Vietnamese migrant networks in Taiwan: the curse and boon of social capital

Drawing on ethnographic research on Vietnamese migrant workers in Taiwan, I seek to engage with and contribute to the scholarship on migrant networks and social capital. My research demonstrates that migrant networks are central to the social life of Vietnamese workers, offering not only a vital source of material and psychological support but also a platform where relationships are developed, sustained and contested. It reveals both productive and destructive potentials of social capital in situations where the migrant labourer becomes a disenfranchized underclass and their radius of trust is unsettled by physical displacement. Through this research I highlight the complexities and subjectivities in individual experiences of social capital and offer important insights into the various ways in which social networks are reinterpreted and reconfigured at the intersection of mobility, class and ethnicity within the context of Asia.     

Migratory connectivity in a declining bird species: using feather isotopes to inform demographic modelling

Aim Conservation programmes for endangered migratory species or populations require locating and evaluating breeding, stopover and wintering areas. We used multiple stable isotopes in two endangered European populations of wrynecks, Jynx torquilla L., to locate wintering regions and assess the degree of migratory connectivity between breeding and wintering populations. Location Switzerland and Germany. Methods We analysed stable nitrogen (δ¹⁵N), carbon (δ¹³C) and hydrogen (δD) isotopes from wing feathers from two populations of wrynecks to infer their wintering origins and to assess the strength of migratory connectivity. We tested whether variation in feather isotopic values within the Swiss population was affected by bird age and collection year and then considered differences in isotopic values between the two breeding populations. We used isotopic values of summer‐ and winter‐grown feathers to estimate seasonal distributions. Finally, we calculated a species‐specific δD discrimination factor between feathers and mean annual δD values to assign winter‐grown feathers to origin. Results Bird age and collection year caused substantial isotopic variation in winter‐grown feathers, which may be because of annually variable weather conditions, movements of birds among wintering sites and/or reflect asynchronous moulting or selection pressure. The large isotopic variance in winter‐grown feathers nevertheless suggested low migratory connectivity for each breeding population, with partially overlapping wintering regions for the two populations. Main conclusions Isotopic variance in winter‐grown feathers of two breeding populations of wrynecks and their geographical assignment point to defined, albeit overlapping, wintering areas, suggesting both leapfrog migration and low migratory connectivity. On this basis, integrative demographic models can be built looking at seasonal survival patterns with links to local environmental conditions on both breeding and wintering grounds, which may elucidate causes of declines in migratory bird species.     

The evolution of dispersal in a two-patch system: some consequences of differences between migrants and residents

We investigate how age-structure and differences in certain demographic traits between residents and immigrants of a single species act to determine the evolutionarily stable dispersal strategy in a two-patch environment that is heterogeneous in space but constant in time. These two factors have been neglected in previous models of the evolution of dispersal, which generally consider organisms with very simple life-cycles and assume that, whatever their origin, individuals in a given habitat have the same bio-demographic characteristics. However, there is increasing empirical evidence that dispersing individuals have different demographic properties from phylopatric ones. We develop a matrix model in which recruitment depends on local population densities. We assume that dispersal entails a proportional cost to immigrant fecundity, which can be compensated by differences in survival rates between immigrants and residents. The evolutionarily stable strategies (ESS) for dispersal are identified using a combination of analytical expressions and numerical simulations. Our results show that philopatry is selected (1) when dispersal rates do not vary in space, (2) when the metapopulation is a source-sink system and (3) when dispersal rates vary in space (asymmetric dispersal) and immigrants do not compensate for their reduced fecundity. We observe that non-zero asymmetric dispersal rates may be evolutionarily stable when (1) immigrants and residents are demographically alike and (2) immigrants compensate totally for their reduced fecundity through an increase in adult survival. Under these conditions, we find that the ESS occurs when the fitnesses at equilibrium in the two habitats, measured in our model by the realized reproductive rates, are each equal to unity. A comparison with previous studies suggests a unifying rule for the evolution of dispersal: the dispersal rates which permit the spatial homogenization of fitnesses are ESSs. This condition provides new insight into the evolutionary stability of source-sink systems. It also supports the hypothesis that immigrants have adapted demographic strategies, rather than the hypothesis that dispersal is costly and immigrants are at a disavantage compared with residents.     

