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En un ecosistema degradado, que actualmente es objeto de restauración, analizar de manera detallada la estructura de la vegetación y describir su relación con especies de aves es muy relevante para su manejo. El análisis de la arquitectura de las plantas es un método visual para describir la estructura de la vegetación como resultado de su estrategia de crecimiento. Por medio de este método se analizó la oferta de hábitat de las aves insectívoras Myrmeciza longipes (hormiguero ventriblanco), Thamnophilus doliatus (batará rayado) y Synallaxis albescens (pijuí pechiblanco) como parte de un estudio poblacional y de calidad de hábitat en un remanente de bosque seco tropical de 11 079 hectáreas, en Huila, Colombia. Por medio de conteos y también con la información secundaria recopilada, se estableció cómo estas especies usan los diferentes estratos de la vegetación. Teniendo en cuenta que árboles con más perchas incrementan el forrajeo de aves insectívoras, que más perchas significan mayor refugio para las aves, y también que mayor cruce de perchas posibilitan la aparición de horquetas para el anclaje de nidos de estas especies, en 186 parcelas se determinó que la zona está dominada por siete modelos arquitectónicos, divididos en tres grupos según su oferta potencial de recursos del hábitat para las tres especies: 1) modelos arquitectónicos Roux, Petit y Prevost con una calidad alta; 2) modelos arquitectónicos Koriba y Nozerán con una calidad intermedia; y 3) modelos arquitectónicos McClure y Holttum con una calidad muy baja.

Social selection, via intra- and intersexual competition for sexual (e.g. mates) and/or nonsexual (e.g. territories) resources, is thought to drive the evolution of ornaments in both sexes. However, the relative importance of intra- and intersexual competition in promoting the evolution of female and male ornamentation and, hence, sexual dichromatism remains poorly understood. We addressed this issue in antbirds (Thamnophilidae), a radiation of sexually dichromatic passerines wherein eumelanic plumage patches have evolved multiple times in both sexes. In antbirds, the degree of sexual dichromatism differs between closely related species primarily due to eumelanic dark patches in either sex. If eumelanic patches evolved by social selection, individuals of species bearing more conspicuous eumelanic patches should display stronger territorial responses regardless of their sex. Using playback experiments, we simulated three conspecific territorial intrusion types – a social pair, a female and a male – and measured responses by social pairs of two sister species pairs exhibiting greater interspecific differences in female coloration and one sister species pair exhibiting greater interspecific differences in male coloration. We found that females of species bearing more conspicuous eumelanic patches responded more strongly than females of species bearing less conspicuous eumelanic patches, but only towards simulated female and/or male intruders. However, males responded similarly to all intrusions regardless of interspecific coloration differences. Our results suggest that eumelanic patches in antbirds may function as ornaments and that greater female ornamentation may function in intra- and intersexual contexts and reflect stronger social competition in ornamented females for territories and, possibly, mates. In contrast, in species pairs with greater interspecific differences in male ornamentation, territorial competition may occur predominantly among males and female mate choice may drive the evolution of male ornamentation. Our study highlights that social selection pressures acting on both sexes may drive the evolution of contrasting sexual dichromatism patterns.

Secondary contact between species often results in the formation of a hybrid zone, with the eventual fates of the hybridizing species dependent on evolutionary and ecological forces. We examine this process in the Amazon Basin by conducting the first genomic and phenotypic characterization of the hybrid zone formed after secondary contact between two obligate army-ant-followers: the White-breasted Antbird (Rhegmatorhina hoffmannsi) and the Harlequin Antbird (Rhegmatorhina berlepschi). We found a major geographic displacement (∼120 km) between the mitochondrial and nuclear clines, and we explore potential hypotheses for the displacement, including sampling error, genetic drift, and asymmetric cytonuclear incompatibilities. We cannot exclude roles for sampling error and genetic drift in contributing to the discordance; however, the data suggest expansion and unidirectional introgression of hoffmannsi into the distribution of berlepschi.

Isleria is a recently described genus in the Neotropical family of antbirds (Thamnophilidae), comprising two species that inhabit the Amazon basin from Colombia to Brazil. Little is known about the...

