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Agriculture and Gamebirds: A Global Synthesis with and emphasis on the Tinamiformes in Argentina
I documented agricultural changes during the mid-18 th century until the present in the principal temperate agricultural regions of the world (western Europe, the United States of America, the Republic of South Africa, and austral South America, with a concentration on the Republic of Argentina) from the perspective of the impacts that intensification in agriculture has on wildlife in agroecosystems. Additionally, I produced an analysis and synthesis of the effects of agricultural land use on birds, with an emphasis on the Galliformes. Based upon these analysis, and field research on the spotted tinamou (Nothura maculosa) in agroecosystems in the Pampas of Argentina, I discuss the past, present, and future implications for wildlife conservation and management in agroecosystems in the Pampas and Chaco and Yungas forest of Argentina. In the regions analyzed, agricultural production has become increasingly intensified since the mid-20 th century; typified by increased mechanization, irrigation, agrochemical use, farm consolidation, regional specialization, area of cultivated pastures, and livestock densities. Combined, these reduce the amount, quality, and heterogeneity in habitats across scales from the region to within fields, which the analysis revealed were the factors most influential in determining distribution and abundance of avian species dependent upon these systems. Specifically, the loss of fallow or idle land, woody encroachment, homogeneity in cover types and vegetation structure and composition, indirect effects of pesticides on food availability, and earlier and more frequent mowing were key in explaining reductions in avian diversity and abundance in temperate agroecosystems. For the Galliformes the loss and/or degradation of preferred habitats, during both the breeding and non-breeding seasons, due to changes in agroecosystem management was related to observed decreases in populations and survival. Over-winter mortality increased during extremes in minimum temperature and snow cover, and was exacerbated where sufficient wintering cover was limited. Moreover, increased over-winter mortality was associated with the proximity of woody areas, which facilitates higher predation. The loss of preferred nesting habitat not only decreases the number of nesting individuals, but increases nest loss and mortality of incubating adults through increased predation and losses to agricultural activities. Of particular importance were decreases in the abundance of preferred arthropod prey for foraging chicks due to direct and indirect effects of pesticides, which were responsible for increased chick mortality. Although there exists a large body research into the effects of land use and birds, particularly gamebirds, little research exists for these species in Argentina or Latin America in general. In Argentina the most important gamebird species is the spotted tinamou (Nothura maculosa). This species has become increasingly scarce in a significant portion of its range, possibly due to agricultural intensification over the last 15 years. Using radio telemetry, I examined habitat use, movements, and survival of spotted tinamous in two landscapes in the province of Buenos Aires, Argentina; one dominated by annual row crops and the other used for annual crops and grazing. During winter, individuals used in order of preference: fallow fields and areas with short herbaceous vegetation, followed by wetlands. Areas in winter wheat and field edges were used least in relation to their availability. Although birds generally maintained small home ranges, in some cases changes in cattle density and the structure of row crops caused birds to move considerable distances. Survival mid-winter to early spring was more than double in the mixed landscape (^s = 0.73, SE = 0.19) compared with the landscape dedicated to row crops (^s = 0.33, SE = 0.19). Given the general trends documented for the Galliformes in relation to agricultural intensification, and considering the Tinamiformes as ecological equivalents to the Galliformes in agroecosystems, these results are not unexpected and suggest a precarious future for the conservation of grassland and agroecosystem species in Argentina in light of present agricultural trends. The intensification and expansion of row crop agriculture and grazing in Argentina have negative implications for wildlife as habitat is converted and degraded as witnessed in the spotted tinamou. In the Pampas, the biggest threat for wildlife conservation is the conversion of remnant grassland and residual areas in row crop regions and the expansion of row crops and perennial forage crops into former extensive grazing areas. In northern Argentina the deforestation of Chaco and Yungas forest for soybean cultivation has been extensive and is accelerating, threatening the relatively high biodiversity of these areas. The lack of sufficient funding and infrastructure, and the decentralized nature of wildlife exploitation in Argentina, hinders effective management. Recent success, however, in managing commercially exploited species (parrots) suggest that innovative specie-specific management actions maybe viable.