Megan M. Friggens

Anthropogenic disturbance and the risk of flea-borne disease transmission

Anthropogenic disturbance may lead to the spread of vector-borne diseases through effects on pathogens, vectors, and hosts. Identifying the type and extent of vector response to habitat change will enable better and more accurate management strategies for anthropogenic disease spread. We compiled and analyzed data from published empirical studies to test for patterns among flea and small mammal diversity, abundance, several measures of flea infestation, and host specificity in 70 small mammal communities of five biomes and three levels of human disturbance: remote/wild areas, agricultural areas, and urban areas. Ten of 12 mammal and flea characteristics showed a significant effect of disturbance category (six), biome (four), or both (two). Six variables had a significant interaction effect. For mammal-flea communities in forest habitats (39 of the 70 communities), disturbance affected all 12 characteristics. Overall, flea and mammal richness were higher in remote versus urban sites. Most measures of flea infestation, including percent of infested mammals and fleas/mammal and fleas/mammal species increased with increasing disturbance or peaked at intermediate levels of disturbance. In addition, host use increased, and the number of specialist fleas decreased, as human disturbance increased. Of the three most common biomes (forest, grassland/savanna, desert), deserts were most sensitive to disturbance. Finally, sites of intermediate disturbance were most diverse and exhibited characteristics associated with increased disease spread. Anthropogenic disturbance was associated with conditions conducive to increased transmission of flea-borne diseases.

Bringing indices of species vulnerability to climate change into geographic space: an assessment across the Coronado national forest

Indices that rate the vulnerability of species to climate change in a given area are increasingly used to inform conservation and climate change adaptation strategies. These species vulnerability indices (SVI) are not commonly associated with landscape features that may affect local-scale vulnerability. To do so would increase their utility by allowing managers to examine how the distributions of vulnerable species coincide with environmental features such as topography and land use, and to detect landscape-scale patterns of vulnerability across species. In this study we evaluated 15 animal species that had been scored with the USDA-Forest Service Rocky Mountain Research Station’s system for assessing vulnerability of species to climate change. We applied the vulnerability scores to each species’ respective habitat models in order to visualize the spatial patterns of cross-species vulnerability across the biologically diverse Coronado national forest, and to identify the considerations of spatially referencing such indices. Across the study extent, cross-species vulnerability was higher in higher-elevation woodlands and lower in desert scrub. The results of spatially referencing SVI scores may vary according to the species examined, the area of interest, the selection of habitat models, and the method by which cross-species vulnerability indices are created. We show that it is simple and constructive to bring species vulnerability indices into geographic space: landscape-scale patterns of vulnerability can be detected, and relevant ecological and socioeconomic contexts can be taken into account, allowing for more robust conservation and management strategies.

An assessment of climate change and the vulnerability of wildlife in the Sky Islands of the Southwest

We evaluated the historical and projected trends in climate and vegetation relevant to the Coronado National Forest in southeast Arizona, USA. We then applied this information in an assessment of the vulnerability of 30 species of terrestrial vertebrates on the Coronado National Forest to the potential effects of future climate change. We used a pilot version of a decision-support tool developed by the U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station that produces scores that represent relative measures of vulnerability to climate change as related to habitat, physiology, phenology, and biotic interactions. Over the next ~100 years, increased temperature and aridity are projected for the region, as well as a reduction in forested areas. All 30 species were considered vulnerable with respect to at least some criteria comprising the decision-support tool. The elegant trogon (Trogon elegans) and Tarahumara frog (Rana tarahumarae) were tied for the largest vulnerability score. The Slevins bunchgrass lizard (Sceloporus slevini) had the smallest vulnerability score. While species varied in their expected responses to climate change, most appeared to be vulnerable relative to one or more expected negative impacts to their habitat, such as an overall reduction in suitable habitat. The assessment results can be used by USFS managers in climate change adaptation planning for these species and their habitats by helping to identify goals for adaptation planning.

Implications of Climate Change for Bird Conservation in the Southwestern U.S. under Three Alternative Futures

Future expected changes in climate and human activity threaten many riparian habitats, particularly in the southwestern U.S. Using Maximum Entropy (MaxEnt3.3.3) modeling, we characterized habitat relationships and generated spatial predictions of habitat suitability for the Lucy’s warbler (Oreothlypis luciae), the Southwestern willow flycatcher (Empidonax traillii extimus) and the Western yellow-billed cuckoo (Coccyzus americanus). Our goal was to provide site- and species-specific information that can be used by managers to identify areas for habitat conservation and/or restoration along the Rio Grande in New Mexico. We created models of suitable habitat for each species based on collection and survey samples and climate, biophysical, and vegetation data. We projected habitat suitability under future climates by applying these models to conditions generated from three climate models for 2030, 2060 and 2090. By comparing current and future distributions, we identified how habitats are likely to change as a result of changing climate and the consequences of those changes for these bird species. We also examined whether land ownership of high value sites shifts under changing climate conditions. Habitat suitability models performed well. Biophysical characteristics were more important that climate conditions for predicting habitat suitability with distance to water being the single most important predictor. Climate, though less important, was still influential and led to declines of suitable habitat of more than 60% by 2090. For all species, suitable habitat tended to shrink over time within the study area leaving a few core areas of high importance. Overall, climate changes will increase habitat fragmentation and reduce breeding habitat patch size. The best strategy for conserving bird species within the Rio Grande will include measures to maintain and restore critical habitat refugia. This study provides an example of a presence-only habitat model that can be used to inform the management of species at intermediate scales.

The importance of assessing climate change vulnerability to address species conservation

Abstract Species conservation often prioritizes attention on a small subset of “special status” species at high risk of extinction, but actions based on current lists of special status species may not effectively moderate biodiversity loss if climate change alters threats. Assessments of climate change vulnerability may provide a method to enhance identification of species at risk of extinction. We compared climate change vulnerability and lists of special status species to examine the adequacy of current lists to represent species at risk of extinction in the coming decades. The comparison was made for terrestrial vertebrates in a regionally important management area of the southwestern United States. Many species not listed as special status were vulnerable to increased extinction risk with climate change. Overall, 74% of vulnerable species were not included in lists of special status and omissions were greatest for birds and reptiles. Most special status species were identified as additionally vulnerab...

Vulnerability of species to climate change in the Southwest: terrestrial species of the Middle Rio Grande

We used a vulnerability scoring system to assess the vulnerability of 117 vertebrate species that occur in the Middle Rio Grande Bosque (MRGB) to expected climate change. The purpose of this project was to guide wildlife managers on options and considerations for climate change adaptation. The 117 species occur regularly in the MRGB during the breeding season, winter, or year-round. In general, future climate scenarios predict warmer temperatures with an altered precipitation regime that will likely lead to reduced water levels in the MRGB. This assessment points to several key issues relating to future habitat changes and individual species physiology that are expected to affect species survival under climate change. Decreased availability of mesic sites is expected to directly impact many amphibian and reptile populations and is expected to have indirect affects for birds and mammals primarily through changes in habitat availability. We predicted that phenological changes will negatively impact many species within all taxonomic groups through altered timing of weather events and river flow. Riparian-dependent species received some of the highest vulnerability scores. Species already at the southern limit of their distributional range were also predicted to be more likely to be vulnerable to climate change. The assessment also identified important data gaps. Management for species conservation under future climate conditions will require increased research and monitoring, greater integration of landscape-scale approaches, consideration of future land-use scenarios, and increased understanding of the consequences of species’ interactions. We review the specific implications of climate change for wildlife in the MRGB in order to identify intervention points and approaches that may achieve management goals.