114 resultados para Plumage
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The species Sporophila bouvreuil comprises four subspecies: S. b. bouvreuil, S. b. pileata, S. b. saturata and S. b. crypta. The males of each subspecies differ in plumage whereas the females and juveniles are very similar and difficult to identify to subspecies. Here we use external morphological characters, mostly plumage, to examine the validity of the subspecies. A total of 209 specimens was examined (131 S. b. bouvreuil, 29 S. b. crypta, 43 S. b. pileata and 6 S. b. saturata). Although morphological measurements did not separate any taxa, plumage patterns support recognition of two taxonomic units, one of birds having reddish brown male plumage and the other of birds with grayish to white male plumage. Discrete diagnostic characters and sympatry in SE Brazil allow separation of Sporophila pileata (Sclater 1864) from S. bouvreuil (Muller 1776). On the other hand, S. b. saturata Hellmayr 1904 and S. b. crypta Sick 1968 should be considered synonyms of S. bouvreuil.
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Theory suggests that carotenoid-based signals are used in animal communication because they contain specific information about parasite resistance or immunocompetence. This implies that honesty of carotenoid-based signals is maintained by a trade-off between pigmentation and immune function for carotenoids, assuming that the carotenoids used for coloration are also immunoenhancing. We tested this hypothesis by altering the diets of nestling great tits (Paris major) with supplementary beadlets containing the carotenoids that are naturally ingested with food or beadlets containing the carotenoids that are incorporated into the feathers; a control group received beadlets containing no carotenoids. We simultaneously immune challenged half of the nestlings of each supplementation group, using a two-factorial design. Activatior of the immune system led to reduced color expression. However, only nestlings fed with the naturally ingested carotenoids and not with the carotenoids deposited in the feathers showed an increased cellular immune response. This shows that the carotenoids used for ornamentation do not promote the immune function, which conflicts with the trade-off hypothesis. Our results indicate that honesty of carotenoid-based signals is maintained by an individual's physiological limitation to absorb and/or transport carotenoids and by access to carotenoids, indicating that preferences for carotenoid-based traits in sexual selection or parent-offspring interactions select for competitive individuals, rather than specifically for immune function.
Ultraviolet reflectance of plumage for parent offspring communication in the great tit (Parus major)
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Avian plumage has long been used to test theories of sexual selection, with humans assessing the colors. However, many birds see in the ultraviolet (<400 nm), to which humans are blind. Consequently, it is important to know whether natural variation in UV reflectance from plumage functions in sexual signaling. We show that female starlings rank males differently when UV wavelengths are present or absent. Principal component analysis of ≈1300 reflectance spectra (300–700 nm) taken from sexually dimorphic plumage regions of males predicted preference under the UV+ treatment. Under UV− conditions, females ranked males in a different and nonrandom order, but plumage reflectance in the human visible spectrum did not predict choice. Natural variation in UV reflectance is thus important in avian mate assessment, and the prevailing light environment can have profound effects on observed mating preferences.
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Mode of access: Internet.
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Unequal sex ratios lead to the loss of genetic variability, decreasing the viability of populations in the long term. Anthropogenic activities often disturb the natural habitats and can cause alterations in sex ratio and morphological characteristics of several species. Forest fragmentation is a major conservation concern, so that understanding its effects in natural populations is essential. In this study, we evaluated the sex ratio and the morphological characteristics of Rufous Gnateaters (Conopophaga lineata (Wied, 1831)) in small and large forest fragments in Minas Gerais, Brazil. Birds (n = 89) were sexed by plumage characteristics and molecular markers. The molecular analysis showed that plumage is not a totally reliable method for sexing Rufous Gnateaters. We observed that sex ratio did not differ between large and small forest fragments, but birds in small fragments had larger wings and tarsus. Wing and tarsus changes may affect the movement ability of individuals within and among forest fragments. In conclusion, Rufous Gnateaters have been able to survive in both small and large Atlantic rain forest fragments without altering their sex ratio, but morphological changes can be prejudicial to their long term survival.
