The Edward Grey Institute of Field Ornithology - EGI Research

Ornithological Research in the Tropics

Rainforest bordering the Río Madre de Dios, Peru.

We are interested in tropical diversity, how it arose, how it is maintained, and how it may be conserved. The phenomenon of diversity in tropical ecosystems raises many interesting biological questions ranging from individual adaptations to community interactions. Focusing on birds as study systems, and using a variety of field-based and lab-based techniques, we are developing five parallel research themes that are conceptually broad but deeply interconnected. Some details about these themes are given below.

At present, we test hypotheses using data generated from (i) field-studies of colour-banded populations, (ii) standardized recordings of birdsong collected in diverse communities, and (iii) an archive and dataset based on the acoustic signals of the suboscine passerine clade. Suboscines are an interesting study system because they are highly speciose (~1100 species) with simple, stereotyped, genetically determined songs. The acoustic structure of their vocalisations is therefore relatively easy to quantify and interpret.

Research Themes

Black-throated antbird (Myrmeciza atrothorax)

Speciation

Nowhere has speciation been more active than in tropical forests, where diversity far exceeds the norm in temperate regions: a 100-ha plot of North American woodland supports up to 70 bird species while the same area of Amazon rainforest may host over 500 species. To study the factors driving diversification in the tropics, and the mechanisms allowing so many forms to co-exist, we focus on signals as key players in the speciation process. We use playback experiments to examine the role of signal divergence as a barrier to gene flow when populations meet (1), and we use phylogenetic comparative analyses to study correlates and drivers of speciation (2). Our fieldwork in Amazonian Peru looks at how signals mediate species interactions in a contact zone between two Hypocnemis antbirds.

Signal evolution

We study the interplay between ecological selection (e.g. transmission properties of the habitat) and social selection (e.g. intrasexual or interspecific competition) in shaping acoustic and visual signals. We are also interested in the evolution of coordinated duets and choruses. Examples of our findings include strong evidence of evolutionary divergence in the songs of sympatric bird species (3), and of sexual conflict in apparently cooperative duetting behaviour (4). Using genetic analyses, comparative studies, and aviary experiments, we are testing some of these ideas in two major radiations of Neotropical suboscine birds, the antbirds (Thamnophilidae) and ovenbirds (Furnariidae).

Long-tailed antbird (Drymophila caudata)

Social evolution

The question of how social behaviour evolves, especially in relation to the balance between cooperation and conflict, remains a major challenge for evolutionary biology. Tropical birds have the potential to make an important contribution simply because they offer some amazing study systems. These include the subdesert mesite (Monias benschi) and the white-winged trumpeter (Psophia leucoptera), two group-living birds with unusual breeding strategies. Our research on these species has shown, amongst other things, that long-term direct fitness benefits may underlie cooperation (5), that complex vocal repertoires may arise through sociality (6), and that social structure and communal signals can influence the outcome of inter-group contests (7). The coordinated duets of suboscine birds offer another opportunity to study conflict and cooperation in social interactions (4), and we are pursuing this idea with playback experiments at our field site in Amazonia.

Community ecology

The build-up of tropical diversity has implications for interspecific competition, both in terms of niche packing and signalling space. We are approaching this topic from two angles, first by studying the acoustic structure of songs and the temporal scheduling of dawn singing in a community of c.200 Amazonian bird species, and second by exploring mechanisms of species co-existence in Hypocnemis antbirds. These datasets will allow us to test hypotheses about interspecific competition, as well as the adaptive significance of dawn singing in avian communities.

Conservation

It is difficult to work in the tropics without running up against the problem that habitats and species are rapidly disappearing. This reality lends a sense of urgency to tropical research, especially when it feeds into conservation biology. Our previous work in this area includes spatial analysis of habitat loss (8), census techniques for threatened terrestrial birds (9), and studies of poorly known species such as the Blue-headed Macaw (Primolius couloni) (10) and the Rufous Twistwing (Cnipodectes superrufus) (11). One fundamental issue is the use of species units to set conservation priorities, and the importance this places on species definitions and taxonomy. In collaboration with colleagues at BirdLife International, we are developing standardised protocols for the use of vocal and morphological characters in assigning species limits in the global avifauna.

For more information about projects, study sites and work opportunities, and for pdfs of publications, click here.

white-winged trumpeter (left) & agami heron (right), Amazonian Peru

Who we are

Nat Seddon, Joe Tobias, Claire Salisbury, Diego García Olaechea (Universidad Nacional de Piura, Peru), and Victor Gamarra-Toledo (Universidad de Arequipa, Peru). Recent alumni: Paulo C. Pulgarín-R and Jorjany Botero (Universidad de Antioquia, Colombia), Julissa Cabrera (Universidad Nacional Agraria La Molina, Lima, Peru) and Job Aben (University of Nijmegen, Netherlands). For a photo of the field team in 2007, click here.

Spectrogram of a warbling antbird duet consisting of male song immediately followed and slightly overlapped by a female song. To hear the vocalization use the player below.