Antbird
263286
222983036
2008-07-02T01:06:24Z
Sabine's Sunbird
123079
correction
{{Taxobox
| name = Antbirds
| image = Gymnopithys-leucaspis-002.jpg
| image_width = 250px
| image_caption = Bicoloured Antbird <br>''[[Gymnopithys leucaspis]]''
| regnum = [[Animal]]ia
| phylum = [[chordate|Chordata]]
| classis = [[bird|Aves]]
| ordo = [[passerine|Passeriformes]]
| subordo = [[Tyranni]]
| familia = '''Thamnophilidae'''
| familia_authority = [[William Swainson|Swainson]], 1824
| subdivision_ranks = Genera
| subdivision =
Some 45, see [[List of antbirds]].
|
| range_map = Thamnophilidae distribution.PNG
| range_map_width = 200px
| range_map_caption = Global range (In green)
}}
The '''antbirds''' are a large [[family (biology)|family]], '''Thamnophilidae''', of smallish [[passerine]] [[bird]] [[species]] of subtropical and tropical [[Central America|Central]] and [[South America]]. The family has [[List of antbirds|around 200 species]] and includes the antshrikes, antwrens, antvireos, fire-eye, bare-eyes and bushbirds. They are closely related to the antthrushes and antpittas in the family [[Formicariidae]], the [[tapaculo]]s, and especially the [[gnateater]]s.<ref name = "Irestedt2002">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. <small>{{doi|10.1016/S1055-7903(02)00034-9}}</small> (HTML abstract)</ref><ref name = "Rice">Rice, Nathan H. (2005): [http://www.ansp.org/research/biodiv/ornithology/pdf/antbird-paraphyly.pdf Further Evidence for Paraphyly of the Formicariidae (Passeriformes). (PDF)] ''[[Condor (journal)|Condor]]'' '''107'''(4): 910–915. {{DOI|10.1650/7696.1}}</ref>
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 feather patches on their back feathers or shoulders. The [[beak|bills]] of most species are heavy and often hooked at the end.
The family is predominantly composed of forest-living species, although a few species are found in other habitats. The most important part of their diet is [[insect]]s 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 flock]]s, and a few species are core members. A minority of them specialize in following columns of [[army ant]]s to eat the small invertebrates that leave hiding to flee the ants, although many other species may feed in this way opportunistically.
Antbirds are [[monogamy|monogamous]], mate for life and defend [[Territory (animal)|territories]]. They usually lay two eggs in a [[bird nest|nest]] that is either suspended from branches or supported on a branch, stump or mound on the ground. Both parents share the tasks of [[avian incubation|incubation]], brooding and feeding the chicks. After [[fledge|fledging]] there is a division of the brood between the parents, with each parent caring exclusively for one chick.
A number of species of antbirds are threatened with [[extinction]] due to human activities. The principal threat is [[habitat loss]], as antbirds are neither targeted by hunters or the pet trade. They are vulnerable to habitat fragmentation and to increased predation in fragmented habitats.
==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 [[wren]]s, [[vireo]]s or [[shrike]]s. The genus ''Phlegopsis'' is the [[bare-eye]]s, ''Pyriglena'' the [[fire-eye]]s and ''Neoctantes'' and ''Clytoctantes'' are the [[Clytoctantes|bushbird]]s. 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-Ahlquist taxonomy|Sibley and Ahlquist's]] examination of [[DNA-DNA hybridisation]] led to the "typical antbirds" (Thamnophilidae) being separated from the "ground antbirds"(Formicariidae).<ref name = "HBW"/><ref>[[Charles Sibley|Sibley, Charles Gald]] & [[Jon Edward Ahlquist|Ahlquist, Jon Edward]] (1990): ''Phylogeny and classification of birds''. Yale University Press, New Haven, Conn.</ref>
Although the taxonomical layout of the group is based on studies from the [[19th century|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|cytochrome ''b'']] [[DNA sequence]]s has largely confirmed it.<ref name = "Irestedt 2004">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. ''[[BioMed Central|BMC Evol. Biol.]]'' '''4''': 23.<!-- BMC journals use article numbers, not page numbers --> {{DOI|10.1186/1471-2148-4-23}} [http://www.biomedcentral.com/content/supplementary/1471-2148-4-23-S1.pdf Supplementary information (PDF)]</ref> Two major [[clade]]s - 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 [[genus|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, hitherto unrecognised clade independently derived from ancestral antbirds.<ref name = "Irestedt 2004"/> 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]].
