Antbird

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Antbirds
Bicoloured Antbird Gymnopithys leucaspis
Bicoloured Antbird
Gymnopithys leucaspis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Suborder: Tyranni
Family: Thamnophilidae
Swainson, 1824
Global range (In red)
Global range (In red)
Genera

Some 45, see List of antbirds.

The antbirds are a large family, Thamnophilidae, of smallish passerine bird species of subtropical and tropical Central and South America. The family has around 200 species and includes the antshrikes, antwrens, antvireos, fire-eyes, bare-eyes and bushbirds. They are closely related to the antthrushes and antpittas in the family Formicariidae, the tapaculos, and especially the gnateaters.[1][2]

Small birds with rounded wings and strong legs, antbirds have mostly sombre grey, white, brown and rufous plumage. Most species exhibit sexual dimorphism in the pattern and colouring. Some species communicate warnings to each other by exposing white patches on their back feathers or shoulders. The bills of most species are heavy and often hooked at the end.

The family is predominantly found in forests, although a few species are found in other habitats. The most important part of their diet is insects and other arthropods, although small vertebrates are taken occasionally. Most species feed in the understory and midstory of the forest, with a few species feeding in the canopy and on the ground. Many species join mixed-species feeding flocks, and a few species are core members. A minority of them specialize in following columns of army ants to eat the small invertebrates that leave hiding to flee the ants, although many other species may feed in this way opportunistically.

Antbirds are monogamous, mate for life and defend territories. They usually lay two eggs in a nest that is either suspended from branches or supported on a branch, stump or mound on the ground. Both parents share the tasks of incubation, brooding and feeding the chicks. After fledging there is a division of the brood between the parents, with each parent caring exclusively for one chick.

Contents

[edit] Systematics

There are some 200 species, variously called antwrens, antvireos, antbirds and antshrikes. The names refer to the relative sizes of the birds (increasing in the order given) rather than any particular morphological resemblance to the true wrens, vireos or shrikes. The genus Phlegopsis is the bare-eyes, Pyriglena the fire-eyes and Neoctantes and Clytoctantes are the bushbirds. The family was once considered to fall within the expanded antbird family Formicariidae, but differences in the structure of the sternum and syrinx, combined with Sibley and Ahlquist's examination of DNA-DNA hybridisation led to the "typical antbirds" (Thamnophilidae) being separated from the "ground antbirds"(Formicariidae).[3]

Although the taxonomical layout of the group is based on studies from the mid-19th century, when fewer than half the present species were known, comparison of the myoglobin intron 2, GAPDH intron 11 and the mtDNA cytochrome b DNA sequences has largely confirmed it.[4] Two major clades - most antshrikes and other larger, strong-billed species as well as Herpsilochmus versus the classical antwrens and other more slender, longer-billed species - exist and the monophyly of most genera was confirmed.

The Thamnophilidae contain several large or very large genera, and a considerable number of small or monotypic ones. Several of these, which have always been difficult to assign, seem to form a third,[clarify] hitherto unrecognized clade independently derived from ancestral antbirds. The results also confirmed suspicions of previous researchers that some species, most notably in Myrmotherula and Myrmeciza, need to be assigned to different genera. Still, due to the difficulties of sampling from such a large number of often poorly known species, the assignment of some genera is still awaiting confirmation.

For a list of genera and species see List of antbirds.

[edit] Morphology

The legs and feet of ant-following antbirds are strong and adapted to gripping vertical stems and branches. The leg muscle of the Bicoloured Antbird comprises 13 % of its body weight.
The legs and feet of ant-following antbirds are strong and adapted to gripping vertical stems and branches. The leg muscle of the Bicoloured Antbird comprises 13 % of its body weight.

The antbirds are a group of small to medium sized passerines that range in size from the large Giant Antshrike, which measures 45 cm (18 in) and weighs 150 g (5.29 oz), to the tiny 8 cm (3 in) Pygmy Antwren, which weighs a mere 7 g (0.25 oz).[3] In general they have short rounded wings that provide good manoeuvrability when flying in dense undergrowth. The legs are large and strong, particularly in species that are obligate ant-followers. In particular these species are adapted to gripping vertical stems and saplings, which are more common than horizontal branches in the undergrowth and thus an advantage when following swarms of army ants. The claws of these species are longer than those of species that do not follow ants, and the soles of some species have projections that are tough and gripping when the foot is clenched. Tarsus length in antbirds is related to foraging strategy. Longer tarsi are favoured by genera like the Thamnophilus antshrikes that forage by perch-gleaning (sitting and leaning forward to snatch insects from the branch), whereas shorter tarsi are favoured by those that catch prey on the wing, like the Thamnomanes antshrikes.[5]

