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Which birds eat aphids

Aphids are known to be an important food resource for many species of birds, especially in providing a source of readily digestible high energy food for the young. But their importance does vary greatly between families of birds, with (not surprisingly perhaps) the smaller bird species being the ones most dependent on aphids as food.

Warblers are probably the biggest consumers of aphids. In Europe and Asia these include the leaf warblers (Phylloscopidae). An example is the chiffchaff which searches the undersides of leaves for insects, mainly aphids, feeding on the plant's sugary sap (= phloem feeders). The true warblers (Sylviidae) such as the blackcap and subalpine warblers feed alternatively on aphids and fruits. The marsh warblers (Acrocephalidae) which include the reed warbler and sedge warbler are major consumers of aphids on reeds. Some of the American or New World warblers (Parulidae) are also important aphid consumers, such as the Tennessee warbler shown below feeding on a vast colony of the beech blight aphid (Grylloprociphilus imbricator).

Image reproduced by permission, Copyright Seasons Flow, all rights reserved.

Other American warblers which are known to eat large numbers of aphids include the palm warbler, blackpoll warbler, magnolia warbler and Cape May warbler.

Sparrows (Passeridae) are another group of aphid eaters, at least at the nestling stage. In Europe these include the house sparrow which eats small insects at the nestling stage, and the hedge sparrow or dunnock. The American sparrows include a number of known aphid predators, including the vesper sparrow, the chipping sparrow, the savannah sparrow and the field sparrow. Vesper and field sparrows are ground foragers that mainly eat insects and seeds. Savanna sparrows and chipping sparrows are thought to mainly eat seeds, but also eat aphids and other insects in the breeding season. Various tits and chickadees (Paridae) are known to take quite large numbers of aphids, especially the blue tit and the coal tit. The great tit is a well known predator of gall aphids, using its heavy bill to break into the gall.

Species in many other bird families also feed on aphids to a lesser degree. Lapwings (Charadriidae) feed on aquatic and terrestrial invertebrates depending on habitat. In India the red-wattled lapwing (Vanellus indicus) is an important aphid predator ion farmland, along with the yellow wattled lapwing (Vanellus indicus). Also various members of the thrush family (Turdidae) such as common myna (Acridotheres tristis), common babbler (Argya (=Turdoides) caudatus) and jungle babbler (Argya (=Turdoides) striatus). The finches (Fringillidae) primarily eat seeds, but those in the genera Euphonia and Chlorophonia also eat a lot of insects. There is also considerable evidence that some other finches, for example the American goldfinch (Carduelis tristis), will on occasions 'switch' to eating aphids. Lastly some woodpeckers (Picidae) consume large numbers of tree-dwelling aphids.

To what extent birds contribute to controlling pest aphid populations in our farms and gardens is not fully resolved. In a review in 1996 Kirk concluded that although few insectivorous bird species are entirely beneficial or entirely harmful to agriculture the overall balance is overwhelmingly positive. Strong experimental evidence indicates that the predatory activities of birds can suppress insect populations, at least at medium to low infestation levels. This "ecological service" should be factored into integrated pest control plans where possible, and the farm landscape should be managed with birds in mind. However it should be borne in mind that, whilst there has been much research on aphid control using invertebrates such as coccinellid beetles, midge larvae and hymenopterous parasitoids, there have been far fewer quantitative studies regarding their vertebrate predators.

Many of the bird species that eat aphids are known amongst wildlife enthusiasts as 'small brown jobs' given the difficulty many have in identifying them. Below we give more information on exactly which species of birds eat aphids and how to identify them. Please note that the list below is certainly not exhaustive - we add new ones from time to time!


Acrocephalidae (marsh warblers)

The marsh warblers are mostly fairly large, brownish warblers found in reedbeds, tall grassland or open woodland. They typically breed in extensive marshes. They tend to have skulking habits making identification by plumage difficult, but their loud songs often reveal their presence and aid identification. They are mainly insectivorous. All the Palearctic marsh warblers are migrants, moving south to winter in Africa, India or southeast Asia. Tropical populations are generally sedentary. Most members of the family are found in Europe and Asia, with a few in Africa, Oceania and Australasia.

