A
mixed-species feeding flock, also termed a
mixed-species foraging flock,
mixed hunting party or informally
bird wave, is a
flockA 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
birdBirds are winged, bipedal, endothermic , vertebrate animals that lay eggs. There are around 10,000 living species, making them the most numerous tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the Bee Hummingbird to the ...
s of different
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
, 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 LankaSri Lanka , officially the Democratic Socialist Republic of Sri Lanka , is an island country in South Asia, located about off the southern coast of India...
for example, vocal mimicry by the
Greater Racket-tailed DrongoThe 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
AmericaThe Americas, or America, are lands in the Western hemisphere or New World, comprising the continents of North America and South America with their associated islands and regions. America may be ambiguous in English, as it is more commonly used to refer to the United States of America...
n tropics noisy packs of foraging
Golden-crowned WarblerThe Golden-crowned Warbler, Basileuterus culicivorus, is a small New World warbler. It breeds from Mexico and south through Central America to northeastern Argentina and Uruguay, and on Trinidad....
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, with different species foraging in their preferred niches (on the ground, on trunks, in high or low foliage, and so on). Some species follow the flock all day, while others – such as the
Long-billed GnatwrenThe Long-billed Gnatwren, Ramphocaenus melanurus, 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.
In the Holarctic
In the North
Temperate ZoneIn 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 mild, rather than extreme hot or cold. But in continental areas, such as central North America the variations between summer...
, they are typically led by Paridae (tits and chickadees), often joined by
nuthatchThe 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),
treecreeperThe 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),
woodpeckerWoodpeckers 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 (
PicidaeThe 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 WoodpeckerThe Downy Woodpecker, Picoides pubescens, is the smallest woodpecker in North America. Adults are mainly black on the upper parts 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 black tail with white outer...
"Picoides" pubescens and
Lesser Spotted WoodpeckerThe Lesser Spotted Woodpecker is a member of the woodpecker family Picidae. It was previously assigned to the genus Dendrocopos , and often still is, but it appears to be closer related to the Downy Woodpecker.The range of the Lesser Spotted Woodpecker is the Palearctic region, but several...
"P." minor),
kingletThe 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-eatingAn insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures.Although individually small, insects exist in enormous numbers and make up a very large part of the animal biomass in almost all non-marine environments...
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
woodpeckerWoodpeckers 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
NeotropicIn biogeography, the Neotropic or Neotropical zone is one of the world's 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...
s the leaders or "core" members may be
Black-throated Shrike-tanagerThe 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
MexicoThe 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 WarblerThe 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....
s (
Basileuterus tristriatus) elsewhere in
Central AmericaManagua
Guatemala City
San Salvador
San Pedro Sula
Panama City
San José, Costa Rica
Santa Ana, El Salvador
León
San Miguel|-|}...
. In
South AmericaSouth America is the southern continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere...
, core species may include
antbirdThe 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
ThamnomanesThamnomanes 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-gleanerThe 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 WoodcreeperThe Olivaceous Woodcreeper is a passerine bird which breeds from southern Mexico through tropical Central and South America to northern Argentina, and also on Tobago. The species is throughout the Amazon Basin, but is absent from the lowest reaches of the basin, including much of the adjacent...
(
Sittasomus griseicapillus), or Parulidae (New World "warblers") like the
Golden-crowned WarblerThe Golden-crowned Warbler, Basileuterus culicivorus, is a small New World warbler. It breeds from Mexico and south through Central America to northeastern Argentina and Uruguay, and on Trinidad....
s (
Basileuterus culicivorus). In open
cerradoThe cerrado is a vast tropical savanna ecoregion of Brazil. The cerrado is characterised by an enormous range of plant and animal biodiversity...
habitat, it may be
White-rumpedThe 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...
s (
Cypsnagra hirundinacea) or
White-banded TanagerThe White-banded Tanager is a bird native to the interior of south-central South America at elevations of 550-1100 m . It is the only member of the genus Neothraupis in the tanager family , nine-primaried oscines of the Passeroidea...
s (
Neothraupis fasciata). Core
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
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 birds species serve as a focal point for flock members, they do not necessarily initiate the flock. In one
NeotropicIn biogeography, the Neotropic or Neotropical zone is one of the world's 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...
mixed flock feeding on swarming termites, it was observed that
Red-rumped Warbling-finchThe 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
BasileuterusBasileuterus 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
TangaraTangara is a large genus of birds of the tanager family. Many have restricted ranges. Most species in the genus are brightly colored. This genus includes some of the most spectacularly colored birds of the world....
species – in particular
Red-neckedThe 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-breastedThe 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 TanagerThe Green-headed Tanager, Tangara seledon, is a bird found in Atlantic forest in south-eastern Brazil, far eastern Paraguay and far north-eastern Argentina . As other members of the genus Tangara, it is a small colorful bird, measuring an average of 13.5 centimeters...
(
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 oscineThe 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
familiesIn 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...
such as the Cardinalidae (cardinals), Parulidae (New World "warblers"), and in particular
EmberizidaeThe Emberizidae are a large family of passerine birds.They are seed-eating birds with a distinctively shaped bill. In Europe, most species are named as buntings....