Most antbirds have proportionately large, heavy bills.[3] Several genera of antshrike have a strongly hooked end to the bill, and all antbirds have a notch or 'tooth' at the end of the bill which helps in holding and crushing insect prey. The two genera of bushbirds have upturned chisel-like bills.[6]

The plumage of antbirds is soft and not brightly coloured, although it is occasionally striking.[3] The colour palette of most species is a combination of blacks, whites, rufous, chestnut and brown. Different species are uniform in colour or at times patterned with barring or spots. Sexual dimorphism in plumage colour and patterns is common in the family, with most species having different male and female plumages. For example, the male Dot-winged Antwren is almost uniformly black, whereas the female has rust underparts.[7] Many species of antbird have a contrasting 'patch' of white (sometimes other colours) feathers on the back, shoulder or underwing. This is usually concealed by the darker feathers on the back but when the bird is excited or alarmed these feathers can be raised to flash the white patch. Dot-winged Antwrens puff out white back patches, whereas Bluish-slate Antshrikes and White-flanked Antwrens the white patch is on the shoulder.[8]

[edit] Voice

The Barred Antshrike is distributed from Mexico to Argentina. It has the hooked bill typical of the antshrikes.
The Barred Antshrike is distributed from Mexico to Argentina. It has the hooked bill typical of the antshrikes.

The songs and calls of antbirds are generally simple uncomplicated notes. The family is one of the suboscines (suborder Tyranni) and like other suboscines they have more simple syrinxes than other songbirds. Nether the less they are long, distinctive and species specific, allowing fieldworkers researching antbirds to identify many species without seeing them. [3] Antbirds rely on their calls for communication, as is typical of birds in dimly lit forests.

[edit] Distribution and habitat

The distribution of the antbirds is entirely Neotropical, with the vast majority of the species being found in the tropics. A few species reach southern Mexico and northern Argentina. Some species, like the Barred Antshrike, have a continental distribution that spans most of the South and Central American distribution of the family, others like the Ash-throated Antwren have a tiny distribution.[9]

Antbirds are mostly birds of humid lowland rainforests.[3] Few species are found at higher elevations, with less than 10% of species having ranges above 2000 m and almost none with ranges above 3000 m. The highest species diversity is found in the Amazon Basin, with up to 45 species being found in single locations in sites across Brazil, Colombia, Bolivia and Peru. The number of species drops dramatically towards the further reaches of the family's range; there are only seven species in Mexico for example. Areas of lower thamnophilid diversity may contain localised endemics, however. The Yapacana Antbird, for example, is restricted to the stunted woodlands that grow in areas of nutrient white-sand soil (the so called Amazonian caatinga) in Brazil, Venezuela and Colombia.[10] Some species are predominately associated within certain microhabitats within a greater ecosystem, for example the Bamboo Antshrike is predominately found in bamboo patches.[11]

[edit] Behaviour

A Variable Antshrike gleaning insects from foliage
A Variable Antshrike gleaning insects from foliage

Antbirds are diurnal, feeding, breeding and defending territories during the day. Many of the are, however, mostly adverse to entering direct sunlight when it breaks through the canopy. Antbirds will engage in anting, a behaviour where ants (or other arthropods) are rubbed on the feathers before being discarded or eaten.[12] While this has conventionally been considered a way to remove and control feather parasites, it has been suggested that for antbirds it may simply be a way to deal with the distasteful substances in prey items.[3]

[edit] Feeding

The main component of the diet of all antbirds is arthropods.[3] These are mostly insects, including grasshoppers and crickets, cockroaches, praying mantises, stick insects and the larvae of butterflies and moths. In addition spiders, scorpions and centipedes are often taken. Smaller prey items are swallowed quickly, whereas larger items are often beaten against branches in order to remove wings and spines. Larger species are capable of killing and consuming frogs and lizards as well, but generally these do not form an important part of the diet of this family.[13] In addition other food items may be eaten, including fruit, eggs and slugs.[3]

The Black-hooded Antshrike is a relatively sluggish species usually found singly or in pairs. Here a male feeds on a caterpillar.
The Black-hooded Antshrike is a relatively sluggish species usually found singly or in pairs. Here a male feeds on a caterpillar.