Historical processes may result in patterns of differentiation among extant populations, which may lead to diversification and speciation. This is often expressed, and measured, as genetic and behavioral variation among populations. Suboscine birds acquire songs by innate mechanisms and are typically poorly studied relative to oscine birds, which may learn songs and thus develop unique dialects among populations. Behavioral features, including song, are extensively used to describe the structure and geographical variation in bird populations. In turn, this knowledge may shed light onto patterns of species diversification across ecoregions, which is particularly relevant in endemic species. Here we investigate for the first time song structure and variation in the Silvery-cheeked Antshrike, an endemic bird of a poorly studied South American dry forest, the Caatinga. We evaluate hypotheses for song diversification, correlating vocal acoustic parameters with geographic patterns and environmental variables. We measured temporal and spectral variables in the song of Sakesphorus cristatus across 14 localities spanning almost the entire range of the species’ distribution. The song presents a clear geographic pattern, and vocal variation was congruent with a barrier by the Sao Francisco River superimposed to a latitudinal clinal variation that was uncorrelated to climate variables. We argue that these regional differences may have a genetic basis since S. cristatus is a suboscine antbird that should not show song learning (social adaptation) and, apparently, does not have the song correlated to habitat features (acoustic adaptation). More detailed studies are required to test further hypotheses about the drivers of this potential genetic variation underlying the geographical variation in this suboscine bird song.

Made available in DSpace on 2022-04-28T19:42:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-07-01 The family Thamnophilidae is a species-rich Neotropical radiation of passerine birds. Current classification of its 235 species is mostly based on morphological similarities, but recent studies integrating comprehensive phenotypic and phylogenetic data have redefined taxonomic limits of several taxa. Here, we assess generic relationships of Herpsilochmus, Sakesphorus, Thamnophilus, Biatas, and Dysithamnus using DNA sequences from the mitochondrion, nuclear exons, and ultraconserved elements, with further attention to interspecific relationships within Herpsilochmus. We show that Herpsilochmus and Sakesphorus are not monophyletic. We resolve Herpsilochmus sellowi as a deep-branch sister to the monotypic genus Biatas and Sakesphorus cristatus as sister to a clade comprising Herpsilochmus sensu stricto and Dysithamnus. These results are consistent across loci, obtained via concatenation and coalescent-based analyses, and supported by likelihood-ratio tests of the distribution of our sampled coalescent histories. The phenotypic distinctiveness of both H. sellowi and Biatas argues against merging them into a single genus. Because no generic name is available for H. sellowi, we describe a monotypic genus. The polyphyly of Sakesphorus warrants recognition of the available generic name Sakesphoroides for the distinctive and monotypic S. cristatus. Furthermore, we recover 6 well-supported species groups within Herpsilochmus sensu stricto. Within the context of the family as a whole, the ubiquity of long terminal branches representing monotypic genera points to extinction events among ancestors of these lineages. We suggest that retention of ancestral characters or random genetic drift coupled with extensive extinction could explain the high degree of morphological and ecological similarity across these taxa, but we highlight the potential role of the environment in driving adaptive phenotypic convergence. Finally, our results send a cautionary message against the blind use of phylogenies containing imputed data based on taxonomy due to the increasingly frequent mismatches between traditional taxonomic classification and molecular phylogenies. LAY SUMMARY We conduct phylogenomic analyses to infer generic relationships of Herpsilochmus, Sakesphorus, Thamnophilus, Biatas, and Dysithamnus. Using thousands of ultraconserved elements, exons, and mitochondrial DNA, we consistently show that the genus Herpsilochmus is not monophyletic because H. sellowi is a sister of the monotypic species Biatas nigropectus. Because the phenotypic distinctiveness of H. sellowi and B. nigropectus argues against merging them into a single genus and there is no available generic name for H. sellowi, we describe a monotypic genus for this species. We also found polyphyly of the genus Sakesphorus, warranting recognition of the available generic name Sakesphoroides for Sakesphorus cristatus. Our results provide a robust framework for downstream analyses of biogeographic and phenotypic evolution of Herpsilochmus antwrens and allies. This study adds to the increasing body of literature documenting the mismatch between traditional avian taxonomic classifications based on external morphology and evolutionary histories traced by modern genetic tools. Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology Harvard University Seção de Aves Museu de Zoologia Universidade de São Paulo Museum of Natural Science and Department of Biological Sciences Louisiana State University Departamento de Zoologia Universidade Federal do Paraná Centro Politécnico Programa de Pós-Graduação em Zoologia Departamento de Zoologia Universidade Federal do Paraná Centro Politécnico Departamento de Ciências Biológicas e Ambientais Instituto de Biociências Universidade Estadual Paulista Mater Natura - Instituto de Estudos Ambientais Gund Institute for Environment The University of Vermont Rubenstein School of Environment and Natural Resources The University of Vermont Departamento de Zoologia Universidade Federal de Pernambuco Coordenação de Zoologia Museu Paraense Emílio Goeldi Finnish Museum of Natural History University of Helsinki Department of Ecology and Evolutionary Biology University of Tennessee Departamento de Ciências Biológicas e Ambientais Instituto de Biociências Universidade Estadual Paulista

