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.

Contributions of Weather and Predation to Reduced Breeding Success in a Threatened Northern Loggerhead Shrike Population

Populations on the periphery of a species' range may experience more severe environmental conditions relative to populations closer to the core of the range. As a consequence, peripheral populations may have lower reproductive success or survival, which may affect their persistence. In this study, we examined the influence of environmental conditions on breeding biology and nest survival in a threatened population of Loggerhead Shrikes (Lanius ludovicianus) at the northern limit of the range in southeastern Alberta, Canada, and compared our estimates with those from shrike populations elsewhere in the range. Over the 2-year study in 1992–1993, clutch sizes averaged 6.4 eggs, and most nests were initiated between mid-May and mid-June. Rate of renesting following initial nest failure was 19%, and there were no known cases of double-brooding. Compared with southern populations, rate of renesting was lower and clutch sizes tended to be larger, whereas the length of the nestling and hatchling periods appeared to be similar. Most nest failures were directly associated with nest predators, but weather had a greater direct effect in 1993. Nest survival models indicated higher daily nest survival during warmer temperatures and lower precipitation, which may include direct effects of weather on nestlings as well as indirect effects on predator behavior or food abundance. Daily nest survival varied over the nesting cycle in a curvilinear pattern, with a slight increase through laying, approximately constant survival through incubation, and a decline through the nestling period. Partial brood loss during the nestling stage was high, particularly in 1993, when conditions were cool and wet. Overall, the lower likelihood of renesting, lower nest survival, and higher partial brood loss appeared to depress reproductive output in this population relative to those elsewhere in the range, and may have increased susceptibility to population declines.

Proceedings of the Ninth Annual Conference of the British Association for Biological Anthropology and Osteoarchaeology, Department of Archaeology, University of Reading

The Proceedings of the Ninth Annual Conference of the British Association for Biological Anthropology and Osteoarchaeology (BABAO) held at the University of Reading in 2007. Contents: 1) A life course perspective of growing up in medieval London: evidence of sub-adult health from St Mary Spital (London) (Rebecca Redfern and Don Walker); 2) Preservation of non-adult long bones from an almshouse cemetery in the United States dating to the late nineteenth to the early twentieth centuries (Colleen Milligan, Jessica Zotcavage and Norman Sullivan); 3) Childhood oral health: dental palaeopathology of Kellis 2, Dakhleh, Egypt. A preliminary investigation (Stephanie Shukrum and JE Molto); 4) Skeletal manifestation of non-adult scurvy from early medieval Northumbria: the Black Gate cemetery, Newcastle-upon-Tyne (Diana Mahoney-Swales and Pia Nystrom); 5) Infantile cortical hyperostosis: cases, causes and contradictions (Mary Lewis and Rebecca Gowland); 6) Biological Anthropology Tuberculosis of the hip in the Victorian Britain (Benjamin Clarke and Piers Mitchell); 7) The re-analysis of Iron Age human skeletal material from Winnall Down (Justine Tracey); 8) Can we estimate post-mortem interval from an individual body part? A field study using sus scrofa (Branka Franicevec and Robert Pastor); 9) The expression of asymmetry in hand bones from the medieval cemetery at Écija, Spain (Lisa Cashmore and Sonia Zakrezewski); 10) Returning remains: a curator’s view (Quinton Carroll); 11) Authority and decision making over British human remains: issues and challenges (Piotr Bienkowski and Malcolm Chapman); 12) Ethical dimensions of reburial, retention and repatriation of archaeological human remains: a British perspective (Simon Mays and Martin Smith); 13) The problem of provenace: inaccuracies, changes and misconceptions (Margaret Clegg); 14) Native American human remains in UK collections: implications of NAGPRA to consultation, repatriation, and policy development (Myra J Giesen); 15) Repatriation – a view from the receiving end: New Zealand (Nancy Tayles).

Economic impact of genetically modified cotton in India

This paper presents the results of a study aimed at measuring the economic impact of genetically modified cotton in Maharashtra State, India. It is the first study of its kind in India in that the data have been collected from farmers growing the crop under market conditions, rather than from trials. The research compares the performance of more than 9,000 Bt and non-Bt cotton farm plots in Maharashtra over the 2002 and 2003 growing seasons. Results show that Bt cotton varieties have had a significant positive impact on average yields and on the economic performance of cotton growers.

Comparing the performance of official and unofficial genetically modified cotton in India

Genetically modified (GM) cotton was approved for commercial cultivation in 2002. Hybrids to date have carried the Bt (Bacillus thuringiensis) gene, which confers resistance to Lepidoptera and certain Coleoptera. As well as "official" Bt hybrids (i.e., those that have gone through a formal approval process), there are "unofficial" Bt hybrids produced without such approval. The owners of the official hybrids, Monsanto-Mahyco, claim that the unofficial hybrids are not as good and could even damage the perception of Bt cotton amongst farmers. Anti-GM groups claim that neither type of Bt hybrid provides either yield or economic advantages over non-Bt hybrids. This paper reports the first study of official versus unofficial versus non-Bt hybrids in India (622 farmers in Gujarat State) with the specific aim of comparing one hypothesized ranking in terms of gross margin of (a) official Bt hybrids, (b) unofficial Bt hybrids, and (c) non-Bt hybrids. Results suggest that the official Bt varieties (MECH 12 and MECH 162) significantly outperform the unofficial varieties in terms of gross margin. However, unofficial, locally produced Bt hybrids can also perform significantly better than non-Bt hybrids, although second-generation (F2) Bt seed appears to have no yield advantage compared to non-Bt hybrids but can save on insecticide use. The paper explores some of the implications of this ranking.