Acrocephalus schoenobaenus (Sedge warbler)

The adult sedge warbler (see first picture below) has black and cream stripes on the and a wide distinctive silver-white stripe over the eye known as supercilium (cf. reed warbler which has only a pale eye ring and a thin partial supercilium in front of the eye). It also has an obvious dark eyestripe. It has a buff chest and a white underside and a tawny back with light grey streaking. The rump is unstreaked tawny brown. Ages and sexes are similar in appearance, although juvenile birds (see second picture below) may have some dark spotting on the breast. The song of the sedge warbler is characteristic: its pitch rises and falls in a jerky way - making the song sound very hurried and not at all 'restful' (cf. reed warbler which has a rhythmic, chattering jit-jit-jit with whistles and mimicry).

First image above copyright Derek Gallagher under a Creative Commons Attribution-Share Alike 4.0 International license.
Second image above copyright bogbumper under a Creative Commons Attribution-Share Alike 3.0 Unported License.

Sedge warblers breed on the edge of wetlands, especially in areas of wet grassland. They are mainly insectivorous, feeding especially on mealy plum aphids when they are abundant on their summer host (reeds). They also feed on dragonflies and damselflies, grasshoppers, lacewings, moths, beetles and flies. Some berries are also taken, including elderberries and blackberries. Prior to migration they may seek out sites that have large numbers of readily captured insects (see below) enabling them to rapidly put on weight before departure. Sedge warblers are migratory, breeding in Europe and temperate western Asia, and wintering in sub-Saharan Africa south to Zambia.


Acrocephalus scirpaceus (Reed warbler)

Reed warblers have an unstreaked brown back with a light buff underside. They have a round head with the forehead flattened, a long slim pointed bill, a narrow faint supercilium not extending behind the eye, and a white throat (cf. sedge warbler which has a broad, pale supercilium). The legs are dark brown or greyish and it has a long powerful tail which is unusually square, usually slightly rounded. Ages and sexes are similar in appearance. It is very similar to other, rarer, warblers and is best distinguished by its song (see Reed Warbler & its Song) which is a slow, chattering jit-jit-jit with whistles and mimicry added (cf. sedge warbler which has the pitch of its song rising and falling in a jerky way making the song sound very hurried and not at all 'restful').

First image copyright Martien Brand, under a Creative Commons Attribution 2.0 Generic License.
Second image copyright Ron Knight, under a Creative Commons Attribution 2.0 Generic License.

Reed warblers are mainly found in reed beds, usually with a few bushes. They are insectivorous, but will also take a few berries. Like sedge warblers they will concentrate on mealy plum aphids when they are abundant on their summer host (reeds), but they may be more ready to go after more mobile prey like mayflies and damselflies. Reed warblers are migratory, breeding in Europe and temperate western Asia, and wintering in sub-Saharan Africa south to Zambia.


Charadriidae (plovers & lapwings)

The plovers and lapwings are usually medium-sized birds with short, thick necks, usually pointed wings, straight bills and relatively short tails. They are found in open country mostly near water. They mainly feed on small invertebrates including insects, worms, molluscs and crustaceans, but also take some plant material. Members of the family are found worldwide.

Vanellus indicus (Red-wattled Lapwing)

The wings and back of adult red-wattled lapwings (see first picture below) are light brown with a purple to green sheen. The head, the front bib and back of the neck are black. A prominent white patch runs between these two colours, from belly to tail, flanking the neck to the sides of the crown. There is a red fleshy wattle in front of each eye, and the bill is red tipped with black. The short tail is tipped with black and the long legs are yellow. In flight the bird displays prominent white wing bars formed by the white on the secondary coverts (see second picture below).