The use of indicator species can simplify bird monitoring by reducing the level of specialized skills needed, which increases the potential pool of participants and reduces training costs and complexity. To facilitate monitoring in the humid forests of northeast Central America, we conducted point count surveys for birds across gradients of disturbance in the Cockscomb Basin Wildlife Sanctuary, Belize, and analyzed the association of bird species with remotely sensed metrics of forest condition and anthropogenic disturbance using indicator species analysis. Twenty species exhibited significant associations with one or more of these metrics. We propose six species as indicators for anthropogenic disturbance based on our criteria of being associated with anthropogenically disturbed sites, or anthropogenically disturbed and riparian sites with no explicit mention in the literature of an obligate association with riparian habitats, or association of remotely sensed metrics that appeared to reflect disturbance: yellow-olive flycatcher, red-legged honeycreeper, dusky antbird, blue ground dove, buff-throated saltator, and brown jay. We propose the keel-billed motmot as an indicator of undisturbed forest based on its association with forested sites in our analyses. Green shrike vireo, collard trogon, rufous-tailed jacamar, and rufous piha were associated with a specific elevational range but not associated with disturbance, so upward shifts in elevation that might indicate response to climate change would not be confounded with habitat disturbance or degradation. This exercise yielded a much-reduced list of monitoring targets, which will greatly reduce the cost and complexity of forest bird monitoring in the region, as well as reducing barriers to participation.

The avifauna on the north bank of the Putumayo River in Colombia is one of the most poorly known in western Amazonia. In February 2017 we spent nine days conducting ornithological field work in and around the community of El Encanto, dpto. Amazonas. We present novel distributional information for six species, the most significant of which concern range extensions for Whiteshouldered Antshrike Thamnophilus aethiops, Imeri Warbling Antbird Hypocnemis flavescens and Black-headed Antbird Percnostola rufifrons minor. We discuss these records in the context of recent ornithological work on the south bank of the Putumayo in Peru and address their biogeographical significance, especially with regards to the definition of areas of endemism in western Amazonia and the role of the Putumayo River as a distributional barrier. Our findings underscore the need for continued ornithological field work in the Putumayo–Caqueta interfluvium and indeed the Colombian Amazon as a whole.

— Information on reproductive biology is limited for many tropical birds, despite the importance of these data in areas such as ecology, taxonomy, and conservation. Hafferia zeledoni belongs to the Thamnophilidae family and was only recently elevated to the species level, and consequently little is known about its ecology and natural history. We found and monitored a dome-shaped nest of this species during 30 days. It was located on a steep slope in a sub-Andean forest, and both male and female participated in the incubation and care of nestlings. Night incubation was only performed by the female, and even though she also incubated during day, it was the male who spent more time on the nest during that period. The eggs were white with reddish blotches, and they measured on average 27.8 ± 1.2 × 19.7 ± 0.1 mm and weighed 5.84 ± 0.17 g. The two nestlings were naked with black skin and weighed 5.64 and 5.60 g at hatching, increasing to 28.61 and 31.60 g prior to fledging. We monitored the incubation ...