==Morphology==
[[Image:Gymnopithys-leucaspis-001 edit2.jpg|thumb|left|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 [[passerine]]s that range in size from the large [[Giant Antshrike]], which measures 45 cm (18 [[inch|in]]) and weighs 150 [[gram|g]] (5.29 [[ounce|oz]]), to the tiny 8 cm (3 in) [[Pygmy Antwren]], which weighs a mere 7 g (0.25 oz).<ref name = "HBW">Zimmer, K. & M. Isler (2003) "Family Thamnophilidae (Typical Antbirds)" P.p. 440–531 ''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</ref> In general they have short rounded wings that provide good manoeuvrability when [[bird flight|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 [[sapling]]s, 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 (skeleton)|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.<ref name = "Schulenberg">Schulenberg, T. S. (1983). [http://elibrary.unm.edu/sora/Wilson/v095n04/p0505-p0521.pdf "Foraging behaviour, ecomorphology and systematic of some antshrikes (Formicariidae: ''Thamnomanes'')." (PDF)] ''Wilson Bulletin''. '''95''': 505–521. </ref>
Most antbirds have proportionately large, heavy [[beak|bills]].<ref name = "HBW"/> 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 [[genus|genera]] of bushbirds have upturned chisel-like bills.<ref>Lanyon, S.; Stotz, D. & Willard, D (1990) [http://elibrary.unm.edu/sora/Wilson/v102n04/p0571-p0580.pdf "''Clytoctantes atrogularis'', a new species of antbird from western Brazil". (PDF)] ''Wilson Bulletin'' '''102''' (4): 571–580</ref>
The [[plumage]] of antbirds is soft and not brightly coloured, although it is occasionally striking.<ref name = "HBW"/> The colour palette of most species is a combination of blacks, whites, rufous, chestnut and brown. Different species can be uniform in colour or at 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 coloured underparts.<ref name = "Greenberg">Greenberg, R & J Gradwohl (1983) [http://elibrary.unm.edu/sora/Auk/v100n04/p0920-p0925.pdf "Sexual Roles in the Dot-Winged Antwren (''Microrhopias quixensis''), a Tropical Forest Passerine". (PDF)] ''Auk'' '''100''' (4): 920–925</ref> 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 in [[Bluish-slate Antshrike]]s and [[White-flanked Antwren]]s the white patch is on the shoulder.<ref name = "Munn">Munn, C.A. & J.W. Terborgh (1979) [http://elibrary.unm.edu/sora/Condor/files/issues/v081n04/p0338-p0347.pdf "Multi-Species Territoriality in Neotropical Foraging Flocks". (PDF)] ''Condor'' '''81''' (4): 338–347.</ref>
===Voice===
[[Image:Song of Thamnophilus doliatus.ogg|right|thumb|Song of the [[Barred Antshrike]].]]
The [[Bird vocalization|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 [[syrinx]]es than other songbirds. Nevertheless they are long, distinctive and species specific, allowing fieldworkers researching antbirds to identify many species without seeing them. <ref name ="HBW"/> Antbirds rely on their calls for communication, as is typical of birds in dimly lit forests.
==Distribution and habitat==
[[Image:Thamnophilus doliatus.jpg|thumb|The [[Barred Antshrike]] is distributed from Mexico to Argentina. It has the hooked bill typical of the antshrikes.]]
