RESUMO

Seed dispersal is one of the principal ecological processes that determine the richness and distribution of plants in tropical forests. Birds play an important role in the zoochoric dispersal of seeds in these forests.The present study investigated the bird-plant interactions involving the ingestion and dispersal of seeds by the birds found in the edge habitat of an isolated forest fragment on the Catuaba Experimental Farm in eastern Acre, in southwestern Brazilian Amazonia. The birds were captured using mist nets, and the seeds were collected from fecal samples obtained during the handling of the animals. These seeds were sorted and identified. The bird and the plant species identified during the study were used to calculate the connectivity and nestedness of the bird-plant interactions. We captured 82 species of birds, with a total sampling effort of 203,180 h.m². Fecal samples obtained from 19 of the bird species contained a total of 2,086 seeds, representing 23 plant species. The interaction network had an intermediate connectance, and significant nestedness. Ramphocelus carbohad the highest importance index and was the bird with the largest number of plant interactions, while Cecropia latilobawas the plant with the highest importance index, followed by Schefflera morototoni. Most of the seed-dispersing birds identified in the present study are generalists found in both the forest core and its edge. The results of the study indicated that the community of generalist-frugivore birds interacts extensively with the plant community of the fragment, providing seed dispersal services that include the deforested areas adjacent to the fragment.

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Seed dispersal and seedling recruitment are crucial phases in the life cycle of all spermatophyte plants. The net contribution of seed dispersers to plant establishment is known as seed dispersal effectiveness (SDE) and is defined as the product of a quantitative (number of seeds dispersed) and a qualitative (probability of recruitment) component. In Galápagos, we studied the direct contribution to SDE (number of seeds dispersed and effect on seedling emergence) provided by the five island groups of frugivores (giant tortoises, lizards, medium-sized passerine birds, small non-finch passerine birds, and finches) in the two main habitats in this archipelago: the lowland and the highland zones, and found 16 vertebrate species dispersing 58 plant species. Data on frequency of occurrence of seeds in droppings and number of seeds dispersed per unit area produced contrasting patterns of seed dispersal. Based on the former, giant tortoises and medium-sized passerines were the most important seed dispersers. However, based on the latter, small non-finch passerines were the most important dispersers, followed by finches and medium-sized passerines. The effect of disperser gut passage on seedling emergence varied greatly depending on both the disperser and the plant species. Although the contribution to SDE provided by different disperser guilds changed across plant species, medium-sized passerines (e.g., mockingbirds) provided a higher contribution to SDE than lava lizards in 10 out of 16 plant species analysed, whereas lava lizards provided a higher contribution to SDE than birds in five plant species. While both the quantitative and qualitative components addressed are important, our data suggests that the former is a better predictor of SDE in the Galápagos archipelago.

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Studies of the dispersal modes of plants aid our understanding of the dynamics of resource and its availability for dispersal agents. The present work sought to characterize the fruiting patterns of the native Caatinga (dryland) cactus Cereus jamacaru, identify its principal dispersers, and evaluate the effects of seed passage through digestive tract of dispersers on its germination. Cereus jamacaru present an annual fruiting pattern and fruiting peaks occurred during June/2009 and February/2010. A total of 135 visits by nine species of resident Caatinga bird species were recorded. The most frequent visiting bird species were Paroaria dominicana and Euphonia chlorotica. Length of bird visits varied from 15 seconds to 4 minutes and seeds removed by birds travelled 10.6 ± 11.2 m until dispersers make the first landing perch, in some cases more than 40 meters away. Germination tests show birds had a high quantity of viable seeds of C. jamacaru in its feces. Seeds that passed through the digestive tract of birds showed a similar germinability of the seeds of the control group. However, the seeds dispersed by birds showed lowest mean germination time related to the control group seeds. This study highlights the potential role of birds as seed dispersers of C. jamacaru, swallowing the whole seeds and defecating intact seeds, accelerating the germination process and transporting seeds away from the mother plant.

