More Like this

1. Social environment influences termination of nomadic migration

   https://doi.org/10.1098/rsbl.2022.0006  

   Robart, Ashley R.; Zuñiga, Hilary X.; Navarro, Guillermo; Watts, Heather E. (March 2022, Biology Letters)

   The final stage of migration, when animals terminate migratory movements and transition to a more sedentary state, remains the least understood phase of migration. Whereas migrants that return to the same locations each year may use mechanisms associated with locating a specific destination, migrants with low site fidelity, such as nomadic migrants, may rely on local environmental cues to determine when to cease migratory movements. Using an experiment with captive birds, we tested whether the presence of a conspecific influences the termination of migration, indicated by changes in behaviour and physiology, in a nomadic migrant (the pine siskin, Spinus pinus ). We paired migratory birds with a non-migratory individual or left migratory and non-migratory individuals unpaired. Migratory paired birds had a significant decline in nocturnal activity immediately after pairing and activity levels remained lower two weeks later, with significant declines in energetic reserves and flight muscle size also observed. By contrast, migratory unpaired birds maintained high levels of activity and energetic reserves. These results provide evidence for a role of the social environment in migratory termination decisions. Social cues may be particularly useful in nomadic migrants, such as pine siskins, to facilitate settling in high quality, but unfamiliar, habitats. 

   more » « less
2. Point of Reference: A Multisited Exploration of African Migration and Fertility in France

   https://doi.org/10.1177/01979183211046571  

   Behrman, Julia A.; Weitzman, Abigail (January 2022, International Migration Review)

   A considerable literature explores whether the fertility of migrants from high-fertility contexts converges with that of women in lower fertility destinations. Nonetheless, much of this research compares migrants’ reproductive outcomes to those of native-born women in destination countries. Drawing on research emphasizing the importance of transnational perspectives, we standardize and integrate data collected in France (the destination) and in six high-fertility African countries (the senders). We show that African migrants in our sample had higher children ever born (CEB) than native French women but lower CEB than women in corresponding origin countries. These findings suggest that socialization into pronatalist norms is an incomplete explanation for migrant fertility in the first generation, an insight that is overlooked when analyzing destination settings only. Next, we conduct multivariate analyses that weight migrants’ background characteristics to resemble women in both origin and destination countries. Findings indicate that observed differences between African migrants in France and women in African origin countries help explain differences in CEB between the two groups, which supports selection. We also demonstrate that African migrants in France had delayed transitions into first, second, and third births and lower completed fertility compared to women in origin countries, thus disputing the disruption hypothesis. Finally, we show that observed differences between African migrants in France and native French women explain differences in CEB between the two groups, which supports adaptation. These multifaceted findings on selection, disruption, and adaptation would be obscured by analyzing destination settings only, thus validating a multisited approach to migrant fertility. 

   more » « less
3. Artificial light at night is a top predictor of bird migration stopover density

   https://doi.org/10.1038/s41467-023-43046-z  

   Horton, Kyle G.; Buler, Jeffrey J.; Anderson, Sharolyn J.; Burt, Carolyn S.; Collins, Amy C.; Dokter, Adriaan M.; Guo, Fengyi; Sheldon, Daniel; Tomaszewska, Monika Anna; Henebry, Geoffrey M. (December 2023, Nature Communications)

   Abstract As billions of nocturnal avian migrants traverse North America, twice a year they must contend with landscape changes driven by natural and anthropogenic forces, including the rapid growth of the artificial glow of the night sky. While airspaces facilitate migrant passage, terrestrial landscapes serve as essential areas to restore energy reserves and often act as refugia—making it critical to holistically identify stopover locations and understand drivers of use. Here, we leverage over 10 million remote sensing observations to develop seasonal contiguous United States layers of bird migrant stopover density. In over 70% of our models, we identify skyglow as a highly influential and consistently positive predictor of bird migration stopover density across the United States. This finding points to the potential of an expanding threat to avian migrants: peri-urban illuminated areas may act as ecological traps at macroscales that increase the mortality of birds during migration. 

   more » « less
4. Exploring the relationship between droughts and rural-to-urban mobility—a mixed methods approach for Pune, India

   https://doi.org/10.3389/fclim.2023.1168584  

   Karutz, Raphael; Kabisch, Sigrun (May 2023, Frontiers in Climate)

   Urbanization in the global South is intricately linked with the internal mobility of people and the impacts of climate change. In India, changing precipitation patterns pose pressure on rural livelihoods through the increasing frequency and severity of droughts, contributing to rural-to-urban mobility. At destination, however, insufficient information is available on the complex mobility backgrounds of the new arrivals. We employ a mixed methods approach to investigate mobility patterns to Pune, India, with a special focus on the role of droughts. Combining a household survey with in-depth interviews and monthly precipitation data on district level, we use descriptive statistics and qualitative content analysis to show a significant relationship between drought at origin and mobility to Pune. Particularly affected are recent arrivals, migrants of rural origin and from other states, and those currently living in informal areas. The link between droughts and mobility decisions is usually indirect, hidden behind economic conditions such as the loss of agricultural jobs. Paradoxically, migrants affected by droughts at origin face increased flood risk at destination. This risk, however, is often consciously taken in favor of better livelihood opportunities in the city. With climate scenarios projecting increasingly variable precipitation patterns, understanding the climate-mobility-urbanization nexus gains importance, especially for destination hotspots like the city of Pune. 

   more » « less
5. Migration and fuel use in rural Zambia

   https://doi.org/10.1007/s11111-021-00385-7  

   Wu, Yu; Entwisle, Barbara; Sinai, Cyrus; Handa, Sudhanshu (December 2021, Population and Environment)

   Abstract What is the effect of migration on fuel use in rural Zambia? Opportunities to increase income can be scarce in this setting; in response, households may pursue a migration strategy to increase resources as well as to mitigate risk. Migrant remittances may make it possible for households to shift from primary reliance on firewood to charcoal, and the loss of productive labor through migration may reinforce this shift. This paper uses four waves of panel data collected as part of the Child Grant Programme in rural Zambia to examine the connection between migration and the choice of firewood or charcoal as cooking fuel and finds evidence for both mechanisms. Importantly, this paper considers migration as a process, including out as well as return migration, embedding it in the context of household dynamics generally. Empirical results suggest that while out-migration helps move households away from firewood as a fuel source, return migration moves them back, but because the former is more common, the overall effect of migration is to shift households away from primary reliance on firewood. 

   more » « less