Mixed-species feeding flock
Encyclopedia
A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock
of usually insectivorous bird
s of different species
, that join each other and move together while foraging. These are different from feeding aggregations, which are congregations of several species of bird at areas of locally high food availability.
A mixed-species foraging flock typically has "nuclear" species that appear to be central to its formation and movement. Species that trail them are termed "attendants". Attendants tend to join the foraging flock only when the flock enters their territory.
How such flocks are initiated is under investigation. But in Sri Lanka
for example, vocal mimicry by the Greater Racket-tailed Drongo
(Dicrurus paradiseus) might have a key role in the initiation of mixed-species foraging flocks, while in parts of the American
tropics noisy packs of foraging Golden-crowned Warbler
s (Basileuterus culicivorus) might play the same role. Forest structure is also believed to be an important factor deciding the propensity to form flocks. In tropical forests, birds that glean
food from foliage were the most abundant species in mixed-species flocks.
A typical Neotropic mixed feeding flock moves through the forest at about 0.3 kilometers per hour (0.19 miles per hour), with different species foraging in their preferred niches (on the ground, on trunks, in high or low foliage, etc.). Some species follow the flock all day, while others – such as the Long-billed Gnatwren
(Ramphocaenus melanurus) – join it only as long as it crosses their own territories.
, they are typically led by Paridae (tits and chickadees), often joined by nuthatch
es (Sitta), treecreeper
s (Certhia), woodpecker
s (Picidae
, such as the Downy Woodpecker
"Picoides" pubescens and Lesser Spotted Woodpecker
"P." minor), kinglet
s (Regulus), and in North America Parulidae (New World "warblers") – all insect-eating
birds. This behavior is particularly common outside the breeding season.
The advantages of this behavior are not certain, but evidence suggests that it confers some safety from predators, especially for the less watchful birds such as Vireonidae (vireos) and woodpecker
s, and also improves feeding efficiency, perhaps because arthropod prey that flee one bird may be caught by another.
s the leaders or "core" members may be Black-throated Shrike-tanager
s (Lanio aurantius) in southern Mexico
, or Three-striped Warbler
s (Basileuterus tristriatus) elsewhere in Central America
. In South America
, core species may include antbird
s (Thamnophilidae) such as Thamnomanes
, antshrikes, Furnariidae (ovenbirds and woodcreepers) like the Buff-fronted Foliage-gleaner
(Philydor rufum) or the Olivaceous Woodcreeper
(Sittasomus griseicapillus), or Parulidae (New World "warblers") like the Golden-crowned Warbler
s (Basileuterus culicivorus). In open cerrado
habitat, it may be White-rumped
(Cypsnagra hirundinacea) or White-banded Tanager
s (Neothraupis fasciata). Core species
often have striking plumage and calls that attract other birds; they are often also known to be very active sentinels, providing warning of would-be predators.
But while such easy-to-locate bird species serve as a focal point for flock members, they do not necessarily initiate the flock. In one Neotropic
mixed flock feeding on swarming termites, it was observed that Red-rumped Warbling-finch
es (Poospiza lateralis) were most conspicuous. As this species is not an aerial insectivore, it is unlikely to have actually initiated the flock rather than happening across it and joining in. And while Basileuterus
species are initiators as well as core species, mixed flocks of Tangara
species – in particular Red-necked
(T. cyanocephala), Brassy-breasted
(T. desmaresti) and Green-headed Tanager
(T. seledon) – often initiate formation of a larger and more diverse feeding flock, of which they are then only a less significant component.
Nine-primaried oscine
s make up much of almost every Neotropical mixed-species feeding flock. Namely, these birds are from families
such as the Cardinalidae (cardinals), Parulidae (New World "warblers"), and in particular Emberizidae
(American "sparrows") and Thraupidae (tanagers). Other members of a Neotropic mixed feeding flock may come from most of the local families of smaller diurnal insectivorous birds, and can also include woodpecker
s (Picidae), toucan
s (Ramphastidae) and trogon
s (Trogonidae). Most Furnariidae do not participate in mixed flocks very often, though there are exceptions such as Synallaxis
spinetail
s and some species of the woodcreeper
subfamily (Dendrocolaptinae) – e.g. those mentioned above or the Lesser Woodcreeper
(Xiphorhynchus fuscus) – are common or even "core" members. Among the tyrant flycatcher
s (Tyrannidae) there are also some species joining mixed flocks on a somewhat regular basis, including the Sepia-capped Flycatcher
(Leptopogon amaurocephalus), Eared Pygmy-tyrant
(Myiornis auricularis), White-throated Spadebill
(Platyrinchus mystaceus) and Oustalet's Tyrannulet
(Phylloscartes oustaleti).