Fourteen microsatellite loci were characterized for the Rufous-throated Antbird (Thamnophilidae: Gymnopithys rufigula), an Amazonian obligate ant-following bird. Eight novel polymorphic microsatellite loci were isolated using next-generation sequencing and six additional loci were cross-amplified using primers previously designed for other bird species. All 14 loci were screened using 40 samples from central Amazon. The number of alleles per locus ranged from 3 to 20, whilst the observed and expected heterozygosities varied from 0.200 to 0.975, and 0.186 to 0.928, respectively. No linkage disequilibrium was found among the loci. Only one locus deviated from Hardy-Weinberg equilibrium. Among the eight novel loci, six were cross-amplified in at least one additional Thamnophilidae species, whilst three loci cross-amplified in two other Dendrocolaptidae species. This set of markers will be useful for future population genetic structure and parentage analysis of Amazonian forest birds.

Many animals use cues from other species to gather information about foraging opportunities, but engaging in such behavior requires balancing the potential benefits with the risks of increased competition. Neotropical birds that follow army ants are an appropriate system within which to study such eavesdropping behavior. Mixed-species groups of these understory birds congregate around ant swarms, where they forage on insects flushed by the ants. Obligate ant-followers have specialized behaviors to track ant swarms and may serve as information sources for facultative ant-followers. Owing to strong dominance hierarchies among species, however, the value of the information likely depends on the competitive relationship between the information provider and the eavesdropper. I investigated whether ant-following birds preferentially followed the songs of some antbird species over others, testing the prediction that the vocalizations of small (subordinate) ant-following species would attract more indivi...

Territorial systems of Neotropical birds remain poorly understood, especially considering the effect of interspecific interactions. Studies on territorial behavior provide information about demography and life history, and are useful for the refinement of conservation strategies. We assessed territories of six species of antbirds (Thamnophilidae) from August 2010 to May 2011 at Pedra Azul State Park, a protected area in southeastern Brazil, in a 30-ha sampling grid. Birds were captured, marked, and followed through the study area. Territory sizes of Plain Antvireo (Dysithamnus mentalis), Ferruginous Antbird (Drymophila ferruginea), Ochre-rumped Antbird (Drymophila ochropyga), White-bibbed Antbird (Myrmeciza loricata), White-shouldered Fire-eye (Pyriglena leucoptera), and Variable Antshrike (Thamnophilus caerulescens) were estimated by the convex polygon method. We found 46 territories of the six species. We compared and evaluated the effect of body size on territories among the species. Males and...

A long-held view in evolutionary biology is that character displacement generates divergent phenotypes in closely related coexisting species to avoid the costs of hybridisation or ecological competition, whereas an alternative possibility is that signals of dominance or aggression may instead converge to facilitate coexistence among ecological competitors. Although this counter-intuitive process—termed convergent agonistic character displacement—is supported by recent theoretical and empirical studies, the extent to which it drives spatial patterns of trait evolution at continental scales remains unclear. By modeling variation in song structure of two ecologically similar species ofHypocnemisantbird across western Amazonia, we show that their territorial signals converge such that trait similarity peaks in the sympatric zone, where intense interspecific territoriality between these taxa has previously been demonstrated. We also use remote sensing data to show that signal convergence is not explained by environmental gradients and is thus unlikely to evolve by sensory drive (i.e. acoustic adaptation to the sound transmission properties of habitats). Our results suggest that agonistic character displacement driven by interspecific competition can generate spatial patterns opposite to those predicted by classic character displacement theory, and highlight the potential role of social selection in shaping geographical variation in signal phenotypes of ecological competitors.

This study aims to uncover patterns of species identification error in bioacoustic surveys of central Amazon birds. To quantify errors, we developed an on-line quiz based on vocalizations of an undisclosed set of 41 antbird (Thamnophilidae) and woodcreeper (Dendrocolaptinae) species. We invited experts to answer the quiz and obtained 820 answers from 20 participants. The answers were compared to the results of a binomial experiment with a success probability of 0.5; i.e. we examined whether participants identified species correctly more often than expected by the toss of a coin with a 50% chance of producing the right identification. We also examined whether species were correctly identified more often than expected under a similar coin toss experiment. Quiz answers were compiled in a triangular matrix showing species ranked by taxonomic order on both axes. From the triangular matrix we can ask whether closely-related species were mistaken for each other, i.e. confused, more often than distantly- related species. We tested this hypothesis with a null model approach that compared the mean taxonomic distance between confused species in the observed matrix to the distribution of mean taxonomic distances between confused species in 10,000 randomized matrices. Finally, we drew a dendrogram to represent the similarity between species with regard to the distribution of identification errors. The 20 participants who took the quiz showed substantial variation in their ability to identify species correctly. Fourteen species were correctly identified more often than expected at random, while only one was misidentified more often than expected at random. The observed mean distance between confused species was smaller than all of the mean distances from the randomized, null-model matrices, indicating that confusions are more frequent between closely related species than between distant ones.