Estudos do modo de dispersão das espécies vegetais permitem o entendimento da dinâmica dos recursos e sua disponibilidade para os dispersores. O objetivo deste trabalho foi caracterizar o padrão de frutificação de Cereus jamacaru, uma espécie nativa da Caatinga, identificar os seus principais dispersores e avaliar o efeito da passagem das sementes pelo trato digestivo destes animais sobre sua germinação. Cereus jamacaru apresentou um padrão de frutificação anual, com pico de frutificação nos meses de Junho/2009 e Fevereiro/2010. No total foram registradas 135 visitas de nove espécies de aves frugívoras da Caatinga, sendo os dispersores mais frequentes Paroaria dominicana e Euphonia chlorotica. O tempo de duração das visitas foi curto, variando de 15 segundos a 4 minutos, e a distância média dos voos pós-alimentação foi 10,6 ± 11,2 m da planta-mãe, podendo também alcançar distâncias superiores a 40 metros. Os resultados dos testes de germinação mostraram que as aves apresentam uma alta quantidade de sementes viáveis de C. jamacaru em suas fezes. As sementes que passaram pelo trato digestivo das aves mostraram germinabilidade semelhante aquelas do grupo controle. No entanto, as sementes dispersadas pelas aves apresentaram um menor tempo médio necessário para germinação. Esse estudo destaca o papel das aves como potenciais dispersores de C. jamacaru, eliminando sementes intactas, acelerando o processo de germinação e carregando as sementes para longe da planta mãe.

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RESUMO

Studies of the dispersal modes of plants aid our understanding of the dynamics of resource and its availability for dispersal agents. The present work sought to characterize the fruiting patterns of the native Caatinga (dryland) cactus Cereus jamacaru, identify its principal dispersers, and evaluate the effects of seed passage through digestive tract of dispersers on its germination. Cereus jamacaru present an annual fruiting pattern and fruiting peaks occurred during June/2009 and February/2010. A total of 135 visits by nine species of resident Caatinga bird species were recorded. The most frequent visiting bird species were Paroaria dominicana and Euphonia chlorotica. Length of bird visits varied from 15 seconds to 4 minutes and seeds removed by birds travelled 10.6 ± 11.2 m until dispersers make the first landing perch, in some cases more than 40 meters away. Germination tests show birds had a high quantity of viable seeds of C. jamacaru in its feces. Seeds that passed through the digestive tract of birds showed a similar germinability of the seeds of the control group. However, the seeds dispersed by birds showed lowest mean germination time related to the control group seeds. This study highlights the potential role of birds as seed dispersers of C. jamacaru, swallowing the whole seeds and defecating intact seeds, accelerating the germination process and transporting seeds away from the mother plant.(AU)

Estudos do modo de dispersão das espécies vegetais permitem o entendimento da dinâmica dos recursos e sua disponibilidade para os dispersores. O objetivo deste trabalho foi caracterizar o padrão de frutificação de Cereus jamacaru, uma espécie nativa da Caatinga, identificar os seus principais dispersores e avaliar o efeito da passagem das sementes pelo trato digestivo destes animais sobre sua germinação. Cereus jamacaru apresentou um padrão de frutificação anual, com pico de frutificação nos meses de Junho/2009 e Fevereiro/2010. No total foram registradas 135 visitas de nove espécies de aves frugívoras da Caatinga, sendo os dispersores mais frequentes Paroaria dominicana e Euphonia chlorotica. O tempo de duração das visitas foi curto, variando de 15 segundos a 4 minutos, e a distância média dos voos pós-alimentação foi 10,6 ± 11,2 m da planta-mãe, podendo também alcançar distâncias superiores a 40 metros. Os resultados dos testes de germinação mostraram que as aves apresentam uma alta quantidade de sementes viáveis de C. jamacaru em suas fezes. As sementes que passaram pelo trato digestivo das aves mostraram germinabilidade semelhante aquelas do grupo controle. No entanto, as sementes dispersadas pelas aves apresentaram um menor tempo médio necessário para germinação. Esse estudo destaca o papel das aves como potenciais dispersores de C. jamacaru, eliminando sementes intactas, acelerando o processo de germinação e carregando as sementes para longe da planta mãe.(AU)