A number of techniques are used by the family in order to obtain prey. The majority of antbirds are arboreal, with most of those feeing in the understory, with many occupying the middle story and some species feeding in the canopy. A few species feed in the leaf litter; for example the Wing-banded Antbird forages in areas of dense leaf-litter. It doesn't use its feet to scratch the leaf litter, as do some other species of bird, instead it uses its long bill to turn over leaves rapidly (the leaves are never picked up).[14] Of those that forage arboreally, an number of techniques and specialisations exist. Species may perch-glean, perching on a branch watching for prey and snatching it by reaching forward, where others may sally from a perch and snatch prey on the wing.[5] In both cases birds will hop through the foliage or undergrowth and pause, scanning for prey, before pouncing or moving on. The time paused varies, although smaller species tend to be more active and pause for shorter periods of time.[3]

[edit] Mixed-species feeding flocks

Antbirds participate in mixed-species feeding flocks,[3] forming a large percentage of the participating species within their range. Some of these form the core or "nuclear species". These nuclear species share territories with other core species but exclude conspecifics (members of the same species) and are found in almost all flocks, these are in turn joined by "attendant species". Loud and distinctive calls and conspicuous plumage are important attributes of nuclear species as they promote cohesion in the flock. The exact composition of these flocks varies geographically, but in Amazonia species of Thamnomanes antshrike are the leading "nuclear species",[8] elsewhere other species, such as the Dot-winged Antwrens and Checker-throated Antwrens fill this role.[3] Other species of antwren and antbird join them along with woodcreepers, ant-tanagers, foliage-gleaners and greenlets.[8] The benefits of the mixed flock are thought to be related to predation, where many eyes are better for spotting predatory hawks and falcons. Comparisons between multi-species feeding flocks in different parts of the world found that instances of flocking were positively correlated with predation risk by raptors.[15] In particular where Thamnomanes antshrikes lead the group they give loud warning calls in the presence of predators. These calls are understood and recated to by all the other species in the flock. The Thamnomanes antshrikes benefit by allowing the rest of the flock, which are typically gleaners, to act as beaters, flushing prey while foraging which the antshrikes can obtain by sallying. Similar roles are filled by other species (in both the antbird family and outside it) in other flocks, for example the shrike-tanagers.[3] Within the feeding flocks competition is reduced by microniche partitioning; where Dot-winged Antwrens, Checker-throated Antwrens and White-flanked Antwrens feed in flocks together the Dot-wings feed in the densest vines, the White-flank in less dense vegetation, and the Checker-throat feeds in the same density as the latter but in dead foliage only.[16]

[edit] Ant-followers

Immaculate Antbirds regularly attend army ant swarms in order to feed, but is not an obligate ant-follower and also forages away from the swarms
Immaculate Antbirds regularly attend army ant swarms in order to feed, but is not an obligate ant-follower and also forages away from the swarms

An important resource used by some species of antbird, and one from which the family's common name is derived, are swarms of army ants. Many species of tropical ant form large raiding swarms, but the swarms are often nocturnal or raid underground and while birds visit them when they occur, the species most commonly attended by birds is the Neotropical species Eciton burchellii,[12] which is both diurnal and surface raiding. It was once thought that attending birds were actually eating the ants, but numerous studies in various parts of E. burchellii's range has shown that the ants act as beaters, flushing insects, other arthropods and small vertebrates into the waiting flocks of "ant-followers". The improvement in foraging efficiency can be dramatic; a study of Spotted Antbirds found that they made attempts at prey every 111.8 seconds away from ants, but at swarms they made attempts every 32.3 seconds.[17] While many species of antbird (and other families) may opportunistically feed at army ant swarms, 18 species of antbird are obligate ant-followers, obtaining most of their diet from swarms.[3] With only three exceptions these species never regularly forage away from ant swarms. A further four species regularly attend swarms but are as often seen away from them. Obligate ant-followers visit the nesting bivouacs of army ants in the morning to check for raiding activities, other species do not.[18] These species tend to arrive at swarms first, and their calls are used by other species in order to locate swarming ants.[19]


