Geology topics

Chris Ray

Publications and source records attributed to Chris Ray.

6 recordsLinked to original sources

USGS2019

Trends in landbird density at two national parks in fragmented, mixed-use landscapes of the Pacific Northwest

National parks play a key role in conserving species by providing landscapes where threats from anthropogenic disturbance are reduced. In a recent study of 3 large wilderness parks in the Pacific Northwest, nearly all landbird species were found to be stable or increasing. Nonetheless, contemporary results from the Breeding Bird Survey and mark-recapture studies fuel concerns that some landbirds in the Pacific Northwest are trending in sync with many North America species in widespread decline. Although landbird populations might be thriving in large parks with extensive old-growth forest, those in smaller parks with less intact wilderness and higher ratios of edge-to-interior habitat might reflect the stressors inherent in more human-dominated landscapes. We conducted landbird point-count surveys from 2005 to 2016 in 2 national historical parks situated in the more human-dominated landscapes of this region, San Juan Island National Historical Park and Lewis and Clark National Historical Park. Established primarily to protect cultural resources, these parks lack old-growth forest and consist of relatively small parcels embedded in fragmented, multi-use landscapes. Here, we apply recent developments in point-count analysis to estimate trends in population density for 50 landbird species commonly detected in these small parks, including lagged effects of precipitation and temperature on the annual density of each species, and effects of survey conditions on species detection. All but 3 species exhibited stable densities in both parks, and more than half of the populations analyzed clearly increased in density over the study period. Notable exceptions were single-park declines in Olive-sided Flycatcher ( Contopus cooperi ), Northern Flicker ( Colaptes anratus ), and Hutton's Vireo ( Vireo huttoni ). Annual variation in population density was often related to climate, with generally positive responses to a recent deficit in annual precipitation-as-snow, and more variable responses to higher mean spring temperature. These results reinforce trends estimated for 3 large national parks in the Pacific Northwest, suggesting recent stability of landbird populations in parks of this region, independent of park size or setting.

Northwestern Naturalist↗

USGS2018

Landbird population trends in mountain and historical parks of the North Coast and Cascades Network: 2005–2016 synthesis

Long-term monitoring of landbird populations within the National Park Service (NPS) North Coast and Cascades Inventory and Monitoring Network (NCCN) began in 2005, with the goal of detecting trends to inform the conservation and management of landbirds and their habitats. Here we use 2005–2016 data from over 3500 point-count stations to report landbird occurrence and trends in each of five NCCN parks, including three national parks in mountain wilderness areas (Mount Rainier National Park, North Cascades National Park Complex and Olympic National Park) and two historical parks (Lewis and Clark National Historical Park and San Juan Island National Historical Park). Recent advances in point-count modeling were applied to characterize population trends for 68 landbird species, including up to 41 species in each park. Fitted models suggest that almost all species exhibited stable or increasing trends over the study period. Notable exceptions were a decline in the Olive-sided Flycatcher in two parks and single-park declines in the Norther Flicker, Hutton’s Vireo, Clark’s Nutcracker, Mountain Chickadee, Wilson’s Warbler and Dark-eyed Junco. Negative effects of precipitation-as-snow were supported in over one-third of our population models. Lower precipitation-as-snow in the mountain parks might have contributed to rising landbird densities during the study period. Population density also varied with elevation in mountain parks, but temporal trends were similar among elevational strata for each species analyzed, suggesting no evidence of elevational range-shifts during this study. These results reinforce recent analyses of the first 10 years of point-count data from the three mountain parks (Ray et al. 2017 a). In the current analysis, models were extended to explore effects of covariates on species detection probability. Negative effects of ambient noise level on detection were supported in several cases, but adding covariates of detection generally did not lead to substantial improvements in model fit. In some cases, model fit was improved by reducing the scope of inference to a portion of the focal region, suggesting important effects of habitat heterogeneity.

Natural Resource Report↗

USGS2017

Recent stability of resident and migratory landbird populations in National Parks of the Pacific Northwest

Monitoring species in National Parks facilitates inference regarding effects of climate change on population dynamics because parks are relatively unaffected by other forms of anthropogenic disturbance. Even at early points in a monitoring program, identifying climate covariates of population density can suggest vulnerabilities to future change. Monitoring landbird populations in parks during the breeding season brings the added benefit of allowing a comparative approach to inference across a large suite of species with diverse requirements. For example, comparing resident and migratory species that vary in exposure to non-park habitats can reveal the relative importance of park effects, such as those related to local climate. We monitored landbirds using breeding-season point-count data collected during 2005–2014 in three wilderness areas of the Pacific Northwest (Mount Rainier, North Cascades, and Olympic National Parks). For 39 species, we estimated recent trends in population density while accounting for individual detection probability using Bayesian hierarchical N -mixture models. Our analyses integrated several recent developments in N -mixture modeling, incorporating interval and distance sampling to estimate distinct components of detection probability while also accommodating count intervals of varying duration, annual variation in the length and number of point-count transects, spatial autocorrelation, random effects, and covariates of detection and density. As covariates of density, we considered metrics of precipitation and temperature hypothesized to affect breeding success. We also considered effects of park and elevational stratum on trend. Regardless of model structure, we estimated stable or increasing densities during 2005–2014 for most populations. Mean trends across species were positive for migrants in every park and for residents in one park. A recent snowfall deficit in this region might have contributed to the positive trend, because population density varied inversely with precipitation-as-snow for both migrants and residents. Densities varied directly but much more weakly with mean spring temperature. Our approach exemplifies an analytical framework for estimating trends from point-count data, and for assessing the role of climatic and other spatiotemporal variables in driving those trends. Understanding population trends and the factors that drive them is critical for adaptive management and resource stewardship in the context of climate change.

