Search results for " MIG"
showing 10 items of 1654 documents
Ecomorphological predictors of natal dispersal distances in birds.
2008
1. Dispersal is one of the key ecological parameters but it is very difficult to quantify directly. As a consequence, empirical studies often ignore dispersal or use indirect measures. 2. Ringing data have previously been used to estimate the natal dispersal distances of 47 British passerine bird species. This provides an excellent opportunity to examine the potential of various indirect measures to predict natal dispersal distances in British birds. 3. We use a phylogenetic comparative framework and single- and multipredictor models including ecomorphological, behavioural or ecological traits to predict natal dispersal distance. 4. A multipredictor model that includes Kipp's distance (a me…
Size distribution of Daphnia longispina in the vertical profile
1997
D. longispina of the meromictic lake El Tobar is a round-headed form. It never has a helmet, but in summer a small proportion of immature individuals (0.9–1.2 mm females and males) have one or two neck teeth. The size structure of this Daphnia population, as well as the vertical distribution and migration of different size-classes, were studied in September and November of 1991 and April of 1992. The large variation in mean size and size at first reproduction, as well as the occurrence of different patterns of vertical migration are interpreted as responses to different predator situations. At the end of April, when Daphnia mortality by visually hunting predators is dominating, a typical no…
Food for flight: pre-migratory dynamics of the Lesser Kestrel Falco naumanni.
2014
Capsule The post-reproductive stage of Lesser Kestrel is crucial for migratory fuelling and survival. Aims To describe the summer pre-migratory ecology of the Lesser Kestrel in Sicily and review existing data in Southern Europe. Methods We identified the main summer roosts and then made roost counts every ten days from 2010 to 2012. We used case-sensitive modelling procedures to detect biases in counts (generalized linear mixed models), assess the annual population trends from 2005 to 2012 (TRends and Indices for Monitoring); and to model habitat preferences (generalized linear model). We sampled pellets to describe the birds’ diet during the peak month prior to migration. Results We discov…
Diel vertical migration by Daphnia longispina in a Spanish lake: Genetic sources of distributional variation
1995
Individuals of many zooplankton species undergo diel vertical migration in which they move toward the surface after sunset and return to deeper waters at dawn. However, even when vertical migration can be clearly demonstrated by mapping the distributions of individuals at noon and midnight, at any given time the population is usually scattered over ‘a broad range of depths. This paper focuses on a major potential source of the variance associated with depth distributions. We have used electrophoretic analysis of isozymes to identify “clones” of Daphnia longispina in a Spanish lake. In September 199 1, two clones constituted 5 5% of the individuals collected at noon and midnight on each oftw…
Economic Factors of Labor Migration Analysis
2021
Population of Latvia is declining every year due to rate of natural decrease and negative rate of net migration indicators [1]. It is a topical issue since it affects stability and growth of the country.
Educational Migration Trends Review in Poland (with Particular Emphasis on the Immigration of Ukrainian Youth)
2023
This article aims to review and synthesise research on educational migration in Poland, particularly youth immigration from Ukraine. The paper collects statistical data from 2004, which allowed for the analysis of the existing trends in educational migration in Poland. The research on the largest group of foreign students – citizens of Ukraine – was reviewed, which resulted in identifying research gaps regarding student mobility in Poland, both in terms of demand and supply of educational migrations. The practical implication appears to show that the governments of the host countries, the business sector, and the academic units – due to the increase in the number of foreign students – can e…
Educational Inequalities and Their Impact on Social Mobility of the second generation: A Comparison of North Africans in France and the Second Genera…
2013
International audience; This paper aims to compare the educational outcomes of children of immigrants in France and in the US to understand the educational inequalities and opportunities for social mobility for the second generation in both countries. The comparison is focused on children from two groups: North Africans in France and Mexicans in the US. By using two longitudinal datasets, the French Educational Panel Survey and Add Health, we examine aspirations, expectations and attainment in secondary education in the two contexts. We explore in particular the role of parental education on attainment. We also utilize in-depth interviews to understand their educational experiences and thei…
Social Inclusion and Exclusion in the Life Stories of Deported Asylum Seekers from Finland to Iraqi Kurdistan
2018
This study explores how social inclusion and exclusion manifest as a dynamic continuum in the everyday lived realities of irregular migrants. Based on narratives of Iraqi Kurdish asylum seekers, who were eventually deported from Finland, the analysis depicts the ways in which societal structures, personal negotiations as well as relationships and social networks interplay in lives characterized by multiple locations, transitions and positions. Establishing and maintaining social contacts, belonging to various networks and being able to decide and act are primary factors that help us understand how the narrators relate to the continuum. The participants construct narratives illustrating seve…
Comment les jeunes issus de l'immigration cherchent-ils et trouvent-ils un emploi ?
2012
"Connaissance de l'emploi" est une publication mensuelle du Centre d'études de l'emploi. Ce quatre pages valorise les travaux du Centre. Il constitue un support de synthèse éclairant une question d'actualité ou présentant un aspect particulier d'une recherche.; L'analyse des données recueillies par l'enquête Trajectoires et Origines (TeO) en 2008-2009 sur la diversité des populations en France éclaire la façon dont les jeunes actifs issus de l'immigration recherchent et trouvent leur emploi. Les descendants d'immigrés effectuent autant de démarches de recherche d'emploi que la population majoritaire. Certains groupes se distinguent par leur propension à activer plus ou moins certains canaux…
Diel feeding periodicity, daily ration and prey selectivity in juvenile brown trout in a subarctic river
1999
Feeding of age-1 brown trout Salmo trutta in a third-order river in northern Finland was usually highest in the twilight hours and lowest around midday. Diel periodicity in food intake was less distinct and rarely significant for age-0 trout. Daily rations declined seasonally, being lowest in October, and highest in June (age-1 trout) or early August (age-0 trout). Prey selection did not differ between day and night, but differences between age classes and sampling dates were distinct. Age-0 trout preferred Ephemerella nymphs in summer and Micrasema larvae later in the season. Age-1 trout fed selectively on caddis larvae on all sample dates. Aerial insects and Baetis nymphs were avoided by …