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The Dark-winged Trumpeter, Psophia viridis (Gruiformes, Psophiidae) is a Brazilian endemic species and includes three subspecies: Psophia viridis viridis Spix, 1825; Psophia v. dextralis Conover, 1934, and Psophia v. obscura Pelzeln, 1857, as well as P. v. interjecta Griscom & Greenway, 1937, whose validity has been questioned by several authors. These taxa are allopatric in distribution along the south of the Amazon River, although the precise limits of their distribution still remain unknown. This complex has never been taxonomically reviewed and this work aims to test the validity of its taxa based on the Phylogenetic Species Concept. Morphometrical characters and plumage colour patterns were analyzed, and the distribution of the taxa was also revised. In this study, 108 specimens from 41 localities were examined (all types included), with each reliable literature-based locality being included in order to delimit the geographical distribution of the complex. Morphometrical data did not point out significant differences between the taxa, also showing no sexual dimorphism among them. Meanwhile, plumage characters showed consistent and distinct patterns for each of the taxa, except for P. v. interjecta, whose features indicated by authors as diagnosable are the result of individual variation. No clinal variation or intergradation were observed, even at regions close to the rivers headwaters, where supposedly populations could be in contact. It is suggested that the currently accepted subspecies be elevated to the species level, such as: Psophia viridis Spix, 1825, distributed in the Madeira-Tapajós interfluvium, P. dextralis, found in the Tapajós-Tocantins interfluvium, and P. obscura, which occurs from the right bank of the Tocantins River to the west of the State of Maranhão.
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A Estação Ecológica Serra Geral do Tocantins (EESGT) é uma das maiores Unidades de Conservação dentro do Bioma Cerrado. A avifauna desta UC foi inventariada entre os dias 25 de janeiro e 15 de fevereiro de 2008. Durante esse trabalho buscou-se amostrar os diferentes hábitats encontrados na EESGT, bem como algumas localidades no entorno. Além de registros auditivos e visuais foram utilizadas redes-de-neblina e armas de fogo para coletas de material testemunho, que se encontra depositado na coleção ornitológica do Museu de Zoologia da Universidade de São Paulo (MZUSP). Os resultados obtidos foram comparados com os dados disponíveis para outras unidades de conservação presentes na região. Foram registradas 254 espécies de aves, incluindo 11 endêmicas do Cerrado e outras três ameaçadas de extinção (Taoniscus nanus, Anodorhynchus hyacinthinus e Procnias averano). Três indivíduos pertencentes ao gênero Picumnus foram coletados; estes apresentam um distinto padrão de plumagem e de vocalização, podendo representar um táxon ainda não descrito.
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Phaethornis longuemareus aethopyga was described by John T. Zimmer in 1950 and treated as a valid subspecies until it was proposed that the three known specimens were hybrids between R ruber and P. rupurumii amazonicus. On the basis of some recently collected specimens, we reevaluated the validity of P. l. aethopyga. Despite showing some differences related to age and sex, all specimens agree in the general plumage pattern and are fully diagnosable when compared with any other taxon of the genus. The hypothesis of a hybrid origin becomes unsustainable when one notes that (1) P. l. aethopyga has characters that are unique and absent in the purported parental species, such as the white outer margins at the base of the rectrices; and (2) P. l. aethopyga occurs far from the distribution of one of the alleged parental species. Furthermore, field data show that P. l. aethopyga has attributes typical of a valid and independent taxon, such as lekking behavior. Therefore, given its overall diagnosis, P. aethopyga could at least be treated as a phylogenetic species. Yet its morphological and vocal distinctiveness with respect to other Phaethornis spp. in the ""Pygmornis group"" is greater than that observed between some species pairs traditionally regarded as separate biological species within the group, which supports its recognition as a species under the biological species concept. Received 13 July 2008, accepted 9 March 2009.
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Studies on keratinolytic microorganisms have been mainly related to their biotechnological applications and association with animal pathologies. However, these organisms have an ecological relevance to recycling keratinous residues in nature. This work aimed to select and identify new culturable feather-degrading bacteria isolated from soils of Brazilian Amazon forest and Atlantic forest. Bacteria that were isolated from temperate soils and bacteria from Amazonian basin soil were tested for their capability to grow on feather meal agar (FMA). Proteolytic bacteria were tested for feather degradation and were further identified according to their morphological and biochemical characteristics. Also, molecular identification based on 165 rDNA gene sequencing was carried out. A total of 24 proteolytic and 20 feather-degrading isolates were selected; Most of the isolates were from the Bacillus genus (division Firmicutes), but one Aeromonas, two Serratia (gamma-Proteobacteria), and one Chryseobacterium (Cytophaga-Flavobacterium group). (C) 2010 Elsevier Ltd. All rights reserved.
