962 resultados para Nest-site Selection


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Differences in the phoresy of the mites Macrocheles muscaedomesticae (Scopoli, 1972) (Macrochelidae) and Uroseius sp. (Polyaspidae) on the house fly, Musca domestica (Linnaeus, 1758) and the similarities in their phoretic dispersal and parasitism are discussed, altogether with the effects on predator-prey interactions. The prevalence and intensity of phoresy in the mite species were significantly related to the attachment site on the hosts. The phoresy of Uroseius sp. was correlated with temperature but not with rainfall and relative humidity. Selective pressure in the environment resulted in displacement and the emergence of local and regional populations. These results suggest that in each habitat the populations will use different resources and will show several relationships with other species, as well as a selection for morphological and behavioral types.

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Shell selection by the hermit crab Paguristes tortugae Schmitt, 1933 from Anchieta Island (Brazil) was analyzed using the six most frequently occupied shell species in the field and taking into account the sexual condition of the individuals, the shell size and the shell species. The experiments were conducted under laboratory conditions and the shell species preference was estimated on the basis of the frequency that each species was chosen by the individuals. The preferred shell species and size were determined by regression analysis. The highest correlation coefficients were obtained for the relations between the hermit dimensions and shell dry weight. The ovigerous females preferred shells with larger internal volume: Leucozonia nassa (Gmelin, 1791) and Cerithium atratum (Born, 1778). In the experiment of shell size, males preferred heavier shells whereas females selected the shape characteristics of the shell, such as the aperture and the internal volume, which are probably related to the growth and offspring guarantee, respectively. In general, and independent of sex condition, P. tortugae showed significant selection among all shells utilized. The results suggest that shell selection by P. tortugae involves sexual and reproductive condition preferences.

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This study aimed to evaluate the water depth selection during foraging, the efficiency in prey capture, and the food items captured by Casmerodius albus (Linnaeus, 1758) and Egretta thula (Molina, 1782). The work was conducted at an urban lagoon, Lagoa Rodrigo de Freitas, Rio de Janeiro. Four transects were made each month (two in the morning and two in the afternoon) for six months. When the birds were detected foraging, the water depth and the types of prey captured were recorded. There was no significant relationship between the foraging efficiencies of the two species. However, they differed in relation to the water depth when foraging, and also in the food items captured. Casmerodius albus captured mainly fishes while Egretta thula captured mainly invertebrates. The results suggest that the differences in water depth when foraging and the food items captured allow a differential use of the food resources available by C. albus and E. thula at Lagoa Rodrigo de Freitas.

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The Rufous Hornero (Furnarius rufus) is one of the most common bird species in Brazil. Anecdotal information indicates that nest opening orientation in this species is contrary to wind or rainfall direction. To check for the existence of such a pattern, F. rufus nests were randomly sampled within an urban area in central Brazil to assess whether factors such as wind and vegetation cover influence nest opening orientation. Using circular statistics, no evidence was found that nest-opening orientation was important for the species. These results refuse the expected pattern for tree hollow or enclosed nests. The results suggest that factors such as nesting architecture, nest material, nest microclimate or a combination of these, instead of local climate, must be conditioning nesting behavior in this species.

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v.39:no.53(1961)