Because army ants are unpredictable in their movements it is impracticable for obligate ant-followers to maintain a territory that always contains swarms to feed around.[3] Antbirds have evolved a more complicated system than the strict territoriality of most other birds. They generally (details very amongst species) maintain breeding territories but travel outside those territories in order to feed at swarms. Several pairs of the same species may attend a swarm, and the dominant pair at the swarm being the pair who hold the territory that the swarm is in. In addition to competition within species there exists competition among species, and larger species are dominant. The Ocellated Antbird is the largest of the obligate ant-following antbirds and is dominant over the other species, although it is itself subordinate to some species of woodcreeper. At a swarm the dominant species occupies positions above the central front of the swarm, which yields the largest amount of prey. Smaller less dominant species locate themselves further away from the centre, or higher above the location of the dominant species, where prey is less plentiful.[12]

[edit] Breeding

Antbirds are monogamous, in almost all cases forming long term pair bonds that last the life of the pair.[3] In the White-plumed Antbird divorces between pairs are common, but this is exceptional. In most species the pair defends a classic territory, although the nesting territories or ant-followers are slightly different (see feeding above). Territories vary in size from as small as 0.5 ha for the Manu Antbird, to being 1500 m in diameter for the Ocellated Antbirds. Ocellated Antbirds have an unusual social system where the breeding pair form the nucleus of a group or clan that includes their male offspring and their mates. These clans, which can number up to eight birds, work together to defend territories against rivals. Pair bonds are formed with courtship feeding, where the male presents food items to the female.[3] In Spotted Antbirds males may actually feed females sufficiently for the female to cease feeding herself, although she will resume feeding once copulation has occurred.[17] Mutual grooming also plays a role in courtship in some species.[20]

The Ocellated Antbird has an unusual social system of shared breeding territories. One dominant pair may share a territory with up six other birds.
The Ocellated Antbird has an unusual social system of shared breeding territories. One dominant pair may share a territory with up six other birds.

What is known about the nests and breeding biology of antbirds is based on the species that have been studied and who's nests have been located. Even relatively well known species are poorly known, for example the nest of the Ocellated Antbird was first described in 2004.[21] Nests are constructed by both parents, although the male undertakes more of the work in some species. Antbird nests are cups of vegetation such as twigs, dead leaves and plant filaments, and they follow two basic patterns, they are either suspended or supported.[3] Suspended cups, which may hang from forks in branches or between two branches, are the more common style of nest. Supported nests rest upon branches, amongst vines, in hollows and sometimes on monds of vegertation on the ground. The level that the nest is built in the understory or canopy is related to the foraging level of the species that build it, so a midstory species would built its nest in the midstory. The tendency to have one kind of nest or another is related to phylogeny, with closely related species nesting in the same ways. For example antvireos in the genus Dysithamnus are all suspension nesters.[22]

Almost all antbirds lay two eggs.[3] A few species of antshrike lay three eggs, and a smaller number or antbirds lay one egg, but this is unusual. Small clutch sizes are typical of tropical birds compared to more temperate species of the same size, possibly due to nest predation, although this is disputed.[23] Both parents participate in incubation, although only the female incubates at night. The length of time taken for chicks to hatch is between 14-16 days in most species, although some, such as the Dusky Antbird, can take as long as 20 days. The altricial chicks are born naked and blind. Both parents brood the young until they are able to thermoregulate, although as with incubation only the female broods at night.[3] In common with many songbirds faecal sacs are taken by the parents for disposal away from the nest. Both parents feed the chicks, often bringing large prey items. When the chicks reach fledging age, after 8-15 days, attending parents call their chicks. As each chick leaves the nest it is cared for exclusively from then on by the parent that was present then. After the first chick fledges and leaves with a parent the remaining parent may increase the supply of food to speed up the process of fledging. After fledging chicks spend the first few days well hidden as the parents bring them food. Chicks of some species may not become independent of the parents for as long as four months in some antwrens, but two months is more typical for the rest of the family.

[edit] Ecology

Antbirds are common components of the avifauna of some parts of the Neotropics and are thought to be important in some ecological processes. They are preyed upon by birds of prey, and their tendency to join flocks is thought to be a protection against such predation.[15] Some species, such as the White-bibbed Antbird, are preyed upon by the Greater Round-eared Bat, and some such as the Scaled Antbird are the preferred prey of that species.[24] Nests, including incubating adults, chicks and eggs, are vulnerable to predators, particularly snakes but also nocturnal mammals.[3] Nesting success is low for many species, particularly in areas of fragmented habitat.[3][25]

It was once suggested that the relationship between the obligate and regular ant-followers and the army ants, particularly Eciton burchellii, was mutualistic, with the ants benefiting by having the birds chase prey back down towards them. However experiments where ant-followers were excluded have shown that the foraging success of the army ants was 30% lower when the birds were present, suggesting that the birds relationship was in fact parasitic.[26] This has resulted in a number of behaviours by the ants in order to reduce kleptoparasitism, including hiding of secured prey in the leaf litter and caching of food on trails. It has been suggested that the depressive effect of this parasitism slows the development of E. burchellii swarms and in turn benefits other ant species which are themselves preyed upon by army ants. The ant-following antbirds are themselves followed by three species of butterfly in the family Ithomiinae which feed on their droppings.[27] Bird droppings are usually an unpredictable resource in a rainforest, but the regular behaviour of ant-followers makes the exploitation of this resource possible.

