Maria Luisa da Silva

Behaviourally driven gene expression reveals song nuclei in hummingbird brain.

Hummingbirds have developed a wealth of intriguing features, such as backwards flight, ultraviolet vision, extremely high metabolic rates, nocturnal hibernation, high brain-to-body size ratio and a remarkable species–specific diversity of vocalizations. Like humans, they have also developed the rare trait of vocal learning, this being the ability to acquire vocalizations through imitation rather than instinct. Here we show, using behaviourally driven gene expression in freely ranging tropical animals, that the forebrain of hummingbirds contains seven discrete structures that are active during singing, providing the first anatomical and functional demonstration of vocal nuclei in hummingbirds. These structures are strikingly similar to seven forebrain regions that are involved in vocal learning and production in songbirds and parrots—the only other avian orders known to be vocal learners. This similarity is surprising, as songbirds, parrots and hummingbirds are thought to have evolved vocal learning and associated brain structures independently, and it indicates that strong constraints may influence the evolution of forebrain vocal nuclei.

Sedentary life style of Neotropical sedge wrens promotes song imitation

To what extent has the style of song development among songbirds coevolved with other life history strategies? Among Cistothorus wrens in North America, it seems that sedentary or site-faithful habits of marsh wrens, C. palustris, favour song imitation, but seminomadic habits of sedge wrens, C. platensis, favour song improvisation, whereby each male generates a large but unique song repertoire. In this study, we tested whether more sedentary populations of sedge wrens in the Neotropics would imitate songs. At our primary study site near Cartago, Costa Rica, breeding birds were colour-banded during 1995 and 1996, and follow-up surveys revealed that the birds remained at this site the year round. Extensive tape recording and analysis of songs showed that males had large song repertoires (200-300+ songs), and that many songs were shared among neighbouring males. In addition, males only 27 km distant, at La Pastora, used different songs. Furthermore, matched countersinging, in which two males answer each other with identical song types, was recorded near Brasilia, in Brazil. The sharing of songs among permanent neighbours, microgeographical variation in song, and matched countersinging can be achieved only through song imitation, thus revealing a striking difference in the style of song development among different populations of the sedge wren. In the Neotropics, having predictable neighbours throughout life appears to have favoured song imitation, so that individuals can interact using a common, learned code typical of the local population; among more mobile populations in North America, however, individuals improvise large repertoires of species-typical songs, thereby enabling singing males to communicate with any individual, no matter what the population of origin. Strategies of song development must correlate with life history features, and further surveys are needed to make sense of the great diversity of singing behaviours among songbirds. Copyright 1999 The Association for the Study of Animal Behaviour.

How a simple and stereotyped acoustic signal transmits individual information: the song of the White-browed Warbler Basileuterus leucoblepharus

The White-browed Warbler Basileuterus leucoblepharus, a common bird of the BrazilianAtlantic forest, emits only one distinct song type in the context of territorial defense. Individual or neighbor-stranger recognition may be more difficult when birds share similar songs. In fact, the analysis of songs of different individuals reveals slight differences in the temporal and the frequency domains. Effectively, a careful examination of the signals of different individuals (21) by 5 complementary methods of analysis reveals first, that one or two gaps in frequency occur between two successive notes at different moments of the song, and second, that their temporal and frequency positions are stereotyped for each individual. Playback experiments confirm these findings. By propagation experiments, we show that this individual information can be only transmitted at short range (< 100 m) in the forest. In regard to the size and the repartition of territories, this communication process appears efficient and adaptive.

Dawn-song onset coincides with increased HVC androgen receptor expression but is decoupled from high circulating testosterone in an equatorial songbird

The song of songbirds is a testosterone-sensitive behavior that is controlled by brain regions expressing androgen receptors. At higher latitudes, seasonal singing is stimulated by increasing day-length and elevated circulating testosterone. However, a large number of songbird species inhabit equatorial regions under a nearly constant photoperiod, and the neuroendocrine mechanisms of seasonal song in these species have rarely been investigated. We studied males from an equatorial population of the silver-beaked tanager (Ramphocelus carbo), an Amazonian songbird. We found seasonality in dawn-song behavior, which was displayed continuously for more than half a year throughout an extended breeding territoriality stage. The seasonal activation of dawn-song was correlated with an increased area of androgen receptor expression in HVC, a major brain area of song control. However, testosterone levels remained low for several weeks after activation of dawn-song. Circulating levels of testosterone were elevated only later in the breeding season, coinciding with a higher dawn-song output and with the mating period. Our results suggest that the seasonal activation of dawn-song and territoriality involves an increase of androgen target cells in HVC. This mechanism could potentially function to circumvent adverse effects of high testosterone levels in a species with an extended breeding season.

VOCAL REPERTOIRE OF WILD BREEDING ORANGE-WINGED PARROTS AMAZONA AMAZONICA IN AMAZONIA

ABSTRACT The vocal repertoire of Amazona amazonica during its breeding season has been recorded from wild individuals in Santa Bárbara do Pará, Pará State, Brazil. At individual nests, we continuously recorded vocalizations and behaviour for four hours in the early morning and three hours in the late afternoon, three times a week throughout the breeding season. We identified nine vocalizations that we classified in three behavioural categories: (1) Flight call—emitted when parrots arrive in the nest area; (2) Perched contact calls—two different vocalizations, one of them related to feeding, were emitted when the pair was perched in the nest area and interacted socially between themselves or with other individuals; (3) Aggressive calls—emitted when birds were in a dangerous situation, i.e. alarm (three types of calls), agonistic contact and distress calls (two types of call). The Orange-winged Parrot is a highly social species and the complexity of its social interactions is reflected in the diversity of its vocal repertoire.

