821 resultados para Rare birds.


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Concern that European forest biodiversity is depleted and declining has provoked widespread efforts to improve management practices. To gauge the success of these actions, appropriate monitoring of forest ecosystems is paramount. Multi-species indicators are frequently used to assess the state of biodiversity and its response to implemented management, but generally applicable and objective methodologies for species' selection are lacking. Here we use a niche-based approach, underpinned by coarse quantification of species' resource use, to objectively select species for inclusion in a pan-European forest bird indicator. We identify both the minimum number of species required to deliver full resource coverage and the most sensitive species' combination, and explore the trade-off between two key characteristics, sensitivity and redundancy, associated with indicators comprising different numbers of species. We compare our indicator to an existing forest bird indicator selected on the basis of expert opinion and show it is more representative of the wider community. We also present alternative indicators for regional and forest type specific monitoring and show that species' choice can have a significant impact on the indicator and consequent projections about the state of the biodiversity it represents. Furthermore, by comparing indicator sets drawn from currently monitored species and the full forest bird community, we identify gaps in the coverage of the current monitoring scheme. We believe that adopting this niche-based framework for species' selection supports the objective development of multi-species indicators and that it has good potential to be extended to a range of habitats and taxa.

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The present study examines knowledge of the discourse-appropriateness of Clitic Right Dislocation (CLRD) in a population of Heritage (HS) and Spanish-dominant Native Speakers in order to test the predictions of the Interface Hypothesis (IH; Sorace 2011). The IH predicts that speakers in language contact situations will experience difficulties with integrating information involving the interface of syntax and discourse modules. CLRD relates a dislocated constituent to a discourse antecedent, requiring integration of syntax and pragmatics. Results from an acceptability judgment task did not support the predictions of the IH. No statistical differences between the HSs’ performance and that of L1-dominant native speakers were evidenced when participants were presented with an offline task. Thus, our study did not find any evidence of “incomplete acquisition” (Montrul 2008) as it pertains to this specific linguistic structure.

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Colour-magnitude diagrams (CMDs) of the Small Magellanic Cloud (SMC) star cluster NGC 419, derived from Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) data, reveal a well-delineated secondary clump located below the classical compact red clump typical of intermediate-age populations. We demonstrate that this feature belongs to the cluster itself, rather than to the underlying SMC field. Then, we use synthetic CMDs to show that it corresponds very well to the secondary clump predicted to appear as a result of He-ignition in stars just massive enough to avoid e(-)-degeneracy settling in their H-exhausted cores. The main red clump instead is made of the slightly less massive stars which passed through e(-) degeneracy and ignited He at the tip of the red giant branch. In other words, NGC 419 is the rare snapshot of a cluster while undergoing the fast transition from classical to degenerate H-exhausted cores. At this particular moment of a cluster`s life, the colour distance between the main-sequence turn-off and the red clump(s) depends sensitively on the amount of convective core overshooting, Lambda(c). By coupling measurements of this colour separation with fits to the red clump morphology, we are able to estimate simultaneously the cluster mean age (1.35(-0.04)(+0.11) Gyr) and overshooting efficiency (Lambda(c) = 0.47(-0.04)(+0.14)). Therefore, clusters like NGC 419 may constitute important marks in the age scale of intermediate-age populations. After eye inspection of other CMDs derived from HST/ACS data, we suggest that the same secondary clump may also be present in the Large Magellanic Cloud clusters NGC 1751, 1783, 1806, 1846, 1852 and 1917.

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Bird communities in tropical forests are strongly affected by both patch area and habitat edges. The fact that both effects are intrinsically confounded in space raises questions about how these two widely reported ecological patterns interact, and whether they are independent or simply different spatial manifestations of the same phenomenon. Moreover, do small patches of secondary forest, in landscapes where the most sensitive species have gone locally extinct, exhibit similar patterns to those previously observed in fragmented and continuous primary forests? We addressed these questions by testing edge-related differences in vegetation structure and bird community composition at 31 sites in fragmented and continuous landscapes in the imperilled Atlantic forest of Brazil. Over a two-year period, birds were captured with mist nets to a standardized effort of 680 net-hours at each site (similar to 22 000 net-hours resulting in 3381 captures from 114 species). We found that the bird community in patches of secondary forest was degraded in species composition compared to primary continuous forest, but still exhibited a strong response to edge effects. In fragmented secondary forests, edge and area effects also interacted, such that the magnitude of edge to interior differences on bird community composition declined markedly with patch size. The change in bird species composition between forest interiors and edges was similar to the change in community composition between large and small patches (because species had congruent responses to edge and area), but after controlling for edge effects community composition was no longer affected by patch area. Our results show that although secondary forests hold an impoverished bird community, ecological patterns such as area and edge effects are similar to those reported for primary forests. Our data provide further evidence that edge effects are the main drivers of area effects in fragmented landscapes.