[edit] Status and conservation

The Pectoral Antwren of Brazil is threatened by the loss of deciduous forest and is listed as vulnerable by the IUCN.
The Pectoral Antwren of Brazil is threatened by the loss of deciduous forest and is listed as vulnerable by the IUCN.

As of April 2008, 38 species are considered near threatened or worse and therefore at risk of extinction by the IUCN.[28] Antbirds are neither targeted by the pet trade nor are large enough to be hunted; the principal cause of the decline in antbird species is habitat loss.[3] The destruction or modification of forests has several effects on different species of antbirds. The fragmentation of forests into smaller patches hits mixed-species feeding flocks, leading to local extinctions.[29] Another risk faced by antbirds in fragmented habitat is increased nest predation. A natural experiment in fragmentation occurred on Barro Colorado Island, a former hill in Panama that became an isolated island during the flooding caused by the creation of the Panama Canal. Numerous species of antbird formerly resident to the area went extinct, in no small part due to increased levels of nest predation on the island.[30] While the species lost from Barro Colorado are not globally threatened, they illustrate the vulnerability of species in fragmented habitats and help explain the declines of some species. The majority of threatened species have very small natural ranges.[3] Some are also extremely poorly known, for example the White-masked Antbird is known only from a single specimen collected in 1937 and is currently listed as data deficient.[31] The Rio de Janeiro Antwren is similarly mysterious; after its discovery in 1982 there have only been unconfirmed reports[32] and it is currently listed as critically endangered.

