan", referring to the shape of the opened tail, and Procne (Πρόκνη), a mythological girl who was turned into a swallow. The specific rupestris means "of rocks", from the Latin rupes "rock". There are no generally recognised subspecies. Two races, Central Asian P. r. centralasica and P. r. theresae in the Atlas Mountains
Atlas Mountains
The Atlas Mountains is a mountain range across a northern stretch of Africa extending about through Morocco, Algeria, and Tunisia. The highest peak is Toubkal, with an elevation of in southwestern Morocco. The Atlas ranges separate the Mediterranean and Atlantic coastlines from the Sahara Desert...
of Morocco, have been proposed, but the slight differences in size and colour show no consistent geographical pattern. Fossils of this species have been found in Late Pleistocene
Late Pleistocene
The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...
deposits in Bulgaria, and in central France in layers dated at 242,000 to 301,000 years ago.
The three Ptyonoprogne species are members of the swallow family of birds, and are placed in the Hirundininae subfamily, which comprises all swallows and martins except the very distinctive river martin
River martin
The river martins form a distinctive subfamily Pseudochelidoninae within the swallow and martin bird family Hirundinidae. The two species are the African River Martin Pseudochelidon eurystomina, found in the Congo and Gabon, and the White-eyed River Martin Pseudochelidon sirintarae, known only from...
s. DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
studies suggest that there are three major groupings within the Hirundininae, broadly correlating with the type of nest built. The groups are the "core martins" including burrowing species like the Sand Martin
Sand Martin
The Sand Martin is a migratory passerine bird in the swallow family. It has a wide range in summer, embracing practically the whole of Europe and the Mediterranean countries, part of northern Asia and also North America. It winters in eastern and southern Africa, South America and South Asia...
, the "nest-adopters", which are birds like the Tree Swallow
Tree Swallow
The Tree Swallow, Tachycineta bicolor, is a migratory passerine bird that breeds in North America and winters in Mexico, Central America and the Caribbean. It is a very rare vagrant to western Europe....
that utilise natural cavities, and the "mud nest builders". The Ptyonoprogne species construct an open mud nest and therefore belong to the last group; Hirundo
Hirundo
The bird genus Hirundo is a group of passerines in the family Hirundinidae . These are the typical swallows, including the widespread Barn Swallow. Many of this group have blue backs, red on the face and sometimes the rump or nape, and whitish or rufous underparts...
species also build open nests, Delichon
Delichon
Delichon is a small genus of passerine birds that belongs to the swallow family and contains three species named as house martins. These are chunky, bull-headed and short-tailed birds, blackish-blue above with a contrasting white rump, and with white or grey underparts. They have feathering on the...
house martins have a closed nest, and the Cecropis
Cecropis
Cecropis is a genus of large swallows found in Africa and tropical Asia. The Red-rumped Swallow's range also extends into southern Europe. This genus is frequently subsumed into the larger genus Hirundo.The species are:...
and Petrochelidon
Petrochelidon
Petrochelidon is a genus of birds known as cliff-nesting swallows.It contains the following species:-Species in taxonomic order:* Red-throated Cliff Swallow * Preuss's Cliff Swallow...
swallows have retort-like
Retort
In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...
closed nests with an entrance tunnel.
Ptyonoprogne is closely related to the larger swallow genus Hirundo into which it is often subsumed, but a DNA analysis showed that an enlarged Hirundo genus should logically contain all the mud-builder genera, including the Delichon
Delichon
Delichon is a small genus of passerine birds that belongs to the swallow family and contains three species named as house martins. These are chunky, bull-headed and short-tailed birds, blackish-blue above with a contrasting white rump, and with white or grey underparts. They have feathering on the...
house martins, a practice which few authorities follow. Although the nests of the Ptyonoprogne crag martins resembles those of typical Hirundo species like the Barn Swallow
Barn Swallow
The Barn Swallow is the most widespread species of swallow in the world. It is a distinctive passerine bird with blue upperparts, a long, deeply forked tail and curved, pointed wings. It is found in Europe, Asia, Africa and the Americas...
, the research showed that if Delichon, Cecropis
Cecropis
Cecropis is a genus of large swallows found in Africa and tropical Asia. The Red-rumped Swallow's range also extends into southern Europe. This genus is frequently subsumed into the larger genus Hirundo.The species are:...
and Petrochelidon
Petrochelidon
Petrochelidon is a genus of birds known as cliff-nesting swallows.It contains the following species:-Species in taxonomic order:* Red-throated Cliff Swallow * Preuss's Cliff Swallow...
are split from Hirundo, Ptyonoprogne should also be treated as a separate genus.