Humaita Forest Reserve (HFR) is a forest fragment in the state of Acre, Brazil. Between 2009 and 2019, this fragment has been inventoried by multiple ornithologists and birdwatchers. To provide a comprehensive list of the avifauna of HFR, we compiled all of the available data, including published reports and recent, unpublished surveys. The list includes 356 bird species belonging to 60 families and 23 orders. This species richness is the greatest recorded in those forest fragments that have been inventoried in eastern Acre. We found that HFR is an important site for the conservation of many threatened species, and migrants, as well as poorly known species with a restricted geographic distribution, such as Semi-collared Puffbird Malacoptila semicincta, Goeldi's Antbird Akletos goeldii, Rufous Twistwing Cnipodectes superrufus and Acre Tody-Tyrant Hemitriccus cohnhafti.

We describe a distinctive new species of antbird (Passeriformes: Thamnophilidae) from humid montane forest (1,340–1,670 m above sea level) of the Cordillera Azul, San Martin Region, Peru. Plumage, voice, and molecular evidence distinguish this species from its sister taxon Myrmoderus ferrugineus (Ferruginous-backed Antbird), which is found in lowland Amazonian rainforests of the Guiana Shield and Madeira-Tapajos interfluvium. The new species is presently known only from one ridge in the Cordillera Azul, and therefore we recommend further fieldwork to better estimate its distribution and population size.

The memorization and production of song in songbirds share important parallels with the process of speech acquisition in humans. In songbirds, these processes are dependent on a group of specialized telencephalic nuclei known as the song system: HVC (used as a proper name), RA (robust nucleus of arcopallium), LMAN (lateral magnocellular nucleus of the nidopallium) and striatal Area X. A recent study suggested that the arcopallium of the Sayornis phoebe, a non vocal learner suboscine species, contains a nucleus with some properties similar to those of songbird RA, suggesting that the song system may have been present in the last common ancestor of these groups. Here we report morphological and gene expression evidence that a region with some properties similar to RA is present in another suboscine, the Amazonian endemic Willisornis poecilinotus. Specifically, a discrete domain with a distinct Nissl staining pattern and that expresses the RA marker RGS4 was found in the arcopallium where the oscine RA is localized. Our findings, combined with the previous report on the S. phoebe, suggest that an arcopallial region with some RA-like properties was present in the ancestor of both Suboscines infraorders Tyranni and Furnarii, and is possibly an ancestral feature of Passeriformes.

Understory insectivorous birds often disappear from fragmented tropical rainforest landscapes before mechanisms such as increased rate of nest depredation can be evaluated. Here, we took advantage of chestnut-backed antbird (Myrmeciza exsul), a representative rainforest understory insectivore that persists in fragments (unlike many other understory species), to identify variables influencing nest predation rate and to test the hypothesis that nest predation underlies avian extirpation in tropical fragments. We compared nest predation rates, bird density, and predator identities in three habitats of lowland Caribbean Costa Rica: two fragments, a peninsular reserve (La Selva Biological Station), and unfragmented rainforest. Our results suggest an inversely density-dependent nest predation pattern: In fragments, chestnut-backed antbirds reached their highest density and—contrary to predictions—experienced their lowest nest predation rates; La Selva on the other hand experienced the lowest density and highest predation rate. Because nest predation decreased with fragmentation, it appears not to explain declines of understory insectivores from forest fragments generally. Nest survival models indicated that habitat best explained nest predation likelihood, whereas edge, annual, and nest age effects were unimportant. Video surveillance documented both bird-eating snake (Pseustes poecilonotus) causing 80% of nest loss overall (37 of 46 nests) and a larger variety of predators in fragments; thus, landscape factors influenced an understory bird’s nest predation. Given the large effect on our focal species, Pseustes likely affects other understory nesters, a topic warranting further study. Tropical reserve conservation plans should consider potential impacts of specialized nest predators on vulnerable understory birds.

