815 resultados para COMMUNAL NESTING


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Observations on the nesting activities of Microthurge corumbae, carried out at the University Campus of Ribeirao Preto, São Paulo, Brazil, from 1977 to 1981, indicated that 61.9% of nests were re-used by succeeding generations. Re-use by one generation was more frequent than by two generations, and re-use by a third was observed only once. Nests were re-used by one or several females. Single females were more frequently in the first re-use. In these cases nest re-use did not differ essentially from the solitary foundation of a new nest, except for the adoption of a pre-existing nest without excavation. In multifemale nests, analysis of relative age (wing wear), ovarian and spermathecal conditions of associated females and the content of nests at excavation indicated that the social pattern in such colonies is communal. There is some evidence that the associated females are relatives. The chalcidoid wasp Leucospis was the principal nest parasite, and ants of the genus Crematogaster were nest predators. In multifemale nests, the rate of parasitism was significantly lower than in solitary nests, indicating that nest-sharing resulted in improved nest defense. on the other hand. The absence of predation on immatures of the first generation of M. corumbue in multifemale nests suggests that such nests are also more resistant to attack by predators.

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Solitary and presocial aculueate Hymenoptera are parasitized by a range of dipteran species in the families Axithomyiidae, Bombyliidae, Conopidae, Phoridae, and Sarcophagidae that are likely to impact on their hosts. We undertook a study over several years of a univoltine and communal bee, Andrena agilissima, and its main dipteran parasites, in particular the satellite fly Leucophora personata (Diptera: Anthomyiidae). Behavioural and ecological data were collected from one nesting aggregation of the host bee on the island of Elba, Italy, from 1993 to 2003, and from a foraging site of the bee, ca 5 km from the nesting aggregation. Other Diptera associated with A. agilissmia at the field site were the bee fly Bombylius fimbriatus (Bombyliidae), the conopid fly Zodion cinereum (Conopidae), and the scuttle fly Megaselia andrenae (Phoridae). The phenology of the Diptera broadly overlapped with that of their host across the season of activity (end of April and all of May). Diurnal activity patterns differed slightly; L. personata in particular was active at the host's nesting site before A. agilissima. Female satellite flies also showed a range of behaviours in gaining entry to a host nest. We summarize published data on this and other Leucophora species that parasitize Andrena host bees. Host bees returning to their nests occasionally undertook zig-zag flight manoeuvres if followed by a satellite fly that were generally successful in evading the fly. Satellite flies that entered a nest, presumably to oviposit, were less likely to remain therein if another host bee entered the same nest, suggesting that one advantage to communal nesting for this host is a reduction in brood cell parasitism by L. personata. We provide the first clear evidence for parasitism by a Zodion of any Andrena host. Both L. personata and M. andrenae concentrated their parasitic activities in the zone of the host nesting aggregation with highest nest densities. Three of the Diptera, L. personata, B. fimbriatus, and Z. cinereum, seemed to have extremely low rates of parasitism whilst that of M. andrenae appeared low. Though they have refined parasitic behaviour that allows them to gain entry into host nests (L. personata, B. fimbriatus, and M. andrenae) or to parasitize adults (Z. cinercum), these parasites seem not to impact upon the dynamics of the host A. agilissima at the nesting aggregation, and the host possesses traits to reduce parasitism.

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This article reports on the design and implementation of a computer-aided sheet nesting system (CASNS) for the nesting of two-dimensional irregular-shaped sheet-metal blanks on a given sheet stock or coil stock. The system is designed by considering several constraints of sheet-metal stamping operations, such as bridge width and grain orientation, and design requirements such as maximizing the strength of the part hen subsequent bending is involved, minimization of scrap, and economic justification for'a single or multiple station operation. Through many practical case studies, the system proves its efficiency, effectiveness and usefulness.

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Collective Coverings, Communal Skin is a large-scale site-specific installation that grows with community contributions created for the 2012 Liverpool Biennial. The work involves transforming objects used in conflict (second hand hunting and camouflage t-shirts) into objects of comfort (hula hoop rag mats) . Many of the shirts were either donated or purchased from thrift stores in Los Angeles and Liverpool. With the massive help of the Liverpool community we transformed individual t-shirts through weaving them into a communal skin that covers the existing internal architecture. There was a workshop space with instruction video, inside the installation where visitors could sit and work on patchwork body-pillows. During structured workshops I talked with the community about meditating while they weave so as to contemplate the spiritual and conceptual dimension of the project. The hula-hoop weavings grew throughout the space for the duration of the 10-week Biennial. The community contributed 770 weavings. This project was funded by the Australia Council for the Arts and FACT.