Species Identity Coding by the Song of a Rainforest Warbler: An Adaptation to Long-Range Transmission?

Thierry Aubin1), Nicolas Mathevon2), Maria Luisa da Silva3) 1) Equipe Communications Acoustiques, CNPS, CNRS UMR 8195, Universite Paris XI, Orsay, France. thierry.aubin@u-psud.fr 2) Equipe Neuro-Ethologie Sensorielle, CNPS, CNRS UMR 8195, Universite Jean Monnet, Saint-Etienne, France 3) Laboratorio de Ornitologia e Bioacustica, Centro de Ciencias Biologicas, Campus Universitario do Guama, Belem, PA, Brasil

Seasonal Fluctuation of the Orange-Winged Amazon at a Roosting Site in Amazonia

Abstract We recorded fluctuations in a population of Orange-winged Amazon (Amazona amazonica) during 1 year at a roosting site on an island near Belém, Pará, Brazil. Parrots were counted from a boat by a minimum of three teams of two observers, each team oriented in different directions. Orange-winged Amazons were observed flying alone (14.2%), in pairs (75.7%), and small numbers in family groups (pairs with young) of three (8.7%), four (1.2%), or five (0.3%) individuals. The larger number of groups of three compared with groups of four and five individuals reflects the low survival rate of nestlings with generally only one surviving offspring per brood. The total number of parrots increased from April (3,899) to July (8,539), and began to decrease in August (5,351). This decrease was presumably due to onset of the breeding season, when paired individuals leave the roost in search of a nest, where they breed, nest, and rear young until the nestlings can fly.

Gestural communication in a new world parrot

Male birds can use visual signals to provide information about their sexual status, via bright coloration, sophisticated sexual displays and elaborate tail and head crests. The majority of forest bird species use vocal communication as their main strategy to show their physiological status during breeding season. It is also used to keep contact between individuals in the same group, in agonistic contexts, and by chicks begging for food. We registered, for the very first time, gestural communication acting in the context of biparental care for the Orange-winged Amazon, Amazona amazonica. This parrot presents at least nine different sounds uttered in contexts of alarm, agonistic, foraging, contact flight and others. This finding suggests that despite being a vocal species, this parrot can perform gestural communication related to parental care. The gestures exhibited by this species represent a strategy for survival, a clever way to protect the nest, reducing the risk of attracting the attention of predators.

Underrepresentation of women in the senior levels of Brazilian science

Despite significant progress, there is still a gender gap in science all over the world, especially at senior levels. Some progressive countries are recognizing the need to address barriers to gender equality in order to retain their best scientists and innovators, and ensure research excellence and social and economic returns on the investment made by taxpayers each year on training women scientists. We investigated the gender distribution of: (i) the productivity scholarship (PS) holders of the Brazilian National Council for Scientific and Technological Development (Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq, N = 13,625), (ii) the members of the Brazilian Academy of Science (Academia Brasileira de Ciências, ABC, N = 899), and (iii) the amount of funding awarded for top quality research (“Universal” Call of CNPq, N = 3,836), between the years of 2013 and 2014. Our findings show evidence for gender imbalances in all the studied indicators of Brazilian science. We found that female scientists were more often represented among PS holders at the lower levels of the research ranking system (2). By contrast, male scientists were more often found at higher levels (1A and 1B) of PS holders, indicating the top scientific achievement, both in “Engineering, Exact Sciences, Earth Sciences”, and “Life Sciences”. This imbalance was not found in Humanities and Social Sciences. Only 14% of the ABC members were women. Humanities and Applied Social Sciences had a relatively low representation of women in the Academy (3.7%) compared to Engineering, Exact and Earth Sciences: 54.9% and Life Sciences: 41.4%. Finally, female scientists obtained significantly more funding at the lower level of the research ranking system (2), whereas male scientists obtained significantly more funding at the higher levels (1A and 1B). Our results show strong evidence of a gender imbalance in Brazilian science. We hope that our findings will be used to stimulate reforms that will result in greater equality in Brazilian science, and elsewhere.

AUTOMATIC CLASSIFICATION OF TURDUS RUFIVENTRIS SONG NOTES BY SPECTROGRAPHIC IMAGE TEMPLATE MATCHING

This paper presents a method for automatic classification of birdsong notes. The elaborate method performs correlation calculationsapplied to spectrographic images to determine the similarity between the notes of a vocal repertoire, so the method was called SITM (Spectrographic Image Template Matching). The notes Nj of each phrase Pi which makes up the song of an individual of aspecie, are generally classified with letters of the alphabet according to the sequence emitted that is viewed in a spectrogram.By setting a minimum degree of similarity between the notes of the repertoire of each individual, it is possible to automate thistype of visual classification. Performance evaluation of automatic classification was performed with the vocal repertoire of threeindividuals of T. ruviventris recorded in to the wild. With 96% confidence, according to statistical inference, the rate of correctclassification via SITM was 77% to 97% of the notes in recording FNJV5915, 64% to 82% of the notes in recording FNJV5932and 74% to 97% of notes in recording FNJV5955.