First image copyright Charles J Sharp under a Creative Commons Attribution-Share Alike 4.0 License
Second image copyright Yogendra Joshi under a Creative Commons Attribution-Share Alike 2.0 License

There are four recognized subspecies:

  • Vanellus indicus aigneri, found from southeast Turkey to Pakistan.
  • Vanellus indicus indicus, found from central Pakistan to Nepal, northeast India and Bangladesh.
  • Vanellus indicus lankae, restricted to Sri Lanka.
  • Vanellus indicus atronuchalis, found from northeast India to south China, southeast Asia, Malay Peninsula and north Sumatra.

The diet of the lapwing includes a range of insects, snails and other invertebrates, picked from the ground and from vegetation. They may also feed on some grains. They feed mainly during the day but they may also feed at night. They may sometimes make use of their legs to disturb insect prey from soft soil. Biological control of cabbage aphids in India is encouraged by the use of bird perches in the crop. The red-wattled lapwing breeds from West Asia eastwards across South Asia, and then further east into Southeast Asia. Populations are mainly resident, but birds in N. Baluchistan and NW Pakistan migrate to higher areas in spring and autumn after being widely spread out in the monsoons.

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Fringillidae (finches)

The finches are small to medium-sized birds which have stout conical bills adapted for eating seeds. Despite this some members of the family are often recorded taking insect food. They are found in a great range of habitats and although not migratory, their range may very seasonally. The family is distributed worldwide except for Australia and the polar regions,

Spinus tristis (American goldfinch)

The American goldfinch (Spinus tristis) is a small, sexually and seasonally dimorphic finch with a short notched tail and (in breeding season) a conical peachy-orange bill. Males in the breeding season are lemon yellow with a jet black cap. The wings are also jet black with white tips. The lesser wing coverts are yellow, and greater coverts are white-tipped. Uppertail coverts, parts of the ventral region, and the undertail coverts are white. Females in the breeding season are brownish olive-yellow on the back, and greenish-yellow on the forehead, throat, abdomen and rump. Parts of the ventral region, and undertail coverts are whitish. Winter birds have a grey or black bill and are drab, unstreaked brown with blackish wings and two pale wingbars.

First image Copyright Mdf under a Creative Commons Attribution-Share Alike 3.0 Unported License
Second image Copyright Eric Dunham under a Creative Commons Attribution-NonCommercial ShareAlike 2.0 Generic License

American goldfinches are found in floodplains, weedy fields and cultivated areas including back yards. They fly with a characteristic undulating pattern, often calling in flight. Spinus tristis are reputed to be almost exclusively seed eaters, although there is considerable evidence that they may be insectivorous on occasions, sometimes specifically targeting aphids. In summer the breeding range stretches across North America from coast to coast, extending northwards to Saskatchewan and southwards to northern California. Their winter range extends from southern Canada to parts of Mexico.

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Paridae (tits and chickadees)

The tits and chickadees are small, stocky birds with short, stout bills. They are generalist insectivores consuming a wide range of insects and other invertebrates, as well as consuming seeds and fruit. The more insectivorous species have finer bills. The tits are woodland birds, but are often found around human habitation and regularly visit bird feeders. The family has representatives over most of Europe, Asia, North America and Africa.

Cyanistes caeruleus (Eurasian blue tit)

The Eurasian blue tit, Cyanistes caeruleus, has an azure blue and dark blue line passing through the eye, and encircling the white cheeks to the chin, giving the bird a very distinctive appearance (see first picture below) (cf. the great tit which has a bluish-black crown, a black neck, throat, bib and head and white cheeks and ear coverts). The forehead and a bar on the wing are white. The nape, wings and tail are blue and the back is yellowish green. The underparts are mostly sulphur-yellow with a narrow blackish line in the breast centre. The bill is black, the legs bluish grey, and the irises dark brown. The sexes are similar, but under ultraviolet light, males have a brighter blue crown. The body length is usually 12 cm (4.7 in) long with a wingspan of 18 cm (7.1 in) for both sexes. Juvenile blue tits (see second picture below) have pale yellow cheek patches (cf. adults which have white cheek patches) and greyish-green upperparts and crown.

First image copyright Francis C. Franklin under a Creative Commons Attribution-Share Alike 3.0 License.
Second image copyright Andrew Morffew under a Creative Commons Attribution 2.0 Generic License.