However, even of commonly-participating families not all species join mixed flocks. There are genera such as Vireo
in which some species do not join mixed flocks, while others (e.g. Red-eyed Vireo
, V. olivaceus) will even do so in their winter quarters. Of the three subspecies
groups of the Yellow-rumped Warbler
(Dendroica coronata), only one (Audubon's Warbler
, D. c. auduboni group) typically does. And while the importance of certain Thraupidae in initiating and keeping together mixed flocks has been mentioned already, for example the Black-goggled Tanager
(Trichothraupis melanops) is an opportunistic feeder that will appear at but keep its distance from any disturbance – be it a mixed feeding flock, an army ant
column or a group of monkey
s – and pick off prey trying to flee.
Conopophagidae (gnateaters) are notable for their absence from these flocks, while Apodidae (swifts) and Hirundinidae (swallows) rarely join them, but will if there is for example an ant
or termite swarm. Cotingidae (cotingas) are mainly opportunistic associates which rarely join flocks for long if they do so at all; the same holds true for most Muscicapoidea (mockingbirds and relatives), though some thrushes
(Turdidae) may participate on more often. And though most Tityridae
rarely join mixed flocks, becards (Pachyramphus) do so regularly. Tapaculo
s (Rhinocryptidae) are rarely seen with mixed flocks, though the Collared Crescentchest (Melanopareia torquata), doubtfully assigned to that family, may be a regular member. Icteridae (grackles and relatives) are also not too often seen to take part in these assemblages, though caciques
like the Golden-winged
(Cacicus chrysopterus) or Red-rumped Cacique
(C. haemorrhous) join mixed flocks on a somewhat more regular basis. Cuculiformes
(cuckoo
s and allies) are usually absent from mixed feeding flocks, but some – e.g. the Squirrel Cuckoo
(Piaya cayana) can be encountered not infrequently.
Some species appear to prefer when certain others are present: Cyanolyca
jay
s like to flock with Unicolored Jay
s (Aphelocoma unicolor) and the Emerald Toucanet
s (Aulacorhynchus prasinus species complex
). Many Icteridae associate only with related species, but the western subspecies of the Yellow-backed Oriole
(Icterus chrysater) associates with jays and the Band-backed Wren
(Campylorhynchus zonatus).
Other species participate to varying extents depending on location or altitude – presumably, the different species composition of mixed flocks at varying locations allows these irregular members more or less opportunity to get food. Such species include the Grey-hooded Flycatcher
(Mionectes rufiventris: Tyrannidae), or the Plain Antvireo
(Dysithamnus mentalis: Thamnophilidae) and the Red-crowned Habia (Habia rubica: Cardinalidae) which are often recorded in lowland flocks but rarely join them at least in some more montane
regions.
in Sri Lanka, the typical daytime quiet of the jungle is broken by the noisy calls of the Orange-billed Babbler
(Turdoides rufescens) and Greater Racket-tailed Drongo
(Dicrurus paradiseus), joined by species such as the Ashy-headed Laughingthrush
(Garrulax cinereifrons), Kashmir Flycatcher
(Ficedula subrubra) and Velvet-fronted Nuthatch
(Sitta frontalis).
A mixed flock in the Cordillera Central of Luzon in the Philippines
was mainly composed of Bar-bellied Cuckoo-shrike
s (Coracina striata: Campephagidae), Philippine Fairy-bluebird
s (Irena cyanogaster: Irenidae) and Violaceous Crows (Corvus (enca) violaceus: Corvidae
). Luzon Tarictic Hornbills (Penelopides manillae: Bucerotidae) were also recorded as present. With the crows only joining later and the large hornbills probably only opportunistic attendants rather than core species, it is likely that this flock was started by one of the former species – probably the bold and vocal cuckoo-shrikes rather than the more retiring fairy-bluebirds, which are known to seek out such opportunities to forage.
African rainforests also hold mixed-species flocks, the core species including Pycnonotidae (bulbuls) and Nectarinidae (sunbirds), and attendants being as diverse as the Red-billed Dwarf Hornbill
(Tockus camurus) and the Tit-hylia
(Pholidornis rushiae), the smallest bird of Africa. Dicruridae (drongos) and Monarchidae (paradise-flycatchers) are sometimes described as the sentinels of the flock, but they are also known to steal prey from other flock members. Acanthizidae
are typical core members in New Guinea (Gerygone) and Australia (Acanthiza); in Australia, fairy-wrens (Malurus) are also significant. The core species are joined by birds of other families such as minivet
s (Pericrocotus).
Flock (birds)
A flock is a group of birds conducting flocking behavior in flight, or while foraging. The term is akin to the herd amongst mammals. The benefits of aggregating in flocks are varied and flocks will form explicitly for specific purposes...
of usually insectivorous 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...
s of different species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, that join each other and move together while foraging. These are different from feeding aggregations, which are congregations of several species of bird at areas of locally high food availability.