Trade-off between reproduction and moult – a comparison of three Fennoscandian pied flycatcher populations

Organisms that reproduce at high latitudes are assumed to have evolved several adaptations to the short summer. For birds, and especially for long-distance migrants, there is a time constraint because both reproduction and moult must be completed before autumn migration. It has therefore been assumed that birds at northern latitudes must initiate their moult during reproduction more often than birds at low latitudes. To investigate how passerine birds breeding at different latitudes allocate their time between reproduction and moult, we compared timing of these activities during three consecutive breeding seasons in three widely separated populations of the pied flycatcher Ficedula hypoleuca. Our results show that the frequency of individuals with moult-breeding overlap, and moult initiation in relation to breeding stage, varied considerably among populations and years. In all three populations, female moult initiation was restricted to the late nestling period. The males had a more pronounced moult-breeding overlap than the females, but its duration was similar in all three study areas. Thus, there was no evidence for a more pronounced moult-breeding overlap at high compared with low latitudes. These results suggest that pied flycatchers sometimes accept a moult-breeding overlap, but that the time gained by having too extensive an overlap between reproduction and moult does not outweigh the associated costs. Long-distance migrants breeding at northern latitudes apparently experience a trade-off between reproduction and somatic investment during moult. We therefore suggest that a pronounced moult-breeding overlap is not a typical strategy used by long-distance migrants to adjust to the short breeding season at northern latitudes. Received: 7 May 1998 / Accepted: 24 August 1998     

Age- and sex-dependent spring arrival dates of Eastern Kingbirds

ABSTRACT.   Among migratory passerines, the first birds to arrive on the breeding grounds are usually older males. Early arrival by older birds may be driven by experience, age-dependent changes in body condition, age-dependent access to resources during the nonbreeding period, or latitudinal segregation by age. Males may arrive earlier than females (protandry) because males maintain better condition due to greater access to resources during the winter, or because selection favors early arriving males that acquire the best territories or experience enhanced mating opportunities. During a 4-yr study (2004–2007) in Oregon, we found that older Eastern Kingbirds ( Tyrannus tyrannus ), regardless of sex, arrived nearly a week before younger birds and that males arrived about 5 d before females. Age- and sex-dependent arrival dates do not appear to be related to differences in body condition, social dominance in winter, or latitudinal segregation, and protandry is unrelated to the ability of early-arriving males to acquire high-quality territories. Instead, we propose that young birds have less to gain from early arrival because of their probable inability to displace experienced birds from prime territories and that protandry evolved due to enhanced mating opportunities for early arriving males that arise from the high rates of extra-pair matings in our population of Eastern Kingbirds.     

Oral health promotion programme for older migrant adults

Objectives: This study evaluated the impact of a community‐based oral health promotion programme on the use of oral health services, oral health knowledge, attitudes, and practices of older Greek and Italian adults attending community clubs and living in Melbourne, Australia. Methods: The oral health promotion intervention consisted of three components: a series of oral health seminars, held at the clubs in the participants’ native languages, the provision of oral health care products, and the production of oral health information sheets. The intervention programme was known as the Oral Health Information Seminars/Sheets (ORHIS). The content of each session was determined following suggestions and findings from the data collected. A pre‐test–post‐test non‐equivalent control group quasi‐experimental design was chosen to evaluate the intervention. A total of 520 independent‐living older adults, members of Greek or Italian social clubs participated in this evaluation. Results: Participants who took part in the intervention responded with higher levels of achievement than those in the control groups. After controlling for baseline variables, experimental groups were significantly more likely than the control groups at post‐test to have improved oral health attitudes, oral health knowledge, and self‐assessed physical health status, as well as, self‐reported oral hygiene practices and use of oral health services. Discussion: The ORHIS approach was successful within the setting of social clubs, and highly acceptable to these communities. As such, it represents a helpful approach for the design of (oral) health interventions in older adults. Further research is required to test the long‐tem impact including the economic evaluation of the ORHIS approach.     

