Search results for " migration"

Emigracja zarobkowa w ukraińskiej rodziny: problemy, dylematy, kontrowersje

2018

Trying to control migration between zones in the world

2019

It is a fact that migration is a worrying problem in some world areas. Literature shows many studies about it. Nevertheless, no sound solutions have been proposed. Assuming that the key implied factors are development and demography, we suggest in this research, as a first step, to state a stochastic and dynamic demographic model neither considering sexes nor ages, but including the necessary and adequate economic, education and health variables. This model will be able to optimize, by means of a genetic algorithm, the amount and proportion of the main development indicators in different areas of the world along time, in order to reach the desired values of the population present in each ar…

Individual consistency and sex differences in migration strategies of Scopoli’s shearwaters Calonectris diomedea despite year differences

2014

Abstract Recently-developed capabilities for tracking the movements of individual birds over the course of a year or longer has provided increasing evidence for consistent individual differences in migration schedules and destinations. This raises questions about the relative importance of individual consistency versus flexibility in the evolution of migration strategies, and has implications for the ability of populations to respond to climatic change. Using geolocators, we tracked the migrations of Scopoli’s shearwaters Calonectris diomedea breeding in Linosa (Italy) across three years, and analysed timing and spatial aspects of their movements. Birds showed remarkable variation in their …

URBANIZATION PROCESSES AND ITS SPECIFICS IN LATGALE

2010

<p>Urbanization is an important demo-geographical process and a complex social phenomenon under impact of which changes are made not only to the global, regional or national settlement systems, but all socio-economic processes are also substantially transformed. Changes caused by urbanization have an impact on traditional way of life, cultural particularity, community and individual psychology and other aspects of spiritual life, therefore expressions and regularities of this process might be of interest not only for demographers, geographers and economists, but also for representatives of the field of humanities.</p><p>Paper presents the progress of urbanization processes…

WHY  DID  THEY  NEED  TO  COME  NOW?  COVID-19  CRISIS  STRAINS  RELATIONSHIPS  WITH  RETURNING  AND  VISITING  COMPATRIOTS

2021

One of the first areas severely hit by the Covid-19 pandemic was international travel. In March/April, with commercial flights coming to a near halt, the governments were struggling to help their stranded citizens to return home. Extra flights and ferry trips were organised, and the opportunity to return was used by many emigrants worried about the uncertainty and the possible future development of the pandemic. This paper containing both data collected through survey and in-depth interviews with people aged 50+ in Latvia, is the first to explore the reactions of the society to repatriation policy implemented by the government of Latvia, and to explore how the Covid-19 situation has affecte…

Baltijos trynukai? Emigracija, migracija ir atsakas krizei

2021

Šiame straipsnyje nagrinėjama migracijos ir ekonominio vystymosi sankirta, kaip viena aktualiausių problemų, su kuriomis susiduria Baltijos šalys. Pasinaudojus empirine prieiga, lyginami vyriausybių veiksmai esant ekonominei 2008 metų krizei. Straipsnyje analizuojama, kaip jie išryškėjo socioekonominę dinamiką atskleidžiančioje statistikoje. Tyrime taikomi lyginamosios statistikos ir antrinių duomenų analizės metodai. Visos trys valstybės patiria panašių ateities iššūkių: visuomenės senėjimas ir gyventojų skaičiaus mažėjimas, tuo tarpu emigrantų sugrįžimas matomas kaip viena iš priemonių, galinčių padėti šias problemas spręsti. Estijoje vykstantys procesai leidžia manyti, kad jos Vyriausybe…

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…