27 resultados para Upland game birds.


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The order Passeriformes comprises the largest number of families and species of birds of any avian order. Brazil is rich in passerine birds, which are a common victim of wildlife trafficking in Brazil. Annually, many birds die as a consequence of illegal trade. To investigate the occurrence of the principle diseases and to identify the main causes of death in smuggled passerine birds, the cause of death was evaluated in 360 passerine birds confiscated within the city of Sao Paulo, Brazil. Causes of death were determined by anatomopathologic and microbiologic studies. Infectious diseases were the cause of death of most birds, which corresponded to 78.6% of cases. The most common infectious diseases were poxvirus infection, aspergillosis, and coccidiosis. Although the etiologic agents of these diseases can coexist asymptomatically within hosts, once the host`s immunity is compromised, the pathogen multiplies quickly and causes disease. The results of this study may help to improve the care of passerine birds in captivity and increase the survival rate of confiscated birds. Results may also be useful for in situ conservation programs that investigate the reintroduction of confiscated species or captive birds.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Thirty-eight captive psittacine birds housed in a bird park in Foz do Iguacu, Parana, Brazil, died within a 15-month period as a result of infection with Sarcocystis falcatula. Although fatalities affected 16 species of psittacine birds, mortality was highest in Old World species, which were most susceptible to the pulmonary form of sarcocystosis. Along with the pathologic findings of this disease outbreak, a review of the pathophysiology of sarcosporidiosis is presented.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In wild and domestic birds, cryptosporidiosis is often associated with infections by Cryptosporidium galli, Cryptosporidium baileyi and Cryptosporidium meleagridis. In addition to these species, a number of avian Cryptosporidium species yet to be fully characterized are commonly found among exotic and wild avian isolates. The present study aimed to detect and identify samples of Cryptosporidium spp. from free-living wild birds, in order to contribute to the knowledge of the variability of this parasite in the free-living population of Brazil. Stool samples were collected from 242 birds, with the following proportions of individuals: 50 Emberizidae (20.7%), 112 Psittacidae (46.3%), 44 Cardinalidae (18.2%), 12 Turdidae (5.0%), eight Ramphastidae (3.3%), seven Icteridae (2.9%), three Estrilididae (1.2%), two Contigidae (0.8%), two Thraupidae (0.8%) and two Fringilidae (0.8%). Among the 242 fecal samples from wild birds, 16(6.6%) were positive for the presence of oocysts of Cryptosporidium. Molecular characterization of the 16 samples of Cryptosporidium, were performed with phylogenetic reconstructions employing 292 positions of 18S rDNA. None of the samples of birds was characterized as C meleagridis. C gall was identified in one rufous-bellied thrush (Turdus rufiventris), five green-winged saltators (Saltator similis), one slate-coloured seedeater (Sporophila schistacea), one goldfinch (Carduelis carduelis) and three saffron finches (Sicalis flaveola). One goldfinch isolate, one buff-fronted seedeater (Sporophila frontalis), one red-cowled cardinal (Paroaria dominicana) and one other saffron finch (S. flaveola) were identified as C. baileyi. Avian genotype II was found in an isolate from a white-eyed parakeet (Aratinga leucophthalma). Clinical symptoms of cryptosporidiosis in birds have already been described and the number of wild birds which were shedding parasites was high. Therefore, further epidemiological research and disease surveillance of birds in the wild is warranted. (C) 2010 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this study was to determine the prevalence of Cryptosporidium species and genotypes in birds kept in captivity in Brazil. A total of 966 samples from 18 families of birds was collected and stored in 5% potassium dichromate solution at 4 degrees C until processing. Oocysts were purified in Sheather sugar solution following extraction of genomic DNA. Molecular analyses were performed using nested-PCR for amplification of fragments of the 18S subunit of rRNA gene and of the actin gene. Amplification of Cryptosporidium DNA fragments was obtained in 47 (4.86%) samples. Sequencing of amplified fragments and phylogenetic analyses allowed the identification of Cryptosporidium baileyi in a black vulture (Coragyps atratus), a domestic chicken (Gallus gallus domesticus) and a saffron finch (Sicalis flaveola); Cryptosporidium galli in canaries (Serinus canaria), a cockatiel (Nymphicus hollandicus) and lesser seed-finches (Oryzoborus angolensis); Cryptosporidium meleagridis in a