A mixed-species foraging flock typically has "nuclear" species that appear to be central to its formation and movement. Species that trail them are termed "attendants". Attendants tend to join the foraging flock only when the flock enters their territory.
How such flocks are initiated is under investigation. But in Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
for example, vocal mimicry by the Greater Racket-tailed Drongo
Greater Racket-tailed Drongo
The Greater Racket-tailed Drongo, Dicrurus paradiseus, is a medium-sized Asian bird which is distinctive in having elongated outer tail feathers with webbing restricted to the tips. They are placed along with other drongos in the family Dicruridae...
(Dicrurus paradiseus) might have a key role in the initiation of mixed-species foraging flocks, while in parts of the American
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
tropics noisy packs of foraging Golden-crowned Warbler
Golden-crowned Warbler
The Golden-crowned Warbler, Basileuterus culicivorus, is a small New World warbler.-Distribution and habitat:It breeds from Mexico and south through Central America to northeastern Argentina and Uruguay, and on Trinidad. It is a species mainly of lowland forests.-Description:The Golden-crowned...
s (Basileuterus culicivorus) might play the same role. Forest structure is also believed to be an important factor deciding the propensity to form flocks. In tropical forests, birds that glean
Gleaning (birds)
Gleaning is a term for a feeding strategy by birds in which they catch invertebrate prey, mainly arthropods, by plucking them from foliage or the ground, from crevices such as rock faces and under the eaves of houses, or even, as in the case of ticks and lice, from living animals. This behavior is...
food from foliage were the most abundant species in mixed-species flocks.
A typical Neotropic mixed feeding flock moves through the forest at about 0.3 kilometers per hour (0.19 miles per hour), with different species foraging in their preferred niches (on the ground, on trunks, in high or low foliage, etc.). Some species follow the flock all day, while others – such as the Long-billed Gnatwren
Long-billed Gnatwren
The Long-billed Gnatwren is a very small bird in the gnatcatcher family. It is the only member of the genus Ramphocaenus ....
(Ramphocaenus melanurus) – join it only as long as it crosses their own territories.
Costs and benefits
Several evolutionary mechanisms have been proposed to explain the formation of mixed-species flocks. These are usually described in terms of the costs and benefits to individuals. The key benefits that have been suggested are a reduction in predation risk through increased vigilance, that is, more eyes that can spot predators and raise an alarm and increased foraging efficiency. Costs could include the risk of kleptoparasitism.In the Holarctic
In the North Temperate ZoneTemperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
, they are typically led by Paridae (tits and chickadees), often joined by nuthatch
Nuthatch
The nuthatches are a genus, Sitta, of small passerine birds belonging to the family Sittidae. Characterised by large heads, short tails, and powerful bills and feet, nuthatches advertise their territory using loud, simple songs...
es (Sitta), treecreeper
Treecreeper
The treecreepers are a family, Certhiidae, of small passerine birds, widespread in wooded regions of the Northern Hemisphere and sub-Saharan Africa. The family contains ten species in two genera, Certhia and Salpornis...
s (Certhia), woodpecker
Woodpecker
Woodpeckers are near passerine birds of the order Piciformes. They are one subfamily in the family Picidae, which also includes the piculets and wrynecks. They are found worldwide and include about 180 species....
s (Picidae
Picidae
The woodpeckers, piculets and wrynecks are a family, Picidae, of near-passerine birds. Members of this family are found worldwide, except for Australia and New Zealand, Madagascar, and the extreme polar regions...
, such as the Downy Woodpecker
Downy Woodpecker
The Downy Woodpecker is a species of woodpecker, the smallest in North America.- Description :Adult Downy Woodpeckers are mainly black on the upperparts and wings, with a white back, throat and belly and white spotting on the wings. There is a white bar above the eye and one below. They have a...
"Picoides" pubescens and Lesser Spotted Woodpecker
Lesser Spotted Woodpecker
The Lesser Spotted Woodpecker is a member of the woodpecker family Picidae. It is assigned to the genus Dendrocopos ....
"P." minor), kinglet
Kinglet
The kinglets or crests are a small group of birds sometimes included in the Old World warblers, but are frequently given family status because they also resemble the titmice. The scientific name Regulidae is derived from the Latin word regulus for "petty king" or prince, and comes from the...
s (Regulus), and in North America Parulidae (New World "warblers") – all insect-eating
Insectivore
An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects....
birds. This behavior is particularly common outside the breeding season.
The advantages of this behavior are not certain, but evidence suggests that it confers some safety from predators, especially for the less watchful birds such as Vireonidae (vireos) and woodpecker
Woodpecker
Woodpeckers are near passerine birds of the order Piciformes. They are one subfamily in the family Picidae, which also includes the piculets and wrynecks. They are found worldwide and include about 180 species....
s, and also improves feeding efficiency, perhaps because arthropod prey that flee one bird may be caught by another.