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A frugivoria é uma das mais importantes interações ecológicas durante a sucessão florestal. Aves frugívoras são responsáveis por até 90% da dispersão de sementes em florestas tropicais. Estudos anteriores têm testado quais características dos frutos dispersos são escolhidos pelas aves, tais como cor, tamanho e posição dos frutos. Contudo, estudos experimentais em ambiente natural são raros. O objetivo deste estudo foi testar se existem diferenças no consumo de frutos por aves dependendo de cores e padrões de disposição espacial em ambientes florestais. O estudo foi realizado em um fragmento de Floresta Estacional Semidecidual de 60,98 hectares. Foram utilizados modelos de frutos artificiais com três cores e dispostos de maneira agregada ou dispersa nos ambientes de interior e borda. Os frutos conspicuos (azul e vermelho) foram mais consumidos do que verdes, e os dispersos foram mais consumidos que os agregados no interior do fragmento. O contraste de cores conspicuas contra a vegetação parece facilitar a visualização dos frutos por frugívoros especialistas do interior. Entretanto, frugívoros oportunistas consumiram principalmente frutos isolados, demonstrando que picos de alta produtividade de frutos parecem estar relacionados à maior procura desse recurso por essas aves.

Frugivory is one of the most important ecological interactions during forest succession. Frugivorous birds are responsible for up to 90% of seed dispersion in tropical forests. Previous studies have tested how birds choose fruits to disperse based on their color, size, and position. However, most of those studies were conducted in artificial conditions. This study investigated whether the rate of fruit consumption by birds is influenced by their colors and spatial patterns in forested environments. The experiment was performed in a 60.98-ha-fragment of Semideciduos Forest. We used artificial fruits with three different colors, disposed in a both clump and scattered fashion, at the edge and interior of the fragment. There was a higher rate of consumption of conspicuous fruits (blue and red). Scattered fruits were also more consumed than clump fruits on forest interior. The contrast of conspicuous colors against their backgrounds allows the visualization of fruits by frugivorous birds specialized on interior environments. Our results also showed that opportunists frugivorous are the main consumers of scattered fruits. This pattern supported the assumption that peaks of high fruit productivity coincide with higher consumption of this resource by these birds.

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Fruit color and odor are the main features regulating the rate of fruit predation and dispersal. The aim of this study was to analyze the effect of odor and color on fruit predators and dispersers. The present study was conducted in a 30ha area of secondary forest in Southeastern Atlantic Brazil. This area was divided into two transects, in which four points were marked with a 30m distance from each other. Each sampling point contained a total of 30 artificial fruit which belong to six different treatment groups, with five artificial fruit per group. Each group was randomly placed on the ground and that artificial fruit was checked every seven days. For each group of five fruit, 5mL of essence (vanilla or pineapple) were placed, and no essence was used in the control group. Artificial fruit was made with green and red nontoxic modeling clay, as well as artificial essences (vanilla and pineapple). A total of 960 fruits were used. Predated fruit equaled 26.9% (258 units), from which the red/pineapple had the highest predation rate (81.9%), followed by red/vanilla (46.3%), while green/control fruits were not predated. Throughout the experiment, bitten fruit and pecked fruit equaled 58.3% and 41.7%, respectively. No significant differences were recorded (x²=7.57, df=5, p=0.182) between bitten and pecked fruit. Fruit color and odor are important in attracting predators and dispersers, which explains the high rate of predation of red/vanilla and red/pineapple, and the absence of predated fruits in the green/control group. Regarding the potential disperser, there was no statistically significant difference between pecked fruit and bitten fruit. As a result, it should be taken into consideration that zoochory (mammalochory and ornithochory) is the most important dispersal; therefore, it should be concluded that birds are more attracted by color and mammals by odor. Rev. Biol. Trop. 60 (2): 925-931. Epub 2012 June 01.

