Studies of Ant-Following Birds North of the Eastern Amazon YOSHIKA ÜNIKI EDWIN 0 . Wn.LIS Department of Biology, Princeton University ABSTRACT [NTRODUCTION Birds that prey on arthropods flushed by army In neotropical forests, many species of ants north of the eastern Amazon were studied at birds prey on arthropods fleeing from advancmg Serra do Navio and Reserva Ducke <Brazil) and at swarms of army ants. In different regions. Nappi Creek and Bartica (Guyana). Regular ant­ different "guilds" (Aoot, 1967) or assemblages followers are two medium-sized antbirds (Percnostola of species follow the army ants. Johnson tufifrons and Gymnopitbys rufigula.) and two smaller (1954), Slud (1960). and Willis (1960, 1967) cnes (Pitbys albifrons and Hylopbylax poecilonota), report on some guílds of ant-following birds of !Jlus five woodcreepers of differing sizes (from very large Hylexetastes perrotti through Dendrocolaptes Caribbean Central America. In Amazonia, ant­ picumnus, D. certhia, and Dendrocincla merula. to following guilds differ across the major rivers medium-sized Dendrocincla fuliginosa). Four other (Willis, 1968b, 1969). Here we give the first regular ant-followers occur in the region but were report, except for a few notes in Beebe, Hartley, not found at the study areas. Forty-five gpecies of and Howes (1917) and in Haverschmidt (1968). casual or nonprofessional ant-followers, including 16 on the ant-following birds of the wide forests antbirds, 5 woodcreepers, and 5 manakins, also were north of the eastern Amazon. recorded. Percnostola rufifrons tends to be at the forest edge or in secohd growth. Pitbys albifrons STUDY AREAS works around Gymnopithys rufiguJa, Hylophylax poecilonota peripheral to both, in the forest interior. To observe these guilds. Oniki visited Ser­ The large Dendrocolaptes picumnus and medium­ ra do Navio (Amapá, Brazil) 15 April to 19 May large Dendrocincla merula often capture prey near 1968 and Willis visited Nappi Creek (Guyana) the ground, like antbirds. Unlike antbirds, which 24 December 1961 to 4 January 1962, Bartica usE: vertical or horizontal slender perches, the wood­ (Guyana) 14-15 January 1962, and Reserva Ducke c.reepers use thick vertical perches. Dendrocolaptes (Amazonas. Brazil) 9 to 12 March 1966. certhia and Dendrocincla fuliginosa also tend te c::.pture prey bigh over the ground-foxaging antbirds. Serra do Navio (0° 55' N, 52° 01' W), a hilly Tbe woodcreepers tend to forage lower at midday. manganese district managed by ICOMI (Indús­ Hylexetastes perrotti is rare, and overlaps strongly tria e Comércio de Minérios S.A.). is at 90 to with D. picumnus. There is fairly large overlap among 360 m elevation on the northeast side of the the 9 professional ant-followers, and large ones chase Amapari River, an affluent of the Araguari River away smaller ones. Nonprofessional birds tend to (Fig. 1). Rainfall averages 2310 mm yearly; it forage briefly or periphcrally wben or slíghtly after was 191 mm in April and 345 mm in May, 1968. lhe professional species are active. They also forage There are areas of second growth near forest above the antbirds and below or above the wood­ areas undisturbed except for mining roads and creepers, and concentrate at forest edges or in second fallen trees. Rodrigues (1963) describes some growth. The guild of ant-following birds in this of the rich upland flora. region differs fairly widely from guilds in Panamá and ut Belém, Brazil; the absence of large antbirds Reserva Ducke (3° 08' S and 60° 02' W) is and the predominance of large woodcreepers north a forest reserve of the Instituto Nacional de Pes­ of the Amazon are the major differences· quisas da Amazônia (INPA) on rolling land with - 127 70 60 50 lO 10 o 100 300 600 Scole in Kil ometers o -o I ~ [ C \ -- lij ! . ~ L ;. i MANAUS MOCO·MOCO GEORGETOWN SERRA 00 NA'.'IO 70 60 50 Fig. 1 - Northeastern South America, showing the study areas and average monthly and yearly rainfalls at nearby stations. Moco-Moco is just west of Nappi, Manaus just west of Reserve Ducke . scattered swampy streams near Km 26 on the reduce annual droughts and permit forest Manaus-ltacoatiara road. lt is about 80 m development (Frost, 1968). A road, clearings, elevation. The rich upland forest (Araújo, 1967) and patches of second growth interrupt the is relatively undisturbed except for some small forest along the main creek, which flows to the clearings, some areas from which undergrowth Rio Takatu and thence to the Rio Branco, the has been cleared, and a grid of compass-line Rio Negro, and the Amazon. trails. The road from Bartica south to Potaro Nappi Creek (about 3° 17' N, 59° 39' W) is passes over terra-firme forested sandy !) lains by a settlement of Macusi lndians at 200 m at