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To understand how bees, birds, and fish may use colour vision for food selection and mate choice, we reconstructed views of biologically important objects taking into account the receptor spectral sensitivities. Reflectance spectra a of flowers, bird plumage, and fish skin were used to calculate receptor quantum catches. The quantum catches were then coded by red, green, and blue of a computer monitor; and powers, birds, and fish were visualized in animal colours. Calculations were performed for different illumination conditions. To simulate colour constancy, we used a von Kries algorithm, i.e., the receptor quantum catches were scaled so that the colour of illumination remained invariant. We show that on land this algorithm compensates reasonably well for changes of object appearance caused by natural changes of illumination, while in water failures of von Kries colour constancy are prominent. (C) 2000 John Wiley & Sons, Inc.
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Recent behavioural experiments have shown that birds use ultraviolet (UV)-reflective and fluorescent plumage as cues in mate choice. It remains controversial, however, whether such UV signals play a special role in sexual communication, or whether they are part of general plumage coloration. We use a comparative approach to test for a general association between sexual signalling and either UV-reflective or fluorescent plumage. Among the species surveyed, 72% have UV colours and there is a significant positive association between UV reflectance and courtship displays. Among parrots (Psittaciformes), 68% of surveyed species have fluorescent plumage, and again there is a strong positive association between courtship displays and fluorescence. These associations are not artefacts of the plumage used in courtship displays, being generally more 'colourful' because there is no association between display and colours lacking UV reflectance or fluorescence. Equally, these associations are not phylogenetic artefacts because all results remain unchanged when families or genera, rather than species, are used as independent data points. We also find that, in parrots, fluorescent plumage is usually found adjacent to UV-reflective plumage. Using a simple visual model to examine one parrot, the budgerigar Melopsittacus undulatus, we show that the juxtaposition of UV-reflective and fluorescent plumage leads to a 25-fold increase in chromatic contrast to the budgerigar's visual system. Taken together, these results suggest that signals based on UV contrast are of special importance in the context of active sexual displays. We review briefly six hypotheses on why this may be the case: suitability for short-range signalling; high contrast with backgrounds; invisibility to predators; exploitation of pre-existing sensory biases; advertisement of feather structure; and amplification of behavioural signals.
Reproductive dynamics of Sterna hirundinacea Lesson, 1831 in Ilha dos Cardos, Santa Catarina, Brazil
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In this work, we intend to describe the reproductive dynamics of Sterna hirundinacea in an island fromSouth Brazil.We studied the reproductive biology of this species in its natural environment and provide data on their growth, survival, and reproductive success in Ilha dosCardos, SantaCatarina, South Brazil. Samplingswere carried out daily on the island throughout the reproductive seasons of 2003, 2005, and 2006 and the different stages of development of the chicks were characterized according to age, length of the beak, and plumage characteristics.We provide a basic equation Lm = 167.91 (1 – e −0.062t−(−0.23)) to determine the approximate age of individuals using their body mass. The main cause of chick mortality on the island was natural (63.17% in 2003, 81.41% in 2005, and 79.96% in 2006), whereas predation contributed to mortality in a proportion of 38.83% in 2003, 18.59% in 2005, and 20.04% in 2006.The absence in the area of the chicks’ main predator, Kelp gull (Larus dominicanus), the large number of chicks that reached the final stages of development, and their reproductive success demonstrate that Ilha dos Cardos is an important breeding site for the species in southern Brazil.
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The characters naked neck and black plumage proved to be due to single genes in a group of chicks growing at the Poultry Department of "Luiz de Queiroz" School of Agriculture, Piracicaba, Brasil. The two characters segregate independently and the animals with known genetical constitution will be used in the formation of a local breed.