Revta bras. Zool., S Paulo 2(7): 433-442 28.vi.1985
MYRMECIZA AND RELATED ANTB1RDS (AVES, FORMICARJIDAE) AS ARMY ANT FOLLOWERS
EDWIN O. WILLlS
ABSTRAcr
Antbirds of the genera Myrmeciza (including Sipia and Myrmoborus), Gym-nocichla, and Sclateria hop near or on the ground in fairly dense vegetation, "pounding" their tails downward. Where dense understory vegetation is wide-spread and ants move in it for long distances, certain of these antbirds become regular ant followers: M. immaculata and M. fortis in cluttered moist foothill forest from Costa Rica to upper Amazonia; Gymnocichla nudiceps in moist cluttered second growth of Central America to Colombia. Where the forest understory is more open, Myrmeciza species follow ants mainly in cluttered patches: M. exsul in lowland forest west of the Andes, M. myotherina east
01
the Andes. Myrmeciza or relatives that specialize on water-edge or very dense zones rarely follow ants.Antbirds of the genera Myrmeciza, Percnostola, and Pyriglena sometimes folIow army ants for fIushed arthropods in neotropical forest (Willis & Oniki, 1972, 1978; Willis, 1981). Here, in the twenty-second report of a series on birds seen with ants, I present additional information on antbirds of the genus Myr-meciza (in which I include Sipia and Myrmoborus), Gymnocichla, and Sclateria.
RESULTS
. 1. Myrmeciza hemimelaena (Chestnut-tailed Antbird), seeminglv a relative of Formicivora antbirds of the preceding report of this series (Willis, 1985), briefIy folIowed Eciton burchelli raids at Cashibococha, Loreto, Peru (2 raids with 2 birds, 3 with 1) and at Palhão, Pará, Brazil (1 raid, 1 bird). The tail is twitched from side to side as tre wings flit outward, just as in Formicivora. M. hemimelaena, like most Formicivora, is a smaIl antbird that darts quickly from one low shrub or sprout to another in relatively dense parts of dry or scrubby forest. It hops on the ground and through dense treefalIs; ones ove r ants pecked prey from a low leaf (1) or hopped up to snap prey oH a leaf (1) at 0.2 m above the ground. The hemimelaena ordinarily wandered past raids or around them without stopping, but once a pair at Cashibococha wandered near an ant raid for 30 mino The usual caIl at humans is a buzzy "chirr", chrrrrt, or a "chipping" dit-it, while the descending and accelerating "song" is a hee, hee, hew - hew - hew - hew or siimlar series.
2. Myrmeciza fortis (Sooty Antbird) regularIy foIlows ants in humid upland or fIoodplain forest just east of the Andes, although it occasionaIly wanders low through dense undergrowth away from ants: it was found at 79 raids east to Brazil (3 Benjamin Constant, 4 Carauari), north to Colombia (12 Umbria, 3 Leticia), west to the Andes of Ecuador (lO Limoncocha, 4 Zatzayacu 770 m, 19 Yaapi, 11 Putuimi), and south to Peru 9 Andoas, 4 San Alejandro). AlI raids were of Eciton burchelli except for Labidus praedator raids with single birds at Zatzayacu, Putuimi, and San Alejandro and with 2 birds at Yaapi. At burchelli raids, there were 10 records of 4 birds (3 Umbria, 2 Yaapi, 2 Ca-rauari, and 1 each Benjamin Constant, Putuimi, and Andoas), 13 of 3 (3 Umbria, 2 Leticia, 5 Yaapi, and 1 each Limoncocha, Putuimi, and Andoas), and 12 of 1 (4 Limoncocha, 3 San Alejandro, 2 Yaapi, and 1 each Leticia, Putuimi, and Andoas). ln many cases the fortis folIowed ants for hours (490 min at
Ca-Department of Biology, University of Miami, Coral Gables. Florida 33124, U.S.A .. and Departamento de Zoologia, Universidade Estadual Paulista "Júlio de Mesquita Filho' -UNESP, Caixa Postal 178, 13500 - Rio Claro, S. Paulo.
rauari), although individuaIs were often hidden in the dense undergrowth that the species favors. Like other regular ant followers, it visits even inactive ant bivouacs repeatedly until the ants start raiding.
ln alarm, M. fortis "pounds" the tail downward and lets it rise slowly, as is typical of birds of this genus. Tame birds rarely pound the ta i!. The species is likely to ruff the crown up, show the bare blue face toward an intruder, and "rattle" di·i·j-i-i - i -ih loudly. It quickly hops behind cover, and is diWcult to study before it becomes tame. Young birds quickly become tame, but adults tend to be secretive, even after one has watched them several hours. One was seen to crouch at the alarm caIl of a treetop wren (Campylorhynchus turdinus) and one fortis gave a cheer "keening" alarm note. M. fortis over 2 m up in vegetation occasionaIly dive for cover near the ground, giving alarm notes; once this behavior was caused by an alarm flight of parrots (Pionites melanocephala) in the canopy.
