Blackcap
The Eurasian Blackcap, usually known simply as the Blackcap, is a typical warbler in the Sylvia genus. It is a mainly grey warbler with distinct male and female plumages. It is about 5.1 inches long with a 2.8 to 3.1 inches wing span. The adult male has olive-grey upperparts, other than a paler grey nape, and a neat black cap on the head. The underparts are light grey, becoming silvery white on the chin, throat and upper breast. The tail is dark grey with an olive tint to the outer edge of each feather. The bill and long legs are grey and the iris is reddish brown. The female resembles the male but has a reddish-brown cap and a slightly browner tone to the grey of the upperparts. Juveniles are similar to the female but their upperparts have a slight rufous tinge and the breast and flanks have a more olive tone. Young males have a darker brown cap than their female counterparts.
The Blackcap is unmistakable and other dark-headed Sylvia species, such as the Sardinian Warbler and the Orphean Warbler, have extensive black on the head instead of a small cap and they are also larger and have white edges on the tail.
The male Blackcap's song is a rich musical warbling, often ending in a loud high-pitched crescendo, which is given in bursts of up to 30 seconds. The song is repeated for about 2 minutes with a short pause before each repetition. The main song can be confused with that of the Garden Warbler but it is slightly higher pitched than in that species, more broken into discrete song segments and less mellow. Both species have a quiet sub-song, a muted version of the full song, which is even harder to separate. The Blackcap also occasionally mimics the song of other birds, the most frequently copied including the Garden Warbler and the Nightingale.
The Blackcap’s breeding range includes much of Europe, west Asia and north west Africa and its preferred habitat is mature deciduous woodland. Birds on the Mediterranean and Atlantic islands and in the milder west and south of the main Eurasian distribution often winter within the breeding range but populations elsewhere are migratory.
The Blackcap is a “leap-frog migrant” meaning that birds from the north of the breeding range travel furthest south whereas Mediterranean breeders move much shorter distances. The wintering areas overlap with the breeding range but also include extensive areas in west Africa, east Africa south to Lake Malawi and further north in Ethiopia, South Sudan and Eritrea. There is a migratory divide in Europe at longitude 10 to 11°E. Birds to the west of this line migrate south west towards Iberia or west Africa whereas populations to the east migrate to the east Mediterranean and on to east Africa.
Climate change appears to be affecting the migration pattern of the Blackcap. It is arriving in Europe earlier than previously and departing nearly 2 weeks later than in the 1980s. In recent decades, some central European birds have taken to wintering in gardens in the UK and, to a lesser extent, in Ireland, where the Blackcap was formerly just a summer visitor. Although the UK climate is sub-optimal, compensatory factors include the ready availability of food (particularly from bird tables), a shorter migration distance and the avoidance of the Alps and the Sahara Desert.
The Blackcap's main breeding habitat is mature deciduous woodland with good scrub cover below the trees. Other habitats, such as parks, large gardens and overgrown hedges, are used as long as they meet the essential requirements of tall trees for song posts and an established under-story. Where other Sylvia warblers also breed, the Blackcap tends to use taller trees than its relatives, preferably those with a good canopy such as pedunculate oak. The preferred winter habitat around the Mediterranean is scrub and olive orchards. In Africa, habitats include cultivated land, acacia scrub, mangroves and forest.
When the male Blackcap returns to its breeding range, it establishes a territory. Adults that have previously bred return to the site they have used in previous summers whereas inexperienced birds either wander until they find a suitable area or establish a very large initial territory which contracts under pressure from neighbours. Territorial boundaries are established initially by loud singing which is performed while the male displays with its crown raised, tail fanned and slow wingbeats. Sylvia warblers are unusual in that they vigorously defend their territories against other members of their genus. Blackcaps and Garden Warblers use almost identical habitats yet aggressive interactions mean that their territories rarely overlap.
