Range-wide abundance and fluctuating asymmetry patterns of sagebrush-obligate passerine birds

North American sagebrush (Artemisia spp.) ecosystems are suffering from reductions in habitat extent and quality. Only about 50% of sagebrush remains from pre-settlement conditions, and much of the remaining habitat is fragmented or degraded by invasive species, fire suppression and overgrazing. Sagebrush-obligate species are experiencing population declines as a result of these ecosystem changes. To effectively conserve this ecosystem, it is essential to understand patterns of abundance and stress of the inhabitants at the landscape-level. Abundance of species across their geographic range is not uniform. Instead, abundance often decreases towards the periphery of the range where resources and habitat conditions become less suitable. In addition, stress in populations closer to the periphery of the range may be expressed in condition-dependent traits where suboptimal environmental conditions occur. Fluctuating asymmetry, random deviations from perfect symmetry in bilateral body parts, may reveal increased stress in these populations. I examined patterns of abundance and fluctuating asymmetry of Brewer’s Sparrow (Spizella breweri), Sage Sparrow (Amphisipiza belli), and Sage Thrasher (Oreoscoptes montanus), in the western United States, to determine how these responses vary with proximity to range periphery of sagebrush. Using negative binomial regression and Akaike’s Information Criterion, I investigated associations between species abundance from North American Breeding Bird Survey count data and several local- and landscapelevel variables derived from digital maps depicting the distribution of sagebrush throughout the United States. Abundance for these three sagebrushobligate passerine birds was greatest in mid-elevation (1,200-2,300 m) areas and increased with sagebrush cover. I found little support for abundance declining as a function of proximity to range periphery. Using mixed model regression, I assessed the relationship between fluctuating asymmetry estimates in the tarsi of juveniles and the proximity of specimens to the periphery of sagebrush distribution. I predicted higher levels of fluctuating asymmetry in individuals nearer the range periphery. However, fluctuating asymmetry decreased with proximity to the range periphery for Sage Sparrow, and, although present Sage Thrasher, fluctuating asymmetry did not differ significantly across the geographic range for this species. Fluctuating asymmetry could not be estimated with confidence for Brewer’s Sparrow. While this study revealed stress in these species, a more logistically complex study to evaluate fluctuating asymmetry patterns across the landscape is necessary for determining areas of conservation priority. Loss of areas of high percent sagebrush cover due to habitat fragmentation and degradation will result in continued declines in abundance of sagebrush-obligate passerine birds. Knowing high abundances of sagebrush-obligate passerine birds occur in locations with high sagebrush cover at mid-elevations will aid land managers and conservation biologists in designing effective conservation strategies for these species

Beyond the ‘Migrant Network’? Exploring assistance received in the migration of brazilians to Portugal and the Netherlands

This paper explores the tenability of three important critiques to the ‘migrant network’ approach in migration studies: (1) the narrow focus on kin and community members, which connect prospective migrants in origin countries with immigrants in the destination areas, failing to take due account of sources of assistance beyond the ‘migrant network’ like institutional or online sources; (2) that it is misleading to assume a general pattern in the role of migrant networks in migration, regardless of contexts of arrival or departure, including the scale and history of migration or the immigration regime; and (3) that ‘migrant networks’ are not equally relevant to all migrants, and that important differences may exist between labour migrants and other types of migrants like family migrants or students. Drawing on survey data on the migration of Brazilians to Portugal and the Netherlands we find support for these critiques but also reaffirm the relevance of ‘migrant networks’.info:eu-repo/semantics/publishedVersio

Harvests of shame: enduring unfree labour in twentieth century United States, 1933-1964

This article reframes the discussion on vulnerable and exploited agricultural labour in twentieth-century United States using the overarching category of unfree labour. In order to do so, it bridges two usually distinct historiographies by linking the phenomenon of ‘peonage’ during the New Deal, with the one of immigrant contract labour southern Florida, under the H2 visa. Archival research on the practices at the US Sugar Corporation in southern Florida exemplifies this link. This article draws on federal archives, government proceedings, papers of political activists and legal and labour scholarship to argue: firstly, that unfree labour has been an enduring feature of agricultural labour relations at regional level during the twentieth century, through both a transmission and a transformation of practice that had their origin in the control of black emancipated labour; secondly, that the introduction of guest workers under the H2 and Bracero programme meant a modernization in the practices of unfree labour, pivoting on the lack of citizenship rights, racial discrimination, debt at home, and threat of deportation; and, finally, that the failure to recognise forms of legal and economic deprivation and coercion as unfree labour has hurt the ability of the United States to enforce protection of human rights at home

Migration Industries and the State: Guestwork Programs in East Asia

Studies of migration industries have demonstrated the critical role that border-spanning businesses play in international mobility. To date, most research has focused on meso-level entrepreneurial initiatives that operate in a legal gray area under a state that provides an environment for their growth or decline. Extending this work, the present article advances a taxonomy of the ways states partner with migration industries based on the nature of their relationship (formal or informal) and the type of actor involved (for-profit or non-profit). The analysis focuses on low-paid temporary migrant work programs — schemes that require substantial state involvement to function — and examines cases from the East Asian democracies with strong economies that have become net importers of migrants: Taiwan, Japan, and South Korea. The conclusion, incorporating cases beyond Asia, explicates the properties and limits of each arrangement based on the degree of formality and importance of profit

"Them" or "Us"?: Assessing Responsibility for Undocumented Migration from Mexico

Empirical studies, theoretical models, and public policies concerning undocumented migration have placed too much emphasis on the “supply-side”. This approach – simultaneously self-serving and self-defeating – emphasizes socioeconomic conditions within Third World countries and immigration enforcement by advanced industrialized nations. Conducting fieldwork in both rural Mexico and the United States, I found that the personnel practices and recruitment activities within three of America’s billion dollar crop industries create and perpetuate unauthorized migrant flows. My study of these rural labor markets contradicts several critical supply-side assumptions, especially pertaining to the origins and composition of international migrant networks. Supply-siders view these networks as systems of mutual aid amongst new immigrants. I found that the networks are also used by employers to maintain access to sources of low cost labor. I conclude that the involvement of an increasing number of US corporations in the development of migrant networks from Mexico shifts responsibility for undocumented migration from “them” to us”

"Them" or "Us"?: Assessing Responsibility for Undocumented Migration from Mexico

Empirical studies, theoretical models, and public policies concerning undocumented migration have placed too much emphasis on the “supply-side”. This approach – simultaneously self-serving and self-defeating – emphasizes socioeconomic conditions within Third World countries and immigration enforcement by advanced industrialized nations. Conducting fieldwork in both rural Mexico and the United States, I found that the personnel practices and recruitment activities within three of America’s billion dollar crop industries create and perpetuate unauthorized migrant flows. My study of these rural labor markets contradicts several critical supply-side assumptions, especially pertaining to the origins and composition of international migrant networks. Supply-siders view these networks as systems of mutual aid amongst new immigrants. I found that the networks are also used by employers to maintain access to sources of low cost labor. I conclude that the involvement of an increasing number of US corporations in the development of migrant networks from Mexico shifts responsibility for undocumented migration from “them” to us”