ln various regions, M. fortis near ants hopped or waited on the ground (19 records) or near it (16-40·25-26-17-11-9-5-6-4 records from O - 1.0 m, by 0.1 m intervals, plus 22-6-6-2-0-1 records from 1 to 7 m, by 1-m intervals), often on perches near the horizontal (34 - 7 - 3 - 6 - 14 records by 20° intervals, O to 100° above horizontal). Excluding ground perches and logs to 50 cm diameter, perch d;ameters ranged from 0-7 cm (10-13-6-9-1-1-1 records, by l-cm intervals). Often the bird hops on the ground between two perches rather than f1y from one to the next, bounding 15 cm at each jump. It sometimes hops under dark logs or into dense treefaIls. The tail is sometimes angled up, some-times down, as fortis hops about. At some-times one moves to 2 m up in moving to a new site, but more often it hops near or on the ground. The very large legs seem weIl adapted for constant hopping.
Most forag;ng records were short (16 records under 0.5 m, 3 more to 0.6 m) or bounding saIlies to the ground (95), with pecks at ground prey (13) or tossing leaves on the ground (5) also frequent. Gleaning (6 liana or stern, 2 trunk, 2 leaf) was otherwise more common than short saIlies (2 Hana, 2 leaf, 1 trunk). Prey items included 2 ant larvae, a roach, a grasshopper, and a walk-ing stick.
M. lortis work at or near the center of .ant swarms much of the time, in direct competition with several other species of antfollowing birds. The lortis outweigh many other foIlowing birds. The lortis outweigh many other ant-foIlowers; 13 individuas from Hac;enda Flor, Rio Pachitea, Peru (Bonn Mu-seum) averaged 52.4 g, not counting a young female that weighed 45.5 g. A large ground-cuckoo (Neomorphus geolfroyi) once displaced a lortis at Putu;mi, while the large antbird Phlegopsis erythroptera normaIly supplants lortis (4 records of supplantings, 3 of displacings) but once was supplanted by it. Many other ant-foIlowing birds are smaIler than fortis, and it is very aggressive to them-attacking with its crest raised and a "snap" of the bill. At various places Pithys albifrons was supplanted 25 times and displaced 2 times; Gymnopithys leucaspis was supplanted 32 times, displaced once, and returned after fortis departed once; G. lunulata was supplanted 9 times, displaced 4 times; G. sal-vini was supplanted 5 times, displaced tw;ce; Hylophylax poecilinota was planted 5 times; Myrmeciza myotherina and Thamnomanes ardesiacus were sup-planted once each. Woodcreepers less often attracted the ire of fortis, but Dendrocincla fuliginosa was supplanted twice and displaced once, while D. merula was supplanted once.
ln the sarne sets of observations, I recorded 67 supplant;ngs of lortis by other fortis, for this species is very aggressive intraspecificaIly. Disputes are noisy affairs, often beginning with loud "songs", peer peer peer peer peer peer peer or similar sedes, which increase in volume and pitch but not in speed. Loud PEEFT or kweek "chips" then introduce a babel of noises, notably varia-bly loud and harsh CHWAINGH "snarls" from upright poses with white corners of the wings f1icking out and with blue faces expanded by ruffing the crests upward. The head and neck, except for the crest, are extended and sleeked. The tail may pound vigorously downward, as in alarm. The b;rd may turn its head one way and then the other, showing the Iarge facial areas as
large "eyespots". The body and tai! are ohen spread, as are the corners of the wings, and the bird may f1utter as slowly and conspicuously as a butterfly from one perch to another, its body still at a 45° angle or more with the horizontal and the spread tai! as much as 70° below horizontal. Occasional rattles punctua-te "snapp'ng" of the beak and "hissing" (angh) noises in supplantings. Yet another call from aggressive birds is a short musical "warble", che-iwoyl or lewoo, sometimes repeated several times at successively higher anel lower pitches and mixed with "grunting" piluk, wip, or wip-wip-wip notes_ "Grl1ttling" Irrrrrrrrr rattles are also given.
A subordinate bird f1ees with "wh:mperirig" series of 1-6 eep notes, crou-ches, e10ses its tail and crest, retracts its neck, and e10ses its pallid blue facial areas. The subordinate often gapes, f1ashing the yellow mouth Iining_
ln disputes, females usually chase females and males other males; and males are more persistent at chasing other males around than are female~, which often return to foraging. However, I saw one male supplant a female twice. If more than one pair are present, the extra birds usually forage at tar ends of the swarm and are repeatedll' attacked by the pair or by a seemingly territorial male.
