Influence of the nycthemeral cycle on the roosting behaviour of the Orange-winged Amazon.

Environmental stimuli exert important effects on the expression of the endogenous rhythms. Daily movements of groups of parrots in response to the light/dark cycle have been studied by several researchers. However, the factors modifying the intrinsic rhythmicity of this behaviour remain little known. This study describes how the nychthemeral/circadian periodicity of roost daily movements of the Orange-winged Amazon Amazona amazonica is modified by weather factors. Numbers of parrots arriving or leaving the roosting site Ilha dos Papagaios were determined on a minute by minute basis. More parrots have significantly arrived at the roost after sunset than before, while more parrots have significantly left the roost before sunrise than after. The peak exodus of parrots occurred at 23 ± 5.24 minutes before sunrise, when the average light intensity was 1 lux. The peak influx of parrots occurred at 6 ± 6.1 minutes after sunset, when the average light intensity was 50 lux. By altering ambient light intensity, weather conditions have significantly influenced the arrival and departure times, with parrots leaving later and arriving earlier when conditions were overcast at the roost site.

Efficiency of playback for assessing the occurrence of five bird species in Brazilian Atlantic Forest fragments.

Playback of bird songs is a useful technique for species detection; however, this method is usually not standardized. We tested playback efficiency for five Atlantic Forest birds (White-browed Warbler Basileuterus leucoblepharus, Giant Antshrike Batara cinerea, Swallow-tailed Manakin Chiroxiphia caudata, Whiteshouldered Fire-eye Pyriglena leucoptera and Surucua Trogon Trogon surrucura) for different time of the day, season of the year and species abundance at the Morro Grande Forest Reserve (South-eastern Brazil) and at thirteen forest fragments in a nearby landscape. Vocalizations were broadcasted monthly at sunrise, noon and sunset, during one year. For B. leucoblepharus, C. caudata and T. surrucura, sunrise and noon were more efficient than sunset. Batara cinerea presented higher efficiency from July to October. Playback expanded the favourable period for avifaunal surveys in tropical forest, usually restricted to early morning in the breeding season. The playback was efficient in detecting the presence of all species when the abundance was not too low. But only B. leucoblepharus and T. surrucura showed abundance values significantly related to this efficiency. The present study provided a precise indication of the best daily and seasonal periods and a confidence interval to maximize the efficiency of playback to detect the occurrence of these forest species.

Efficiency of playback for assessing the occurrence of five bird species in Brazilian Atlantic Forest fragments

Playback of bird songs is a useful technique for species detection; however, this method is usually not standardized. We tested playback efficiency for five Atlantic Forest birds (White-browed Warbler Basileuterus leucoblepharus, Giant Antshrike Batara cinerea, Swallow-tailed Manakin Chiroxiphia caudata, Whiteshouldered Fire-eye Pyriglena leucoptera and Surucua Trogon Trogon surrucura) for different time of the day, season of the year and species abundance at the Morro Grande Forest Reserve (South-eastern Brazil) and at thirteen forest fragments in a nearby landscape. Vocalizations were broadcasted monthly at sunrise, noon and sunset, during one year. For B. leucoblepharus, C. caudata and T. surrucura, sunrise and noon were more efficient than sunset. Batara cinerea presented higher efficiency from July to October. Playback expanded the favourable period for avifaunal surveys in tropical forest, usually restricted to early morning in the breeding season. The playback was efficient in detecting the presence of all species when the abundance was not too low. But only B. leucoblepharus and T. surrucura showed abundance values significantly related to this efficiency. The present study provided a precise indication of the best daily and seasonal periods and a confidence interval to maximize the efficiency of playback to detect the occurrence of these forest species.

A técnica de play-back é muito útil para a detecção de aves, mas este método geralmente não é padronizado. Sua eficiência em atestar a ocorrência de cinco espécies de aves da Mata Atlântica (Pula-pula-assobiador Basileuterus leucoblepharus, Batará Batara cinerea, Tangará Chiroxiphia caudata, Olho-de-fogo Pyriglena leucoptera e Surucuá-de-barriga-vermelha Trogon surrucura) foi analisada de acordo com o horário do dia, estação do ano e abundância das espécies na Reserva Florestal do Morro Grande (São Paulo, Brasil) e em treze fragmentos florestais de uma paisagem adjacente. Gravações das vocalizações foram emitidas mensalmente ao amanhecer, meio do dia e entardecer, durante um ano. Para B. leucoblepharus, C. caudata e T. surrucura, o amanhecer e o meio do dia apresentaram-se mais eficientes que o entardecer. Batara cinerea apresentou maior eficiência de julho a outubro. O uso do play-back aumentou o período de maior eficiência dos levantamentos de aves em matas tropicais, comumente restrito ao período da manhã durante a estação reprodutiva. A técnica utilizada foi eficiente na detecção da ocorrência de todas as espécies, salvo quando sua abundância se apresentou muito baixa. Porém, apenas B. leucoblepharus e T. surrucura apresentaram abundância significativa e positivamente relacionada com essa eficiência. O presente estudo proporciona uma indicação precisa sobre o melhor horário do dia e época do ano, assim como um intervalo de confiança, com o intuito de aumentar a eficiência do play-back em detectar a ocorrência dessas espécies.