El olor y el color de los frutos son las características principales que regulan el nivel de consumo y la dispersión de las semillas. Este estudio tuvo como objetivo analizar el efecto que tiene el olor y el color de los frutos sobre los depredadores y dispersores de semillas. El área de estudio abarca 30ha de bosque secundario localizado en el Atlántico sureste de Brasil. Este espacio se dividió en dos sectores, en los cuales se marcaron cuatro puntos con una distancia de 30m entre sí. En cada punto de muestreo se utilizaron 30 frutos que se distribuyeron en seis tratamientos, con cinco frutos artificiales para cada tratamiento. Además, cabe resaltar que cada tratamiento se colocó en el suelo de forma aleatoria y que los frutos artificiales se verificaron cada siete días. Para cada grupo de cinco frutos se utilizaron 5mL de esencia (vainilla y ananá) y para el grupo de control no se utilizó ningún aditivo de olor. Los frutos se confeccionaron con plastilina atóxica de color verde y roja, además de esencias artificiales (ananá y vainilla), asimismo se obtuvieron 960 frutos. El nivel de frutos consumidos fue del 26.9% (258 unidades), de los cuales los rojos/ananá fueron los más consumidos (81.9%), seguidos del rojo/vainilla (46.3%), mientras que los verde/control no fueron comidos. Durante el experimento la tasa de frutos mordidos fue del 58.3% y de picoteados un 41.7%. No se registró una diferencia significativa (x²=7.57, gl=5, p=0.182) entre frutos mordidos y picoteados. El color y el olor de los frutos son aspectos importantes para atraer depredadores y dispersores, lo que explica los niveles de consumo de los frutos rojos/vainilla y rojo/ananá y la ausencia de frutos comidos en el tratamiento del verde/control. En cuanto al potencial dispersor, no hubo una diferencia estadística significativa entre frutos mordidos y picoteados, por lo que se debe tomar en cuenta que la dispersión principal es la zoocoria (ornitocoria y mamalocoria). Por lo tanto, se puede concluir que las aves son atraídas por el color y los mamíferos por el olor.

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Several plant characteristics, such as fruit production, nutrient reward, secondary compounds, and fruit color display, affect fruit choice by birds. On the other hand, several bird attributes affect their efficiency as dispersers. Here we investigate the ornithochoric seed dispersal of Pera glabrata Schott (Euphorbiaceae) in a cerrado fragment in southeastern Brazil. A set of bird attributes, such as frequency of visits, number of diaspores eaten, time spent foraging, methods of taking and handling the diaspores and agonistic interactions were analyzed in order to infer about the potential of each species to act as a seed disperser. Birds were the unique seed dispersers of these oil-rich diaspores. We observed 414 bird visits during 60 hours of focal observations in five trees from December 1999 to January 2000. Twenty bird species from seven families ate the diaspores of P. glabrata, but only 14 species were considered potential seed dispersers because they swallowed the diaspores, increasing the probabilities for the seeds to be defecated and/or regurgitated away from the parent trees. The main potential seed dispersers were: Turdus leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) and Elaenia spp. (Tyrannidae). We did not find any significant seasonal change in the number of visits on the fruiting trees throughout the day. We also did not find any relation between the number of visits per tree and fruit production. The most effective seed dispersers of P. glabrata were generalist birds, which have a high visiting rate, high fruit consumption rate, and spend short periods on the plants. The large number of species recorded as potential seed dispersers of P. glabrata, being most of them very abundant even in Brazilian disturbed areas, may guarantee seed dispersal of this plant in small fragments and regenerating areas.

As diferentes espécies de plantas apresentam características que podem influenciar na atração das aves frugívoras, como a quantidade de frutos produzidos, o valor nutritivo dos frutos, a presença de compostos secundários e o display de cores. Por outro lado, diversos estudos têm demonstrado que as espécies de aves que consomem frutos não apresentam a mesma eficiência como dispersores das sementes. Embora estudos sobre a frugivoria e dispersão de sementes sejam de grande importância para a realização de planos de manejo e recuperação de áreas degradadas, pouco tem sido pesquisado sobre o assunto no cerrado brasileiro. Neste trabalho são apresentados aspectos da frugivoria e dispersão ornitocórica das sementes de Pera glabrata Schott (Euphorbiaceae) num fragmento de cerrado do sudeste do Brasil. Atributos das aves, como freqüência de visitas, número de diásporos consumidos, tempo de permanência sobre as plantas, métodos de captura e mandibulação dos diásporos, bem como interações antagônicas, foram analisados para se inferir sobre o potencial de cada espécie para atuar como dispersora das sementes. As aves foram os únicos potenciais dispersores dos diásporos. Em 60 horas de observações focais, realizadas entre dezembro de 1999 e janeiro de 2000, foram registradas 414 visitas de 20 espécies de aves pertencentes a sete famílias. No entanto, apenas 14 destas espécies foram consideradas como potenciais dispersores. Os principais potenciais dispersores foram Turdus -leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) e Elaenia spp. (Tyrannidae). O número de visitas não diferiu significativamente entre os diferentes intervalos de hora do dia. Não foi encontrada correlação significativa entre o número de visitas e o número de frutos presentes em cada árvore. As aves generalistas foram as principais potenciais dispersoras de P. glabrata, tendo apresentado altas taxas de visitação, alto consumo de diásporos,...