The Blackcap first breeds at 1 year old. It is mainly monogamous although both sexes may sometimes deviate from this. A male attracts a female to his territory through song and a display involving raising the black crown feathers, fluffing the tail, slow wingbeats and a short flapping flight. He also builds one or more simple nests (cock nests) usually near his song post. The final nest, which may be one of the cock nests or built from scratch, is a neat cup of roots, stems and grasses lined with fine material such as hair. The nest is built in the cover of bramble, scrub or trees and it is constructed mainly by the female and may be up to 15 feet above the ground although lower than 3 feet is more typical. The clutch is 2 to 7 eggs (typically 4 to 6) which are incubated by both adults for 10 to 16 days (average 11 days). The chicks are fed by both parents and fledge about 11 to 12 days after hatching, leaving the nest shortly before they are able to fly. They are assisted with feeding for a further 2 or 3 weeks. The Blackcap normally raises just 1 brood but second broods are sometimes recorded, particularly in the milder climate of the Mediterranean and the Atlantic islands.
The Blackcap feeds mainly on insects during the breeding season and then switches to fruit in late summer, the change being triggered by an internal biological rhythm. When migrants arrive on their breeding territories they initially take berries, pollen and nectar if there are insufficient insects available but then soon switch to their preferred diet. The Blackcap mainly picks prey off foliage and twigs but it may occasionally hover, flycatch or feed on the ground. It eats a wide range of invertebrate prey, although aphids are particularly important early in the season, and flies, beetles and caterpillars are also taken in large numbers. In July, the diet switches increasingly to a wide range of small fruit. The protein needed for egg-laying and for the chicks to grow is replaced by fruit sugar which helps the birds to fatten for migration. Aphids are still taken while they are available since they often contain sugars from the plant sap on which they feed.
The Blackcap has a very large range and a very large population. It is therefore classified by the IUCN as being of “Least Concern”. The Blackcap and other small birds are illegally trapped and hunted in large numbers in Mediterranean countries, particularly in Lebanon, Syria, Palestine, Malta, Libya, Egypt and Cyprus, where they are considered as a delicacy. Despite hunting and natural hazards, the European population of the Blackcap has been increasing for several decades as the range extends northwards. There are occasional nesting records from outside the main range such as in north Israel and the Faroe Islands and wandering birds may appear further afield in Iceland or on the islands of Arctic Russia. In the Baltic region, the spread of the Blackcap appears to have been helped by the availability of territories formerly occupied by the declining Barred Warbler.
Date: 3rd April 2023
Location: Laindon, Essex
The Blackcap is unmistakable and other dark-headed Sylvia species, such as the Sardinian Warbler and the Orphean Warbler, have extensive black on the head instead of a small cap and they are also larger and have white edges on the tail.
The male Blackcap's song is a rich musical warbling, often ending in a loud high-pitched crescendo, which is given in bursts of up to 30 seconds. The song is repeated for about 2 minutes with a short pause before each repetition. The main song can be confused with that of the Garden Warbler but it is slightly higher pitched than in that species, more broken into discrete song segments and less mellow. Both species have a quiet sub-song, a muted version of the full song, which is even harder to separate. The Blackcap also occasionally mimics the song of other birds, the most frequently copied including the Garden Warbler and the Nightingale.
The Blackcap’s breeding range includes much of Europe, west Asia and north west Africa and its preferred habitat is mature deciduous woodland. Birds on the Mediterranean and Atlantic islands and in the milder west and south of the main Eurasian distribution often winter within the breeding range but populations elsewhere are migratory.
The Blackcap is a “leap-frog migrant” meaning that birds from the north of the breeding range travel furthest south whereas Mediterranean breeders move much shorter distances. The wintering areas overlap with the breeding range but also include extensive areas in west Africa, east Africa south to Lake Malawi and further north in Ethiopia, South Sudan and Eritrea. There is a migratory divide in Europe at longitude 10 to 11°E. Birds to the west of this line migrate south west towards Iberia or west Africa whereas populations to the east migrate to the east Mediterranean and on to east Africa.
