531 research outputs found

    Temporary caging results in reduced levels of circulating melatonin in migratory robins.

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    The hormone melatonin, a main component of the avian circadian system, plays an important role in the physiological transitions that accompany the activation of the migratory phenotype in passerine birds. Most small passerines migrate at night when circulating concentrations of melatonin are elevated. Previous work measured nocturnal melatonin levels of migratory birds only in captive animals, because free-living individuals are usually caught at day time. In this study, we compared nocturnal melatonin levels of European robins (Erithacus rubecula) caught during the day and held in cages overnight with those of birds that were caught at night and sampled immediately. We found that circulating melatonin at night was lower in birds held in cages compared to birds that were actively migrating. This result suggests that temporary caging affects the melatonin system and that in nature melatonin levels could be generally higher than those previously described by studies on captive birds

    Damages and Benefits of Certification: A perspective from an Independent Assessment Body

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    The paper investigates on the nature of software certification and its reasons of being. The numerous factors that impact on the achievement of its purposes are discussed, and also compared in the cases of Proprietary Software and Open Source Software. Some relevant features of a certification process for Open Source Software are finally proposed

    Ex-situ evaluation of morphological, agronomic and qualitative traits of a naturalized population of parsley (Petroselinum crispum (Mill) Nyman])

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    A naturalized population of parsley of the province of Trento, Italy, was evaluated ex-situ for its morphological and agronomic traits in a field trial in which it was compared with three commercial cultivars of the species. The naturalized population belongs to the smooth leaf type for the absence of curling, and differed from the other smooth leaf type accessions for the lower plant height, the smaller length of petiole and the prostrate attitude of the plant, all undesirable characteristics which make the harvest of plants more difficult. The yields of aerial parts and leaves were higher in the commercial cultivars, while the naturalized population had the highest yield and content of essential oil. Due to the high content and yield of essential oil, the naturalized population could be the object of an eventual breeding program aiming to improve the morphologic and agronomic undesirable characteristics

    Process Scenarios in Open Source Software Certification

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    Certification of Open Source Software (OSS) presents inherent trade-offsdue to the necessity of precisely identifying both a product and an independent certificationagent, and on the other of maintain the peculiar, valuable OSS characteristicof being available to an unlimited multiplicity of actors for trial, use and change.This is an intriguing challenge, usually solved by removing from the picture thecertifying agent and providing an intrinsic certification by means of rigorous, reapplicableproperty demonstrations, adopting Formal Methods (FM) in expressingand verifying the code. As such approach, yet quite valuable and good-promising,has some restrictions (such as the limited set of provable product qualities), we proposeto tackle the problem by analysing the various processes executed by differentOSS stakeholders, including the process of an independent Certification Body. Inthe paper some kinds of representative scenarios in which such processes interleaveare presented and discussed. The aim is to introduce a process-centered perspectivefor OSS that can stimulate research to further understand and mitigate the mentionedtrade-offs

    Stopover dynamics of 12 passerine migrant species in a small Mediterranean island during spring migration

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    Small coastal islands offer landing opportunities for large numbers of migratory birds following long sea crossings. However, they do not always provide sufficient refueling opportunities, thus raising questions about their importance for the success of migratory journeys. Here we analyzed a large dataset collected during 3 years of captures and recaptures of 12 species on the island of Ponza, central Italy, to determine the importance of the island for refueling. Despite the very large amount of birds on the island, only a very small fraction (usually below 2%) stayed on the island for longer than 1 day. These birds had low energy stores and, in most cases, they were not able to successfully refuel on Ponza. Only two species (Subalpine Warbler and Common Chiffchaff) had a positive fuel deposition rate, possibly as a result of the better suitability of the island's habitat to these two species. We underline that the large use of the island despite the relatively low refueling opportunities may be due to other aspects that it may offer to the birds. Possibly, birds just landed after a long sea crossing may require a short rest or sleep and can find opportunities to do that on the islands, reinitiating their onward flight after just a few hours. Understanding the role of these islands for migratory birds will be important for conservation, since setting priorities for protection might be misled if considering only refueling success as an important variable

    Heat loss in sleeping Garden Warblers (Sylvia borin) during migration

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    For small songbirds, energy is often a limiting factor during migration and, for this reason, they are forced to alternate nocturnal flights with stopovers to rest and replenish energy stores. Stopover duration has a key role for a successful migration and may have an important impact on fitness. Thus, migrants need to optimize their energy consumption at this stage to reduce their permanence at the site. A recent study has shown that lean individuals reduce their metabolic rate when tucking the head in the feathers during sleep. The underlying mechanism is very likely a reduction in conductance, but the thermoregulatory benefit of the increased insulation has never been quantified yet. Here, we compared heat loss in individual migratory birds while sleeping in different postures. Using a thermal camera and a within-individual approach, we estimated that Garden Warblers can reduce their rate of heat loss by 54% by sleeping with the head tucked in the feathers. This energy saving has a relevant impact on the individual’s energy balance because it can account for up to 8.69% of daily energy expenditure during stopover. Our study provides novel and important information to understand the fundamental role of thermoregulatory strategies on bird’s energy management
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