Description
The Eurasian Crag Martin is 13–15 cm (5.1–5.9 in) long with a 32–34.5 cm (12.6–13.6 in) wingspan, and weighs an average 23 g (0.81 oz). It has ash-brown upperparts and paler underparts, and has a broader body, wings and tail than any other European swallow. The tail is short and square, with white patches near the tips of all but the central and outermost pairs of feathers. The underwing and undertail covertsCovert (feather)
A covert feather on a bird is one of a set of feathers, called coverts, which as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail.- Wing-coverts :...
are blackish, the eyes are brown, the small bill is mainly black, and the legs are brownish-pink. The sexes are alike, but juveniles have buff-brown tips to the plumage of the head, upperparts and wing coverts. This species can be distinguished from the Sand Martin
Sand Martin
The Sand Martin is a migratory passerine bird in the swallow family. It has a wide range in summer, embracing practically the whole of Europe and the Mediterranean countries, part of northern Asia and also North America. It winters in eastern and southern Africa, South America and South Asia...
by its larger size, the white patches on the tail, and its lack of a brown breast band. Where the range overlaps with that of another Ptyonoprogne species, the Eurasian Crag Martin is darker, browner and 15% larger than the Rock Martin, and larger and paler, particularly on its underparts than the Dusky Crag Martin. The white tail spots of the Eurasian Crag Martin are significantly larger than those of both its relatives.
The Crag Martin's flight appears relatively slow for a swallow. Rapid wing beats are interspersed with flat-winged glides, and its long flexible primaries give it the agility to manoeuvre near cliff faces. The average migration flight speed has been measured at 9.9 m/s (32.5 ft/s), less than the roughly 11 m/s (36 ft/s) typical for hirundines, but the data is limited. The bird often flies high, and shows the white spots as it spreads its tail. The vocalisations include short high pli, and piieh and tshir calls resembling those of the Linnet
Linnet
The Linnet is a small passerine bird in the finch family Fringillidae.The Linnet derives its scientific name from its fondness for hemp and its English name from its liking for seeds of flax, from which linen is made.- Description :...
and the House Martin respectively.
Distribution and habitat
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
and northwesternmost Africa through southern Europe, the Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...
and the Himalayas
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
to southwestern and northeastern China. Northern populations are migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, with European birds wintering in north Africa, Senegal, Ethiopia and the Nile Valley
Nile
The Nile is a major north-flowing river in North Africa, generally regarded as the longest river in the world. It is long. It runs through the ten countries of Sudan, South Sudan, Burundi, Rwanda, Democratic Republic of the Congo, Tanzania, Kenya, Ethiopia, Uganda and Egypt.The Nile has two major...
, and Asian breeders going to southern China, the Indian subcontinent and the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
. Some European birds stay north of the Mediterranean, and, like martins in warmer areas such as India, Turkey and Cyprus, just move to lower ground after breeding. The breeding range is bounded by the 20 °C (68 °F) July isotherm, and wintering areas need a temperature of about 15 °C (58 °F) for enough insect food to be available. This is a rare species any distance north of its breeding areas. For example, there are only eight records from the UK, none from Ireland, and the first record for Sweden was reported as recently as 1996. South of its normal wintering range, it has occurred as a vagrant in The Gambia.
Crag Martins breed on dry, warm and sheltered cliffs in mountainous areas with crags and gorges. The typical altitude is 2,000–2,700 m (6,600–8,900 ft) but breeding occurs up to 5,000 m (16,500 ft) in Central Asia. The Eurasian Crag Martin's choice of nest sites is very similar to that of Savi's Pipistrelle
Savi's Pipistrelle
Savi's Pipistrelle, Hypsugo savii is a species of vesper bat found across Eurasia. Its summer habitat is not known, but in winter it favors caves, old buildings, and rock crevices. The Hypsugo savii and the Pipistrellus kuhlii have a share of similarities...
, Hypsugo savii; the bird and the bat often breed in the same locations and have almost identical ranges in Europe. In South Asia, migrant Eurasian birds sometimes join with flocks of the Dusky Crag Martin and roost communally on ledges of cliffs or buildings.
Breeding
Crag Martin pairs nest alone or in small coloniesBird colony
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in close proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony...
, usually containing fewer than ten nests. Nests are on average 30 m (100 ft) apart and each pair aggressively defends its breeding territory against other Crag Martins and most other bird species. Nesting takes place from May to August, and usually two broods are raised. The nest, built by both adults, is an open half cup made of mud and lined with soft material such as feathers or dry grass. It is constructed under an overhang on a rock cliff face, in a crevice or cave, or on a man-made structure. It takes one to three weeks to build and is re-used for the second brood and in subsequent years. The clutch is two to five eggs with an average of three. The eggs are white with brownish blotches particularly at the wide end, and average 20.2 x 14.0 mm (0.80 x 0.55 in) with a weight of 2.08 g (0.073 oz). The eggs are incubated mainly by the female for 13–17 days to hatching, and the chicks take another 24–27 days to fledge. Both parents feed the chicks bringing food every two to five minutes, and the young are fed for 14–21 days after fledging. With such frequent feeding rates the adults mainly forage in the best hunting zones in the immediate vicinity of the nest, since the further they fly to forage the longer it would take to bring food to the chicks in the nest. In an Italian study, the hatching rate was 80.2 percent, and the average number of fledged young was 3.1.