Paired males and females sometimes perch as little as 1 cm apart, although they usual1y wander separately. The pai r exchange either faint grunts and warbles or less aggressive cheu "chirping" notes as they pass each other. At t;mes a bird alternates chirping and faint songs as an up-and-down "serpentine song". One male froze and raised his head and cresto as if for mutual grooming, when the female alighted beside h:m (Willis & Oniki, 1972, record mutual grooming for Myrmeciza exsul). At times the mal e chirps with food, and the female bounds over to him to get the food as he ruffs out h:s crest, standing somewhat upright and showing a bright blue face. Faint cha-a-a-a-a-a-a-a-ah
"murmuring" series come from the female as she takes the food. One male
(Limoncocha, 6 Nov 1965) hopped on the back of the female, but she slipped out and returned to take food from him. ln one case (Carauari, 19 Mar 1966), both birds crouched, and the female had her crest up. The female usually í1ies off with the food, and the male lowers his crest and body as he champs the beak or wipes it on a perch. When the food-carrying male cannot locate the female, he may wander with chirps, warbles, faint songs, or even loud songs. An answering female may give a short song, or more often warbles and chirps as she f1ies to the male. Feedings were recorded at Zatzayacu (23 Oct 1965), Yaapi (19 Nov 1965) and Putuimi (27 Nov 1965) in addition to the above records.
Nearly grown young with dusky faces, in molt to the adult male or female plumages, "peeped" chree notes every 2-3 sec and followed adults, then "squea·· ked" chiahh noises and gaped their yellow mouth linings as they crouc~1ed, b:)oy feathers f1uffed, and were fed: Umbria 21-23 May 1962; Andoas 25-26 May 1979. The single young at Umbria was fed only by a female, and ignored by the nearby male. Slightly older young, in very heavy molt, seemed independent and were harassed by aggressive adults at Umbria, 25-31 May 1962, and at Benjamin Constant 16 Apr 1966.
Molting immature males at about this stage in various museums include ones from Andoas (lO Oct 1937, Paris 38/750), the Rio Conambo (Ecuador, 1 June 1955, Bonn 72427) and Rio Pucayacu (Ecuador, 25 July 1960, Bonn 72428), Hacienda Flor (Rio Pachitea, Peru, 25 Feb, 16 and 26 March 1960, and 26 June 1961, Bonn 62812, 13, 14, and 15; also 13 Aug 1959, Chicago 256664), Pebas (Peru, 2 April 1967, Tring), Tutinum (Rio Cenepa, Peru, 6 Aug 1964, Louisiana State Univers:ty 34225), Boca Rio Curaray (Ecuador, 21 Nov 1925, Am. Museum Natural History 255959), Rio Cen;pa (22 Sep 1929, AMNH 407122), Chuchu nas (Peru, July 1904, AMNH 491459), Rio Suno abajo (Ecuador, 7 Mar 1924, AMNH 184479), Apayacu (Peru, 26 and 27 Jan 1927, p.MNH 231822 and 23), Sarayacu (Ucayali, Peru, 1 Apr 1927, AMNH 23R21'i), and, in Brazil: Jaburu (Rio Purus, 1 Oct 1935, Stockholm), Rio Juruá (Oct 1902, Museu Paulista 3644), Caviana (30 May 1924, Carnegie Museum 99352), São Paulo de Olivença (19 Feb 1923, Carnegie 95536, 1 Mar 1923, Carnegie 95627, and 16
Apr 1923, Carnegie 96464), Tonantins (9 June 1973, Carnegie 96581), Arimã (5 and 17 Oct 1922, Carnegie 93490 and 93754), Nova Olinda (26 July 1922, Carnegie 92189), Tefé (31 July 1928, AMNH 309229); One even younger male is in f1uffy brown juvenal plumage, with blackish across the chest, face, and forehead (São Paulo de Olivença, 26 Mar 1923, Carnegie 96068), Severa I other birds, most\y in the American Museum of Natural History and collected by the Olallas, are in female plumage but are marked males; some of these have black on the chest and crown and may be juveni!e males. However, some are in molt from one female plumage to another and must be females that were mis· takenly labeled .as male. Several specimens in museums are probably young females in molt to the first-year plumage, as they have some dark feathers of the juvenal plumage on the chest.
The records suggest a long nesting season, perhaps ali year: young males Feb to Aug at Hacienda Flor, Peru, peaks Feb-July and Oct in southwestern Brazil. The large number of young males collected (29 of male 203 specimens examined) suggests a long period of molt to the adult plumage for them, perhaps as long as the 5-6 months recorded for Pithys albifrons. Apparent\y, as in rela-ted pyriglena species, the plumage of the first-year male is duller than that of the adult; several male specimens in molt show a transition from a dull to a dark black plumage.
Museum specimens in molt come from ali seasons of the year, with no evidence of seasonnality. ln other maintenance aspects, fortis is like many other antbirds: it shakes its head at mosquitoes, and wipes the side of its head on a perch at times.
