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Abstract
I conducted a synthesis of agricultural changes during the mid-18th century until thepresent in the principal temperate agricultural regions of the world (western Europe, theUnited States of America, the Republic of South Africa, and austral South America, with aconcentration on the Republic of Argentina) from the perspective of the impacts thatintensication in agriculture has on wildlife in agroecosystems. Additionally, I produced areview and synthesis of the eects of agricultural land use on birds, with an emphasis onthe Galliformes. Based upon these analysis, and eld 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 inagroecosystems in the Pampas and Chaco and Yungas forest of Argentina.In the regions analyzed, agricultural production has become increasingly intensiedsince the mid-20th century; typied by increased mechanization, irrigation, agrochemicaluse, farm consolidation, regional specialization, area of cultivated pastures, and livestockdensities. Combined, these reduce the amount, quality, and heterogeneity in habitats acrossscales from the region to within elds, which the analysis revealed were the factors mostinuential in determining distribution and abundance of avian species dependent uponthese systems. Specically, the loss of fallow or idle land, woody encroachment,homogeneity in cover types and vegetation structure and composition, indirect eects ofpesticides on food availability, and earlier and more frequent mowing were key inexplaining reductions in avian diversity and abundance in temperate agroecosystems.For the Galliformes the loss and/or degradation of preferred habitats, during both thebreeding and non-breeding seasons, due to changes in agroecosystem management wasrelated to observed decreases in populations and survival. Over-winter mortality increasedduring extremes in minimum temperature and snow cover, and was exacerbated wheresucient wintering cover was limited. Moreover, increased over-winter mortality wasassociated with the proximity of woody areas, which facilitates higher predation. The lossof preferred nesting habitat not only decreases the number of nesting individuals, butincreases nest loss and mortality of incubating adults through increased predation andlosses to agricultural activities. Of particular importance were decreases in the abundanceof preferred arthropod prey for foraging chicks due to direct and indirect eects ofpesticides, which were responsible for increased chick mortality.Although there exists a large body research into the eects of land use and birds,particularly gamebirds, little research exists for these species in Argentina or LatinAmerica in general. In Argentina the most important gamebird species is the spottedtinamou (Nothura maculosa). This species has become increasingly scarce in a signicantportion of its range, possibly due to agricultural intensication over the last 15 years. Usingradio telemetry, I examined habitat use, movements, and survival of spotted tinamous in 2landscapes in the province of Buenos Aires, Argentina; one dominated by annual row cropsand the other used for annual crops and grazing. During winter, individuals used in orderof preference: fallow elds and areas with short herbaceous vegetation, followed bywetlands. Areas in winter wheat and eld edges were used least in relation to theiravailability. Although birds generally maintained small home ranges, in some cases changesin cattle density and the structure of row crops caused birds to move considerabledistances. Survival mid-winter to early spring was more than double in the mixedlandscape (^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 toagricultural intensication, and considering the Tinamiformes as ecological equivalents tothe Galliformes in agroecosystems, these results are not unexpected and suggest aprecarious future for the conservation of grassland and agroecosystem species in Argentinain light of present agricultural trends.The intensication and expansion of row crop agriculture and grazing in Argentina hasnegative implications for wildlife as habitat is converted and degraded as witnessed in thespotted tinamou. In the Pampas, the biggest threat for wildlife conservation is theconversion of remnant grassland and residual areas in row crop regions and the expansionof row crops and perennial forage crops into former extensive grazing areas. In northernArgentina the deforestation of Chaco and Yungas forest for soybean cultivation has beenextensive and is accelerating, threatening the relatively high biodiversity of these areas.The lack of sucient funding and infrastructure, and the decentralized nature of wildlifeexploitation in Argentina, hinders eective management. Recent success, however, inmanaging commercially exploited species (parrots) suggest that innovative specie-specicmanagement actions maybe viable.