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 America|South]] and [[Central America]]n distribution of the family, others like the [[Ash-throated Antwren]] have a tiny distribution.<ref>[[BirdLife International]] (2007) [http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=4672&m=0 Species factsheet: ''Herpsilochmus parkeri''.] Downloaded from Birdlife International on [[3 April]] 2008</ref>
Antbirds are mostly birds of humid lowland [[rainforest]]s.<ref name = "HBW"/> Few species are found at higher elevations, with less than 10% of species having ranges above 2000 m (6500 ft)and almost none with ranges above 3000 m (10000 ft). 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-poor white-sand [[soil]] (the so-called Amazonian caatinga) in Brazil, Venezuela and Colombia.<ref name = "Zimmer">Zimmer, K (1999) [http://elibrary.unm.edu/sora/Wilson/v111n02/p0195-p0209.pdf "Behavior and vocalizations of the Caura and the Yapacana Antbirds" (PDF)] ''Wilson Bulletin'' '''111''' (2): 195–209</ref> Some species are predominantly associated with certain microhabitats within a greater ecosystem, for example the [[Bamboo Antshrike]] is predominantly found in bamboo patches.<ref>Pierpont, N. & J.W. Fitzpatrick (1983) [http://elibrary.unm.edu/sora/Auk/v100n03/p0645-p0652.pdf "Specific Status and Behavior of ''Cymbilaimus sanctaemariae'', the Bamboo Antshrike, from Southwestern Amazonia". (PDF)] ''Auk'' '''100''' (3): 645–652</ref>
==Behaviour==
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 (bird activity)|anting]], a behaviour where ants (or other arthropods) are rubbed on the feathers before being discarded or eaten.<ref name = "Willis">Willis, E. & Y. Oniki (1978). [http://www.google.co.nz/url?sa=t&ct=res&cd=2&url=http%3A%2F%2Flinks.jstor.org%2Fsici%3Fsici%3D0066-4162(1978)9%253C243%3ABAAA%253E2.0.CO%3B2-M&ei=2Yz1R8mWEIHEgwPrqs3ZBg&usg=AFQjCNHJl5QDV5cPLR8PbTIOQitio1X87A&sig2=aLaS5B5EnslJBOeKrbPkoQ "Birds and Army Ants"] ''Annual Review of Ecology and Systematics'' '''9''': 243–263 </ref> While this has conventionally been considered a way to remove and control feather [[parasite]]s, it has been suggested that for antbirds it may simply be a way to deal with the distasteful substances in prey items.<ref name = "HBW"/>
===Feeding===
[[Image:Thamnophilus caerulescens gleaning.jpg|thumb|left|A [[Variable Antshrike]] gleaning insects from foliage]]
The main component of the diet of all antbirds is [[arthropod]]s.<ref name = "HBW"/> These are mostly [[insect]]s, 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 [[frog]]s and [[lizard]]s as well, but generally these do not form an important part of the diet of this family.<ref>Lopes, L.E; Fernandes, A.M. & A.M. Marini (2005). "Predation on vertebrates by Neotropical passerine birds". ''Lundiana'' '''6''' (1): 57–66 </ref> In addition other food items may be eaten, including fruit, eggs and slugs.<ref name = "HBW"/>
[[Image:Dotted winged antwren (Drake Bay).jpg|thumb|The [[Black-hooded Antshrike]] is a relatively sluggish species usually found singly or in pairs. Here a male feeds on a caterpillar.<!--originally misidentified as a Dot-winged Antwren, hence the misleading file-name -->]]
A number of techniques are used by the family in order to obtain prey. The majority of antbirds are arboreal, with most of those feeding in the understory, 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 does not 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).<ref>Tostain, O. & J. Dujardin (1988) [http://elibrary.unm.edu/sora/Condor/files/issues/v090n01/p0236-p0239.pdf "Nesting of the Wing-Banded Antbird and the Thrush-like Antpitta in French Guiana".] ''Condor'' '''90''' (1): 236–239</ref> Of those that forage arboreally, an number of techniques and specialisations exist. Species may [[Gleaning (birds)|perch-glean]], perching on a branch watching for prey and snatching it by reaching forward, where others may [[Hawking (birds)|sally]] from a perch and snatch prey on the wing.<ref name = "Schulenberg"/> 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.<ref name = "HBW"/>
====Mixed-species feeding flocks====
Many species of antbirds participate in [[mixed-species feeding flock]]s,<ref name = "HBW"/> 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 [[conspecific]]s (members of the same species) and are found in almost all flocks, these are in turn joined by "attendant species". Loud and distinctive [[Bird vocalization|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; in Amazonia species of ''[[Thamnomanes]]'' antshrike are the leading "nuclear species",<ref name = "Munn"/> elsewhere other species, such as the [[Dot-winged Antwren]]s and [[Checker-throated Antwren]]s fill this role.<ref name = "HBW"/> Other species of antwren and antbird join them along with [[woodcreeper]]s, [[Habia (bird)|ant-tanagers]], [[Ovenbird (family)|foliage-gleaner]]s and [[greenlet]]s.<ref name = "Munn"/> 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.<ref name = "Thiollay">Thiollay, J (1999) [http://www.jstor.org/sici?sici=0908-8857(199909)30%3A3%3C282%3AFOMSFI%3E2.0.CO%3B2-C "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 </ref> In particular where ''Thamnomanes'' antshrikes lead the group they give loud warning calls in the presence of predators. These calls are understood and reacted 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 [[Beat#Hunting|beaters]], flushing prey while foraging which the antshrikes can obtain by sallying. Similar roles are filled by other species (in both the antbird [[family (biology)|family]] and outside it) in other flocks, for example the [[Lanio|shrike-tanager]]s.<ref name = "HBW"/> Within the feeding flocks [[Competition (biology)|competition]] is reduced by microniche partitioning; where Dot-winged Antwrens, Checker-throated Antwrens and [[White-flanked Antwren]]s 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.<ref>Wiley, R.H. (1971) [http://elibrary.unm.edu/sora/Auk/v088n04/p0881-p0892.pdf "Cooperative Roles in Mixed Flocks of Antwrens (Formicariidae)". (PDF)] ''Auk'' '''88''' (4): 881–892</ref>
====Ant-followers====
[[Image:Myrmeciza-immaculata-001.jpg|thumb|left|[[Immaculate Antbird]]s regularly attend army ant swarms in order to feed, but they are not an obligate ant-followers and also forage away from the swarms.]]