3. Myrmeciza immaculata (Immaculate Antbird), which replaces the cio-sely related M. fortis as a regular ant follower in foothill wet forests from the Andes (Hi!ty, 1974; Gochfeld & Tudor, 1978) to Costa Rica (Slud, 1964), attended 7 Eciton burchelli and 1 Labidus praedator raids at EI Tigre, Chocó, and 1 burchelli raid at Tucurá, Córdoba, Colombia. Pairs were at 4 of the burchelli raids at EI Tigre, single birds at other raids. M. immaculata hops lo\\" in dense sprouts and herbs or across the ground, pounding its tai! downward and giving di-i-i-i-i-i-i "rattles" or teef "chips" like those of fortis. The "song" is a series of 5-10 peef notes at 4 notes/sec, as in fortis. Over ants, immaculata sallied to the ground (4) or pecked prey from the ground (1). Most perches were low (33-2:1 records from 0-3 m, by l-m intervals), horizontal (8 records to 20° above horizontal), and slender (2 records to 1 cm, 4 more to 2 cm diame-ter), but more study would probably show it to behave like fortis in nearly ali respects. M. immaculata supplanted Gymnopithys bicolor 2 times and displaced one once; it was supplanted once and displaced once by Phaenostictus mcIean-nani; and Pittasoma rufipifeatum supplanted immaculata once. Specimens from western Ecuador in the University of Miami Museum weighed 47.0 and 46.3 g for rnales and 38.2 g for a female, less than for" fortis.
Many (418) specimens were examined in museums, but few young were located. Fledglings are blackish, judging by a shorHailed young mal e from Santa Cruz de Turrialba, Costa Rica, 4 Oct 1922 (Chicago Museum 73562). Young females molt to a brown plumage, without wing molt (Chimbo, Ecuador, 3 Aug 1922, Am. Mus. Nat. Hist. 173296; Hacienda Santana, Colombia, 4 Oct 1949, U. S. Nat. Museum 411507; Cana, Panama, 30 July 1928, Museum of Comparative Zoology 140667).
Young male immaculata apparent\y molt to a brown female plumage and later to a dull black one. Wing molt occurs with the latter molt (Vienna Mu-seum 3672, Lita, Ecuador, 3 Oct 1899) but apparent\y not with the forme r one. Unfortunately, for most young males I did not note whether black feathers were new or old (Carrillo, Costa Rica, 26 Apr 1924, AMNH 390333; La Gu~ya cana, Colombia, May 1944, 18 and 26 Apr 1958 and 28 Aug 1959, specimens Philadelphia 157338, Los Angeles 31274 and 31277, and Louisiana State Uni-versity 38696, respectively; Gualea, Ecuador, 7 June 1913, AMNH 124421; Paramba, Ecuador, 14 July 1899, Chicago 57192). Apparent\y the dull black plumage that follows the brown pI um age is later replaced by the dark black
plumage of the adult male, perhaps 2 years after fledging (USNM 402396, Valdivia, Colombia, 25 May 1948, shows molt from dull to dark black). Male M. immacula/a apparently differ from mal e for/is in assum:ng a female plumage after the juvenal plumage. However, it is possible that some of the specimens of young immacula/a (including a few birds in female plumage that are mar-ked "male") were sexed incorrectly, even if the Vienna specimen indicates that some males must pass through a brown plumage. Related Pyriglena species, in which juvenal males and females have different plumages, have a dull black firts-year male plumage; but in related Percnostola rufifrons, young males do indeed assume a female plumage for the first 6 mo. after independence.
Molt in Costa Rican adult immacula/a is recorded from late A.ugust to early February, and a plot of primary molt against month (not shown) indicates that molt should start in August and end in January for the median individuaIs, hence take 5 months. Southward, molt is recorded nearly every month of the year in western Colombia and Ecuador. Probably nesting precedes or overlaps with molt, indicating breeding in the northern summer and fali northward and throughout the year southward.
4. Myrmeciza melanoceps (White-shouldered Antbird) single individuais
followed Eciton burchelli raids at Tres Esquinas, Colombia (2 males) and at
Cashibococha (1 female) and Andoas Viejo (1 female), Peru, mainly in dense
second growth. Novaes (1958) also records it following ants. The species
nor-mally wanders low in bushy pastures and dense second growth near rivers and ignores ants. The black male looks like the male M. for/is, but the bare blue facial area is small and restricted to a spot in front of the eye. Usually the black-headed rufous females (black bare area by the eye) wander separately from the males, which "sing" a characteristic deliberate (2 notes/sec) si/ sit PEEYER PEEYER PEEYER PEEYER repeatedly. ln alarm, the tail is
"poun-ded" downward. Females (at Umbria, Colombia) gave loud choorp and wooraih
calls, also a rapid series of cher notes. Over ants melanoceps perched 0-2 m up, flying rapidly from one perch to another but waiting long periods on each perch. Foraging tries were short sallies (ground 2, liana 1) or pecks (ground 1, liana 2). Scratching the head over the wing was noted.