The Eurasian blue tit is found in a range of habitats from gardens to forest, wherever there are trees. They mainly feed on invertebrates but switch to seeds and other plant material in the winter when insects are scarce. The blue tit is well known as an important predator of several species of aphids, and doubtless makes an important contribution to the biological control of aphids in gardens where supplementary feeding ensures artificially high blue tit populations. They appear to especially target aphids when feeding older nestlings. Cyanistes caeruleus is found throughout most of Europe, as well as North Africa, Turkey and Iran.


Parus major (Great tit)

Males of Parus major (see first picture below) have a bluish-black crown, a black neck, throat, bib and head and white cheeks and ear coverts. The breast is bright lemon yellow and there is a broad black mid-line stripe running from the bib to the vent. Most of the nape and back are greenish, but there is a dull white patch on the neck. The wing coverts are green and the rest of the wings is bluish-grey with a white wing-bar. The tail is bluish grey with white outer tips. The female (see second picture below) has slightly duller colours and the line running down the belly is narrower and sometimes broken. Immatures resemble females, but with a dull olive brown nape and neck and a grey tail. The various Parus major subspecies, of which there are fifteen, differ somewhat in colour.

First image male: Copyright Jean-Jacques Boujot under a Creative Commons Attribution-Share Alike 3.0 License
Second image female: Copyright Darkone under a Creative Commons Attribution-Share Alike 2.5 Generic License

The great tit is found in a range of habitats from dense to open deciduous and coniferous woodland, riverine forest, scrubland and gardens. Parus major is found across most of Europe, North Africa, the Middle East and parts of central Asia. Parus major are not major predators of free-living aphids, but are known to frequently predate gall-living aphids.


Poecile atricapillus (Black-capped chickadee)

Adult black-capped chickadees are small rather compact birds with a fairly short dark beak and a long narrow tail. The black-capped chickadee has a black cap that extends down to just below the eyes, a black 'bib' and white cheeks. The underparts are white with rusty brown on the flanks. Its back is grey and the tail is slaty grey with the outer tail feathers edged with white. The wing feathers are grey, also with conspicuous white edges (cf. Carolina chickadee the wing feathers of which only have narrow faint white edges). Males and females have similar coloration, but males are slightly larger and longer than females. The black-capped Chickadee has complex songs with 16 unique types of vocalizations. The whistled song is typically two clear tones with a higher-pitched 'fee' note followed by a lower-pitched 'bee' note. The Black-capped Chickadee also has a 'chick-a-dee' call that is the namesake of the genus.

First image taken by John Carr, USFWS; public domain.
Second image copyright Tim Sackton under a CC BY-SA 2.0 licence.

The black capped chickadee is a non-migratory bird that lives in deciduous, mixed deciduous-coniferous, and open coniferous forests, shrub thickets, and riparian woodlands. It also visits orchards. It prefers habitats with a rich understory of brush such as riparian woodlands and shrub thickets. The bird primarily forages on trees by gleaning insects off the bark and leaves and has been often observed consuming gall aphids . It is found throughout Canada and in the northern states of the USA.


Parulidae (New World warblers, Wood warblers)

Wood warblers are small, often colourful birds not closely related to other warbler families. They are mainly insectivorous, gleaning insects from the foliage or catching them in the air. They play an important role in forests consuming large numbers of leaf-feeding caterpillars as well as aphids. Many supplement their diet with seeds and fruit, especially in autumn and winter, and some also eat nectar. They are only found in the Americas, with those in North America migrating to central and South America for the winter.

Oreothlypis peregrina (Tennessee warbler)

The Tennessee Warbler (Oreothlypis peregrina) has long wings, a short tail and a thin pointy bill. The breeding male has an olive back, shoulders, rump and vent (see first picture below). It has a slate grey neck, crown and eyeline, and brownish-black flight feathers. The underside is plain whitish, although some have yellow-washed undersides. There are no strong wingbars. The female is similar to the male, but is duller and has a green tinge to the underside (second picture below is either a female or immature).

