Skip to main content
Advanced Search

Filters: Tags: Population size (X)

16 results (107ms)   

View Results as: JSON ATOM CSV
Synopsis: This study aimed to independently examine the effects of varying amounts and configurations of habitat at a landscape scale, with particular attention to critical persistence thresholds. A discrete reaction-diffusion model was used to estimate long-term equilibrium population persistence of a hypothetical species in a patchy landscape. When examined over a broad range of habitat amount and arrangements, population size was largely determined by the proportion of habitat (amount) in a landscape. However, when habitat coverage dropped below 30-50%, population response deviated, coinciding with a persistence threshold. Species persistence declined rapidly at this threshold range (50% for low degrees of aggregation,...
The endangered Indiana bat (Myotis sodalis) has declined dramatically and continuing threats have made it necessary to understand population dynamics and life history throughout the year. Specifically, demographic information (e.g., population size, reproductive success, survival) from the summer range where females raise their young in maternity colonies is difficult to estimate precisely using traditional techniques (such as emergence counts). Further, the familial makeup of maternity colonies is unknown. Genetic mark-recapture methods are increasingly being used to estimate demographic parameters in species where traditional techniques are problematic and can also provide insight into relatedness among individuals....
thumbnail
Data is included for two types of field surveys conducted for freshwater mussels in the mainstem of the middle and upper Delaware River in the Mid-Atlantic region of the United States from 2000-2002. Timed search (qualitative) surveys were conducted during 2000-2001 from a point at the confluence of the East and West Branches of the Delaware River near Hancock, NY continuously downstream to a point at the mouth of the Paulins Kill River near Columbia, NJ. In this qualitative survey, mussel species and counts were collected in the field catch-per-unit-effort (CPUE) data was determined for all mussel species within each of 1,095 consecutive stream sections ~200 m in length. Subsequent quantitative surveys were conducted...
thumbnail
This dataset depicts settlements in Belize created using various sources: International Travelers Map of Belize (1:350.000) and 2001 CSO Abstract of Statistics + own point data.
    map background search result map search result map Settlements in Belize Qualitative and quantitative surveys of native freshwater mussels in the upper and middle Delaware River (2000-2002) Qualitative and quantitative surveys of native freshwater mussels in the upper and middle Delaware River (2000-2002) Settlements in Belize