5. Myrmeciza longipes (White-bellied Antbird), which replaces melano-ceps northward, attended Labidus praeda/or swarms in central Panama (Buena-vista Point, 4 birds at 3 swarms; Madden Forest Reserve, 4 birds at 3 swarms) and Eci/on burchelli swarms in Trinidad (9 raids, including one with 3 birds and three with I, at Simla; 1 raid with 1 bird at Bush-bush Island, Nariva Swamp) and Guyana (3 raids with 2 birds and 1 with 3, Nappi Creek; see Oniki & WiIFs, 1972). On Buenavista Point and Trinidad they occur well back in second-growth woodlands, but in regions with more species of antbirds they usually occur only at the edges of dense second growth or bushy pastures. Unlike melanoceps, longipes mostly hops on low perches or the ground, except at Nappi where it worked 2-4 m up on limbs of saplings as if forced upward by the numerous competing antbirds. The long legs of the species are adapted for hopping on horizontal perches or the ground; I never saw it cling to vertical perches, which are common only in tall moist forest where it sei dom
ventures. It acts very much like a thrush (Turdus, Hylocichla, or Alethe
spe-cies), waiting long periods between hops. ln Trinidad, it pecked prey on the
ground (15) or debris (2), sallied to the ground (1), or leaped to catch a
flying prey (1). ln the Forest Reserve, it once supplanted a similarly foraging but forest-interior migrant warbler (Oporornis formosus), and one on Trinidad displaced a spinetail (Synallaxis cinnamomea) creeping over low logs. Forest-interior Bicolored Antbirds (Gymnopi/hys bicolor) twice supplanted longipes in the Forest Reserve. Male and female longipes exchange faint cheu "chirps" or cho/ "grunts" when together (the latter is even given when alone) and occasional loud descending "songs" (that of the female often shorf, 10-15 notes) when apart. One singing mal e looked about as he sang, and merely extended his neck upward and opened his beak slightly rather than perform a special display. ln Trinidad, one male sang a clear peer peer peer peer as well as the descending song. ln alarm, the tail is pounded downward and the wings flit
outward slightly; the bird is likely to give a di-i-i-i-i-it "rallle" or a chirr and hop behind cover or into a nearby treefall.
6. Myrmeciza laemosticta (Dull-mantled Antbird), which locally replaces
M. exsul (Willis & Oniki, 1972) low in wet ravines in foothill forests west
of the Andes, followed an Eciton burchelli raid once at Remedios, Antioquia, Colombia 2 May 1962. II gave chiii "chirrs·' as it hopped through low shrubs, 0.2-1.5 m up, peering much like an exsul and pounding its tail like it. Hilty (1974) and Wetmore (1972) also record it following ants, but it usually forages away from ants. Apparently it is replaced ai ong creeks east of the Andes by
Schistocichla leucostigma, which also follows ants inf requently. Other calls of
laemosticta inelude a catlike meow, a scat or scat-at "chipping", and a wheezy
whistled "song" heer, hee, zeeoop-zoop-zee (Serrania de Abibe, NW Colombia). When a female sings, the throat puffs out so the white barring is conspicuous. At 800 m on a forested steep slope above a gorge of the Cano Remolina on the Serrania, I flushed one off 2 white eggs (spolled brown at the large end) in a tnin cup low in a Piper shrub, 26 March 1965.
7. Myrmeciza exsul (Chestnut-backed Antbird) follow ants fairly often on
Barro Colorado Island, Panama, but normally forages away from ants (Will"s & Oniki, 1972). Pairs were also at 4 Eciton burchelli raids at Golfito, Costa Rica, at 4 at El Tigre, Colombia, at I at Tucurá, and a single bird at 1 at Remedios, Colombia. On the Serrania de Adibe, Córdoba, pairs were at a
burchelli raid and a Labidus praedator raid. ln central Panama, 8 Eciton
burchelli raids were attended: 2 and I birds at the Pina Road, I, 4, I, and 1
on the Bohio Peninsula, I on the Agua Salud River, and 2 at the nearby Limbo Hunt Club. Hilty (1974) recorded it with ants in Colombia.
On Barro Colorado, between 1960 and 1981, 321 raids of burchel/i were attended (153-139-24-5 records of I, 2, 3, and 4 birds) and 45 of praedator (26-18-0-1). Comparing July-August for each of the 10 years, 1961-1970, there were these records: 8-4 (July only)-12-25-24-38-29-15-4-21 raids. The increase from 1963 to 1967 is attributed to extensive treefalls 1 Oct 1961, creating new habitat: a decrease in 1968 and 1969 is perhaps due to unusually dry weather in 1968. January-February records in 1965 were only 15, compared to 15 records in 1971 (1 month only), 49 records in 1977, and 37 in 1981, suggesting a permanent increase in ant following after the mid-1960's. This increase may have been due to local extirpation of aggressive ant-following
Phaenostictus mcleannani after the unusual drought of 1968 (Willis, 1974).
M. exsul is replaced ecologically by Myrmeciza myotherina east Df the Andes.
8. Myrmeciza berlepschi (Stub-tailed Antbird), formerly placed elose to
long-tailed Cercomacra in the genus Sipia, is not especially stub-tailed when compared to its stub-tai!ed true relatives in the genus Myrmeciza. A dark-eyed male that followed ants in second growth at El Tigre, Chocó, Colombia 5 Mar 1962 pounded the tai! downward, hopped in dense vegetation near the ground, and gave a cha-a-a-a-a-a-at "rattle" of alarmo Pairs hopping low on the ground in dense tangles away from ants gave peep "chi ps" of alarm as well, and general1y behaved like M. laemosticta or M. exsul.