In the Neotropics
Insectivorous feeding flocks reach their fullest development in tropical forests, where they are a typical feature of bird life. In the NeotropicNeotropic
In biogeography, the Neotropic or Neotropical zone is one of the eight terrestrial ecozones. This ecozone includes South and Central America, the Mexican lowlands, the Caribbean islands, and southern Florida, because these regions share a large number of plant and animal groups.It is sometimes used...
s the leaders or "core" members may be Black-throated Shrike-tanager
Black-throated Shrike-tanager
The Black-throated Shrike-tanager is a species of bird in the Thraupidae family.It is found in Belize, Guatemala, Honduras, and Mexico.Its natural habitat is subtropical or tropical moist lowland forests.-References:...
s (Lanio aurantius) in southern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, or Three-striped Warbler
Three-striped Warbler
The Three-striped Warbler is a species of bird in the Parulidae family.It is found in Bolivia, Colombia, Costa Rica, Ecuador, Panama, Peru, and Venezuela. Its natural habitats are subtropical or tropical moist montane forests and heavily degraded former forest.-References:* BirdLife International...
s (Basileuterus tristriatus) elsewhere in Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
. In South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, core species may include antbird
Antbird
The antbirds are a large family, Thamnophilidae, of passerine birds found across subtropical and tropical Central and South America, from Mexico to Argentina. There are more than 200 species, known variously as antshrikes, antwrens, antvireos, fire-eyes, bare-eyes and bushbirds...
s (Thamnophilidae) such as Thamnomanes
Thamnomanes
Thamnomanes is a genus of antshrikes in the perching bird family Thamnophilidae. They are restricted to the Neotropics and are important components of forest mixed-species feeding flocks.This genus contains the following species:...
, antshrikes, Furnariidae (ovenbirds and woodcreepers) like the Buff-fronted Foliage-gleaner
Buff-fronted Foliage-gleaner
The Buff-fronted Foliage-gleaner is a species of bird in the Furnariidae family, the ovenbirds. It is found in southeastern regions of South America in the cerrado and pantanal of Brazil and Paraguay as well as areas of southeast coastal Brazil; also extreme northeast Argentina...
(Philydor rufum) or the Olivaceous Woodcreeper
Olivaceous Woodcreeper
The Olivaceous Woodcreeper is a passerine bird of the tropical Americas. It belongs to the true woodcreepers of the ovenbird family ....
(Sittasomus griseicapillus), or Parulidae (New World "warblers") like the Golden-crowned Warbler
Golden-crowned Warbler
The Golden-crowned Warbler, Basileuterus culicivorus, is a small New World warbler.-Distribution and habitat:It breeds from Mexico and south through Central America to northeastern Argentina and Uruguay, and on Trinidad. It is a species mainly of lowland forests.-Description:The Golden-crowned...
s (Basileuterus culicivorus). In open cerrado
Cerrado
The Cerrado, is a vast tropical savanna ecoregion of Brazil, particularly in the states of Gioas and Minas Gerais...
habitat, it may be White-rumped
White-rumped Tanager
The White-rumped Tanager is a tanager. It is the only member of the genus Cypsnagra. Length 16 cm. Weight 25-34 g. Live mostly in Brazil, also in Paraguay, Bolivia and Suriname. Elevation 700–1000 m. Inhabit grasslands with short trees. In Brazil exist in territorial groups of three to six...
(Cypsnagra hirundinacea) or White-banded Tanager
White-banded Tanager
The Shrike-like Tanager , also known as the White-banded Tanager, is the only member of the genus Neothraupis in the tanager family , nine-primaried oscines of the Passeroidea.-Distribution and habitat:...
s (Neothraupis fasciata). Core species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
often have striking plumage and calls that attract other birds; they are often also known to be very active sentinels, providing warning of would-be predators.
But while such easy-to-locate bird species serve as a focal point for flock members, they do not necessarily initiate the flock. In one Neotropic
Neotropic
In biogeography, the Neotropic or Neotropical zone is one of the eight terrestrial ecozones. This ecozone includes South and Central America, the Mexican lowlands, the Caribbean islands, and southern Florida, because these regions share a large number of plant and animal groups.It is sometimes used...
mixed flock feeding on swarming termites, it was observed that Red-rumped Warbling-finch
Red-rumped Warbling-finch
The Red-rumped Warbling-finch is a species of bird in the Thraupidae family. It is found in forest borders and woodland in south-eastern Brazil, far eastern Paraguay, far north-eastern Argentina, and Uruguay...