First image Copyright Jerry Oldenettel under a Creative Commons Attribution-Share Alike 2.0 Generic license
Second image Copyright Brian Plunkett under a Creative Commons Attribution 2.0 Generic License

The Tennessee Warbler breeds in the north of the USA and throughout much of Canada. It migrates to Central America and northern Colombia and Venezuela where it overwinters. Oreothlypis peregrina is a diet generalist feeding mainly on insects, especially spruce budworm, but also taking nectar, fruit and seeds. Bird numbers show a large and rapid response to budworm outbreaks, and there is evidence that birds may play a role in determining the mean level of oscillations (Venier & Holmes, 2010). Oreothlypis peregrina will also feed on aphids if available, and appear to aggregate in areas where there are large aphid populations.


Setophaga coronata (Yellow-rumped warbler)

The adult male yellow-rumped warbler (Setophaga coronata, see first picture below) in summer has a streaked back of black on slate blue, white wing patches, a streaked breast and conspicuous yellow patches on the crown, flank and rump. Females (see second picture below) in summer have streaked backs of black on blue-green and similar conspicuous yellow patches. There are marked differences between the subspecies: Male myrtle warblers (Setophaga coronata subspecies coronata) have a white throat and eye stripe, and a contrasting black cheek patch, whilst male Audubon's warbler (subspecies auduboni) have an additional yellow throat patch. Goldman's warbler (ssp. goldmani) is similar to Audubon's warbler, but has a white lower border to the yellow throat and otherwise darker plumage; in males the back is black. The black-fronted warbler (subspecies nigrifons) has a black head and front.

First image copyright Russ under a Creative Commons Attribution 2.0 Generic Licence
Second image copyright tgreyfox under a Creative Commons Attribution -ShareAlike 2.0 Generic Licence

The eastern subspecies of the yellow-rumped warbler (the myrtle warbler, Setophaga coronata coronata) breeds in summer in much of Canada and the northeastern USA, migrating to the southeastern USA, Central America and the Caribbean for overwintering. The western subspecies (Setophaga coronata coronata, Audubon's warbler) breeds in western Canada, the western USA and into Mexico, overwintering from the south western USA to Central America. Goldman's yellow-rumped warbler (Setophaga coronata goldmani) is a non-migratory endemic in the highlands of Guatemala, and the black-fronted warbler (Setophaga coronata nigrifons) is a non-migratory endemic in Mexico.

Yellow-rumped Warblers are opportunistic foraging generalists. They are mainly insectivorous in summer, eating a variety of insects, but are especially known for eating insect species undergoing population irruptions, such as spruce budworm and various aphid species. On migration and in winter yellow-rumped Warblers also eat fruits, including bayberry and wax myrtle, and wild seeds. On their wintering grounds in Mexico they've been seen sipping aphid honeydew, as well no doubt as consuming the honeydew producers.


Setophaga fusca (Blackburnian warbler)

The adult male Blackburnian warbler (Setophaga fusca, see first picture below) is a medium sized warbler with a short thin pointed bill and a medium length tail. The male in summer has a unique black triangular facial pattern with a yellow-orange supercilium and a flaming orange throat. It has a dark grey back, double white wing bars, a yellowish rump and a dark crown. The underparts are white tinged with yellow and streaked with black. Female Setophaga fusca (see second picture below), and males out of the breeding season, have the orange on the head and throat replaced with dull yellow, and the head pattern is grey not black.

First image copyright Laura Gooch under a Creative Commons BY-NC-SA License.
Second image copyright Andy Reago & Chrissy McClarren under a Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0).

In the breeding season Blackburnian warblers prefer mature coniferous or mixed coniferous-deciduous forest, but during migration and on their wintering grounds they may be found in a wide range of habitats. The foraging technique of the Blackburnian warbler is described as passing from limb to limb with rapid gleaning, occasional hovering or hawking. Blackburnian warblers are mainly insectivorous, eating caterpillars (especially of the spruce budworm) and a variety of insects including aphids, as well as spiders. There is little evidence for aphids forming a significant part of the diet of Blackburnian warblers in the northern breeding grounds where there is an abundance of lepidopteran larvae on spruce trees. But, when the birds are migrating in autumn, there are very few lepidopteran larvae available. At this time there have been several observational accounts of Blackburnian warblers using aphids as a high energy food source. They will occasionally also eat berries. The Blackburnian warbler breeds in southern Canada and north-eastern USA. It overwinters in Central America and northwest South America.


