Modeling Habitat Suitability for Complex Species Distributions by Environmental-Distance Geometric Mean

This paper presents a new habitat suitability modeling method whose main properties are as follows: (1) It is based on the density of observation points in the environmental space, which enables it to fit complex distributions (e.g. nongaussian, bimodal, asymmetrical, etc.). (2) This density is modeled by computing the geometric mean to all observation points, which we show to be a good trade-off between goodness of fit and prediction power. (3) It does not need any absence information, which is generally difficult to collect and of dubious reliability. (4) The environmental space is represented either by an expert-selection of standardized variables or the axes of a factor analysis [in this paper we used the Ecological Niche Factor Analysis (ENFA)].We first explain the details of the geometric mean algorithm and then we apply it to the bearded vulture (Gypaetus barbatus) habitat in the Swiss Alps. The results are compared to those obtained by the "median algorithm” and tested by jack-knife cross-validation. We also discuss other related algorithms (BIOCLIM, HABITAT, and DOMAIN). All these analyses were implemented into and performed with the ecology-oriented GIS software BIOMAPPER 2.0.The results show the geometric mean to perform better than the median algorithm, as it produces a tighter fit to the bimodal distribution of the bearded vulture in the environmental space. However, the "median algorithm” being quicker, it could be preferred when modeling more usual distributio

Fitness-related parameters improve niche-based distribution modelling: the case of the red-backed shrike

The red-backed shrike (Lanius collurio L.) is a bird living in human-altered agricultural areas that are managed by extensive farming techniques. This passerine species has declined significantly in Western Europe over the last 30-40 years. The development of efficient species-specific conservation strategies relies on fine-grained information about the ecological resources and environmental conditions that make up its reproductive habitat in this agricultural landscape. Species distribution models have become increasingly used in conservation biology to provide such information. Most studies investigate the environmental pattern of species distribution, assuming that species records are reliable indicators of habitat suitability. However, ecological theory on source-sink dynamics and ecological traps points out that some individuals may be located outside the environmental bounds of their species reproductive niche. Those individuals could lead to confounding information to the models and are therefore expected to limit their utility. Parameters related to the reproductive success of this shrike in Southern Belgium were integrated into a fine-scale presence-only modelling framework to demonstrate this problem and to address the critical habitat requirements of this species relative to conservation management. Integrating reproductive parameters into the modelling framework showed that individuals occurred, but did not reproduce successfully, above a certain environmental threshold. This indicated that the reproductive niche of the shrike is ecologically narrower than standard practise in species distribution modelling would suggest. The major required resources for the reproduction of the red-backed shrike were quantified and ranked to offer concrete species-specific conservation management guidelines

Fitness-related parameters improve presence-only distribution modelling for conservation practice: The case of the red-backed shrike

The red-backed shrike (Lanius collurio L.) is a bird living in human-altered agricultural areas that are managed by extensive farming techniques. This passerine species has declined significantly in Western Europe over the last 30-40 years. The development of efficient species-specific conservation strategies relies on fine-grained information about the ecological resources and environmental conditions that constitute its reproductive habitat in this agricultural landscape. Species distribution models are used increasingly in conservation biology to provide such information. Most studies investigate the environmental pattern of species distribution, assuming that species records are reliable indicators of habitat suitability. However, ecological theory on source-sink dynamics and ecological traps points out that some individuals may be located outside the environmental bounds of their species' reproductive niche. Those individuals could reduce model accuracy and limit model utility. Parameters related to the reproductive success of this shrike in Southern Belgium were integrated into a fine-scale presence-only modelling framework to demonstrate this problem and to address critical habitat requirements of this species relative to conservation management. Integrating reproductive parameters into the modelling framework showed that individuals occurred, but did not reproduce successfully, above a certain environmental threshold. This indicated that the reproductive niche of the shrike is ecologically narrower than standard practice in species distribution modelling would suggest. The major resources (nest sites availability, distance to human settlements, suitable perching sites, foraging areas and insect abundance) required for the reproduction of the red-backed shrike were quantified and ranked to offer concrete species-specific conservation management guidelines. © 2007 Elsevier Ltd. All rights reserved

State of Emergency Medicine in Switzerland: a national profile of emergency departments in 2006

BACKGROUND Emergency departments (EDs) are an essential component of any developed health care system. There is, however, no national description of EDs in Switzerland. Our objective was to establish the number and location of EDs, patient visits and flow, medical staff and organization, and capabilities in 2006, as a benchmark before emergency medicine became a subspecialty in Switzerland. METHODS In 2007, we started to create an inventory of all hospital-based EDs with a preliminary list from the Swiss Society of Emergency and Rescue Medicine that was improved with input from ED physicians nationwide. EDs were eligible if they offered acute care 24 h per day, 7 days per week. Our goal was to have 2006 data from at least 80% of all EDs. The survey was initiated in 2007 and the 80% threshold reached in 2012. RESULTS In 2006, Switzerland had a total of 138 hospital-based EDs. The number of ED visits was 1.475 million visits or 20 visits per 100 inhabitants. The median number of visits was 8,806 per year; 25% of EDs admitted 5,000 patients or less, 31% 5,001-10,000 patients, 26% 10,001-20,000 patients, and 17% >20,000 patients per year. Crowding was reported by 84% of EDs with >20,000 visits/year. Residents with limited experience provided care for 77% of visits. Imaging was not immediately available for all patients: standard X-ray within 15 min (70%), non-contrast head CT scan within 15 min (38%), and focused sonography for trauma (70%); 67% of EDs had an intensive care unit within the hospital, and 87% had an operating room always available. CONCLUSIONS Swiss EDs were significant providers of health care in 2006. Crowding, physicians with limited experience, and the heterogeneity of emergency care capabilities were likely threats to the ubiquitous and consistent delivery of quality emergency care, particularly for time-sensitive conditions. Our survey establishes a benchmark to better understand future improvements in Swiss emergency care

Landscape genetics of the Alpine newt (Mesotriton alpestris) inferred from a strip-based approach

Habitat destruction and fragmentation are known to strongly affect dispersal by altering the quality of the environment between populations. As a consequence, lower landscape connectivity is expected to enhance extinction risks through a decrease in gene flow and the resulting negative effects of genetic drift, accumulation of deleterious mutations and inbreeding depression. Such phenomena are particularly harmful for amphibian species, characterized by disjunct breeding habitats. The dispersal behaviour of amphibians being poorly understood, it is crucial to develop new tools, allowing us to determine the influence of landscape connectivity on the persistence of populations. In this study, we developed a new landscape genetics approach that aims at identifying land-uses affecting genetic differentiation, without a priori assumptions about associated ecological costs. We surveyed genetic variation at seven microsatellite loci for 19 Alpine newt (Mesotriton alpestris) populations in western Switzerland. Using strips of varying widths that define a dispersal corridor between pairs of populations, we were able to identify land-uses that act as dispersal barriers (i.e. urban areas) and corridors (i.e. forests). Our results suggest that habitat destruction and landscape fragmentation might in the near future affect common species such as M. alpestris. In addition, by identifying relevant landscape variables influencing population structure without unrealistic assumptions about dispersal, our method offers a simple and flexible tool of investigation as an alternative to least-cost models and other approaches