Many insectivorous birds of the tropical rainforest understory, particularly terrestrial species, are prone to local extinctions in fragmented forests. We evaluated the hypothesis that vegetation structural changes in rainforest fragments reduce the availability of microhabitats used by terrestrial insectivores. Near Manaus, Brazil, we compared the vegetation in forest fragments to the vegetation in a continuous forest site where nine species of terrestrial insectivores were observed foraging. Our focal species included those that are extinction prone in fragments ( Myrmornis torquata [Wing-banded Antbird], Grallaria varia [Variegated Antbird], Hylopezus macularius [Spotted Antpitta]), a fragmentation-tolerant species ( Myrmothera campanisona [Thrush-like Antpitta]), and species that have and intermediate response ( Myrmeciza ferruginea [Ferruginous-backed Antbird], Formicarius colma [Rufous-capped Anttrush], Formicarius analis [Black-faced Antthrush], Conopophaga aurita [Chestnut-belted Gnateater], and Corythopis torquata [Ringed Antpipit]). To quantify vegetation, we measured sixteen habitat variables in 8-m radius plots where birds were observed foraging as well as random points in continuous forest and forest fragments of 1-, 10-, and 100-ha. Four principal components were produced from a principal component analysis and we selected a variable (leaf litter depth, plant cover 3–10 m, density of plants 1–2 m, and plant cover >20 m) from each principal component for our fragment vs continuous forest comparisons. Using Markov chain Monte Carlo (MCMC) simulation, we estimated the probabilities that the density of plants 1–2 m, proportion of plant cover 3–10 m, and leaf litter depth increased with decreasing fragment area and also exceeded the values associated with fragmentation-sensitive species. We also tested the prediction that plant cover >20 m decreased in forest fragments and that those sites became more open than typical sites used by our focal species. Our predictions were strongly supported: decreasing fragment size was correlated with increasing density of tall plants, increasing mid-story vegetation cover, decreased canopy cover, and increasing leaf litter depth. Even if our focal species are able to disperse to small forest fragments, our results suggest that they may not find enough appropriate habitat.

Summary Loss of a dominant competitor can open ecological opportunities. Ecological opportunities are considered prerequisites for adaptive radiations. Nonetheless, initiation of diversification in response to ecological opportunity is seldom observed, so we know little about the stages by which behavioural variation either increases or coalesces into distinct phenotypes. Here, a natural experiment showed that in a tropical island's guild of army ant-following birds, a new behavioural phenotype emerged in subordinate spotted antbirds (Hylophylax naevioides) after the socially dominant ocellated antbird (Phaenostictus mcleannani) died out. Individuals with this behavioural phenotype are less territorial; instead, they roam in search of ant swarms where they feed in locations from which dominant competitors formerly excluded them. Roaming individuals fledge more young than territorial individuals. We conclude that ecological opportunity arising from species loss may enhance the success of alternative behavioural phenotypes and can favour further intraspecific diversification in life-history traits in surviving species.

We report the opportunistic predation of a female Common Scale-backed Antbird (Willisornis poecilinotus) entangled in a mist-net by a Goliath bird-eating spider (Theraphosa blondi) in the Brazilian Amazon. We suggest that the predation event occurred for the following combination of reasons: the spider is common in the study area; the bird became entangled at dusk, when the spider begins its activity; and the lowest mist-net shelf was suspended close to the ground. To reduce opportunistic predation events we recommend that it is critical to keep intervals between mist-net checks to a maximum of 15 min in Amazon forests. We also emphasize that attention is required when installing mist-nets to avoid nets touching the ground when animals become trapped in them.