Complex communication signals: the case of the Blue-black Grassquit Volatinia jacarina (Aves, Emberizidae) song. Part I--a structural analysis.

The song of the Blue-black Grassquit Volatinia jacarina is different for every individual and the structural differences between individuals are quite complex. Samples of songs from different Brazilian localities, as well as from Venezuela and Mexico, were studied through a comparative analysis of their sonograms. From the structural point of view, the results show a song composed of a single note that is compacted in a "window" between 2 and 13 kHz and rarely occupying more than half of a second. The note is essentially pure and is repeatedly uttered with a high level of fidelity. A global frequency modulation decreases from the beginning to the end of the song. The main song components are referred to as "Blocks" and are of three types: "Vibrations" (Buzzes or Vibratos), "Arabesques" (complex notes) and "Isolated Modulations" (simple syllables). Among other characteristics are double voices, which are quite diverse and probably function as codes for individual recognition. This song is considered a special case where a signature system has been developed to a high level of inter-individual variability.

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.

Comparative analysis of the song of the Rufous-collared Sparrow Zonotrichia capensis (Emberizidae) between Campinas and Botucatu, São Paulo State, Brazil.

The regional dialects or regiolects of the Rufous-collared Sparrow Zonotrichia capensis were compared between Campinas (47 degrees 06'W-22 degrees 90'S) and Botucatu (48 degrees 44'W-22 degrees 88'S), São Paulo State, Southeastern Brazil. Songs of 88 individuals from thirteen localities were recorded. Sonograms showed that two areas presented more homogeneous songs, forming two regiolects. In 11 localities most individuals shared the same song type. At the other two localities, they sang up to 5 different song types. This occurs at the boundaries of the regiolects, and was also where individuals singing more than one song type were found. Similarities between song types were not related to geographic distance between the respective singers. A comparative analysis showed similarities in these regiolects with song of populations from Northeastern Brazil.

The song of the Brazilian population of Humpback Whale Megaptera novaeangliae, in the year 2000: individual song variations and possible implications.

The song of the Brazilian population of the Humpback Whale Megaptera novaeangliae was studied in its breeding and calving ground, the Abrolhos Bank, Bahia, Brazil, from July to November 2000. Aural and spectral analyses of digital recordings were completed for approximately 20 song cycles, totaling 5 hours of song from 10 different recording events. We identified 24 note types, organized in five themes. All songs presented the same themes and the order in which they were sung did not vary. We registered the appearance of a note type and the disappearance of a phrase ending, which indicate that the song changed as the season progressed. Moreover, we detected individual variation in the way singers performed certain complex note types. As songs are transmitted culturally, it is likely that singers have different abilities to compose and/or learn new notes. If, as it has been previously suggested, 'new' songs are preferred to 'old' ones, these more able singers will be sending out information about their learning abilities that could be used by other whales to decide whether or not to interact with them.

Comparative analysis of the song of the Rufous-collared Sparrow Zonotrichia capensis (Emberizidae) between Campinas and Botucatu, São Paulo State, Brazil

Nesta pesquisa foram analisados os dialetos do Tico-tico Zonotrichia capensis que ocorrem entre Campinas e Botucatu, Estado de São Paulo, Sudeste do Brasil. Treze localidades foram visitadas e os cantos de 88 indivíduos gravados com um gravador DAT (Digital Audio Tape) e um microfone cardióide montado em uma parábola acústica. Comparaçäes de sonogramas mostraram a existência de duas áreas onde os cantos foram mais homogêneos, formando dois dialetos. Em 11 localidades, muitos indivíduos compartilham o mesmo tipo de canto. Em outras duas localidades, houve até cinco tipos diferentes de cantos. Isto ocorreu nas fronteiras dos dialetos e onde foram encontrados indivíduos cantando mais que um tipo de canto. A similaridade entre os tipos de canto não está relacionada com a distância geográfica entre os cantores. Comparaçäes foram feitas também com gravaçäes de outras localidades do Brasil e similaridades foram encontradas com cantos de aves de localidades como Conchas e Macururé, na Bahia, distantes mais de 1800 km.