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Herbivorous turtle, Chelonia mydas, inhabiting the south China Sea and breeding in Peninsular Malaysia, and Natator depressus, a carnivorous turtle inhabiting the Great Barrier Reef and breeding at Curtis Island in Queensland, Australia, differ both in diet and life history. Analysis of plasma metabolites levels and six sex steroid hormones during the peak of their nesting season in both species showed hormonal and metabolite variations. When compared with results from other studies progesterone levels were the highest whereas dihydrotestosterone was the plasma steroid hormone present at the lowest concentration in both C. mydas and N. depressus plasma. Interestingly, oestrone was observed at relatively high concentrations in comparison to oestradiol levels recorded in previous studies suggesting that it plays a significant role in nesting turtles. Also, hormonal correlations between the studied species indicate unique physiological interactions during nesting. Pearson correlation analysis showed that in N. depressus the time of oviposition was associated with elevations in both plasma corticosterone and oestrone levels. Therefore, we conclude that corticosterone and oestrone may influence nesting behaviour and physiology in N. depressus. To summarise, these two nesting turtle species can be distinguished based on the hormonal profile of oestrone, progesterone, and testosterone using discriminant analysis.

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Males of lek-breeding species defend clustered territories from which they display to visiting females. However, the mechanisms leading to the adoption of clustered male display sites are often unknown. In this study, we examined the possibility of a resource-based lek in New Zealand’s lesser short-tailed bat (Mystacina tuberculata) (Mammalia: Chiroptera), by assessing the placement of “singing roosts” used by males in relation to communal roosting sites used by females. The “resource-based lek” model posits that males settle near resources required by females to increase female encounter rates. For most bat species, where females are highly mobile and widely dispersed across landscapes while foraging, communal daytime roosts dominated by females may represent such a resource. Through use of video footage, spatial analyses of singing-roost locations, and passive-integrated transponder tags we confirmed that M. tuberculata employs a lek mating system. We found that male singing roosts were significantly clustered in space, were defended by resident individuals, and were visited by females (who did not receive resources from males) for mating purposes. Transponder records also indicated that some singing roosts were shared between multiple males. Spatial logistic regression indicated that singing-roost locations were associated with communal roosting sites. Communal roosts are selected based on criteria independent of the locations of singing roosts, suggesting that males responded to the location of communal roosts and not the reverse. Mystacina tuberculata thus provides evidence of a resource-based lek, and is only the second bat species worldwide confirmed to use a lek-mating system.

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Background At Queensland University of Technology (QUT), the Bachelor of Radiation Therapy course evaluation has previously suffered from low online survey participation rates. A communal instantaneous feedback event using an audience response system (ARS) was evaluated as a potential solution to this problem. The aims of the project were to determine the extent to which this feedback event could be facilitated by ARS technology and to evaluate the impact the technology made on student satisfaction and engagement. Methods Students were invited to a timetabled session to provide feedback on individual study units and the course overall. They provided quantitative Likert-style responses to prompts for each unit and the course using an ARS as well as anonymous typed qualitative comments. Data collection was performed live so students were able to view collective class responses. This prompted further discussion and enabled a prospective action plan to be developed. To inform future ARS use, students were asked for their opinions on the feedback method. Results Despite technological difficulties, student evaluation indicated that all responders enjoyed the session and the opportunity to view the combined responses. All students felt that useful feedback was generated and that this method should be used in the future. The student attendance and response rates were high, and it was clear that the session had led to the development of some insightful qualitative feedback comments. Conclusions: An ARS contributed well to the collection of course feedback in a communal and interactive environment. Students found it enjoyable to use, and it helped to stimulate useful qualitative comments

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Report of field observations April 2007 to September 2011