Although mixed-species associations of birds or primates have been well studied, primate–bird associations have received comparatively little attention. Additionally, benefits accruing with such associations have rarely been quantified. Over 13 months, 17 insectivorous bird species were observed associating with golden-backed uacaris. Detailed study of four found that feeding sally frequency significantly increased for sit-and-wait foragers (bronzy jacamar, Galbula leucogastra; black-fronted nunbird, Monasa nigrifrons), when uacaris were present within 14.9 m, but not when within 15–30 m. Contemporaneously, no significant differences were observed in peck bout frequency for two uacari-following bark- and leaf-gleaning antbirds (black-crested antshrike, Sakesphorus canadensis, black-winged antbird, Hypocnemoides melanopogon) when uacaris were present or absent. Antbird/uacari approximation is attributed to significant reductions in the presence of small bird-eating raptors when uacaris are present. Reasons for this are uncertain but may be because large raptors (e.g. harpy eagles) follow uacaris. So, while some bird species may gain foraging benefits from uacari presence, others may follow them because their proximity reduces predation risk. This appears foraging guild dependent. Except for work linking increased jacana peck rates with swamp-visiting gorilla presence, this study is the first to quantify benefits to birds of following primates, and the first such Neotropical study.

Avian molt, or the regularly scheduled replacement of feathers, is an important life history event, particularly in central Amazonian rainforest birds for which a relatively high proportion of the annual cycle can be dedicated to this process. Here, we detail molt strategies of 18 antbird species (Thamnophilidae) based on 2,362 individuals captured from lowland tropical rainforest at the Biological Dynamics of Forest Fragmentation Project near Manaus, Brazil. All species exhibited a molt strategy consistent with the Complex Basic Strategy, in which birds undergo an inserted preformative molt within the first cycle, but apparently lack prealternate molts. The preformative molt and resulting formative plumage aspect of the 18 antbird species can be grouped by three distinct patterns: 1) a complete molt resulting in an adult-like formative plumage without molt limits; 2) a partial molt involving body feathers, lesser coverts, at least some or all median and greater coverts, and sometimes tertials or...

We present a review on the range of the endemic and near-threatened Rio de Janeiro Antbird Cercomacra brasiliana, based on new field records and extensive search in literature, museums and bird sound databases. Our records extend the species’ known range over 200 km westwards to the hinterlands of Minas Gerais state. Nevertheless, no records were done within federal or state reserves, and the conservation of the remaining forest fragments where the species was recorded is urgent.

The vocal repertoire is a tool that can be used to support systematics, conservation, ecology and behavioural studies. We characterize the acoustic parameters of the vocal repertoire of the white-bibbed antbird (Myrmeciza loricata) and describe the possible functions of each vocalization. The male’s song is related to territorial defence, and we found three calls in the repertoire. Call I is an alarm call, and call II is used for mutual recognition and remaining in contact with one another. Call III was emitted when the animals were foraging and when the individuals of the couple were very near to each other. Males and females sing as a duet, and their songs were individually distinct. The duet is possibly related to maintaining the pair bond, synchronizing breeding and warning potential intruders of the mated condition of the pair. This work is the first to describe the vocal repertoire of the white-bibbed antbird.

Aim To investigate the role of historical processes in the evolution of the spot-backed antbird species complex Hylophylax naevius/Hylophylax naevioides (Aves, Thamnophilidae). Location Throughout the Amazon Basin and across the Andes in Central and northern South America. Methods We investigated the evolutionary history of the H. naevius/H. naevioides complex based on a total of 100 individuals from opposite banks of the major Amazonian rivers and both sides of the Andes. Nucleotide sequences from two mitochondrial DNA genes [1015 bp of cytochrome b (cyt b) and 1023 bp of NADH dehydrogenase subunit 2 (ND2)] and one nuclear marker [539 bp of intron 5 of the β-fibrinogen (BF5)] were obtained. Phylogenetic relationships were inferred using Bayesian and maximum likelihood methods. We used Bayesian coalescent-based approaches to evaluate demographic changes through time, and to estimate the timing of the diversification events. Results Well-supported allopatric and parapatric lineages were recovered within the H. naevius/H. naevioides complex, with high levels of genetic differentiation, both on opposite sides of rivers (0.6–7.1%) and across the Andes (6.9%). Molecular dating and population demography suggest cladogenesis in various periods, associated with distinct vicariance and dispersal events. Main conclusions Our data support the hypothesis that the uplift of the northern Andes and the consolidation of the modern Amazon drainage system were key to promoting the diversification of forest-dwelling bird lineages in the northern Neotropics.