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When assessing fragmentation effects on species, not only habitat preferences on the landscape scale, but also microhabitat selection is an important factor to consider, as microhabitat is also affected by habitat disturbance, but nevertheless essential for species for foraging, nesting and sheltering. In the Atlantic Rainforest of Brazil we examined microhabitat selection of six Pyriglena leucoptera (white-shouldered fire-eye), 10 Sclerurus scansor (rufous-breasted leaftosser), and 30 Chiroxiphia caudata (blue manakin). We radio-tracked the individuals between May 2004 and February 2005 to gain home ranges based on individual fixed kernels. Vegetation structures in core plots and fringe plots were compared. In C. caudata, we additionally assessed the influence of behavioural traits on microhabitat selection. Further, we compared microhabitat structures in the fragmented forest with those in the contiguous, and contrasted the results with the birds` preferences. Pyriglena leucoptera preferred liana tangles that were more common in the fragmented forest, whereas S. scansor preferred woody debris, open forest floor (up to 0.5 m), and a thin closed leaf litter cover which all occurred significantly more often in the contiguous forest. Significant differences were detected in C. caudata for vegetation densities in the different strata; the distance of core plots to the nearest lek site was significantly influenced by sex and age. However, core sites of C. caudata in fragmented and contiguous forests showed no significant differences in structure. Exploring microhabitat selection and behavior may greatly support the understanding of habitat selection of species and their susceptibility to fragmentation on the landscape scale.

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Even among forest specialists, species-specific responses to anthropogenic forest fragmentation may vary considerably. Some appear to be confined to forest interiors, and perceive a fragmented landscape as a mosaic of suitable fragments and hostile matrix. Others, however, are able to make use of matrix habitats and perceive the landscape in shades of grey rather than black-and-white. We analysed data of 42 Chiroxiphia caudata (Blue Manakin), 10 Pyriglena leucoptera (White-shouldered Fire-eye) and 19 Sclerurus scansor (Rufous-breasted Leaftosser) radio-tracked in the Atlantic Rainforest of Brazil between 2003 and 2005. We illustrate how habitat preferences may determine how species respond to or perceive the landscape structure. We compared available with used habitat to develop a species-specific preference index for each of six habitat classes. All three species preferred old forest, but relative use of other classes differed significantly. S. scansor perceived great contrast between old forest and matrix, whereas the other two species perceived greater habitat continuity. For conservation planning, our study offers three important messages: (1) some forest specialist species are able to persist in highly fragmented landscapes; (2) some forest species may be able to make use of different anthropogenic habitat types to various degrees; whereas (3) others are restricted to the remaining forest fragments. Our study suggests species most confined to forest interiors to be considered as potential umbrella species for landscape-scale conservation planning.

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One of the main consequences of habitat loss and fragmentation is the increase in patch isolation and the consequent decrease in landscape connectivity. In this context, species persistence depends on their responses to this new landscape configuration, particularly on their capacity to move through the interhabitat matrix. Here, we aimed first to determine gap-crossing probabilities related to different gap widths for two forest birds (Thamnophilus caerulescens, Thamnophilidae, and Basileuterus culicivorus, Parulidae) from the Brazilian Atlantic rainforest. These values were defined with a playback technique and then used in analyses based on graph theory to determine functional connections among forest patches. Both species were capable of crossing forest gaps between patches, and these movements were related to gap width. The probability of crossing 40 m gaps was 50% for both species. This probability falls to 10% when the gaps are 60 m (for B. culicivorus) or 80 m (for T caerulescens). Actually, birds responded to stimulation about two times more distant inside forest trials (control) than in gap-crossing trials. Models that included gap-crossing capacity improved the explanatory power of species abundance variation in comparison to strictly structural models based merely on patch area and distance measurements. These results highlighted that even very simple functional connectivity measurements related to gap-crossing capacity can improve the understanding of the effect of habitat fragmentation on bird occurrence and abundance.

