Distribution models are increasingly being used to understand how landscape and climatic changes are affecting the processes driving spatial and temporal distributions of plants and animals. However, many modeling efforts ignore the dynamic processes that drive distributional patterns at different scales, which may result in misleading inference about the factors influencing species distributions. Current occupancy models allow estimation of occupancy at different scales and, separately, estimation of immigration and emigration. However, joint estimation of local extinction, colonization, and occupancy within a multi‐scale model is currently unpublished. We extended multi‐scale models to account for the dynamic processes governing species distributions, while concurrently modeling local‐scale availability. We fit the model to data for lark buntings and chestnut‐collared longspurs in the Great Plains, USA, collected under the Integrated Monitoring in Bird Conservation Regions program. We investigate how the amount of grassland and shrubland and annual vegetation conditions affect bird occupancy dynamics and local vegetation structure affects fine‐scale occupancy. Buntings were prevalent and longspurs rare in our study area, but both species were locally prevalent when present. Buntings colonized sites with preferred habitat configurations, longspurs colonized a wider range of landscape conditions, and site persistence of both was higher at sites with greener vegetation. Turnover rates were high for both species, quantifying the nomadic behavior of the species. Our model allows researchers to jointly investigate temporal dynamics of species distributions and hierarchical habitat use. Our results indicate that grassland birds respond to different covariates at landscape and local scales suggesting different conservation goals at each scale. High turnover rates of these species highlight the need to account for the dynamics of nomadic species, and our model can help inform how to coordinate management efforts to provide appropriate habitat configurations at the landscape scale and provide habitat targets for local managers.
Habitat specialists are declining worldwide, often paralleling rapid loss of habitat. Grassland habitats across North America are declining precipitously, due in part to intense conversion of grasslands to agriculture and rangelands, and specialist communities reliant upon this landscape are at particular risk of decline and collapse. We explored the relationship between grassland habitat specialism in birds and species population trends using several different grassland specialism indices (GSIs). Our data sources for these indices included (1) a regional bird dataset employing a spatially stratified sampling design (Integrated Monitoring of Bird Conservation Regions) of bird surveys in the Northern Great Plains of North America, and (2) geospatial data of species ranges (BirdLife Int'l) and grassland habitat (CEC North American Land Cover). We found a negative relationship between degree of habitat specialism and species population trends for all specialism metrics. We also found some evidence to support that specialism to grasslands on the wintering grounds partially explains population trends during the breeding season, giving added weight to the consideration of habitat conservation across the full annual cycle of a species to reverse or lessen population decline. Our work is the first to use quantitative methods to confirm the precarious state of grassland specialist songbirds in North America as well as demonstrate multiple methods for quantifying habitat specialism across different types of datasets.
Background: Spinal cord stimulation (SCS) is an established treatment option for chronic pain. Prior to permanent implantation, temporary trials are performed to evaluate the SCS treatment. During the trial period, it is common for the patients to experience changes in paresthesias. However, it is unclear what the role of lead migration is, if any, in the changes in paresthesia. Objective: To evaluate the role of lead migration on the effect of postural stimulation changes during SCS trials. Study Design: Case series. Setting: University pain management center. Methods: X-rays of the patients with successful trials, in sitting and standing position, were obtained at the end of a 7 day SCS trial. Data were collected based on the need for adjustment of the stimulation settings due to changes in paresthesias with postural change of sitting versus standing. Results: The average lead migration was 3.05 mm inferiorly from a standing to sitting position for all subjects. The average migration was 2.85 mm in subjects requiring adjustment of the SCS setting due to change in paresthesia compared to 3.24 mm for those who did not require adjustment regardless of position. The results were insignificant based on P = 0.17. Limitations: Small sample size, case series. Conclusions: This case series demonstrates continued support for the role of the width of the cerebral spinal fluid space as the significant factor on paresthesia changes in SCS with respect to postural changes, even during the trial period. Key words: Spinal cord stimulation, postural change, lead migration, paresthesia, neurostimulation, chronic pain, dorsal column
The decline of biodiversity from anthropogenic landscape modification is among the most pressing conservation problems worldwide. In North America, long-term population declines have elevated the recovery of the grassland avifauna to among the highest conservationpriorities. Because the vast majority of grasslands of the Great Plains are privately owned, the recovery of these ecosystems and bird populations within them depend on landscape-scale conservation strategies that integrate social, economic, and biodiversity objectives.The Conservation Reserve Program (CRP) is a voluntary program for private agricultural producers administered by the United States Department of Agriculture that provides financial incentives to take cropland out of production and restore perennial grassland. We investigated spatial patterns of grassland availability and restoration to inform landscape-scale conservation for a comprehensive community of grassland birds in the Great Plains. The research objectives were to (1) determine how apparent habitat loss has affected spatial patterns of grassland bird biodiversity, (2) evaluate the effectiveness of CRP for offsetting the biodiversity declines of grassland birds, and (3) develop spatially explicit predictions to estimate the biodiversity benefit of adding CRP to landscapes impacted by habitat loss. We used the Integrated Monitoring in Bird Conservation Regions program to evaluate hypotheses for the effects of habitat loss and restoration on both the occupancy and species richness of grassland specialists within a continuum-modeling framework. We found the odds of community occupancy declined by 37% for every 1 SD decrease in grassland availability [log e (km 2 )] and increased by 20% for every 1 SD increase in CRP land cover [log e (km 2 )]. There was 17% turnover in species composition between intact grasslands and CRP landscapes, suggesting that grasslands restored by CRP retained considerable, but incomplete, representation of biodiversity in agricultural landscapes. Spatially explicit predictions indicated that absolute conservation outcomes were greatest at high latitudes in regions with high biodiversity, whereas the relative outcomes were greater at low latitudes in highly modified landscapes. By evaluating community-wide responses to landscape modification and CRP restoration at bioregional scales, our study
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