9. Myrmeciza myotherina (Black-faced Antbirds), formerly placed in the
barely separable genus Myrmoborus, followed 99 Amazonian raids north to Colombia (Mitú, 4 with 1 bird and 6 with 2; Tres Esquinas, 1 with I; Umbria, 3 with 1 and 2 with 2; Leticia, 1 with 1 and 1 with 2), west to eastern Ecuador (Limoncocha, 3 with 1 and 1 with 3; Zatzayacu 700 m, 3 with 2; Yaapi, 6 with 1 and 7 with 2; Putuimi, 1 with 1 and 7 with 2), south to Peru (Andoas, 5 with 1 and 1 with 2; San Alejandro, 2 with I and 1 with 2; Cashibococha, 2 with 1 and 2 with 2), and east to the Negro and Xingu Rivers in Brazil (Benjamin Constant, 1 with 1 and 1 with 3; Carauari, 2 with 2; Manacapuru, 1 with 2; Serra dos Pareeis, 1 with 1 and 3 with 2; Borba, 2 with 1; Coatá, 2 with 2; Nova Olinda do Norte, 1 with I; Itaituba, 1 with 1 and 1 with 2; Maloquinha, 6 with I, 8 with 2, 2 with 3, and 1 with 4; Itapucurá, 1 with 2; Diamantina, 2 with 1; Palhão, 2 with 1 and 2 with 2). While it circles persistently around ant raids for up to 4 hours
(Cashiboco-cha), it readily deserls anIs and is oflen seen away from them. At limes one follows a line Df ants lo a distant raid, just like a regular ant follower. Most
birds followed Ecilon burchelli; but an Umbria raid with 2 birds and a
Limoncocha raid with I bird were of Eciton rapax, while s'ngle birds were at Labidus praedator rajds at Tres Esquinas, Andoas, San Alejandro, and Diamantina; 2 birds were at Itapucurá praedator.
OveI' ants in various regions, myotherina hops Dr f1ies low (66·3-4 records from 0·3 m, including 7 records on lhe ground) on mostly horizontal
(10·1-1-1-2 records from O-100° above horizontal, by 20° intervals) slender or thick perches (diameters of 0.2 -7 cm recorded). Most prey comes from the ground (sallies 01' hopping sallies, 19; pecks,4; leaf tossing, 2), some from low foliage (peck at twig, stern, and liana, plus short sally at a leaf, 1 each). A mal c at Yaapi pecked and pried off a huge caterpillar (twice his tarsal length) that had been abandoned by a Cercomacra nil!,rescens, carr'ed the caterpillar nearby, shook and crushed it in the bill, swaUowed it whole, and then sat (crest raised and body fluffed) on one foot for several minutes. M. myotherina usually wanders around the far margins of ant raids, as it is subordinate to many species of ant-following birds that crowd near the centers of raids. Gymnopi-thys leucaspis supplanted myotherina at Umbria and Zatzayacu, G. lunulata
at Cashibococha, Myrmeciza fortis at Zatzayacu, and Formicarius analis
dis-placed it aI Diamantina. M. mvotherina disdis-placed Myrmotherula hauxwelli aI Coa tá. M. myotherina was difficult to see at a raid, for it hopped mostly in dense treefalls and dense patches of seedlings, flying 1 m at a time between dense zones, but loud alarm "chipping" pseef, "booing" rneeyou, or "rattling" de-e-e-e-e-ee notes often marked its progresso One bird at Umbr'a chipped as grisons (Galictis sp.) ran past. Alarmed birds pound their short tails down-ward, flit Iheir wings, and crouch or dart behind cover, unless they hop upwud and rattle at the observer.
"Songs" are rapid downscale series of bzeep notes, usually 10-15 notes per song, and pairs occasionaUy sing back and forth. At cIose range, pa'rs "chirp" peep or teup to each other. A male with food at Putuimi. 26 Nov 1965, extended varied series of chirps with faint songs as a "serpentine·song", the female answered with isolated chirps and faint songs, and she gave a fa'nt che-e-e·e-a-a-a-a-a-a "murmuring" as he chirped and fed her. One mal e at San Alejandro, 19 Dec 1965, gave wrieeh "snarls" unt;l the female answer-ed; sounds from the undergrowth suggested a feeding. 11 Apr 1966 at Coa tá and 1
J
une 1979 at Andoas, the female crouched but extended her neck for a feeding, while the male stood rather upright over heI'. One female at Yaapi sat and champed her beak as her mate worked; she shook heI' head atmos-quitoes and dropped a spider from a nearby web when she wiped it oH on
lhe perch after it stuck to her bill.
Noisy disputes occur whenever two pairs vis't the sarne swarm of anIs.
