Agricultural Policy and Nest Success of Prairie Ducks in Canada and the United States

The Prairie Pothole Region of North America has been modified by agriculture during the past 100 yr, resulting in habitat loss, fragmentation, and degradation that have reduced the abundance and productivity of many wildlife species. The 1985 U.S. Farm Bill provided economic incentives to agriculture that are considered by many to be beneficial to nesting waterfowl and other wildlife. Canada has not experienced an equally comprehensive legislative initiative, which would seem to indicate that benefits to waterfowl in Canada should lag behind those in the United States. However, with the removal of some agricultural subsidies in Canada during the 1990s, the amount of perennial cover in the Canadian prairies increased to levels similar to those of the 1970s. Therefore, it is unclear whether and how the U.S. and Canadian prairies might differ with regard to habitat quality for nesting waterfowl. We used historical and contemporary data to compare temporal trends in duck nest success between the United States and Canada and to assess how mean nest success varied with proportion of cropland and wetland density. The data best supported models with nonlinear temporal trends that varied between the two countries and suggested that mean nest success in Canada declined from its high point in 1930s and remained below the long-term value of 0.16 until the end of the time series in 2005. Mean nest success in the United States also declined from its high point in the 1930s, but increased to above the long-term value of 0.25 during the early 2000s. Mean nest success varied negatively with proportion of cropland in both the United States and Canada. Mean nest success was positively correlated with pond density at Canadian sites, but showed only a weak association with pond density at U.S. sites. All models explained the low proportions of the variation in nest success, suggesting that unmeasured factors such as the abundance and identity of nest predators may have strong effects on nest success. Nonetheless, these results support earlier suggestions that agricultural policy that encourages permanent cover positively influences duck reproductive success. We also found that, for reasons that are not entirely clear, nest success for the same intensity of row cropping was generally higher in the United States than in Canada. Further research is required to elucidate the exact nature of the composition, size, and distribution of permanent cover that coincides with greater average nest success by dabbling ducks in the United States. In addition, the data suggest that the benefits that might accrue from increases in the amount of perennial cover in Canada would be better realized if these efforts are accompanied by strong measures to conserve wetlands.

Risk of Agricultural Practices and Habitat Change to Farmland Birds

Many common bird species have declined as a result of agricultural intensification and this could be mitigated by organic farming. We paired sites for habitat and geographical location on organic and nonorganic farms in Ontario, Canada to test a priori predictions of effects on birds overall, 9 guilds and 22 species in relation to candidate models for farming practices (13 variables), local habitat features (12 variables), or habitat features that influence susceptibility to predation. We found that: (1) Overall bird abundance, but not richness, was significantly (p < 0.05) higher on organic sites (mean 43.1 individuals per site) than nonorganic sites (35.8 individuals per site). Significantly more species of birds were observed for five guilds, including primary grassland birds, on organic vs. nonorganic sites. No guild had higher richness or abundance on nonorganic farms; (2) Farming practice models were the best (ΔAIC < 4) for abundance of birds overall, primary grassland bird richness, sallier aerial insectivore richness and abundance, and abundance of ground nesters; (3) Habitat models were the best for overall richness, Neotropical migrant abundance, richness and abundance of Ontario-USA-Mexico (short-distance) migrants and resident richness; (4) Predation models were the best for richness of secondary grassland birds and ground feeders; (5) A combination of variables from the model types were best for richness or abundance overall, 13 of 18 guilds (richness and abundance) and 16 of 22 species analyzed. Five of 10 farming practice variables (including herbicide use, organic farm type) and 9 of 13 habitat variables (including hedgerow length, proportion of hay) were significant in best models. Risk modeling indicated that herbicide use could decrease primary grassland birds by one species (35% decline from 3.4 to 2.3 species) per site. Organic farming could benefit species of conservation concern by 49% (an increase from 7.6 to 11.4 grassland birds). An addition of 63 m of hedgerow could increase abundance and richness of short distance migrants by 50% (3.0 to 4.8 and 1.3 to 2.0, respectively). Increasing the proportion of hay on nonorganic farms to 50% could increase abundance of primary grassland bird by 40% (6.7 to 9.4). Our results provide support for alternative farmland designs and agricultural management systems that could enhance select bird species in farmland.