domestic chicken (G. g. domesticus); Cryptosporidium parvum in a cockatiel (N. hollandicus); Cryptosporidium avian genotype I in a canary (S. canaria) and an Indian peafowl (Pavo cristatus); Cryptosporidium avian genotype II in ostriches (Struthio camelus) and Cryptosporidium avian genotype III in a cockatiel (N. hollandicurs) and a peach-faced lovebird (Agapornis roseicolis). (C) 2009 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Deforestation in Brazilian Amazonia accounts for a disproportionate global scale fraction of both carbon emissions from biomass burning and biodiversity erosion through habitat loss. Here we use field- and remote-sensing data to examine the effects of private landholding size on the amount and type of forest cover retained within economically active rural properties in an aging southern Amazonian deforestation frontier. Data on both upland and riparian forest cover from a survey of 300 rural properties indicated that 49.4% (SD = 29.0%) of the total forest cover was maintained as of 2007. and that property size is a key regional-scale determinant of patterns of deforestation and land-use change. Small properties (<= 150 ha) retained a lower proportion of forest (20.7%, SD = 17.6) than did large properties (>150 ha; 55.6%, SD = 27.2). Generalized linear models showed that property size had a positive effect on remaining areas of both upland and total forest cover. Using a Landsat time-series, the age of first clear-cutting that could be mapped within the boundaries of each property had a negative effect on the proportion of upland, riparian, and total forest cover retained. Based on these data, we show contrasts in land-use strategies between smallholders and largeholders, as well as differences in compliance with legal requirements in relation to minimum forest cover set-asides within private landholdings. This suggests that property size structure must be explicitly considered in landscape-scale conservation planning initiatives guiding agro-pastoral frontier expansion into remaining areas of tropical forest. (C) 2010 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Estimating the sizes of hard-to-count populations is a challenging and important problem that occurs frequently in social science, public health, and public policy. This problem is particularly pressing in HIV/AIDS research because estimates of the sizes of the most at-risk populations-illicit drug users, men who have sex with men, and sex workers-are needed for designing, evaluating, and funding programs to curb the spread of the disease. A promising new approach in this area is the network scale-up method, which uses information about the personal networks of respondents to make population size estimates. However, if the target population has low social visibility, as is likely to be the case in HIV/AIDS research, scale-up estimates will be too low. In this paper we develop a game-like activity that we call the game of contacts in order to estimate the social visibility of groups, and report results from a study of heavy drug users in Curitiba, Brazil (n = 294). The game produced estimates of social visibility that were consistent with qualitative expectations but of surprising magnitude. Further, a number of checks suggest that the data are high-quality. While motivated by the specific problem of population size estimation, our method could be used by researchers more broadly and adds to long-standing efforts to combine the richness of social network analysis with the power and scale of sample surveys. (C) 2010 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Structured meaning-signal mappings, i.e., mappings that preserve neighborhood relationships by associating similar signals with similar meanings, are advantageous in an environment where signals are corrupted by noise and sub-optimal meaning inferences are rewarded as well. The evolution of these mappings, however, cannot be explained within a traditional language evolutionary game scenario in which individuals meet randomly because the evolutionary dynamics is trapped in local maxima that do not reflect the structure of the meaning and signal spaces. Here we use a simple game theoretical model to show analytically that when individuals adopting the same communication code meet more frequently than individuals using different codes-a result of the spatial organization of the population-then advantageous linguistic innovations can spread and take over the population. In addition, we report results of simulations in which an individual can communicate only with its K nearest neighbors and show that the probability that the lineage of a mutant that uses a more efficient communication code becomes fixed decreases exponentially with increasing K. These findings support the mother tongue hypothesis that human language evolved as a communication system used among kin, especially between mothers and offspring.