Transnational families and the subjective well-being of migrant parents: Angolan and Nigerian parents in the Netherlands

Studies on transnational families argue that the subjective well-being of migrant parents is negatively affected by living separated from their children. Most studies employ qualitative methods without a control group and hence are not able to distinguish whether the effects found are associated with separation only or with other factors. This paper investigates the association between parental subjective well-being and parent–child separation by comparing migrant parents who have at least one child in their country of origin with those who live with all their children in the Netherlands. The paper further investigates whether the same associations are found between migrant groups from Angola and Nigeria. Results indicate that transnational parents indeed report lower subjective well-being, as measured by happiness, life satisfaction and mental health for both groups and additionally, self-assessed health for Angolans. However, legal status, socio-economic status and the quality of the parent–child relationship are found to be important mediators.     

The emergence of an ‘ethnic economy’? The spatial relationships of migrant workers in London's health and hospitality sectors

This paper examines how the globalized nature of London's service sector redefines spatial relationships for recent migrants working in the health and hospitality industries. Findings from the qualitative data demonstrate that recent temporary migrants to the UK employ broader strategies to secure employment than accounted for by current theories. The migrants in our case studies overwhelmingly utilized global and local recruitment and employment agencies, as well as sought employment in industries already established as ‘ethnic economies’. We suggest that this might be attributed to a lack of interaction with established co-ethnic immigrant communities; temporary migration trajectories; and living arrangements with co-migrants. We conclude by emphasizing the need to broaden our understanding of ethnic economies and social networks in light of these changing spatial relationships that have emerged through the globalization of the service sector in the UK.     

Getting to know the Amakwerre-kwerre: the socio-economic circumstances of Zimbabwean day labourers in South Africa

Over the past decade, in the face of volatile economic conditions at home, there has been an influx of Zimbabweans into South Africa looking for work and a better life. Many of these jobseekers have moved into the day labourer market, offering their services on street corners and other pickup points in the main metropolitan areas. While their working and living conditions leave much to be desired and their pay is very uncertain, Zimbabwean day labourers – with better education – often are the preferred candidates for the limited jobs on offer and earn more than their counterparts in South Africa. Not surprisingly, South African day labourers often resent Zimbabwean workers in the country. This study is the first of its kind in that it delves into the hopes, fears and daily routines of Zimbabwean day labourers, and offers new perspectives on this important economic segment.     

Medium‐term changes in coastal bird communities in the Western Cape,South Africa

There are few studies of medium‐term, quantitative changes in faunal communities in the southern hemisphere. The linear nature of coastlines makes populations of coastal birds easy to count. Repeat surveys of 278 km of coastline in three regions of the Western Cape, South Africa show marked differences in coastal bird community structure over the last 30 years, despite limited human impacts on coastal habitats (mainly increased human disturbance). The total number of birds has not changed, but species richness increased following colonization of the coast by Egyptian geese (Alopochen aegyptiaca, Anatidae) and three species of ibises (Threskiornithidae). Biomass also increased due to greater numbers of large‐bodied birds. Contrary to the prediction that large birds are more susceptible to human disturbance, most small birds decreased in abundance. Among waders that breed along the coastline, numbers of African oystercatchers (Haematopus moquini, Haematopodidae) doubled, linked to increased food availability following invasions by alien mussels (Mytilidae). By comparison, numbers of white‐fronted plovers (Charadrius marginatus, Charadriidae) decreased by 37% (59% close to Cape Town), at least in part as a result of increasing human disturbance. The greatest decreases occurred among migrant waders (Scolopacidae and Charadriidae), with numbers of the four most abundant species falling by >50%, and both common Calidris species by >90%. Migrant wader populations decreased in all three regions, irrespective of whether surveys were in protected areas or not, suggesting that factors outside the region are driving these trends. Some species may have decreased due to changes in their preferred wintering areas, but others probably reflect population decreases, confirming the generally poor conservation status of migrant waterbirds worldwide.