(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
woodpeckerWoodpeckers 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),
toucanToucans are a 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, colorful bills. The family includes five genera and about forty different species...
s (Ramphastidae) and
trogonThe 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
SynallaxisSynallaxis 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...
spinetailSpinetail 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
woodcreeperThe woodcreepers comprise a subfamily of sub-oscine passerine birds endemic to the Neotropics. They were formerly considered a distinct family Dendrocolaptidae. They superficially resemble the Old World treecreepers, but they are unrelated and the similarities are due to convergent evolution...
subfamily (Dendrocolaptinae) – e.g. those mentioned above or the
Lesser WoodcreeperThe 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 flycatcherThe tyrant flycatchers are a family of passerine birds which occur throughout North and South America, but are mainly Neotropical in distribution. They are now considered the largest family of birds on Earth, with around 400 species. In every country in the Americas, except for the United States...
s (Tyrannidae) there are also some species joining mixed flocks on a somewhat regular basis, including the
Sepia-capped FlycatcherThe 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-tyrantThe 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 SpadebillThe 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 TyrannuletThe 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
VireoVireo 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 VireoThe 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
subspeciesSubspecies in biological classification, is 1) a taxonomic rank subordinate to species, or 2) a taxonomic unit, a taxon in that rank...
groups of the
Yellow-rumped WarblerFour 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 WarblerThe 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 TanagerBlack-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 antThe 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 species,...
column or a group of
monkeyA monkey is any cercopithecoid or platyrrhine primate. All primates that are not prosimians or apes are monkeys. The 264 known extant monkey species represent two of the three groupings of simian primates...
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
antAnts are social insects of the family Formicidae , and along with the related wasps and bees, they 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...
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
thrushThe Thrushes, family Turdidae, are a group of passerine birds that occur mainly but not exclusively in the Old World.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat rose hips...
es (Turdidae) may participate on more often. And though most
TityridaeTityridae 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.
TapaculoThe 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
caciqueThe 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...
s like the
Golden-wingedThe 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 CaciqueThe 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.
CuculiformesThe near passerine bird order Cuculiformes traditionally included three families as below:* Musophagidae - turacos and allies* Cuculidae - cuckoos, coucals and anis* Opisthocomidae - Hoatzin...
(
cuckooThe 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 CuckooThe Squirrel Cuckoo, Piaya cayana, is a cuckoo breeding from northwestern Mexico to northern Argentina and Uruguay, and on Trinidad....
(
Piaya cayana) can be encountered not infrequently.
Some species appear to prefer when certain others are present:
CyanolycaCyanolyca 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...
jayThe 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 JayThe 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 ToucanetThe 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 complexIn 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 their morphology is very similar ....
). Many Icteridae associate only with related species, but the western subspecies of the
Yellow-backed OrioleThe Yellow-backed Oriole is a species of bird in the Icteridae family.-Geographic Distribution:It is found in Belize, Colombia, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, and Venezuela.-Habitats:...
(
Icterus chrysater) associates with jays and the
Band-backed WrenThe 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 FlycatcherThe 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 AntvireoThe Plain Antvireo, Dysithamnus mentalis, is a passerine bird species in the antbird family. It is a resident breeder in tropical Central and South America from southern Mexico south to northern Argentina, and on Trinidad and Tobago.-Description:...
(
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
montaneIn 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.
Old World tropics
Mixed-species flocks on other continents resemble those of the Neotropics. The core members in
AfricaAfrica is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area. With a billion people in 61 territories, it accounts for about 14.8% of the...
are often Paridae (tits). In
AsiaAsia is the world's largest and most populous continent, located in the eastern and northern hemispheres. It covers 8.6% of the earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population.Asia is traditionally defined as part of the...
, they are often Dicruridae (drongos), Timaliidae (Old World babblers) and the
Green IoraThe Green Iora is a species of bird in the Aegithinidae family. It is found in Brunei, Indonesia, Malaysia, Myanmar, Singapore, and Thailand....
(
Aegithina viridissima).
AcanthizidaeThe 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 on
New GuineaNew Guinea, located north of Australia, is the world's second largest island. It became separated from the Australian mainland when the area now known as the Torres Strait flooded after the last glacial period. The name Papua has long been associated with the island...
(
GerygoneGerygone, the gerygones, is a genus of bird in the Acanthizidae family. The genus ranges from South East Asia through New Guinea and Australia to New Zealand and the Chatham Islands...
) and
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
(
AcanthizaAcanthiza is a genus of passeriform birds, mostly found in Australia but with one species restricted to New Guinea. These birds are commonly known as thornbills. They are not closely related to species in the hummingbird genus Chalcostigma which are also called thornbills.They are found...
); in Australia, fairy-wrens (
Malurus) are also significant. The core species are joined by birds of other families such as Pycnonotidae (bulbuls), or
minivetThe 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) of the Campephagidae.
In tropical Asia, flocks 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 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 LankaSri Lanka , officially the Democratic Socialist Republic of Sri Lanka , is an island country in South Asia, located about off the southern coast of India...
, the typical daytime quiet of the jungle is broken by the noisy calls of
Orange-billed BabblerThe 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...
s (
Turdoides rufescens) and a
Greater Racket-tailed DrongoThe 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). As the birds pass, the observer can glimpse the quieter, more inconspicuous, members of the flock. If the flock crosses a track, its true numbers become clearer – instead of two
Ashy-headed LaughingthrushThe 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. These are birds of tropical areas, with the greatest variety in southeast Asia.-Description:The Ashy-headed...
es (
Garrulax cinereifrons) there may be ten, and previously-missed small species such as the
Kashmir FlycatcherThe 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) or the
Velvet-fronted NuthatchThe 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) reveal themselves.
A mixed flock in the Cordillera Central of Luzon in the
PhilippinesThe Philippines officially known as the Republic of the Philippines, is a country in Southeast Asia with Manila as its capital city. It comprises 7,107 islands in the western Pacific Ocean....
was mainly composed of
Bar-bellied Cuckoo-shrikeThe Bar-bellied Cuckoo-shrike 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-bluebirdThe 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:
CorvidaeCorvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers. The common English name used is 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 seek out such opportunities to forage.