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In fragmented landscapes, agroforest woodlots can potentially act as stepping stones facilitating movement between forest fragments. We assessed the influence of agroforest woodlots on bird distribution and diversity in the Atlantic forest region (SE Brazil), and also tested which categories of species can use different types of connection elements, and whether this use is influenced by the distance to large forest patches. We studied two fragmented landscapes, with and without stepping stones linking large fragments, and one forested landscape. Using a point count, a bird survey was undertaken in the fragmented landscapes in five different elements: large remnants (> 400 ha), agroforest woodlots (0.4-1.1 ha), small patches (0.5-7 ha), riparian corridor, and pasture areas (the main matrix). Generalist and open-area species were commonly observed in the agroforest system or other connection elements, whereas only a few forest species were present in these connections. For the latter species, the distance of woodlots to large patches was essential to determine their richness and abundance. Based on our results and data from literature, we suggest that there is an optimal relationship between the permeability of the matrix and the efficiency of stepping stones, which occurs at intermediate degrees of matrix resistance, and is species-dependent. Because the presence of agroforest system favors a higher richness of generalist species, they appeared to be more advantageous for conservation than the monoculture system; for this reason, they should be considered as a management alternative, particularly when the matrix permeability requirement is met.

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Supernumerary marker chromosomes (sSMC) may or may not be associated with an abnormal phenotype, depending on the presence of euchromatin, on their chromosomal origin and whether they are inherited. Over 80% of sSMCs are derived from acrocentric chromosomes and half of them include the short arm of chromosome 15. Generally, they appear as bisatellited isodicentric marker chromosomes, most of them are symmetric. These chromosomes are normally originated de novo and are associated with mild to severe intellectual disability but not with physical abnormalities. We report on a patient with an SMC studied using classical and molecular cytogenetic procedures (G and C banding, NOR staining, painting and centromeric fluorescent in situ hybridization (FISH), BAC-FISH, and SKY). The MLPA technique and DNA polymorphic markers were used in order to identify its parental origin. The marker chromosome, monosatellited and monocentric, was found to be derived from a maternal chromosome 15 and was defined as 15pter-q21.2. This is the report of the largest de novo monosatellited 15q marker chromosome ever published presenting detailed cytogenetic and clinical data. It was associated with a phenotype including cardiac defect, absence of septum pellucidum, and dysplasia of the corpus callosum. (C) 2010 Wiley-Liss, Inc.

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Fecal samples and behavioral data were collected at a fortnightly basis during 11 months period from free-living male American kestrels living in southeast Brazil (22 degrees S latitude). The aim was to investigate the seasonal changes in testicular and adrenal steroidogenic activity and their correlation to reproductive behaviors and environmental factors. The results revealed that monthly mean of fecal glucocorticoid metabolites in May and June were higher than those estimated in November. in parallel, monthly mean of androgen metabolites in September was higher than those from January to April and from October to November. Molt took place from January to March, whereas copulation was observed from June to October but peaked in September. Nest activity and food transfer to females occurred predominantly in October, and parental behavior was noticed only in November. Territorial aggressions were rare and scattered throughout the year. Multiple regression analysis revealed that fecal androgen levels are predicted by photoperiod and copulation, while fecal glucocorticoid levels are only predicted by photoperiod. Bivariate correlations showed that fecal androgen metabolites were positively correlated with fecal glucocorticoid metabolites and copulation, but negatively correlated with molt. Additionally, copulation was positively correlated with food transfer to females and nest activity, but negatively correlated with molt. These findings suggest that male American kestrels living in southeast Brazil exhibit significant seasonal changes in fecal androgen and glucocorticoid concentrations, which seem to be stimulated by decreasing daylength but not by rainfall or temperature. (C) 2009 Elsevier Inc. All rights reserved.

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In this work we report results on the influence of heavy rare earth ions substitution on microstructure and magnetism of nanocrystalline magnetite. A series of Fe(2.85)RE(0.15)O(4) (RE = Gd, Dy, Ho, Tm and Yb) samples have been prepared by high energy ball milling. Structure/microstructure investigations of two selected samples Fe(2.85)Gd(0.15)O(4) and Fe(2.85)Tm(0.15)O(4), represent an extension of the previously published results on Fe(3)O(4)/gamma-Fe(2)O(3), Fe(2.85)Y(0.15)O(4) and Fe(2.55)In(0.45)O(4) [Z. Cvejic, S. Rakic, A. Kremenovic, B. Antic, C. Jovalekic. Ph. Colomban, Sol. State Sciences 8 (2006) 908], while magnetic characterization has been done for all the samples. Crystallite/particle size and strain determined by X-ray diffractometry and Transmission electron microscopy (TEM) confirmed the nanostructured nature of the mechanosynthesized materials. X-ray powder diffraction was used to analyze anisotropic line broadening effects through the Rietveld method. The size anisotropy was found to be small while strain anisotropy was large, indicating nonuniform distribution of deffects in the presence of Gd and Tm in the crystal structure. Superparamagnetic(SPM) behavior at room temperature was observed for all samples studied. The Y-substituted Fe(3)O(4) had the largest He and the lowest M(S). We discuss the changes in magnetic properties in relation to their magnetic anisotropy and microstructure. High field irreversibility (H>20kOe) in ZFC/FC magnetization versus temperature indicates the existence of high magnetocrystalline and/or strain induced anisotropy. (C) 2008 Elsevier B.V. All rights reserved.