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Rising global temperatures threaten the survival of many plant and animal species. Having already risen at an unprecedented rate in the past century, temperatures are predicted to rise between 0.3 and 7.5C in North America over the next 100 years (Hawkes et al. 2007). Studies have documented the effects of climate warming on phenology (timing of seasonal activities), with observations of early arrival at breeding grounds, earlier ends to the reproductive season, and delayed autumnal migrations (Pike et al. 2006). In addition, for species not suited to the physiological demands of cold winter temperatures, increasing temperatures could shift tolerable habitats to higher latitudes (Hawkes et al. 2007). More directly, climate warming will impact thermally sensitive species like sea turtles, who exhibit temperature-dependent sexual determination. Temperatures in the middle third of the incubation period determine the sex of sea turtle offspring, with higher temperatures resulting in a greater abundance of female offspring. Consequently, increasing temperatures from climate warming would drastically change the offspring sex ratio (Hawkes et al. 2007). Of the seven extant species of sea turtles, three (leatherback, Kemp’s ridley, and hawksbill) are critically endangered, two (olive ridley and green) are endangered, and one (loggerhead) is threatened. Considering the predicted scenarios of climate warming and the already tenuous status of sea turtle populations, it is essential that efforts are made to understand how increasing temperatures may affect sea turtle populations and how these species might adapt in the face of such changes. In this analysis, I seek to identify the impact of changing climate conditions over the next 50 years on the availability of sea turtle nesting habitat in Florida given predicted changes in temperature and precipitation. I predict that future conditions in Florida will be less suitable for sea turtle nesting during the historic nesting season. This may imply that sea turtles will nest at a different time of year, in more northern latitudes, to a lesser extent, or possibly not at all. It seems likely that changes in temperature and precipitation patterns will alter the distribution of sea turtle nesting locations worldwide, provided that beaches where the conditions are suitable for nesting still exist. Hijmans and Graham (2006) evaluate a range of climate envelope models in terms of their ability to predict species distributions under climate change scenarios. Their results suggested that the choice of species distribution model is dependent on the specifics of each individual study. Fuller et al. (2008) used a maximum entropy approach to model the potential distribution of 11 species in the Arctic Coastal Plain of Alaska under a series of projected climate scenarios. Recently, Pike (in press) developed Maxent models to investigate the impacts of climate change on green sea turtle nest distribution and timing. In each of these studies, a set of environmental predictor variables (including climate variables), for which ‘current’ conditions are available and ‘future’ conditions have been projected, is used in conjunction with species occurrence data to map potential species distribution under the projected conditions. In this study, I will take a similar approach in mapping the potential sea turtle nesting habitat in Florida by developing a Maxent model based on environmental and climate data and projecting the model for future climate data. (PDF contains 5 pages)

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Terns and skimmers nesting on saltmarsh islands often suffer large nest losses due to tidal and storm flooding. Nests located near the center of an island and on wrack (mats of dead vegetation, mostly eelgrass Zostera) are less susceptible to flooding than those near the edge of an island and those on bare soil or in saltmarsh cordgrass (Spartina alterniflora). In the 1980’s Burger and Gochfeld constructed artificial eelgrass mats on saltmarsh islands in Ocean County, New Jersey. These mats were used as nesting substrate by common terns (Sterna hirundo) and black skimmers (Rynchops niger). Every year since 2002 I have transported eelgrass to one of their original sites to make artificial mats. This site, Pettit Island, typically supports between 125 and 200 pairs of common terns. There has often been very little natural wrack present on the island at the start of the breeding season, and in most years natural wrack has been most common along the edges of the island. The terns readily used the artificial mats for nesting substrate. Because I placed artificial mats in the center of the island, the terns have often avoided the large nest losses incurred by terns nesting in peripheral locations. However, during particularly severe flooding events even centrally located nests on mats are vulnerable. Construction of eelgrass mats represents an easy habitat manipulation that can improve the nesting success of marsh-nesting seabirds.

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Foraging habitat selection of nesting Great Egrets ( Ardea alba ) and Snowy Egrets ( Egretta thula ) was investigated within an estuary with extensive impounded salt marsh habitat. Using a geographic information system, available habitat was partitioned into concentric bands at five, ten, and 15 km radius from nesting colonies to assess the relative effects of habitat composition and distance on habitat selection. Snowy Egrets were more likely than Great Egrets to depart colonies and travel to foraging sites in groups, but both species usually arrived at sites that were occupied by other wading birds. Mean flight distances were 6.2 km (SE = 0.4, N = 28, range 1.8-10.7 km) for Great Egrets and 4.7 km (SE = 0.48, N = 31, range 0.7-12.5 km) for Snowy Egrets. At the broadest spatial scale both species used impounded (mostly salt marsh) and estuarine edge habitat more than expected based on availability while avoiding unimpounded (mostly fresh water wetland) habitat. At more local scales habitat use matched availability. Interpretation of habitat preference differed with the types of habitat that were included and the maximum distance that habitat was considered available. These results illustrate that caution is needed when interpreting the results of habitat preference studies when individuals are constrained in their choice of habitats, such as for central place foragers.