an elevation of 20 m or so. Birds were elevation on the flats and lower slopes of the accompanying ants 14 January near the 24-mile northern base of Kanaku Mountains. The latter point (6° 10' N, 58° 41' W) and the next day near and nearby flats form a forested península into the 3-mile point (6° 21 ' N, 58° 40' W). Forestry lhe Rtlpununi savannahs, which are an eastern trails and logging trails for greenheart (Ocotea extension otf the Venezuelan llanos and Bra­ rodeiai) grid the area at 24 miles, and there are zilian campos cerrados (Gilliard, 1962). There extensive areas of clearings and second growth is a major rainy sason May to September, as well at 3 miles, but otherwise the ex· and near the mountains cloud cover and tensive forest are little disturbed . Occasional occasional rain in the dry season perhaps streams provide minor swampy areas in flowing 128 - to the Mazaruni River to the west. The rainy MATERlALS AND METHODS seasons are November to January and May to August, as at nearby Georgetown. We watched with 7 x 35 mm or 8 x 40 mm binoculars from· 5 to 20 m behind swarm raids ARMY ANTS of colonies of Eciton burchelli in both nomadic and statary phases. Most birds became tame From Mexico to Argentina, Eciton burchelli to moderately tame after a few hours of is the major species of army ant followed by observation, as long as we did not move through birds (Willis, 1967). A colony forms a swarm or ahead of the ants. Oniki watched colonies up to 20 m across, which moves up to 200 m a (A-1, A-2, A-3) for a total of 117 hours. Willis day over the leaf litter and probes briefly up watched four colonies (C-1 to C-4) at Nappi for trunks of palms and other trees above the e total of 52.5 hours, two (B-1, B-2) near Bartica ground. Schneirla (1957) and Rettenmeyer for 1. 6 hours, and four (D-1 to D-4) at Reserva ( 1963) describe the biology of the species. A Ducke for 8.9 hours. colony stays in one bivouac or nest site for We recorded in field notes data on foraging about three weeks of a "statary" period. then perches used, foraging motions at differernt changes the bivouac site every night for the heights, and calls and other behavior of the two weeks of a "nomadic" period. During each birds. A bird was listed as following ants statary period, successive raids of the colony only if it actively foraged around a place where 1 adiate like spokes from a wheel; but on some ants were flushing prey. Birds that seemed to days the ants do not raid at ali. During the ignore the ants were recorded only as "passing nomadic period, raiding is da ily and individual birds that ignored ants" and are not listed in the ant-following birds often depend on a single species accounts below. colony. BlRD SPEClES THAT FOLLOW ANTS Other species of army ants are less important for birds. Labidus praedator is often North of the eastern Amazon there are followed from Mexico to Argentina, but is so probably 13 kinds of "professional" ant­ irregular at raiding that it is not very important followers, ones that depend on following army for birds even where it is common (Willis, 1967). ants for 50 or more percent of their food. We did not encounter four of these species in the In Amazonia, straggling swarms of Eciton rapax study areas. Neither of us has seen the occasionally attract birds (Willis, 1968a). Rufous-winged Ground-Cuckoo (Neomorphus During our studies, Oniki for the first time rufipennis, Cuculidae). which extends from recorded birds following a swarm raid of the southern Venezuela and northern Brazil east to tiny black Labidus spininodis. The ants were the Essequibo River in Guyana (Snyder, 1966). swarming under leaf litter and perhaps under­ lt may be conspecific with the Rufous-vented ground about 75 m from the inactive statary Ground-Cuckoo (Neomorphus geoffroyi}, which normally runs around swarms of army ants like bivouac of a colony of Eciton burchelli; the a forest roadrunner (Geococcyx sp.) in vine­ previous day a statary raid had passed nearby tangled riverine or second-growth forests from An adult and young Rufous-throated Antbird Nicaragua (Howell, 1957) to central Brazil. (Gymnopithys rufigula), one Chestnut- belted The Black-spotted Bare-Eye (Ph/egopsis Gnateater (Conopophaga aurita}, and a Rufous­ nigromacu/ata, Formicariidae) barely crosses bellied Antwren (Myrmotherula guttata) fol lowed north of the Amazon near Macapá, Amapá (No­ the L. spininodis raid, but a male Scale-backed vaes, 1957), and the Rufous-winged Bare-Eye Antbir~ (Hylophylax poecilonota) and a Plam­ (Phlegopsis erythroptera) of western Amazonia brown Woodcreeper (Dendrocincla fuliginosa) barely crosses the Rio Negro in southern Vene­ ignored the raid and waited near the statary zuela (Phelps and Phelps, 1963).