Setophaga nigrescens (Black-throated gray warbler)

Adult male black-throated gray warblers (see first picture below) have a black and white face. They have a black stripe on the crown, throat and below the eye, and a white stripe below the chin and above the eye. There is also a characteristic small yellow spot between its eye and bill. The female black-throated gray warbler (see second picture below) has more dingy plumage on the head, with a white throat and dark grey cheeks. Both sexes have a grey back, white underparts and black side streaks. Both sexes give a call described as a flat 'chupp' or 'tup'. The male sings a buzzy song variously described as having the 'earlier notes doubled and the next to last note high' or 'zeedle zeedle zeedle zeet-chee'.

Both images reproduced by permission, copyright Mark Rauzon, all rights reserved.

In the breeding season black-throated gray warblers live in open pine forests, pine-oak woodlands, and pinyon-juniper forests with a brushy understory. During migration and on the wintering grounds, they use a variety of woodlands, scrub, and thickets. The breeding grounds are in western North America from British Columbia to northern California and east to New Mexico and Montana. It overwinters from southern California to Mexico. No detailed studies have been carried out on the diet of the black-throated gray warbler, but they are known to be primarily insectivorous, eating insects and their larvae that they pluck from trees and shrubs. They also hover briefly to pick insects from various surfaces, and may fly out after flying insects. They tend to forage in the lower to middle levels of the forest, moving with slow, deliberate hops while looking around for insects.


Setophaga tigrina (Cape May warbler)

The adult Cape May warbler (Setophaga tigrina) has a short tail, a thin bill and white undertail coverts. The male (see first picture below) has a chestnut cheek patch, a dark crown and nape and a yellow collar. The yellow breast is marked with black streaks which continue down the flanks. The rump is bright yellow. The female Cape May warbler (see second picture below) has a grey cheek patch, an olive-gray crown and a somewhat paler yellow collar and breast. The breast is marked with paler dark streaks than the male. Immature Setophaga tigrina are generally dull gray, usually with a little yellow on the rump.

First image Copyright Andy Reago & Chrissy McClarren under a Creative Commons Attribution 2.0 Generic License
Second image Copyright Philip R Brown under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License

In its breeding grounds the Cape May warbler's preferred prey is spruce budworm (tortricid moths of the Choristoneura genus, including the pests Choristoneura fumiferana & Choristoneura freemani). It feeds on other insects when migrating south and when its preferred prey of spruce budworm is unavailable, there is considerable anecdotal evidence that the Cape May warbler is very partial to aphid colonies. In the West Indies it also feeds on nectar with its curled, semitubular tongue. Setophaga tigrina breeds across the boreal forests of Canada and the northern United States. It migrates through central and southern United States to overwinter in the West Indies.


Phylloscopidae (leaf warblers)

Leaf warblers are small birds with fine pointed bills reflecting their insectivorous diet. They live in scrub and forest often up in the canopy. They are active, constantly moving , often flicking their wings as they glean the foliage for insects in trees and bushes. Species breeding in temperate zones are strongly migratory, wintering in southeast Asia, India or Africa. The family is mainly found in Eurasia extending into Africa, the Indonesian islands and the Arctic.

Phylloscopus collybita (Chiffchaff)

The adult chiffchaff of the western subspecies (Phylloscopus collybita collybita, see first picture below) has brown-washed dull green upperparts, off-white underparts becoming yellowish on the flanks and a short whitish supercilium. Phylloscopus collybita collybita has dark brown to blackish legs (cf. willow warbler, which has paler pinkish-yellow legs), a fine dark bill (cf. willow warbler, which has a longer paler bill) and a short extension of flight feathers beyond the folded wing (cf. willow warbler, which has a longer extension of flight feathers beyond the folded wing). These features may seem clear enough, but can be difficult to see in the field. Fortunately their song and call are distinct. The song of the chiffchaff is a monotonous chiff-chaff (cf. the song of the willow warbler, which is a melodic rippling phrase with a descending trill at the end). The call of the chiffchaff is a monosyllabic 'hweet' (cf. the call of the willow warbler, which is a bisyllabic 'hu-eet' with the second syllable slurred upwards) (see also: chiffchaff versus willow warbler).