The use of agricultural, open and forest habitats by juvenile Mauritius Kestrels Falco punctatus

Knowledge of tropical raptor habitat use is limited and yet a thorough understanding is vital when trying to conserve endangered species. We used a well studied, reintroduced population of the vulnerable Mauritius Kestrel Falco punctatus to investigate habitat preferences in a modified landscape. We constructed a high resolution digital habitat map and radiotracked 13 juvenile Kestrels to quantify habitat preferences. We distinguished seven habitat types in our study area and tracked Kestrels from 71 to 130 days old during which they dispersed from their natal territory and settled within a home-range after reaching independence. Mean home-range size was 0.95 km(2) characterized by a bimodal pattern of intensity around the natal site and post-independence home-range. Compositional analysis showed that home-ranges were located non-randomly with respect to habitat but there was no evidence to suggest differential use of habitats within home-ranges. Native and semi-invaded forest and grassland were consistently preferred, whereas agriculture was used significantly less than other habitats. No difference was found between the available length of edge dividing native forest and grassland within a home-range when compared to that available within a 2.35-km buffer around their nest-site, based on the maximum distance a juvenile was found to disperse. Repeating the analysis in three dimensions gave very similar results. Our results suggest that Mauritius Kestrels are not obligate forest dwellers as was once thought but can also exploit open habitats such as grassland. Kestrels may be using isolated mature trees within grassland as vantage points for hunting in the same way as they use the natural stratified forest structure. We suggest that the avoidance of agriculture is partly due to a lack of such vantage points. The conservation importance of forest degradation and agricultural encroachment is highlighted and comparisons with the habitat preferences of other tropical falcons are discussed.

The visibility of agricultural subsidies and market illusions in the Common Agricultural Policy: Some evidence from farmers' views in Germany, Portugal and the United Kingdom

This article demonstrates that the design and nature of agricultural support schemes has an influence on farmers' perception of their level of dependence on agricultural support. While direct aid payments inform farmers about the extent to which they are subsidised, indirect support mechanisms veil the level of subsidisation, and therefore they are not fully aware of the extent to which they are supported. To test this hypothesis, we applied data from a survey of 4,500 farmers in three countries: the United Kingdom, Germany and Portugal. It is demonstrated that indirect support, such as that provided through artificially high consumer prices, gives an illusion of free and competitive markets among farmers. This 'visibility' hypothesis is evaluated against an alternative hypothesis that assumes farmers have complete, or at least a fairly comprehensive level of, information on agricultural support schemes. Our findings show that this alternative hypothesis can be ruled out.

Seeds of growth? Agricultural productivity and the transitional dynamics of the Ramsey model

A two-sector Ramsey-type model of growth is developed to investigate the relationship between agricultural productivity and economy-wide growth. The framework takes into account the peculiarities of agriculture both in production ( reliance on a fixed natural resource base) and in consumption (life-sustaining role and low income elasticity of food demand). The transitional dynamics of the model establish that when preferences respect Engel's law, the level and growth rate of agricultural productivity influence the speed of capital accumulation. A calibration exercise shows that a small difference in agricultural productivity has drastic implications for the rate and pattern of growth of the economy. Hence, low agricultural productivity can form a bottleneck limiting growth, because high food prices result in a low saving rate.

Video activity extraction and reporting with incremental unsupervised learning

The present work presents a new method for activity extraction and reporting from video based on the aggregation of fuzzy relations. Trajectory clustering is first employed mainly to discover the points of entry and exit of mobiles appearing in the scene. In a second step, proximity relations between resulting clusters of detected mobiles and contextual elements from the scene are modeled employing fuzzy relations. These can then be aggregated employing typical soft-computing algebra. A clustering algorithm based on the transitive closure calculation of the fuzzy relations allows building the structure of the scene and characterises the ongoing different activities of the scene. Discovered activity zones can be reported as activity maps with different granularities thanks to the analysis of the transitive closure matrix. Taking advantage of the soft relation properties, activity zones and related activities can be labeled in a more human-like language. We present results obtained on real videos corresponding to apron monitoring in the Toulouse airport in France.