Climate change appears to be affecting the migration pattern of the Blackcap. It is arriving in Europe earlier than previously and departing nearly 2 weeks later than in the 1980s. In recent decades, some central European birds have taken to wintering in gardens in the UK and, to a lesser extent, in Ireland, where the Blackcap was formerly just a summer visitor. Although the UK climate is sub-optimal, compensatory factors include the ready availability of food (particularly from bird tables), a shorter migration distance and the avoidance of the Alps and the Sahara Desert.
The Blackcap's main breeding habitat is mature deciduous woodland with good scrub cover below the trees. Other habitats, such as parks, large gardens and overgrown hedges, are used as long as they meet the essential requirements of tall trees for song posts and an established under-story. Where other Sylvia warblers also breed, the Blackcap tends to use taller trees than its relatives, preferably those with a good canopy such as pedunculate oak. The preferred winter habitat around the Mediterranean is scrub and olive orchards. In Africa, habitats include cultivated land, acacia scrub, mangroves and forest.
When the male Blackcap returns to its breeding range, it establishes a territory. Adults that have previously bred return to the site they have used in previous summers whereas inexperienced birds either wander until they find a suitable area or establish a very large initial territory which contracts under pressure from neighbours. Territorial boundaries are established initially by loud singing which is performed while the male displays with its crown raised, tail fanned and slow wingbeats. Sylvia warblers are unusual in that they vigorously defend their territories against other members of their genus. Blackcaps and Garden Warblers use almost identical habitats yet aggressive interactions mean that their territories rarely overlap.
The Blackcap first breeds at 1 year old. It is mainly monogamous although both sexes may sometimes deviate from this. A male attracts a female to his territory through song and a display involving raising the black crown feathers, fluffing the tail, slow wingbeats and a short flapping flight. He also builds one or more simple nests (cock nests) usually near his song post. The final nest, which may be one of the cock nests or built from scratch, is a neat cup of roots, stems and grasses lined with fine material such as hair. The nest is built in the cover of bramble, scrub or trees and it is constructed mainly by the female and may be up to 15 feet above the ground although lower than 3 feet is more typical. The clutch is 2 to 7 eggs (typically 4 to 6) which are incubated by both adults for 10 to 16 days (average 11 days). The chicks are fed by both parents and fledge about 11 to 12 days after hatching, leaving the nest shortly before they are able to fly. They are assisted with feeding for a further 2 or 3 weeks. The Blackcap normally raises just 1 brood but second broods are sometimes recorded, particularly in the milder climate of the Mediterranean and the Atlantic islands.
The Blackcap feeds mainly on insects during the breeding season and then switches to fruit in late summer, the change being triggered by an internal biological rhythm. When migrants arrive on their breeding territories they initially take berries, pollen and nectar if there are insufficient insects available but then soon switch to their preferred diet. The Blackcap mainly picks prey off foliage and twigs but it may occasionally hover, flycatch or feed on the ground. It eats a wide range of invertebrate prey, although aphids are particularly important early in the season, and flies, beetles and caterpillars are also taken in large numbers. In July, the diet switches increasingly to a wide range of small fruit. The protein needed for egg-laying and for the chicks to grow is replaced by fruit sugar which helps the birds to fatten for migration. Aphids are still taken while they are available since they often contain sugars from the plant sap on which they feed.
The Blackcap has a very large range and a very large population. It is therefore classified by the IUCN as being of “Least Concern”. The Blackcap and other small birds are illegally trapped and hunted in large numbers in Mediterranean countries, particularly in Lebanon, Syria, Palestine, Malta, Libya, Egypt and Cyprus, where they are considered as a delicacy. Despite hunting and natural hazards, the European population of the Blackcap has been increasing for several decades as the range extends northwards. There are occasional nesting records from outside the main range such as in north Israel and the Faroe Islands and wandering birds may appear further afield in Iceland or on the islands of Arctic Russia. In the Baltic region, the spread of the Blackcap appears to have been helped by the availability of territories formerly occupied by the declining Barred Warbler.
Date: 3rd April 2023
Location: Laindon, Essex
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