[edit] References

  1. ^ Irestedt, Martin; Fjeldså, Jon; Johansson, Ulf S. & Ericson, Per G.P. (2002): Systematic relationships and biogeography of the tracheophone suboscines (Aves: Passeriformes). Molecular Phylogenetics and Evolution 23(3): 499–512. doi:10.1016/S1055-7903(02)00034-9 (HTML abstract)
  2. ^ Rice, Nathan H. (2005): Further Evidence for Paraphyly of the Formicariidae (Passeriformes). Condor 107(4): 910-915. doi:10.1650/7696.1 PDF fulltext
  3. ^ a b c d e f g h i j k l m n o p q r s t u v w x Zimmer, K. & M. Isler (2003) "Family Thamnophilidae (Typical Antbirds)" in del Hoyo, J.; Elliot, A. & Christie D. (editors). (2003). Handbook of the Birds of the World. Volume 8: Broadbills to Tapaculos. Lynx Edicions. ISBN 8487334504
  4. ^ Irestedt, M.; Fjeldså, J.; Nylander, J.A.A. & Ericson, P.G.P. (2004): Phylogenetic relationships of typical antbirds (Thamnophilidae) and test of incongruence based on Bayes factors. BMC Evol. Biol. 4: 23. doi:10.1186/1471-2148-4-23 Supplementary information
  5. ^ a b Schulenberg, T. S. (1983). "Foraging behaviour, ecomorphology and systematic of some antshrikes (Formicariidae: Thamnomanes). Wilson Bulletin. 95: 505-521. [1]
  6. ^ Lanyon, S.; Stotz, D. & Willard, D (1990) "Clytoctantes atrogularis, a new species of antbird from western Brazil" Wilson Bulletin 102 (4): 571-580[2]
  7. ^ Greenberg, R & J Gradwohl (1983) "Sexual Roles in the Dot-Winged Antwren (Microrhopias quixensis), a Tropical Forest Passerine" Auk 100 (4): 920-925 [3]
  8. ^ a b c Munn, C.A. & J.W. Terborgh (1979) "Multi-Species Territoriality in Neotropical Foraging Flocks" Condor 81 (4): 338-347. [4]
  9. ^ BirdLife International (2007) Species factsheet: Herpsilochmus parkeri. Downloaded from http://www.birdlife.org on 3/4/2008
  10. ^ Zimmer, K (1999) "Behavior and vocalizations of the Caura and the Yapacana Antbirds" Wilson Bulletin 111 (2): 195-209 [5]
  11. ^ Pierpont, N. & J.W. Fitzpatrick (1983) "Specific Status and Behavior of Cymbilaimus sanctaemariae, the Bamboo Antshrike, from Southwestern Amazonia" Auk 100 (3): 645-652 [6]
  12. ^ a b c Willis, E. & Y. Oniki (1978). "Birds and Army Ants" Annual Review of Ecology and Systematics 9: 243-263 Abstract
  13. ^ Lopes, L.E; Fernandes, A.M. & A.M. Marini (2005). "Predation on vertebrates by Neotropical passerine birds". Lundiana 6 (1): 57-66
  14. ^ Tostain, O. & J. Dujardin (1988) "Nesting of the Wing-Banded Antbird and the Thrush-like Antpitta in French Guiana" Condor 90 (1): 236-239 [7]
  15. ^ a b Thiollay, J (1999) "Frequency of Mixed Species Flocking in Tropical Forest Birds and Correlates of Predation Risk: An Intertropical Comparison" Journal of Avian Biology. 30 (3): 282-294 (abstract)
  16. ^ Wiley, R.H. (1971) "Cooperative Roles in Mixed Flocks of Antwrens (Formicariidae)" Auk 88 (4): 881-892 [8]
  17. ^ a b Willis, E.O. (1972) "The Behavior of Spotted Antbirds" Ornithological Monographs 10 P. 103 [9]
  18. ^ Swartz, M.B. (2001) "Bivouac Checking, a Novel Behavior Distinguishing Obligate from Opportunistic Species of Army-Ant-Following Birds". Condor 103 (3): 629-633
  19. ^ Chaves-Campos, J (2003) " Localization of army-ant swarms by ant-following birds of the Caribbean slope of Costa Rica: following the vocalization of antbirds to find the swarms" Ornitología Neotropical 14 (3): 289-294
  20. ^ Willis, E.O. & Y. Oniki (1972) "Ecology and Nesting Behavior of the Chestnut-Backed Antbird (Myrmeciza exsul)". Condor 74 (1): 87-98)
  21. ^ Buehler, D.M.; Castillo, A.I.; & J.D. Brawn (2004) "First Nest Description for the Ocellated Antbird (Phaenostictus mcleannani)". Wilson Bulletin 116 (3): 277–279 (Abstract.)
  22. ^ Greeney, H.F. (2004). "Breeding behavior of the Bicolored Antvireo (Dysithamnus occidentalis)". Ornithologia Neotropical 15: 349–356
  23. ^ Roper, J.J & R.R. Goldstein (1997). "A Test of the Skutch Hypothesis: Does Activity at Nests Increase Nest Predation Risk?" Journal of Avian Biology, 28 (2): 111-116
  24. ^ Martuscelli, P. (1995) "Avian Predation by the Round-Eared Bat (Tonatia bidens, Phyllostomidae) in the Brazilian Atlantic Forest" Journal of Tropical Ecology, 11 (3): 461-464
  25. ^ Loiselle, B.A. & W.G. Hoppes (1983) "Nest Predation in Insular and Mainland Lowland Rainforest in Panama". Condor 85 (1): 93-95
  26. ^ Wrege, P.H.; Wikelski, M.; Mandel, J.T.; Rassweiler, T. & I.D. Couzin (2005) " Antbirds parasitize foraging army ants". Ecology 86 (3): 555-559
  27. ^ Ray, T. & C.C. Andrews (1980) "Antbutterflies: Butterflies That Follow Army Ants to Feed on Antbird Droppings" Science 210: 1147-1148
  28. ^ IUCN (2007). 2007 IUCN Red List of Threatened Species: Thamnophilidae. Downloaded on 23 April 2008.
  29. ^ Stouffer, P.C & R.O. Bierregaard, Jr. (1995) "Use of Amazonian Forest Fragments by Understory Insectivorous Birds". Ecology 76 (8): 2429-2445
  30. ^ Sieving, K. (1992) "Nest Predation and Differential Insular Extinction among Selected Forest Birds of Central Panama". Ecology 73 (6): 2310-2328
  31. ^ BirdLife International (2007) Species factsheet: Pithys castaneus. Downloaded from http://www.birdlife.org on 26/4/2008
  32. ^ BirdLife International (2007) Species factsheet: Myrmotherula fluminensis. Downloaded from http://www.birdlife.org on 26/4/2008

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