Loud songs, snarls and chipping move through the understory, and
puffed-bodied birds with white back patches pound their spread tails slowly. Their heads and necks are sleeked, 50 that the black face and throat of the male seem to cover his entire neck. The wings are out and quiver along the'r
edges, showing white corners and wing bars iry the male. The bird jerks
upright now and then. One defeated male sang occasionaJIy as he drifted
away, but his head and neck were fluffed and his fluffed belly feathers were over the edges of his wings, while h;s tail was cIosed. The dominant male had sleeked his body as he returned to foraging, but kept his tail spread for some time.
10. Myrmeciza leucophrys (White·browed Antbird) followed 9 Ecitor, burchelli raids at Nappi Creek, Guyana (Oniki & Willis, 1972) and 2 (with 2 birds each) at Maloquinha, Brazil. It usuaUy wanders low away from anIs in dense second growth, but follows the infrequent swarms in its habitat for
long periods (253 min at Maloquinha). Prey captures over ants were mostly
sallies (6) or pecks (3) at the ground, less often pecks (2) or a sally (I) at leaves or a peck at a limb (1). Perches were much like those taken by rnyo-therina, which attended the sarne ant raids at Maloquinha but tended to stay
back in the forest rather than in roadside second growth. M. leucophrys hops
rapidly, mouselike, aI ong the ground or across a road, but in other respects
forages Iike myotherina. M. leucophrys pounds the tail downward rapidly when alarmed, and gives pseef "chips", feeyou "boing", or di-i-i-i-i-i-i-it
"rat-tles". The song is a very rapid descending trill or buzz of 15 to 25 notes,
that of the female generally being shorter; one singing female quivered her
wings as she sang.
11. Gymnocichla nudiceps (Bare-crowned Antbird), probably a
Myrme-ciza or a Percnostola related to slender P. rufifrons east of the Andes
(Perc-nostola is itself a minor side branch of Myrmeciza) , followed Eciton burchelli
swarms at Tucurá (2 raids, 2 pairs), San Pedro (1 raid, 1 pair), and on the
Rio Verde dei Sinú (2 raids, 3 birds), ali in Córdoba, Colombia. It is
proba-bly a regular ant follower, as Slud (1964) records it following ants in Costa
Rica. It is agile at hopping or f1ying from one perch .to another in the dense
second growth it favors, although it clings close and somewhat clumsily to
vertical perches. Unlike ant-following antbirds of the Gymnopithys group,
nudiceps seldom waits for ants to flush prey, but like related Myrmeciza
hops constantly, looking and pecking prey from the ground (I record) or
Eana (1), and sallying to the ground (6), or to a trunk (1). It occasionally
wanders to 3 m up, but usually stays near the ground. It pounds the tail
downward if alarmed, giving a di-i-i-i-i-i-i "rattle" or a wheesp "chip" much like those of related Percnostola and Myrmeciza. Phaenostictus mcleannani supplanted nudiceps twice on the Rio Verde and displaced it twice at
Tu-curá, while Dendrocincla fuliginosa supplanted it once but was supplanted
once at San Pedro. Seven adult specimes weighed 28.1-37.6 g (x = 31.9),
except for one female with large ovary that weighed 45.2 g; the species
we'ghs less than either mcleannani or fuliginosa. One male nudiceps
supplan-ted a female at Rio Verde, even though ali pairs at swarms seemed mated
birds. ln the early morning at San Pedro, pairs wandered along the bushy
edges of second-growth and fields "singing" chief chief chief chief
cheif-cheif-cheif, faster toward the end.
Examination of 390 specimens in museums indicates that juveniles of
both sexes are blackish, with brownish edges of wing and tail feathers. The
young female (20.0 g, EI Encanto, Costa Rica, 26 May 1951, Univ. Michigan 132690) soon molts to a brown plumage, without wing or tail molt (Rio
Si-xaola, Costa Rica, 12 Oct 1904, Carneg'e Museum 24189; Boruca, Costa Rica,
5 June 1906, Museum of Comparative Zoology 119009). The juvenile male
lacks white on wing and back (La lberia, Costa Rica, 30 July 1926, Yale
Museum 56650; EI Recreo, Nicaragua, 12 July 1954, Univ. Calif. Los Angeles,
Howell Collection 956). He soon undergoes body molt to a dull black plu-mage, in which much of the crown is still covered with black feathers, but dull white wing bars and shoulders are present. Most first-year males start body and wing molt to the adult plumage early in May of the year after f1edging, at least in Costa Rica; but one Colombian young male (Hacienda Santana, USNM 411908) was in wing molt 24 Sep 1949, hence at the time
of molt of adults.
Based on a graph of wing molt in specimens (not shown), adults from
Nicaragua to Colombia generally molt from June to December, and complete
wing molt takes about 180 days. Some Panama specimens (mostly birds
sup-posedly collected by J. H. Batty from some coastal islands) were ending wing
molt in "February", and one Honduras specimen 'was in early wing molt in
November, so some populations ar individuais may molt later than the
ma-jority of adults; but mislabeling of specimens may have occurred in some
cases. Breeding and molt evidently start early in the year for the most part.