First image Copyright Ken Billington under a Creative Commons Attribution-Share Alike 3.0 Unported License
Second image Copyright Mike Pennington under a Creative Commons Attribution 2.0 Generic License

There are three commonly accepted subspecies:

The western subspecies Phylloscopus collybita collybita is described above.
It breeds in Europe and winters around the Mediterranean and North Africa.
The north-western subspecies (Phylloscopus collybita abietinus) has a pale yellow supercilium and whitish underparts.
It occurs in Scandinavia and northern Russia, and winters from southeastern Europe and northeastern Africa to Iraq and Iran.
The Siberian chiffchaff (Phylloscopus collybita tristis, see second picture above) is duller in colour, with a longer supercilium than in the western subspecies.
It breeds in Siberia, and winters in the lower Himalayas and sometimes Western Europe.

Chiffchaffs feed on insects such as midges and other flies, aphids, caterpillars and moths, which they find by foraging in tree canopies and among bushes. We have termed it a generalist aphid predator but, when sufficiently large aphid populations are available, the chiffchaff probably comes closer than any other bird species to being a specific aphid predator. Birds in the genus Phylloscopus (meaning 'leaf explorer') are known as leaf warblers.


Picidae (woodpeckers)

Woodpeckers are small to medium sized birds that are mostly arboreal living in wooded habitats. They have characteristic feet well suited to grasping the limbs and trunks of trees, strong pointed bills for drilling, drumming and probing on trees, and long sticky tongues for extracting insects and their larvae. Some species seem to concentrate on the large tree-dwelling aphids which live on trunk and branches. Woodpeckers are found worldwide except for Australasia, Madagascar and the polar regions.

Dryobates pubescens (Downy woodpecker)

The downy woodpecker is the smallest of North American woodpeckers. The adult bird is mainly black on the upperparts and wings with a white back, throat and belly, and white spotting on the wings. The male (see first picture below) has a red patch on the back of the head, the female (see second picture below) has no red patch, and juveniles have a red cap. There are also two white bars on the head, one above the eye and one below. The bill is shorter than the head length (cf. hairy woodpecker which has its bill equal to its head length). The tail is black with white outer feathers barred with black (cf. hairy woodpecker which has no black bars on the white outer tail feathers).

First image copyright Betty Matsubara under a Creative Commons Attribution-Share Alike 2.0 Unported License
Second image copyright Russ under a Creative Commons Attribution 2.0 Generic License

Downy woodpeckers are found in open woodlands, particularly amongst deciduous trees. It has also adapted well to the man-made environment being found in orchards, city parks, backyards and vacant lots. The distribution of the downy woodpecker covers most of the United States and Canada apart from the deserts of the southwest and the tundra of the north. They are not generally migratory although northern birds may move further south in winter.


Sylviidae (true warblers)

The true warblers (or 'typical warblers') are small to medium-sized birds which live in variety of habitats including woods, scrubland and marshes. They have a small, finely pointed bill and are primarily insectivorous, often concentrating on aphids feeding on the leaves of trees, although they will also eat fruit, nectar or small seeds. They are found in Eurasia and Africa, with one species on the west coast of North America.

Sylvia atricapilla (Blackcap)

Adult male blackcaps (see first picture below) have a heavy build for a warbler and can appear quite large. They have pale grey underparts, mainly olive-grey upperparts and a distinctive black cap. The male bird often raises his black crown feathers in display (see first picture below in section on predation of sycamore aphids). The female blackcap (see second picture below) has a browner back than the male, a grey face and throat, a tinge of brown on the breast and a reddish brown cap. Immatures are browner overall than adults, with pale chestnut caps like those of adult females. The song typically starts with soft, staccato chattering and mimicry, which after a few seconds changes to a much louder, pure and resonant stream of notes for about 3-5 seconds. It may sing the first part of the song for extended periods without ever reaching the characteristic ending. The alarm call is a hard 'check', sometimes with an additional hoarse and nasal 'cherrr'.