The song of the Brazilian population of Humpback Whale Megaptera novaeangliae, in the year 2000: individual song variations and possible implications

Estudamos o canto da população brasileira de Baleia-jubarte Megaptera novaeangliae em sua área de reprodução - a região do Banco dos Abrolhos, Bahia - de julho a novembro do ano 2000. Completamos análises auditiva e espectral de aproximadamente 20 ciclos de canto, em um total de 5 horas de gravaçäes provenientes de 10 ocasiäes diferentes. Identificamos 24 tipos de notas, organizadas em cinco temas. Todos os cantos são formados pelos mesmos temas e não houve variação na ordem na qual foram cantados. Registramos o aparecimento de um tipo de nota e o desaparecimento de uma terminação de frase, o que indica que o canto mudou ao longo da temporada de reprodução. Mais ainda, detectamos variação individual na forma como os cantores emitiam certos tipos de notas mais complexos. Uma vez que o canto é transmitido culturalmente, é provável que os cantores tenham habilidades diferentes para compor e aprender novas notas. Se, como já foi sugerido anteriormente, cantos 'novos' são preferidos a cantos 'antigos', cantores mais capazes estariam mandando informação sobre suas habilidades de compor e aprender que pode ser usada por outros indivíduos para decidir quanto a interagir ou não com eles.

Complex communication signals: the case of the Blue-black Grassquit Volatinia jacarina (Aves, Emberizidae) song. Part I - A structural analysis

O canto do Tiziu Volatinia jacarina é único para cada indivíduo e as diferenças estruturais entre um e outro indivíduo são muito complexas. Cantos gravados em diversos lugares do Brasil e alguns da Venezuela e do México foram estudados através de uma análise comparativa dos seus sonogramas. Do ponto de vista estrutural, os resultados mostram que o canto é constituído por uma nota única que se encontra compactada numa "janela" entre 2 e 13 kHz e raramente ultrapassa meio segundo de duração. A nota, essencialmente pura, é repetida com alto grau de fidelidade entre uma emissão e outra. Constata-se uma modulação de freqüência global descendente do início ao fim do canto. Os principais componentes do canto do Tiziu foram denominados "Blocos" e são basicamente de três tipos: as "Vibrações" (Buzzes ou Vibratos), os "Arabescos" (notas complexas) e as "Modulações Isoladas" (sílabas simples). Entre outras características estão as "duplas vozes" que mostram ampla diversificação e têm por função servir de códigos para o reconhecimento individual. Consideramos o canto do Tiziu como um caso especial em que um "sistema de assinatura" foi desenvolvido a um elevado nível de variabilidade interindividual.

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

O Pula-pula-assobiador Basileuterus leucoblepharus, um pássaro comum da Mata Atlântica, emite um único e distintivo tipo de canto para defesa territorial. O reconhecimento individual ou entre vizinho e estranho pode ser mais difícil quando as aves compartilham cantos semelhantes. De fato, a análise dos cantos de diferentes indivíduos revelou ligeiras diferenças nos domínios temporal e das freqüências. Efetivamente, um exame cuidadoso dos sinais de 21 indivíduos diferentes por 5 métodos complementares de análise revelou que, primeiro, um ou dois espaços na série tonal ocorrem entre duas notas sucessivas em determinados momentos do canto e, segundo, ocupam posiçäes em tempo e freqüência estereotipadas para cada indivíduo. Experiências de "play-back" confirmam esses dados. Através de experiências de propagação, mostramos que esta informação individual pode ser transmitida somente a curta distância ( < 100 m) na mata. Considerando o tamanho e a repartição dos territórios, este processo de comunicação mostra-se eficiente e bem adaptado.

Bird community as an indicator of biodiversity: results from quantitative surveys in Brazil

This short review presents the results obtained in several localities of Brazil on the composition of forest bird communities. Data were collected since the late 80's, after we introduced a new methodology of quantitative survey, based on acoustic identification and unlimited-radius point census. Although these data are still scattered, they show uniquely precise and coherently comparative patterns of composition of forest bird communities. Our methodology has the advantage of being absolutely non-disturbing, highly efficient in the field and immediately processed. Results confirm that the structure of a bird community is a good indicator of biodiversity, particularly useful where biodiversity is high. Many of these data are available only in unpublished dissertations and abstracts of congress communications, or are being analysed. A cooperative program is needed to promote new surveys and publish their results, as a contribution for measuring and monitoring biodiversity, especially in complex endangered habitats.