Swarms of [[army ant]]s are an important resource used by some species of antbird, and one from which the family's common name is derived. Many species of tropical [[ant]] form large raiding swarms, but the swarms are often [[nocturnal animal|nocturnal]] or raid underground. While birds visit these swarms when they occur, the species most commonly attended by birds is the [[Neotropical]] species ''[[Eciton burchellii]]'',<ref name = "Willis"/> 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 Antbird]]s found that they made attempts at prey every 111.8 seconds away from ants, but at swarms they made attempts every 32.3 seconds.<ref name = "Spotted">Willis, E.O. (1972) [http://elibrary.unm.edu/sora/om/om010.pdf "The Behavior of Spotted Antbirds." (PDF)] ''Ornithological Monographs'' '''10''' 103</ref> 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.<ref name = "HBW"/> 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.<ref>Swartz, M.B. (2001) "Bivouac Checking, a Novel Behavior Distinguishing Obligate from Opportunistic Species of Army-Ant-Following Birds". ''Condor'' '''103''' (3): 629–633</ref> These species tend to arrive at swarms first, and their [[bird vocalization|calls]] are used by other species in order to locate swarming ants.<ref name = "calls">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</ref>
Because army ants are unpredictable in their movements it is impracticable for obligate ant-followers to maintain a [[Territory (animal)|territory]] that always contains swarms to feed around.<ref name = "HBW"/> Antbirds have [[evolution|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.<ref name = "Willis"/>
===Breeding===
Antbirds are [[monogamy|monogamous]], in almost all cases forming long term [[pair bond]]s that last the life of the pair.<ref name = "HBW"/> In the [[White-plumed Antbird]] divorces between pairs are common, but this species is exceptional. In most species the pair defends a classic [[Territory (animal)|territory]], although the nesting territories or ant-followers are slightly different (see [[Antbird#Ant-followers|feeding]] above). Territories vary in size from as small as 0.5 ha for the [[Manu Antbird]], to being 1500 m (5000 ft) 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.<ref name = "HBW"/> 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.<ref name = "Spotted"/> Mutual grooming also plays a role in courtship in some species.<ref>Willis, E.O. & Y. Oniki (1972) [http://elibrary.unm.edu/sora/Condor/files/issues/v074n01/p0087-p0098.pdf "Ecology and Nesting Behavior of the Chestnut-Backed Antbird (''Myrmeciza exsul'')". (PDF)] ''Condor'' '''74''' (1): 87–98)</ref>
[[Image:Phaenostictus-mcleannani-001.jpg|thumb|left|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 whose nests have been located. Even in relatively well known species the breeding behaviour can be poorly known, for example the nest of the [[Ocellated Antbird]] was first described in 2004.<ref>Buehler, D.M.; Castillo, A.I.; & J.D. Brawn (2004) [http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1676%2F04-006 "First Nest Description for the Ocellated Antbird (''Phaenostictus mcleannani'')".] ''Wilson Bulletin'' '''116''' (3): 277–279 </ref> [[bird nest|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.<ref name = "HBW"/> 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 mounds of vegetation 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.<ref>Greeney, H.F. (2004). "Breeding behavior of the Bicolored Antvireo (''Dysithamnus occidentalis'')". ''Ornithologia Neotropical'' '''15''': 349–356 </ref>
Almost all antbirds lay two eggs.<ref name = "HBW"/> 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.<ref>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</ref> Both parents participate in [[avian incubation|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 [[thermoregulation|thermoregulate]], although as with incubation only the female broods at night.<ref name = "HBW"/> 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 [[fledge|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.