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The structure of laser glasses in the system (B(2)O(3))(0.6){(Al(2)O(3))(0.4-x)(Y(2)O(3))(x)} (0.1 <= x <= 0.25) has been investigated by means of (11)B, (27)Al, and (89)Y solid state NMR as well as Y-3d core-level X-ray photoelectron spectroscopy, (11)B magic-angle spinning (MAS) NMR spectra reveal that the majority of the boron atoms are three-coordinated, and a slight increase of four-coordinated boron content with increasing x can be noticed. (27)Al MAS NMR spectra show that the alumina species are present in the coordination states four, five and six. All of them are in intimate contact with both the three- and the four-coordinate boron species and vice versa, as indicated by (11)B/(27)Al rotational echo double resonance (REDOR) data. These results are consistent with the formation of a homogeneous, nonsegregated glass structure. For the first time, (89)Y solid state NMR has been used to probe the local environment of Y(3+) ions in a glass-forming system. The intrinsic sensitivity problem associated with (89)Y NMR has been overcome by combining the benefits of paramagnetic doping with those of signal accumulation via Carr-Purcell spin echo trains. Both the (89)Y chemical shifts and the Y-3d core level binding energies are found to be rather sensitive to the yttrium bonding state and reveal that the bonding properties of the yttrium atoms in these glasses are similar to those found in the model compounds YBO(3) and YAl(3)(BO(3))(4), Based on charge balance considerations as well as (11)B NMR line shape analyses, the dominant borate species are concluded to be meta- and pyroborate anions.

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A new preparation route towards rare-earth (RE) doped polycrystalline lead lanthanum zirconate titanate (PLZT) ceramics (RE = Y(3+), Nd(3+), Yb(3+)), based on the use of doped lanthanum oxide or zirconia, is reported. Structural characterization by X-ray powder diffraction reveals that secondary phase formation can be substantially diminished in comparison to conventional preparation methods. The distribution of the rare-earth dopants was investigated as a function of concentration by static (207)Pb spin echo NMR spectra, using Fourier Transformation of Carr-Purcell-Meiboom-Gill spin echo trains. For the Nd- and Yb-doped materials, the interaction of the (207)Pb nuclei with the unpaired electron spin density results in significant broadening and shifting of the NMR signal, whereas these effects are absent in the diamagnetic Y(3+) doped materials. Based on different concentration dependences of the NMR lineshape parameters, we conclude that the structural role of the Nd(3+) dopants differs significantly from that of Yb(3+). While the Nd(3+) ions appear to be statistically distributed in the PLZT lattice, incorporation of Yb(3+) into PLZT appears to be limited by the appearance of doped cubic zirconia as a secondary phase. (C) 2009 Elsevier Masson SAS. All rights reserved.

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To facilitate the design of laser host materials with optimized emission properties, detailed structural information at the atomic level is essential, regarding the local bonding environment of the active ions (distribution over distinct lattice sites) and their extent of local clustering as well as their population distribution over separate micro- or nanophases. The present study explores the potential of solid state NMR spectroscopy to provide such understanding for rare-earth doped lead lanthanum zirconate titanate (PLZT) ceramics. As the NMR signals of the paramagnetic dopant species cannot be observed directly, two complementary approaches are utilized: (1) direct observation of diamagnetic mimics using Sc-45 NMR and (2) study of the paramagnetic interaction of the constituent host lattice nuclei with the rare-earth dopant, using Pb-207 NMR lineshape analysis. Sc-45 MAS NMR spectra of scandium-doped PLZT samples unambiguously reveal scandium to be six-coordinated, suggesting that this rare-earth ion substitutes in the B site. Static Pb-207 spin echo NMR spectra of a series of Tm-doped PLZT samples reveal a clear influence of paramagnetic rare-earth dopant concentration on the NMR lineshape. In the latter case high-fidelity spectra can be obtained by spin echo mapping under systematic incrementation of the excitation frequency, benefiting from the signal-to-noise enhancement afforded by spin echo train Fourier transforms. Consistent with XRD data, the Pb-207 NMR lineshape analysis suggests that statistical incorporation into the PLZT lattice occurs at dopant levels of up to 1 wt.% Tm3+, while at higher levels the solubility limit is reached. (C) 2008 Elsevier Masson SAS. All rights reserved.