es (Poospiza lateralis) were most conspicuous. As this species is not an aerial insectivore, it is unlikely to have actually initiated the flock rather than happening across it and joining in. And while Basileuterus
Basileuterus
Basileuterus is a genus of New World warblers, best represented in Central and South America. This is one of only two warbler genera that are well represented in the latter continent...
species are initiators as well as core species, mixed flocks of Tangara
Tangara (genus)
Tangara is a large genus of birds of the tanager family. It includes about 50 species, but as currently defined the genus is polyphyletic. All are from the Neotropics, and while most are fairly widespread, some have small distributions and are threatened. They are fairly small, ranging in size from...
species – in particular Red-necked
Red-necked Tanager
The Red-necked Tanager is a species of bird in the Thraupidae family.It is found in Argentina, Brazil, and Paraguay. Its natural habitats are subtropical or tropical moist lowland forests and heavily degraded former forest....
(T. cyanocephala), Brassy-breasted
Brassy-breasted Tanager
The Brassy-breasted Tanager is a species of bird in the Thraupidae family. It is endemic to Brazil.Its natural habitat is subtropical or tropical moist montane forests.-References:...
(T. desmaresti) and Green-headed Tanager
Green-headed Tanager
The Green-headed Tanager, Tangara seledon, is a bird found in Atlantic forest in south-eastern Brazil, far eastern Paraguay and far north-eastern Argentina ....
(T. seledon) – often initiate formation of a larger and more diverse feeding flock, of which they are then only a less significant component.
Nine-primaried oscine
Nine-primaried oscine
The nine-primaried oscines are a group of songbird families from the superfamily Passeroidea. It is composed of the Fringillidae , Emberizidae , Parulidae , Thraupidae , Cardinalidae , Icteridae and the monotypic Peucedramidae...
s make up much of almost every Neotropical mixed-species feeding flock. Namely, these birds are from families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
such as the Cardinalidae (cardinals), Parulidae (New World "warblers"), and in particular Emberizidae
Emberizidae
The Emberizidae are a large family of passerine birds. They are seed-eating birds with a distinctively shaped bill.In Europe, most species are called buntings. In North America, most of the species in this family are known as sparrows, but these birds are not closely related to the sparrows, the...
(American "sparrows") and Thraupidae (tanagers). Other members of a Neotropic mixed feeding flock may come from most of the local families of smaller diurnal insectivorous birds, and can also include woodpecker
Woodpecker
Woodpeckers are near passerine birds of the order Piciformes. They are one subfamily in the family Picidae, which also includes the piculets and wrynecks. They are found worldwide and include about 180 species....
s (Picidae), toucan
Toucan
Toucans are members of the family Ramphastidae of near passerine birds from the Neotropics. The family is most closely related to the American barbets. They are brightly marked and have large, often colorful bills. The family includes five genera and about forty different species...
s (Ramphastidae) and trogon
Trogon
The trogons and quetzals are birds in the order Trogoniformes which contains only one family, the Trogonidae. The family contains 39 species in eight genera. The fossil record of the trogons dates back 49 million years to the mid-Eocene. They might constitute a member of the basal radiation of...
s (Trogonidae). Most Furnariidae do not participate in mixed flocks very often, though there are exceptions such as Synallaxis
Synallaxis
Synallaxis is a genus of passerine birds in the ovenbird family. They are a member of the spinetails and thistletails, a group of 2 large and some 10 small or monotypic genera.-List of species:*Rufous-capped Spinetail, Synallaxis ruficapilla...
spinetail
Spinetail
Spinetail can refer to birds of several genera:* Family Apodidae :** Mearnsia** Zoonavena** Telacanthura** Rhaphidura** Neafrapus* Family Furnariidae :** Oreophylax** Schoeniophylax** Synallaxis...
s and some species of the woodcreeper
Woodcreeper
The woodcreepers comprise a subfamily of sub-oscine passerine birds endemic to the Neotropics. They have traditionally been considered a distinct family Dendrocolaptidae, but most authorities now place them as a subfamily of the ovenbirds...
subfamily (Dendrocolaptinae) – e.g. those mentioned above or the Lesser Woodcreeper
Lesser Woodcreeper
The Lesser Woodcreeper is a species of bird in the woodcreeper subfamily .It is found in Argentina, Brazil, and Paraguay....
(Xiphorhynchus fuscus) – are common or even "core" members. Among the tyrant flycatcher
Tyrant flycatcher
The tyrant flycatchers are a family of passerine birds which occur throughout North and South America. They are considered the largest family of birds on Earth, with more than 400 species. They are the most diverse avian family in every country in the Americas, except for the United States and...
s (Tyrannidae) there are also some species joining mixed flocks on a somewhat regular basis, including the Sepia-capped Flycatcher
Sepia-capped Flycatcher
The Sepia-capped Flycatcher is a species of bird in the Tyrannidae family.It is found in Argentina, Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, and Venezuela...