Ecosphere↗

USGS2017

Development of a robust analytical framework for assessing landbird trends, dynamics and relationships with environmental covariates in the North Coast and Cascades Network

During 2015-2016, we completed development of a new analytical framework for landbird population monitoring data from the National Park Service (NPS) North Coast and Cascades Inventory and Monitoring Network (NCCN). This new tool for analysis combines several recent advances in modeling population status and trends using point-count data and is designed to supersede the approach previously slated for analysis of trends in the NCCN and other networks, including the Sierra Nevada Network (SIEN). Advances supported by the new model-based approach include 1) the use of combined data on distance and time of detection to estimate detection probability without assuming perfect detection at zero distance, 2) seamless accommodation of variation in sampling effort and missing data, and 3) straightforward estimation of the effects of downscaled climate and other local habitat characteristics on spatial and temporal trends in landbird populations. No changes in the current field protocol are necessary to facilitate the new analyses. We applied several versions of the new model to data from each of 39 species recorded in the three mountain parks of the NCCN, estimating trends and climate relationships for each species during 2005-2014. Our methods and results are also reported in a manuscript in revision for the journal Ecosphere (hereafter, Ray et al.). Here, we summarize the methods and results outlined in depth by Ray et al., discuss benefits of the new analytical framework, and provide recommendations for its application to synthetic analyses of long-term data from the NCCN and SIEN. All code necessary for implementing the new analyses is provided within the Appendices to this report, in the form of fully annotated scripts written in the open-access programming languages R and JAGS.

Natural Resource Report↗

USGS2016

Distribution of a climate-sensitive species at an interior range margin

Advances in understanding the factors that limit a species’ range, particularly in the context of climate change, have come disproportionately through investigations at range edges or margins. The margins of a species’ range might often correspond with anomalous microclimates that confer habitat suitability where the species would otherwise fail to persist. We addressed this hypothesis using data from an interior, climatic range margin of the American pika ( Ochotona princeps ), an indicator of relatively cool, mesic climates in rocky habitats of western North America. Pikas in Lava Beds National Monument, northeastern California, USA, occur at elevations much lower than predicted by latitude and longitude. We hypothesized that pika occurrence within Lava Beds would be associated primarily with features such as “ice caves” in which sub-surface ice persists outside the winter months. We used data loggers to monitor sub-surface temperatures at cave entrances and at non-cave sites, confirming that temperatures were cooler and more stable at cave entrances. We surveyed habitat characteristics and evidence of pika occupancy across a random sample of cave and non-cave sites over a 2-yr period. Pika detection probability was high (~0.97), and the combined occupancy of cave and non-cave sites varied across the 2 yr from 27% to 69%. Contrary to our hypothesis, occupancy was not higher at cave sites. Vegetation metrics were the best predictors of site use by pikas, followed by an edge effect and elevation. The importance of vegetation as a predictor of pika distribution at this interior range margin is congruent with recent studies from other portions of the species’ range. However, we caution that vegetation composition depends on microclimate, which might be the proximal driver of pika distribution. The microclimates available in non-cave crevices accessible to small animals have not been characterized adequately for lava landscapes. We advocate innovation in the acquisition and use of microclimatic data for understanding the distributions of many taxa. Appropriately scaled microclimatic data are increasingly available but rarely used in studies of range dynamics.

Ecosphere↗

USGS2015

Alpine biodiversity and assisted migration: The case of the American pika ( Ochotona princeps )

Alpine mammals are predicted to be among the species most threatened by climate change, due to the projected loss and further fragmentation of alpine habitats. As temperature or precipitation regimes change, alpine mammals may also be faced with insurmountable barriers to dispersal. The slow rate or inability to adjust to rapidly shifting environmental conditions may cause isolated alpine species to become locally extirpated, resulting in reduced biodiversity. One proposed method for mitigating the impacts of alpine species loss is assisted migration. This method, which involves translocating a species to an area with more favourable climate and habitat characteristics, has become the subject of debate and controversy in the conservation community. The uncertainty associated with climate change projections, coupled with the thermal sensitivity of many alpine mammals, makes it difficult to a priori assess the efficacy of this technique as a conservation management tool. Here we present the American pika ( Ochotona princeps ) as a case study. American pikas inhabit rocky areas throughout the western US, and populations in some mountainous areas have become locally extirpated in recent years. We review known climatic and habitat requirements for this species, and also propose protocols designed to reliably identify favourable relocation areas. We present data related to the physiological constraints of this species and outline specific requirements which must be addressed for translocation of viable populations, including wildlife disease and genetic considerations. Finally, we discuss potential impacts on other alpine species and alpine communities, and overall implications for conserving alpine biodiversity in a changing climate.

Biodiversity↗