ABSTRACT
Haemosporidian parasites can cause pathogenic infections, leading to death or a reduction in the physical and reproductive abilities of the host. Several studies have identified haemosporidian infections in neotropical bird communities, but few have been conducted in populations, relating the infection to the biological attributes of the species. To determine haemosporidian prevalence in a population of Antilophia galeata and to assess factors that may be associated with parasitaemia, we analysed blood smears of 62 individuals from a Cerrado forest fragment. For each individual, the body mass, length of tarsus, sex, presence/absence of brood patch and feather moult were recorded. In total, 33 (53.2%) individuals were infected with haemosporidian parasites, 32 (51.6%) were infected with Plasmodium spp. and one (1.61%) was infected with Haemoproteus sp. Parasitaemia was not related to seasons, sex, reproduction, moulting or body condition but correlated positively with total leucocyte count, suggesting that individuals may be effective in infection control. This population may be tolerant to haemosporidian parasites because, despite the high prevalence, parasitaemia was low and constant; this is a potentially chronic infection that showed no adverse effects on the parameters analysed in this population.
ABSTRACT
Fruit colour is considered an important feature mediating interactions between plants and frugivorous birds. Despite that, colour mediated interactions are context-dependent, and habitat disturbances may affect how frugivorous birds perceive fruit colours. This study assessed the influence of fruit colour and edge effect on the consumption of artificial fruits by frugivorous birds in three disturbed semideciduous forests in southeastern Brazil. In each of those areas, we performed a field experiment in which we placed artificial fruits of three different colours on plants and recorded their consumption by birds. Red-coloured fruits were ingested more often than yellow, but neither of them was consumed differently from dark-blue. Edge effect only affected consumption of yellow fruits. Our data neither support the hypothesis of preferential consumption of the highest contrasting colours nor of increased fruit consumption in the forest interior. These findings indicate that colour and edge effects, as well as the interaction between them, may not be strong predictors of fruit choice by birds in disturbed environments, especially because generalist species, which are less sensitive to the physical alterations in forests, are favoured in these areas.
A cor dos frutos é importante nas interações entre plantas e aves. Apesar disso, as interações mediadas por cores são contexto-dependentes e as alterações no habitat podem afetar a maneira como os frugívoros percebem a coloração dos frutos. Este estudo avaliou a influência da cor e do efeito de borda no consumo de frutos artificiais por aves em três florestas semidecíduas degradadas no sudeste brasileiro. Em cada uma dessas áreas, foi conduzido um experimento no qual foram colocados frutos artificiais de três cores diferentes nas plantas e foi registrado o seu consumo pelas aves. Os frutos vermelhos foram mais consumidos do que os amarelos, mas nenhum deles foi consumido mais frequentemente do que os azulescuros. O efeito de borda afetou apenas o consumo de frutos amarelos. Nossos dados não suportam as hipóteses de consumo preferencial da coloração mais contrastante nem do aumento do consumo de frutos no interior dos fragmentos. Estes resultados indicam que a cor dos frutos, o efeito de borda e a interação entre estes dois fatores, não são fortes preditores da escolha do fruto por aves em ambientes degradados, principalmente pela ocorrência de espécies generalistas nestas áreas, que são menos sensíveis às alterações físicas nos fragmentos.
Subject(s)
Birds/physiology , Nutrition Ecology , Fruit/anatomy & histologyABSTRACT
Frugivorous animals may use morphological traits of food items such as size, hardness, shape, color and smell as cues that allow them to assess cost-benefit relationship of foraging activity. Fruit size is an important trait that influences feeding behavior of most frugivores, since there is a functional correlation between fruit size and frugivores' body size. Therefore, size-based preference is fundamental to understand plant-frugivore interactions and seed dispersal. In this sense, we tested the hypothesis of preferential consumption of larger fruits of Piper arboreum by the short-tailed fruit bat Carollia perspicillata in the Brazilian tropical dry forest. Results showed considerable variation in fruit size among and within plants. There was also significant difference in fruit ripening time among plants, which was not related to fruit size. Average size of remaining fruits reduced as they were removed from plants by the bats, which indicates preferential consumption of larger fruits. On the other hand, plant phenology constrained consumption of bigger fruits. Only a small fraction of plant crop was available for consumption each night, regardless of fruit size, which probably coerced bats to feed on smaller fruits as the availability of larger ones decreased. Results suggest that bat preference on fruit size is mediated by plant phenological strategies.
Os frugívoros utilizam as características morfológicas dos frutos tais como tamanho, dureza, forma, cor e cheiro, como pistas para avaliar o custo-benefício da atividade de forrageio. O tamanho dos frutos é uma característica importante que influencia o comportamento alimentar dos frugívoros, já que existe uma correlação funcional entre tamanho do fruto e o do tamanho do frugívoro. Por isso, a seleção do fruto a partir do seu tamanho é um elemento fundamental para a compreensão das interações frugívoro-planta e da dispersão de sementes. Neste sentido, nós testamos a hipótese de consumo preferencial de frutos maiores de Piper arboreum pelo morcego Carollia perspicillata em uma floresta tropical brasileira. Os resultados mostraram ampla variação no tamanho do fruto entre e dentro das plantas parentais. Também houve diferença significativa no tempo de maturação dos frutos entre as plantas, o qual não esteve relacionado com o tamanho do fruto. O tamanho médio dos frutos restantes na planta após a remoção pelos morcegos decresceu, o que indicou o consumo preferencial dos frutos maiores. Por outro lado, a fenologia da planta restringiu o consumo destes frutos. Um número pequeno de frutos maduros esteve disponível para o consumo por noite, independentemente de seu tamanho, o que provavelmente limitou a escolha dos morcegos, obrigando-os a se alimentarem dos frutos menores conforme a disponibilidade dos maiores reduziu-se. Os resultados sugerem que a preferência dos morcegos pelo tamanho dos frutos é mediada pelas estratégias fenológicas das plantas.