927 resultados para Jim Bird
Resumo:
One could be seduced into a critique of this volume that focuses on its potential to overstate the momentum for a shift in Western social work ideology when faced with the conundrum of cultural difference. One could posit that the discussion is too broad, the topics covered too numerous, the opportunity for detail missed, the urgency of the messages unnecessarily exaggerated, the “proof” not beyond anecdote and so forth. I reject this temptation to conform to the dominant professional dynamic most emphatically and offer that what Gray, Coates and Yellow Bird have presented to the social work field in this volume is the first tangible step towards an alternative paradigm for an occupation afflicted with unsustainable hypocrisy and thus at the brink of irrelevancy.
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The conversion of forest into farmland has resulted in mosaic landscapes in many parts of the tropics. From a conservation perspective, it is important to know whether tropical farmlands can buffer species loss caused by deforestation and how different functional groups of birds respond to land-use intensification. To test the degree of differentiation between farmland and forest bird communities across feeding guilds, we analyzed stable C and N isotopes in blood and claws of 101 bird species comprising four feeding guilds along a tropical forest-farmland gradient in Kenya. We additionally assessed the importance of farmland insectivores for pest control in C4 crops by using allometric relationships, C stable isotope ratios and estimates of bird species abundance. Species composition differed strongly between forest and farmland bird communities. Across seasons, forest birds primarily relied on C3 carbon sources, whereas many farmland birds also assimilated C4 carbon. While C sources of frugivores and omnivores did not differ between forest and farmland communities, insectivores used more C4 carbon in the farmland than in the forest. Granivores assimilated more C4 carbon than all other guilds in the farmland. We estimated that insectivorous farmland birds consumed at least 1,000 kg pest invertebrates km−2 year−1. We conclude that tropical forest and farmland understory bird communities are strongly separated and that tropical farmlands cannot compensate forest loss for insectivorous forest understory birds. In tropical farmlands, insectivorous bird species provide a quantitatively important contribution to pest control.
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Aim The Neotropical parrots (Arini) are an unusually diverse group which colonized South America in the Oligocene. The newly invaded Neotropics may have functioned as an underused adaptive zone and provided novel ecological opportunities that facilitated diversification. Alternatively, diversification may have been driven by ecological changes caused by Andean uplift and/or climate change from the Miocene onwards. Our aim was to find out whether Arini diversified in a classical adaptive radiation after their colonization of South America, or whether their diversification occurred later and was influenced by more recent environmental change. Location Neotropics. Methods We generated a time-calibrated phylogeny of more than 80% of all Arini species in order to analyse lineage diversification. This chronogram was also used as the basis for the reconstruction of morphological evolution within Arini using a multivariate ratio analysis of three size measurements. Results We found a concentration of size evolution and partitioning of size niches in the early history of Arini consistent with the process of adaptive radia- tion, but there were no signs of an early burst of speciation or a decrease in speci- ation rates through time. Although we detected no overall temporal shifts in diversification rates, we discovered two young, unexpectedly species-rich clades. Main conclusions Arini show signs of an early adaptive radiation, but we found no evidence of the slowdown in speciation rate generally considered a feature of island or lake radiations. Historical processes and environmental change from the Miocene onwards may have kept diversification rates roughly constant ever since the colonization of the Neotropics. Thus, Arini may not yet have reached equilibrium diversity. The lack of diversity-dependent speciation might be a general feature of adaptive radiations on a continental scale, and diversification processes on continents might therefore not be as ecologically limited as in isolated lakes or on oceanic islands.
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Many studies have examined whether communities are structured by random or deterministic processes, and both are likely to play a role, but relatively few studies have attempted to quantify the degree of randomness in species composition. We quantified, for the first time, the degree of randomness in forest bird communities based on an analysis of spatial autocorrelation in three regions of Germany. The compositional dissimilarity between pairs of forest patches was regressed against the distance between them. We then calculated the y-intercept of the curve, i.e. the ‘nugget’, which represents the compositional dissimilarity at zero spatial distance. We therefore assume, following similar work on plant communities, that this represents the degree of randomness in species composition. We then analysed how the degree of randomness in community composition varied over time and with forest management intensity, which we expected to reduce the importance of random processes by increasing the strength of environmental drivers. We found that a high portion of the bird community composition could be explained by chance (overall mean of 0.63), implying that most of the variation in local bird community composition is driven by stochastic processes. Forest management intensity did not consistently affect the mean degree of randomness in community composition, perhaps because the bird communities were relatively insensitive to management intensity. We found a high temporal variation in the degree of randomness, which may indicate temporal variation in assembly processes and in the importance of key environmental drivers. We conclude that the degree of randomness in community composition should be considered in bird community studies, and the high values we find may indicate that bird community composition is relatively hard to predict at the regional scale.
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We present the postmortem findings of a fatal road accident involving a motorcyclist, a car, and a common buzzard. Both the motorcyclist and the bird died on the scene of the accident and were examined by postmortem full-body CT and autopsy. In addition, a facial injury of the motorcyclist was compared with the dimensions of the buzzard’s beak and claws by 3D scan technologies. Blood splatters collected on the bird’s beak, feet, and tail were examined by DNA analysis. The overall findings suggested a collision of a common buzzard with a motorcyclist in full speed, causing the motorcyclist to lose control of his vehicle and crash with an approaching car on the oncoming lane.
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Das «Dodo-Bird-Verdikt», Ende der achtziger Jahre Resultat einer Metaanalyse, stellte fest, dass sich die etablierten Psychotherapieschulen in ihrer Wirksamkeit statistisch nicht bedeutsam unterscheiden. Der Begriff hat seinen Ursprung in «Alice im Wunderland», wo ein Dodo den Vorschlag macht, ein Rennen zu veranstalten, bei dem am Ende alle gewinnen, weil es kein Ziel gibt und auch die Zeit nicht gemessen wird. – Ist die These unter Akteuren der Psychotherapie en vogue? Ein Kommentar.
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Jos.