==Ecology==
Antbirds are common components of the avifauna of some parts of the Neotropics and are thought to be important in some [[ecology|ecological processes]]. They are preyed upon by [[bird of prey|birds of prey]], and their tendency to join flocks is thought to be a protection against such predation.<ref name = "Thiollay"/> 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.<ref>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</ref> Nests, including incubating adults, chicks and eggs, are vulnerable to predators, particularly [[snake]]s but also [[nocturnal animal|nocturnal mammals]].<ref name = "HBW"/> Nesting success is low for many species, particularly in areas of fragmented habitat.<ref name = "HBW"/><ref name = "Loiselle">Loiselle, B.A. & W.G. Hoppes (1983) [http://www.google.co.nz/url?sa=t&ct=res&cd=3&url=http%3A%2F%2Felibrary.unm.edu%2Fsora%2FCondor%2Ffiles%2Fissues%2Fv085n01%2Fp0093-p0095.pdf&ei=iRhTSOa4JJG6sAOY4eGMDw&usg=AFQjCNGo7rm8mm2a3c_Vxkj7fwRxttHniw&sig2=kap2WZ71Mr-PXzT3zgQzlQ "Nest Predation in Insular and Mainland Lowland Rainforest in Panama".] ''Condor'' '''85''' (1): 93–95</ref>
It was once suggested that the relationship between the obligate and regular ant-followers and the army ants, particularly ''Eciton burchellii'', was [[mutualism|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 [[parasite|parasitic]].<ref>Wrege, P.H.; Wikelski, M.; Mandel, J.T.; Rassweiler, T. & I.D. Couzin (2005) " Antbirds parasitize foraging army ants". ''Ecology'' '''86''' (3): 555–559</ref> 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 [[guano|droppings]].<ref>Ray, T. & C.C. Andrews (1980) "Antbutterflies: Butterflies That Follow Army Ants to Feed on Antbird Droppings" ''Science'' '''210''': 1147–1148</ref> Bird droppings are usually an unpredictable resource in a rainforest, but the regular behaviour of ant-followers makes the exploitation of this resource possible.
==Status and conservation==
[[Image:Pectoral Antwren.jpg|thumb|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]].<ref>[[IUCN]] (2007). [http://www.iucnredlist.org/search/search.php?freetext=Thamnophilidae&modifier=phrase&criteria=wholedb&terrestrial=1&taxa_species=1&redlistCategory%5B%5D=allex&country%5B%5D=all&cty_default=1&aquatic%5B%5D=all&aqu_default=1®ions%5B%5D=all®_default=1&habitats%5B%5D=all&threats%5B%5D=all&redlistAssessyear%5B%5D=all&growths%5B%5D=all 2007 IUCN Red List of Threatened Species: Thamnophilidae]. Downloaded on [[23 April]] 2008.</ref> 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]].<ref name = "HBW"/> 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.<ref>Stouffer, P.C & R.O. Bierregaard, Jr. (1995) "Use of Amazonian Forest Fragments by Understory Insectivorous Birds". ''Ecology'' '''76''' (8): 2429–2445</ref> Another risk faced by antbirds in fragmented habitat is increased [[bird nest|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.<ref>Sieving, K. (1992) "Nest Predation and Differential Insular Extinction among Selected Forest Birds of Central Panama". ''Ecology'' '''73''' (6): 2310–2328</ref> 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.<ref name = "HBW"/> 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]].<ref>[[BirdLife International]] (2007) [http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=4755&m=0 Species factsheet: ''Pithys castaneus''.] Downloaded from Birdlife International on [[26 April]] 2008</ref> The [[Rio de Janeiro Antwren]] is similarly mysterious; after its discovery in 1982 there have only been unconfirmed reports<ref>[[BirdLife International]] (2007) [http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=4658&m=0 Species factsheet: ''Myrmotherula fluminensis''.] Downloaded from Birdlife International on [[26 April]] 2008</ref> and it is currently listed as [[critically endangered]].
==References==
{{reflist|2}}
==External links==
{{commonscat|Thamnophilidae}}
*Internet Bird Collection: [http://ibc.hbw.com/ibc/phtml/familia.phtml?idFamilia=108 Antbird videos]
* Xeno-Canto.org: [http://www.xeno-canto.org/browse.php?query=thamnophilidae Antbird sounds]
[[Category:Higher-level bird taxa restricted to the Neotropics]]
[[Category:Thamnophilidae|*]]
[[de:Ameisenvögel]]
[[es:Thamnophilidae]]
[[eo:Tamnofiledoj]]
[[fr:Thamnophilidae]]
[[lt:Tikrieji skruzdlesiniai]]
[[hu:Hangyászmadárfélék]]
[[ja:アリドリ科 (Sibley)]]
[[pt:Thamnophilidae]]
[[fi:Puumuurat]]