The Crag Martin has over the last few decades increasingly used houses and other man-made sites to nest. This greater availability of breeding sites has enabled the species to expand its range, but it is possible that this will lead to competition with other hirundines, such as the Barn Swallow and Common House Martin, which also use artificial nest sites.
An Italian study showed that, as with other aerial feeders, the start of breeding was delayed by cold or wet weather, but this had no influence on the clutch size nor on the number of fledged young. Unexpectedly, it was found that once the eggs had hatched there was a negative relationship between temperature and the number of fledged young. The authors suggested that hot weather dried up the small rivers where the parents found food. Colony size did not influence the laying date, the clutch size or the number of successfully fledged young, but this species does not form large colonies anyway.
Feeding
The Eurasian Crag Martin feeds mainly on insects caught in its beak in flight, although it will occasionally take prey items off rocks, the ground, or a water surface. When breeding, birds often fly back and forth near to a rock face hunting for insects, feeding both inside and outside the nesting territory. At other times, they may hunt flying above streams or alpine meadows. The insects taken depend on what is locally available and may include fliesFly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
, ants, aerial spiders, and beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s. Aquatic species such as stoneflies
Plecoptera
Plecoptera are an order of insects, commonly known as stoneflies. There are some 3,500 described species worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica...
, caddisflies and pond skaters appear to be important in at least Spain and Italy. Unlike other hirundines, these birds feed close to their breeding sites, and may be locally vulnerable to fluctuations in insect availability. This martin is gregarious outside the breeding season, and may form sizeable flocks where food is abundant. Cliff faces generate standing wave
Standing wave
In physics, a standing wave – also known as a stationary wave – is a wave that remains in a constant position.This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling...
s in the airflow which concentrate insects near vertical areas. The Crag Martin exploits the area close to the cliff when it hunts, relying on its high manoeuvrability and ability to perform tight turns.
Predators and parasites
This species is occasionally hunted by the Peregrine FalconPeregrine Falcon
The Peregrine Falcon , also known as the Peregrine, and historically as the Duck Hawk in North America, is a widespread bird of prey in the family Falconidae. A large, crow-sized falcon, it has a blue-gray back, barred white underparts, and a black head and "moustache"...
, which shares its mountain habitat, and during its migration over the Himalayas, it is reported to be subject to predation by crows. Common Kestrel
Common Kestrel
The Common Kestrel is a bird of prey species belonging to the kestrel group of the falcon family Falconidae. It is also known as the European Kestrel, Eurasian Kestrel, or Old World Kestrel. In Britain, where no other brown falcon occurs, it is generally just called "the kestrel".This species...
s, Eurasian Sparrowhawks, Eurasian Jay
Eurasian Jay
The Eurasian Jay is a species of bird occurring over a vast region from Western Europe and north-west Africa to the Indian Subcontinent and further to the eastern seaboard of Asia and down into south-east Asia...
s and Common Raven
Common Raven
The Common Raven , also known as the Northern Raven, is a large, all-black passerine bird. Found across the northern hemisphere, it is the most widely distributed of all corvids...
s are also treated as predators and attacked by repeated dives if they approach nesting cliffs. Despite the general aggressiveness of the martin, it tolerates sympatric Common House Martins, perhaps because the large numbers of that highly colonial species provide an early warning of predators.
The Crag Martin is a host of blood-sucking mites of the genus Dermanyssus, including D. chelidonis, and of the nasal mite Ptilonyssus ptyonoprognes. Two new species of parasites were first discovered on this martin, the fly Ornithomya rupes in Gibraltar and the flea Ceratophyllus nanshanensis from China.
Status
The European population of the Eurasian Crag Martin is estimated to be 360,000–1,110,000 individuals, including 120,000–370,000 breeding pairs. A rough estimate of the worldwide population is 500,000–5,000,000 individuals, with Europe hosting between one-quarter and one-half of the total. The population is estimated to be increasing following a northward expansion, which may be partly due to increased use of man-made structures as nest sites. Expansions of the range have been reported in Austria (where motorway bridges are used as nest sites), Switzerland, the former Yugoslavia, Romania, and Bulgaria. With its very large range and high numbers, the Eurasian Crag Martin is not considered to be threatened, and it is classed as Least ConcernLeast Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
.