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Several plant characteristics, such as fruit production, nutrient reward, secondary compounds, and fruit color display, affect fruit choice by birds. On the other hand, several bird attributes affect their efficiency as dispersers. Here we investigate the ornithochoric seed dispersal of Pera glabrata Schott (Euphorbiaceae) in a cerrado fragment in southeastern Brazil. A set of bird attributes, such as frequency of visits, number of diaspores eaten, time spent foraging, methods of taking and handling the diaspores and agonistic interactions were analyzed in order to infer about the potential of each species to act as a seed disperser. Birds were the unique seed dispersers of these oil-rich diaspores. We observed 414 bird visits during 60 hours of focal observations in five trees from December 1999 to January 2000. Twenty bird species from seven families ate the diaspores of P. glabrata, but only 14 species were considered potential seed dispersers because they swallowed the diaspores, increasing the probabilities for the seeds to be defecated and/or regurgitated away from the parent trees. The main potential seed dispersers were: Turdus leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) and Elaenia spp. (Tyrannidae). We did not find any significant seasonal change in the number of visits on the fruiting trees throughout the day. We also did not find any relation between the number of visits per tree and fruit production. The most effective seed dispersers of P. glabrata were generalist birds, which have a high visiting rate, high fruit consumption rate, and spend short periods on the plants. The large number of species recorded as potential seed dispersers of P. glabrata, being most of them very abundant even in Brazilian disturbed areas, may guarantee seed dispersal of this plant in small fragments and regenerating areas.

As diferentes espécies de plantas apresentam características que podem influenciar na atração das aves frugívoras, como a quantidade de frutos produzidos, o valor nutritivo dos frutos, a presença de compostos secundários e o display de cores. Por outro lado, diversos estudos têm demonstrado que as espécies de aves que consomem frutos não apresentam a mesma eficiência como dispersores das sementes. Embora estudos sobre a frugivoria e dispersão de sementes sejam de grande importância para a realização de planos de manejo e recuperação de áreas degradadas, pouco tem sido pesquisado sobre o assunto no cerrado brasileiro. Neste trabalho são apresentados aspectos da frugivoria e dispersão ornitocórica das sementes de Pera glabrata Schott (Euphorbiaceae) num fragmento de cerrado do sudeste do Brasil. Atributos das aves, como freqüência de visitas, número de diásporos consumidos, tempo de permanência sobre as plantas, métodos de captura e mandibulação dos diásporos, bem como interações antagônicas, foram analisados para se inferir sobre o potencial de cada espécie para atuar como dispersora das sementes. As aves foram os únicos potenciais dispersores dos diásporos. Em 60 horas de observações focais, realizadas entre dezembro de 1999 e janeiro de 2000, foram registradas 414 visitas de 20 espécies de aves pertencentes a sete famílias. No entanto, apenas 14 destas espécies foram consideradas como potenciais dispersores. Os principais potenciais dispersores foram Turdus -leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) e Elaenia spp. (Tyrannidae). O número de visitas não diferiu significativamente entre os diferentes intervalos de hora do dia. Não foi encontrada correlação significativa entre o número de visitas e o número de frutos presentes em cada árvore. As aves generalistas foram as principais potenciais dispersoras de P. glabrata, tendo apresentado altas taxas de visitação, alto consumo de diásporos, e permaneceram sobre as plantas durante curtos períodos de tempo. Muitas das espécies de aves observadas são bastante abundantes mesmo em ambientes antrópicos, o que deve garantir a dispersão das sementes de P. glabrata em pequenos fragmentos e em áreas que se encontram em estágio de recuperação.