First image copyright Tony Hisgett under a Creative Commons Attribution-Share Alike 2.0 Unported License.
Second image copyright Stefan Berndtsson under a Creative Commons Attribution-Share Alike 2.0 Unported License.

There are five subspecies:

  • Sylvia atricapilla atricapilla: breeds in Europe except Mediterranean area and NW Asia; winters in Europe and tropical West Africa.
  • Sylvia atricapilla gularis: greyer underparts and nape. Breeds and winters in Azores and Cape Verde.
  • Sylvia atricapilla heineken: males browner above, females more rufous above. Breeds and winters in Madeira, Canary Islands and south-western Iberia,
  • Sylvia atricapilla pauluccii: greyer above and darker below; white only in centre of belly. Breeds & winters eastern Iberia, Italy and western Mediterranean islands.
  • Sylvia atricapilla dammholzi: longer winged and paler. Breeds in SW Asia and winters in tropical East Africa.

Blackcaps breed in mature deciduous woodland with an established understory of shrubs and herbs. The wintering habitat ranges from gardens (the British population) to scrub and olive orchards in the Mediterranean, and Acacia scrub and mangroves in Africa. Blackcaps mainly pick their prey off the leaves and twigs, but may occasionally hover or feed on the ground. They eat a wide range of invertebrate prey, with aphids especially important in spring when adults are feeding their chicks, and again in autumn before and during migration. In July their diet switches to include a larger fruit component.


Sylvia cantillans (Subalpine warbler)

The adult male of Sylvia cantillans species group (first image, below) has a grey back, brick red underparts and white malar stripes. The female (second image, below) is mainly brown above with a greyer head, and whitish below with a pink flush.

First image copyright Mick Sway under a Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0).
Second image copyright BirdingInSpain under a Creative Commons BY-NC-SA License.

The most recent proposals by Svensson (2016) split the complex into three different species:

  1. Western Subalpine Warbler (Sylvia inornata), with two subspecies: Sylvia inornata inornata in North Africa, and Sylvia inornata iberiae in south-west Europe. The white malar streak is narrow, sometimes much reduced. The brown-orange colour below is quite extensive, strongest on the throat and breast, but washed prominently along the flanks, and paling on to the central belly and undertail coverts. The call is a hard 'tek'.
  2. Eastern Subalpine Warbler (Sylvia cantillans), with two subspecies: Sylvia cantillans cantillans in southern Italy and Sicily, and Sylvia cantillans albistriata in south-east Europe. The white malar streak is usually quite broad. The brown-orange colour below is largely restricted to the throat and upper breast, contrasting with the rest of the off-white underparts. The call is a dry, slightly rolling 'trret'.
  3. Moltoni's Warbler (Sylvia subalpina), in Corsica, Sardinia and north Italy. The white malar streak is intermediate to the other two species. The underparts are noticeably paler than the other two species, being dusty buff or brownish pink. The call is quite a dry 'ttrrrrrr'.

The subalpine warbler species group are birds of dry open country, often on hill slopes. They are insectivorous, but will also take berries. The subalpine warbler forages by actively moving through dense vegetation and picking prey off vegetation with its bill. It is therefore well adapted to being an aphid predator when the prey is available, and there are several accounts of subalpine warblers feeding on aphids. The breeding ranges of the different species are given above, but vagrants can be found over much of western and northern Europe.



Full acknowledgements for assistance and contributions are given on the individual species pages.

We have taken the key characteristics for identification of European birds from the BTO Bird identification videos together with Nord University species comparisons and the latest Wikipedia account for each species. For American birds we have relied on the Cornell Lab of Ornithology, again with the latest Wikipedia account for each species.

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