12. Selateria naevia (Silvered Antbird) individuais twice followed Eciton burchelli very br'efly at Belém. Oniki (1972) recorded one briefly following
ants there. They hopped on low roots and .debris in forest pools, pecking
prey from the ground once and from the water once, and seemed uninterested
in the ants and ant-following birds. ln most regions, naevia hops over water
cannot reach. A bob-tailed black young bird was noted at Belém, 11 May 1973. The "song" of naevia is a rapid series of 20 or so short pee notes, increasing in volume toward the end. Foraging birds "grunt" a faint beak or /ik frequently as they move, as in the genus Pyriglena. The alarm calls are a "rattling" de-e-e-e-e-e-ee, a "booing" peeeeooh, a "chipping" pseef, and a "chitter;ng" di/-it much like those of many.Myrmeciza. The tail twitches from side to si de like a Cereomaera or Formicivora, to which this species may be related. It is not certain whether lhis species is related to tail-pounding For-micivora, Myrmeciza and Pyriglena or to tail-flicking (or twitching)
Cereoma-era. Since Cereomaera itself seems a primitive form closely related to both the
Myrmeciza group and to "other" antbirds, it may be that Se/ateria is a pri-mitive and somewhat intermediate form that branched off close to the main split belween these two groups.
13. Other species. Novaes (1958) records Myrmeciza hyperythra following ants.
DISCUSSION
Most Myrmeciza and relatives hop constantly on or near the forest fIoor, and hence prefer cluttered undergrowth (treefalls, second growth, seep or stream vegetation) that provides dense or nearbv folia~e and hence prey.
Myrmeciza sei dom use the open forest understory, where better-flying antbirds
that wait on vertical perches and sally for occasional leaf-litter prey (Hylophy-lax, Gymnopithys, etc.) are more common. The latter group of antbirds follow ants better than do hopp;ng Myrmeciza, probably because the ants tend to move into open understory too often. Many Myrmeciza are restricted to local dense habitats that ants pass only brief1y.
A few Myrmeciza and relatives regularly follow ants in cluttered wood-lands or subtropical' forest, notably Pyriglena in liana-cluttered forests from southern Brazil to the Andes, Perenoslola rufifrons in second growth of northeastern South. America, Gymnociehla nudieeps in wet second growth of Central America to Colombia, and Myrmeciza immaeulata and M. fortis in cluttered wet upland forests from Costa Rica to upper Amazonia. These antbirds probably depend on ants for prey. None occur in tal1 forests with open undergrowth unless sal1ying members of the Gymnnpithys group are absent. Where sallying members of the Gymnopilhys group are present, one f;nds Myrmeeiza exsul, M. myotherina, or similar species that fol1ow ants only irregularly. One also finds Formiearius species fol1owing ants, as is discussed in the next report of this series. The Formiearius species are tail-pounding walking antb;rds, seemingly related to Myrmeciza, which can use open undergrowth because they can walk on the ground rather than hop from one perch to another.
The taxonomy of antbirds of the genus Myrmeciza needs anatomical and DNA study. ln the Formicariidae, I attribute considerable importance to the manner of tail movement, a downward "pounding" in typical Myrmeciza (and in seem;ngly related Formiearius, Perenostola, Gymnociehla, Pyriglena, Rhopornis, Formicivora and probably Hypoenemis) rather than the upward "flicking" characteristic of the Thamnophilus - Myrmotherula - Terenura - Hylophylax - Hypoenemoides - Pithys - Gymnopithys - Rhegmatorhina - Phlegopsis - Skutehia - Phaenostielus group. Where flicking is found in birds sometimes put in Myrmeeiza, I ilssign these birds to posit;ons near Hylophylax and Cereomaera (which flick the tail): Diehrozona, Myrmoderus and Myrmornis seem derived from Hylophylax, and Sehistoeiehla from
Cer-eomaera. Twitching the ta:1 from side to side is found in Se/ateria,
Cereoma-era, Formicivora and Herpsiloehmus. ln one or two cases tail twitching seems
derived from tail pounding (Formicivora and Myrmeciza hemimelaena), in another from tail Wcking (Cereomaera). These birds, and Se/ateria, are ten-tatively considered primitive forms that branched off close to the major fork that led to the Thamnophilus group on one side ançi to the Myrmeciza group on lhe other. I thus consider lhat ground foraging evolved separately in the
two large lineages of antbirds, probably from arboreal small or medium-sized
species, and that ant follow;ng is a behavior pattem derived rather recently
among a few species in separate ground-foraging groups.
ACKNOWLEDGMENTS
Studies were supported by the National Science Foundation and by the
Chapman Memorial Fund of the American Museum of Natural History. I
appreciate the help of curators of the American and European Museums visi-ted. Yoshika Oniki hl!!ped in many ways.
REFERENCES
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