Many terrestrial species of birds have been observed to depend on large contiguous areas of forest; in the tropics this appears to be especially true for terrestrial insectivores. Far less is understood about how more-common species, that are less dependent on interior forests, use both forested and non-forested habitat in fragmented landscapes. Using both behavioral observations and radio-tracking relocation data, I quantified the within-territory use of different land cover types for three tropical songbird species, the dusky antbird (Cercomacra tyrannina), red-throated ant-tanager (Habia fuscicauda), and cocoa woodcreeper (Xiphorhynchus susurrans). Small forest fragments ( 75%), with different amounts of non-forested land cover. As predicted, all three species had increased use in forest cover and decreased use where neighboring territories overlapped. In addition all three species had higher use of areas where there were more forest gaps and/or ‘soft edges’ in the vicinity. Dusky antbirds were less likely to use monocultures of non-native grass and impervious surfaces, while the other two species had mixed responses to non-forested habitats. Dusky antbirds and cocoa woodcreepers were observed foraging at higher-than-expected frequencies along ‘hard edges’ of forested habitat. All three species were found in forest fragments even smaller than a minimal home range area estimate. Conservation of more-common bird species in fragmented landscapes can include secondary forests and small remnants but for these three species non-forested land cover alone would not be expected to provide breeding habitat.

Many social animals use long-distance signals to attract mates and defend territories. They face the twin challenges of discriminating between species to identify conspecific mates, and between individuals to recognize collaborators and competitors. It is therefore often assumed that long-distance signals are under strong selection for species-specificity and individual distinctiveness, and that this will drive character displacement when closely related species meet, particularly in noisy environments. However, the occurrence of signal stereotypy and convergence in rainforest species seems to contradict these ideas, and raises the question of whether receivers in these systems can recognize species or individuals by long-distance signals alone. Here, we test for acoustically mediated recognition in two sympatric antbird species that are known to have convergent songs. We show that male songs are stereotyped yet individually distinctive, and we use playback experiments to demonstrate that females can discriminate not only between conspecific and heterospecific males, but between mates and strangers. These findings provide clear evidence that stereotypy and convergence in male signals can be accommodated by fine tuning of perceptual abilities in female receivers, suggesting that the evolutionary forces driving divergent character displacement in animal signals are weaker than is typically assumed.

We tested whether the probability of detecting avian haemosporidia (Plasmodium and Haemoproteus) using molecular techniques differs among blood, liver, heart, and pectoral muscle tissues. We used a paired design, sampling the 4 tissue types in 55 individuals of a wild South American suboscine antbird, the white-shouldered fire-eye (Pyriglena leucoptera). We also identified parasites to cytochrome b lineage. Detection probability was significantly lower in blood compared to the other 3 tissue types combined. Eight of 22 infections were not detected in blood samples; 4–7 infections were not detected in the other individual tissues. The same parasite lineage was recovered from different tissues.

Tropical birds forage at army ant raids on several continents. Obligate foraging at army ant raids evolved several times in the Neotropical true antbird family (Thamnophilidae), and recent evidence suggests a diversity of bird species from other families specialize to varying degrees on army ant exploitation. Army ant raids offer access to high prey densities, but the ant colonies are mobile and widely spaced. Successful army ant exploitation requires solving a complex foraging problem because army ant raids are unpredictable in space and time. Birds can counteract the challenges posed by the ants by using strategies that raise their chances of detecting army ant raids, and birds can use additional strategies to track army ant colonies they have located. Some features of army ant biology, such as their conspicuous swarms and columns, above-ground activity, and regular cycles of behavior, provide opportunities for birds to increase their effectiveness at exploiting raids. Changes in sensory, cognitive and behavioral systems may all contribute to specialized army ant exploitation in a bird population. The combination of specializations that are employed may vary independently among bird species and populations. The degree of army ant exploitation by birds varies geographically with latitude and elevation, and with historical patterns such as centers of distribution of obligate thamnophilid antbirds. We predict the set of specializations a given bird population exhibits will depend on local ecology, as well as phylogenetic history. Comparative approaches that focus on these patterns may indicate ecological and evolutionary factors that have shaped the costs and benefits of this foraging strategy. The development of army ant exploitation in individual birds is poorly understood, and individual expression of these specializations may depend on a combination of genetic adaptation with cognitive plasticity, possibly including social and experiential learning. Future studies that measure developmental changes and quantify individual differences in army ant exploitation are needed to establish the mechanisms underlying this behavior.