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The only breeding record of Spartonoica maluroides (d'Orbigny & Lafresnaye, 1837) for Brazil is based on the observation of a fledgling in southern Rio Grande do Sul in January 1976. On 7 December 2005 we discovered a nest containing three nestlings at the southeastern end of Lagoa Pequena, municipality of Pelotas, Rio Grande do Sul. The nest was concealed at the base of a cavity in a Spartina densiflora (Poaceae) tussock located at the edge of a saltmarsh. The nest was built of fine pieces of dead Scirpus olneyi (Cyperaceae) and S. densiflora leaves firmly interlaced to the internal leaves of the tussock. Live leaves of S. densiflora lining the cavity comprised a substantial part of the nest's architecture, forming most of its upper lateral walls and roof. The lower section was more elaborate, resembling a deep cup and forming a distinct incubation chamber. Adults reached the nest's interior through an irregular apical opening amidst the leaves. The nest was 244 mm high and 140 mm wide. The incubation chamber had an external diameter of 138.5 mm, an internal diameter of 79.4 mm and was 86 mm deep. It was lined with fine leaves and white plant fibers. Nestlings were five to six days old. A total of 107 neossoptiles restricted to the capital, spinal and alar tracts were recorded in one nestling. The distribution of neossoptiles in the ocular region of S. maluroides forms a distinct pattern which can be typical of Furnariidae and related families. Two adults attended the nest, bringing small insects to the nestlings and removing fecal sacs. We recorded at least 74 visits to the nest during a ca. 6 h period during an afternoon. The average number of visits per hour was 12.8 ± 1.3. An adult bird spent on average 0.7 ± 0.56 minutes inside the nest attending nestlings. The nest remained unattended on average for 3.61 ± 3.13 minutes. The hour of the day had no influence on the amount of time spent by an adult in the nest or away from it. We returned to the area on 15 December 2005 and found the nest abandoned. Observations confirm that S. maluroides is a resident breeder in southern Brazil and that the saltmarshes of the Lagoa do Patos estuary are an important year-round habitat for the species. A nestling and the nest were collected to document the record.

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We document the expansion of the breeding distribution of the Little Blue Heron Egretta caerulea (Linnaeus, 1758) to 850 km beyond its previous southern limit in South America. In addition we present data on abundance, breeding biology and food of the species in the Patos Lagoon estuary, the area which the species recently colonized. The maximum abundance recorded in the breeding colony and in a nocturnal roosting site was 53 and 49 individuals respectively. Nesting occurred from September to March. Birds nested in a mixed breeding colony together with about 3,000 breeding pairs of seven other species of Pelecaniformes, in a swampy forest near the margin of the estuary. Five nests were between 1.5 and 4.3 m from the ground, on the shrub Daphnopsis racemosa (Thymelaeaceae), on the trees Sebastiana brasiliensis (Euphorbiaceae) and Mimosa bimucronata (Leguminosae), or on the bamboo Bambusa sp. (Poaceae). Four nests produced two fledglings each, while one nest was abandoned. Of 13 grouped samples of food regurgitated by five nestlings, Pink Shrimp Farfantepenaeus paulensis (Perez-Farfante, 1967) constituted 70% in mass, while total length of ingested fishes and shrimps varied mostly between 20 and 50 mm. Estuarine prey items represented 99% of the total food mass. The recent southward expansion of the breeding range of the Little Blue Heron in South America may be a response to climate warming of the Patos Lagoon estuary. Degradation of estuaries in the southwestern Atlantic may also be forcing the birds to breed in areas outside previous geographical range.

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Markowitz portfolio theory (1952) has induced research into the efficiency of portfolio management. This paper studies existing nonparametric efficiency measurement approaches for single period portfolio selection from a theoretical perspective and generalises currently used efficiency measures into the full mean-variance space. Therefore, we introduce the efficiency improvement possibility function (a variation on the shortage function), study its axiomatic properties in the context of Markowitz efficient frontier, and establish a link to the indirect mean-variance utility function. This framework allows distinguishing between portfolio efficiency and allocative efficiency. Furthermore, it permits retrieving information about the revealed risk aversion of investors. The efficiency improvement possibility function thus provides a more general framework for gauging the efficiency of portfolio management using nonparametric frontier envelopment methods based on quadratic optimisation.

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This comment corrects the errors in the estimation process that appear in Martins (2001). The first error is in the parametric probit estimation, as the previously presented results do not maximize the log-likelihood function. In the global maximum more variables become significant. As for the semiparametric estimation method, the kernel function used in Martins (2001) can take on both positive and negative values, which implies that the participation probability estimates may be outside the interval [0,1]. We have solved the problem by applying local smoothing in the kernel estimation, as suggested by Klein and Spady (1993).