(Leptopogon amaurocephalus), Eared Pygmy-tyrant
Eared Pygmy-tyrant
The Eared Pygmy Tyrant is a species of bird in the Tyrannidae family.It is found in Argentina, Brazil, and Paraguay.Its natural habitats are subtropical or tropical moist lowland forests and heavily degraded former forest....
(Myiornis auricularis), White-throated Spadebill
White-throated Spadebill
The White-throated Spadebill, Platyrinchus mystaceus, is a tiny passerine bird in the tyrant flycatcher family. It lives in the tropical Americas.-Description:...
(Platyrinchus mystaceus) and Oustalet's Tyrannulet
Oustalet's Tyrannulet
The Oustalet's Tyrannulet is a species of bird in the Tyrannidae family.It is endemic to Brazil.Its natural habitat is subtropical or tropical moist lowland forests.It is becoming rare due to habitat loss.-Source:...
(Phylloscartes oustaleti).
However, even of commonly-participating families not all species join mixed flocks. There are genera such as Vireo
Vireo (genus)
Vireo are a genus of small passerine birds restricted to the New World. They typically have dull greenish plumage , but some are brown or gray on the back and some have bright yellow underparts...
in which some species do not join mixed flocks, while others (e.g. Red-eyed Vireo
Red-eyed Vireo
The Red-eyed Vireo, Vireo olivaceus, is a small American songbird, 13–14 cm in length. It is somewhat warbler-like but not closely related to the New World warblers...
, V. olivaceus) will even do so in their winter quarters. Of the three subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
groups of the Yellow-rumped Warbler
Yellow-rumped Warbler
Four closely related North American bird forms—the eastern Myrtle Warbler , its western counterpart, Audubon's Warbler , the northwest Mexican Black-fronted Warbler , and the Guatemalan Goldman's Warbler —are periodically lumped as the Yellow-rumped Warbler .-Classification:Since...
(Dendroica coronata), only one (Audubon's Warbler
Audubon's Warbler
The Audubon's Warbler, Dendroica coronata auduboni, is a small New World warbler.This passerine bird was long known to be closely related to its eastern counterpart, the Myrtle Warbler, and at various times the two forms have been classed as separate species or grouped as the Yellow-rumped Warbler,...
, D. c. auduboni group) typically does. And while the importance of certain Thraupidae in initiating and keeping together mixed flocks has been mentioned already, for example the Black-goggled Tanager
Black-goggled Tanager
Black-goggled Tanager is a species of bird in the family, Thraupidae. It is the only member of the genus Trichothraupis...
(Trichothraupis melanops) is an opportunistic feeder that will appear at but keep its distance from any disturbance – be it a mixed feeding flock, an army ant
Army ant
The name army ant is applied to over 200 ant species, in different lineages, due to their aggressive predatory foraging groups, known as "raids", in which huge numbers of ants forage simultaneously over a certain area, attacking prey en masse.Another shared feature is that, unlike most ant...
column or a group of monkey
Monkey
A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...
s – and pick off prey trying to flee.
Conopophagidae (gnateaters) are notable for their absence from these flocks, while Apodidae (swifts) and Hirundinidae (swallows) rarely join them, but will if there is for example an ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
or termite swarm. Cotingidae (cotingas) are mainly opportunistic associates which rarely join flocks for long if they do so at all; the same holds true for most Muscicapoidea (mockingbirds and relatives), though some thrushes
Thrush (bird)
The thrushes, family Turdidae, are a group of passerine birds that occur worldwide.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat small fruit. The smallest thrush may be the Forest Rock-thrush, at and...
(Turdidae) may participate on more often. And though most Tityridae
Tityridae
Tityridae is family of suboscine passerine birds found in forest and woodland in the Neotropics. The approximately 30 species in this family were formerly spread over the families Tyrannidae, Pipridae and Cotingidae . As yet, no widely accepted common name exists for the family, although Tityras...
rarely join mixed flocks, becards (Pachyramphus) do so regularly. Tapaculo
Tapaculo
The tapaculos are a group of small suboscine passeriform birds with numerous species, found mainly in South America and with the highest diversity in the Andean regions...
s (Rhinocryptidae) are rarely seen with mixed flocks, though the Collared Crescentchest (Melanopareia torquata), doubtfully assigned to that family, may be a regular member. Icteridae (grackles and relatives) are also not too often seen to take part in these assemblages, though caciques
Cacique (bird)
The caciques are passerine birds in the New World blackbird family. Members of the family are resident breeders in tropical South America and north to Mexico. All of the group are in the genus Cacicus, except the aberrant Yellow-billed Cacique , which constitutes a monotypic genus...
like the Golden-winged
Golden-winged Cacique
The Golden-winged Cacique is a species of bird in the Icteridae family.It is found in Argentina, Bolivia, Brazil, Paraguay, and Uruguay....
