Skip to main content
Advanced Search

Filters: Tags: Population Viability (X)

6 results (42ms)   

Date Range
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
[Excerpt from Introduction] "The San Francisco Bay Estuary supports a large and diverse bird community. More than 50% of most Pacific flyway diving duck populations are found in the Estuary during the winter months (Trost 2002; U.S. Fish and Wildlife Service 2002). San Francisco Bay has been designated as a site of international importance for shorebirds (Western Hemisphere Shorebird Reserve Network), supporting millions of individuals (Morrison et al. 2001; Takekawa et al. 2001; Warnock et al. 2002), including species that use tidal marsh habitats. In total, the Bay’s tidal marshes support at least 113 bird species that represent 31 families (Takekawa et al., in press)..."
This layer represents least-cost (shortest-path) habitat centrality across potentiall suitable habitat for gray wolves in the Western United States. Here, least-cost centrality measures the relative role of a given portion of a potential movement path to facilitating movement of wolves across the landscape. Centrality metrics are based on graph theory. A graph is a set of nodes in which pairs of nodes can be connected by edges representing functional connections (e.g., dispersal) between the nodes. Edges can be assigned weights that represent attributes such as habitat quality. A sequence of nodes connected by edges forms a path. Landscape lattices are graphs in which every cell in a raster is treated as a node...
Detailed empirical models predicting both species occurrence and fitness across a landscape are necessary to understand processes related to population persistence. Failure to consider both occurrence and fitness may result in incorrect assessments of habitat importance leading to inappropriate management strategies. We took a two-stage approach to identifying critical nesting and brood-rearing habitat for the endangered Greater Sage-Grouse (Centrocercus urophasianus) in Alberta at a landscape scale. First, we used logistic regression to develop spatial models predicting the relative probability of use (occurrence) for Sage-Grouse nests and broods. Secondly, we used Cox proportional hazards survival models to identify...
Conclusions: Reduction in landscape carrying capacity for wolf population distribution and viability depends largely on the degree of road density, public land ownership, amount of forest cover and high elk densities (another indicator of suitable habitat). Synopsis: This study employed two types of spatial models to evaluate the potential of wolf reintroduction in the southern Rocky Mountain region. A multiple logistic regression was used to develop a resource-selection function relating wolf distribution in the Greater Yellowstone region with regional-scale habitat variables. Researchers also used a spatially explicit population model to predict wolf distribution and viability at several potential reintroduction...
Abstract: Accelerating climate change and other cumulative stressors create an urgent need to understand the influence of environmental variation and landscape features on the connectivity and vulnerability of freshwater species. Here, we introduce a novel modeling framework for aquatic systems that integrates spatially-explicit, individual-based, demographic and genetic (demogenetic) assessments with environmental variables. To show its potential utility, we simulated a hypothetical network of 19 migratory riverine populations (e.g., salmonids) using a riverscape connectivity and demogenetic model (CDFISH). We assessed how stream resistance to movement -- a function of water temperature, fluvial distance, and...

    map background search result map search result map Impacts of landscape change on wolf restoration success: planning a reintroduction program based on static and dynamic spatial models. Western United States Gray Wolf Least-Cost Habitat Centrality Impacts of landscape change on wolf restoration success: planning a reintroduction program based on static and dynamic spatial models. Western United States Gray Wolf Least-Cost Habitat Centrality