Search results for "Spatial"
showing 10 items of 2121 documents
Competition for breeding sites and site-dependent population regulation in a highly colonial seabird, the common guillemot Uria aalge
2004
Summary 1. The hypothesis of site-dependent population regulation predicts that birds utilize available nesting sites in a pre-emptive (ideal despotic) manner, leading to density dependence in heterogeneous habitats as poorer sites are used at higher population densities. At small population sizes adaptive site choice protects populations against fluctuations (the buffer effect). 2. Common guillemots Uria aalge (Pontoppidan) breed at high density on sea-cliffs. The population breeding on the Isle of May, Scotland increased by 60% between 1981 and 2000. A good nest-site is a prerequisite for successful breeding and there is much competition for the best sites. Throughout this period, site us…
Noise in ecosystems: a short review
2004
Noise, through its interaction with the nonlinearity of the living systems, can give rise to counter-intuitive phenomena such as stochastic resonance, noise-delayed extinction, temporal oscillations, and spatial patterns. In this paper we briefly review the noise-induced effects in three different ecosystems: (i) two competing species; (ii) three interacting species, one predator and two preys, and (iii) N-interacting species. The transient dynamics of these ecosystems are analyzed through generalized Lotka-Volterra equations in the presence of multiplicative noise, which models the interaction between the species and the environment. The interaction parameter between the species is random …
Urban green spaces and childhood leukemia incidence: A population-based case-control study in Madrid.
2021
Abstract Background Childhood leukemia is the most common childhood cancer. To date, few risk factors related to predisposition have been identified; therefore, new hypotheses should be considered. Objective To explore the possible relationship of residential proximity to urban green spaces on childhood leukemia. Methods We conducted a population-based case control study in the metropolitan area of Madrid from 2000 to 2015. It included 383 incident cases and 1935 controls, individually matched by birth year, sex and area of residence. Using the geographical coordinates of the participants’ home residences, we built a proxy for exposure with four distances (250 m, 500 m, 750 m and 1 km) to u…
Foraging site fidelity shapes the spatial organisation of a population of female western barbastelle bats
2009
Abstract Information about the spatial distribution of individual foraging habitats, which determines the space required by a population to be viable, is vitally important for the conservation of bats. Detailed knowledge of this kind is crucial for the design of nature reserves and management plans. Recent field studies that examined habitat use and home range distribution of bats largely ignored factors like traditional range use vs. intra- and interspecific competition, which may be responsible for the spatial organisation of a population home range. We investigated the home range sizes and distribution of a maternity colony of the western barbastelle bat via radio telemetry in four conse…
Spatial ecology of coastal Atlantic cod Gadus morhua associated with parasite load
2015
Acoustic tags and receivers were used to investigate the spatial ecology of coastal Atlantic cod Gadus morhua (n = 32, mean fork length: 50 cm, range: 33–80 cm) on the Norwegian Skagerrak coast in 2012. Monthly home ranges (HR), swimming activity and depth use varied considerably among individuals and through the months of June, July and August. HR sizes for the period ranged from 0·25 to 5·20 km2 (mean = 2·30 km2). Two thirds of the tagged G. morhua were infected with black spot disease Cryptocotyle lingua parasites; these fish had larger HRs and occupied deeper water compared with non-infected fish. The infected fish also tended to be more active in terms of horizontal swimming. From an e…
L'idée de région et le fait urbain The idea of region and the urban fact
2009
Bien que la region soit un concept multiforme, voire omniforme, le decoupage regional est le cadre privilegie de la pensee spatiale et de l'action territoriale. Or la moitie des etre humains du monde, et plus des trois quarts des europeens, habitent dans une ville. Les villes produisent plus que proportionnellement a leur poids demographique, et concentrent les activites economiques de haut niveau, particulierement la production de haute technologie, les sieges sociaux, la finance et les services aux entreprises. Dans l'economie globalisee, les performances regionales semblent etre soumises a celles des villes, et les interactions economiques regionales, nationales et mondiales sont princip…
The Fluid City Experience: An Update
2016
This chapter describes the actual status of thirteen European cities that become fluid cities through their strategies for urban regeneration. These cities are divided into three groups: the large port-cities, the medium rank “city-port” cities, the riverfront cities. For every city, we define the status of urban environment and population, the trend for port and airport traffic and the strategies for urban regeneration.
Modelling drift of pelagic offspring: the importance of egg surveys in providing a realistic model initialization
2015
Abstract Having valid information about the location and dynamics of biological processes is important for coastal management. In this context modelling, the pelagic drift of early life stages has been shown to be an important tool for understanding the spatial scale of population dynamics in marine systems. Often simulated particles are released in hypothetical quantities at assumed spawning grounds with no or few field data to guide the model parametrization. In this study, we combine high-resolution field data and state-of-the-art oceanographic modelling and use a probabilistic approach to construct kernel density distributions of the dispersal of pelagic fish eggs. Specifically, the pot…
Context-dependent foraging habitat selection in a farmland raptor along an agricultural intensification gradient
2021
Abstract Gradients of agricultural intensification in agroecosystems may determine uneven resource availability for predators relying on these man-made habitats. In turn, these variations in resource availability may affect predators’ habitat selection patterns, resulting in context-dependent habitat selection. We assessed the effects of gradients of landscape composition and configuration on habitat selection of a colonial farmland bird of prey, the lesser kestrel (Falco naumanni), relying on 76 GPS-tracked nestling-rearing individuals from 10 populations scattered along an agricultural intensification gradient. Analyses were conducted considering two ecological levels of aggregation (the …
An Analysis of the Residential Segregation of Foreigners in the Municipality of Palermo
2021
Ethnic residential segregation in Italy is emerging as a key question, which will be crucial in the definition and implementation of both urban and social policies. This chapter focuses on this phenomenon in the Italian Metropolitan Area of Palermo. We use individual data for all the population residing in the city on 31 December 2011, organised by ethnicity and neighbourhood to describe the spatial distribution and the residential segregation of foreigners in the city, applying many different segregation measures. Results show that the top ten nationalities in Palermo are not uniformly spread across the different parts of the city but tend to cluster in specific areas. The most segregated …