(Cacicus chrysopterus) or Red-rumped Cacique
Red-rumped Cacique
The Red-rumped Cacique is a species of bird in the Icteridae family. It is a species of the Amazon Basin and the Guyanas in northern South America, and is only coastal there in the Guyanas and the Amazon River outlet to the Atlantic; a separate large disjunct range exists in all of southeastern...
(C. haemorrhous) join mixed flocks on a somewhat more regular basis. Cuculiformes
Cuculiformes
The near passerine bird order Cuculiformes traditionally included three families as below:* Musophagidae - turacos and allies* Cuculidae - cuckoos, coucals, roadrunners and anis* Opisthocomidae - Hoatzin...
(cuckoo
Cuckoo
The cuckoos are a family, Cuculidae, of near passerine birds. The order Cuculiformes, in addition to the cuckoos, also includes the turacos . Some zoologists and taxonomists have also included the unique Hoatzin in the Cuculiformes, but its taxonomy remains in dispute...
s and allies) are usually absent from mixed feeding flocks, but some – e.g. the Squirrel Cuckoo
Squirrel Cuckoo
The Squirrel Cuckoo, Piaya cayana, is a large and active species of cuckoo found in wooded habitats from northwestern Mexico to northern Argentina and Uruguay, and on Trinidad.-Description:...
(Piaya cayana) can be encountered not infrequently.
Some species appear to prefer when certain others are present: Cyanolyca
Cyanolyca
Cyanolyca is a genus of small jays found in humid highland forests in southern Mexico, Central America and the Andes in South America. All are largely blue and have a black mask. They also possess black bills and legs and are skulking birds...
jay
Jay
The jays are several species of medium-sized, usually colorful and noisy, passerine birds in the crow family Corvidae. The names jay and magpie are somewhat interchangeable, and the evolutionary relationships are rather complex...
s like to flock with Unicolored Jay
Unicolored Jay
The Unicolored Jay is an Aphelocoma jay native to cloud forests of northwestern Central America and southern and southeastern Mexico, from central Honduras west to central Guerrero, southern Veracruz and extreme southern San Luis Potosi...
s (Aphelocoma unicolor) and the Emerald Toucanet
Emerald Toucanet
The Emerald Toucanet, Aulacorhynchus prasinus, is a near-passerine bird occurring in mountainous regions from Mexico, through Central America, to northern Venezuela and along the Andes as far south as central Bolivia...
s (Aulacorhynchus prasinus species complex
Cryptic species complex
In biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each other—but whose morphology is very similar ....
). Many Icteridae associate only with related species, but the western subspecies of the Yellow-backed Oriole
Yellow-backed Oriole
The Yellow-backed Oriole is a species of bird in the Icteridae family.-Physical description:Yellow-backed orioles are a yellow-bodied, sexually monomorphic species. Howell and Webb note that this species tends to average 21.5 cm in length from beak to tail; making Icterus chrysater a...
(Icterus chrysater) associates with jays and the Band-backed Wren
Band-backed Wren
The Band-backed Wren, Campylorhynchus zonatus, is a small songbird of the wren family.The Band-backed Wren is a resident breeding species from south-central Gulf Coast Mexico to northwestern Ecuador. It occurs in five disjunct areas, the central region being in southern Central America, in Costa...
(Campylorhynchus zonatus).
Other species participate to varying extents depending on location or altitude – presumably, the different species composition of mixed flocks at varying locations allows these irregular members more or less opportunity to get food. Such species include the Grey-hooded Flycatcher
Grey-hooded Flycatcher
The Grey-hooded Flycatcher is a species of bird in the Tyrannidae family.It is found in Argentina, Brazil, and Paraguay....
(Mionectes rufiventris: Tyrannidae), or the Plain Antvireo
Plain Antvireo
The Plain Antvireo, Dysithamnus mentalis, is a passerine bird species in the antbird family , wherein it belongs to the antshrike subfamily . It is a resident breeder in tropical Central and South America....
(Dysithamnus mentalis: Thamnophilidae) and the Red-crowned Habia (Habia rubica: Cardinalidae) which are often recorded in lowland flocks but rarely join them at least in some more montane
Montane
In biogeography, montane is the highland area located below the subalpine zone. Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals.The term "montane" means "of the...
regions.
In the Old World tropics
The flocks in the Old World are often much more loosely bonded than in the Neotropics, many being only casual associations lasting the time the flock of core species spends in the attendants' territory. The more stable flocks are observed in tropical Asia, and especially Sri Lanka. Flocks there may number several hundred birds spending the entire day together, and an observer in the rain forest may see virtually no birds except when encountering a flock. For example, as a flock approaches in the Sinharaja Forest ReserveSinharaja Forest Reserve
Sinharaja Forest Reserve is a national park and a biodiversity hotspot in Sri Lanka. It is of international significance and has been designated a Biosphere Reserve and World Heritage Site by UNESCO....
in Sri Lanka, the typical daytime quiet of the jungle is broken by the noisy calls of the Orange-billed Babbler
Orange-billed Babbler
The Orange-billed Babbler, Turdoides rufescens, also known as Ceylon Rufous Babbler or Sri Lankan Rufous Babbler is an Old World babbler. The Old World babblers are a large family of Old World passerine birds characterised by soft fluffy plumage...
(Turdoides rufescens) and Greater Racket-tailed Drongo
Greater Racket-tailed Drongo
The Greater Racket-tailed Drongo, Dicrurus paradiseus, is a medium-sized Asian bird which is distinctive in having elongated outer tail feathers with webbing restricted to the tips. They are placed along with other drongos in the family Dicruridae...
(Dicrurus paradiseus), joined by species such as the Ashy-headed Laughingthrush
Ashy-headed Laughingthrush
The Ashy-headed Laughingthrush, Garrulax cinereifrons, is an Old World babbler. The Old World babblers are a large family of Old World passerine birds characterised by soft fluffy plumage...
(Garrulax cinereifrons), Kashmir Flycatcher
Kashmir Flycatcher
The Kashmir Flycatcher, Ficedula subrubra, is a small passerine bird in the flycatcher family Muscicapidae. At one time it was considered to be a subspecies of the Red-breasted Flycatcher, Ficedula parva....
(Ficedula subrubra) and Velvet-fronted Nuthatch
Velvet-fronted Nuthatch
The Velvet-fronted Nuthatch, Sitta frontalis, is a small passerine bird found in southern Asia from Pakistan, India and Sri Lanka east to south China and Indonesia...
(Sitta frontalis).
A mixed flock in the Cordillera Central of Luzon in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
was mainly composed of Bar-bellied Cuckoo-shrike
Bar-bellied Cuckoo-shrike
The Bar-bellied Cuckooshrike is a species of bird in the Campephagidae family.It is found in India, Indonesia, Malaysia, the Philippines, Singapore, and Thailand....
s (Coracina striata: Campephagidae), Philippine Fairy-bluebird
Philippine Fairy-bluebird
The Philippine Fairy-bluebird is a species of bird in the Irenidae family. It is endemic to the Philippines.Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montane forests.-References:* BirdLife International 2004. . Downloaded on 26...
s (Irena cyanogaster: Irenidae) and Violaceous Crows (Corvus (enca) violaceus: Corvidae
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...
). Luzon Tarictic Hornbills (Penelopides manillae: Bucerotidae) were also recorded as present. With the crows only joining later and the large hornbills probably only opportunistic attendants rather than core species, it is likely that this flock was started by one of the former species – probably the bold and vocal cuckoo-shrikes rather than the more retiring fairy-bluebirds, which are known to seek out such opportunities to forage.
African rainforests also hold mixed-species flocks, the core species including Pycnonotidae (bulbuls) and Nectarinidae (sunbirds), and attendants being as diverse as the Red-billed Dwarf Hornbill
Red-billed Dwarf Hornbill
The Red-billed Dwarf Hornbill is a species of hornbill in the Bucerotidae family.It is found in Angola, Benin, Cameroon, Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Equatorial Guinea, Gabon, Ghana, Guinea, Liberia, Nigeria, Sierra Leone, Sudan,...
(Tockus camurus) and the Tit-hylia
Tit-hylia
The Tit Hylia is a species of bird in the Remizidae family. It is monotypic within the genus Pholidornis....
(Pholidornis rushiae), the smallest bird of Africa. Dicruridae (drongos) and Monarchidae (paradise-flycatchers) are sometimes described as the sentinels of the flock, but they are also known to steal prey from other flock members. Acanthizidae
Acanthizidae
The Acanthizidae, also known as the Australasian warblers, are a family of passerine birds which include gerygones, thornbills, and scrubwrens. The Acanthizidae consists of small to medium passerine birds, with a total length varying between 8 and 19 cm. They have short rounded wings, slender...
are typical core members in New Guinea (Gerygone) and Australia (Acanthiza); in Australia, fairy-wrens (Malurus) are also significant. The core species are joined by birds of other families such as minivet
Minivet
The minivets are passerine birds belonging to the genus Pericrocotus in the cuckoo-shrike family Campephagidae. There are about 13 species, occurring mainly in forests in southern and eastern Asia. They are fairly small, slender birds with long tails and an erect posture. Many species have bright...
s (Pericrocotus).