Geology topics

Scott McCorquodale

Publications and source records attributed to Scott McCorquodale.

5 recordsLinked to original sources

USGS2018

Factors influencing elk recruitment across ecotypes in the Western United States

Ungulates are key components in ecosystems and economically important for sport and subsistence harvest. Yet the relative importance of the effects of weather conditions, forage productivity, and carnivores on ungulates are not well understood. We examined changes in elk ( Cervus canadensis ) recruitment (indexed as age ratios) across 7 states and 3 ecotypes in the northwestern United States during 1989–2010, while considering the effects of predator richness, forage productivity, and precipitation. We found a broad‐scale, long‐term decrease in elk recruitment of 0.48 juveniles/100 adult females/year. Weather conditions (indexed as summer and winter precipitation) showed small, but measurable, influences on recruitment. Forage productivity on summer and winter ranges (indexed by normalized difference vegetation index [NDVI] metrics) had the strongest effect on elk recruitment relative to other factors. Relationships between forage productivity and recruitment varied seasonally and regionally. The productivity of winter habitat was more important in southern parts of the study area, whereas annual variation in productivity of summer habitat had more influence on recruitment in northern areas. Elk recruitment varied by up to 15 juveniles/100 adult females across the range of variation in forage productivity. Areas with more species of large carnivores had relatively low elk recruitment, presumably because of increased predation. Wolves ( Canis lupus ) were associated with a decrease of 5 juveniles/100 adult females, whereas grizzly bears ( Ursus arctos ) were associated with an additional decrease of 7 juveniles/100 adult females. Carnivore species can have a critical influence on ungulate recruitment because their influence rivals large ranges of variation in environmental conditions. A more pressing concern, however, stems from persistent broad‐scale decreases in recruitment across the distribution of elk in the northwestern United States, irrespective of carnivore richness. Our results suggest that wildlife managers interested in improving recruitment of elk consider the combined effects of habitat and predators. Efforts to manage summer and winter ranges to increase forage productivity may have a positive effect on recruitment.

Journal of Wildlife Management↗

USGS2015

Elk monitoring in Mount Rainier and Olympic national parks: 2008-2011 synthesis report

In 2008, the USGS collaborated with the NPS, the Muckleshoot and Puyallup Indian Tribes, and WDFW to develop a protocol tor monitor changes in abundance, population composition, and spatial distribution of elk on summer ranges in MORA and OLYM and winter ranges in OLYM. We developed double-observer sightability (DO-S) models that adjusted raw counts of elk as a function of factors influencing detection probabilities from the air, e.g. vegetation, elk group size, light, elk activity, and pilot experience. We plan to develop DO-S models for both MORA and OLYM summer ranges, but due to radiotelemetry collar failures in OLYM, we do not yet have enough data to model detection probabilities in OLYM. We analyzed results of the first 4 years of elk monitoring conducted under the new protocol from 2008-2011. Objectives of this first synthetic analysis are to: • update the DO-S model for MORA aerial survey results • examine abundance, composition, and distribution of elk trends in MORA summer ranges • establish a baseline of counts, population composition, and distribution of elk in OLYM summer ranges • examine trends in counts and distribution of elk in OLYM low-elevation winter ranges during early spring • determine environmental factors influencing abundance and composition of elk in selected MORA summer ranges and unadjusted counts of elk on selected OLYM winter ranges • review progress in developing a DO-S model for OLYM elk surveys • examine aerial survey operations and provide suggestions for future surveys. There was no trend in elk numbers in the N. Rainier TCA from 2008-2011; the trend in the S. Rainier TCA was not statistically significant but increased 3.3%/year. Maximum counts increased in the N. Rainier TCA ~6%/year. Maximum counts in the S. Rainier TCA increased at a rate of 17% annually. Due to failed radiocollars, weather, and other problems, we completed surveys in 2 of 5 OLYM summer range TCAs; no trend data are available. In OLYM winter ranges, we surveyed the Hoh TCA during early spring 2008-10 and of the S. Fork Hoh and Queets in 2008 and 2010. No surveys were done for early-spring counts in 2011 and 2012 due to high snowfall and lack of funding. Legacy early-spring surveys in OLYM since 1985 allowed us to assess trends in counts in the early-spring TCAs from 1985-2010. Counts of elk in the early-spring TCAs declined: 63% in the S. Fork Hoh, 18% in the Hoh, and 22% in the Queets Valley. We continue to develop and improve the DO-S model for application to OLYM summer surveys. In the next synthesis report, we will update findings with additional data following the 2015 field season, based on 8 years of survey results; it will be a more complete analysis of elk population trends.

Washington↗

USGS2013

Relative influence of human harvest, carnivores, and weather on adult female elk survival across western North America

Well-informed management of harvested species requires understanding how changing ecological conditions affect demography and population dynamics, information that is lacking for many species. We have limited understanding of the relative influence of carnivores, harvest, weather and forage availability on elk Cervus elaphus demography, despite the ecological and economic importance of this species. We assessed adult female survival, a key vital rate for population dynamics, from 2746 radio-collared elk in 45 populations across western North America that experience wide variation in carnivore assemblage, harvest, weather and habitat conditions. Proportional hazard analysis revealed that 'baseline' (i.e. not related to human factors) mortality was higher with very high winter precipitation, particularly in populations sympatric with wolves Canis lupus. Mortality may increase via nutritional stress and heightened vulnerability to predation in snowy winters. Baseline mortality was unrelated to puma Puma concolor presence, forest cover or summer forage productivity. Cause-specific mortality analyses showed that wolves and all carnivore species combined had additive effects on baseline elk mortality, but only reduced survival by <2%. When human factors were included, ‘total’ adult mortality was solely related to harvest; the influence of native carnivores was compensatory. Annual total mortality rates were lowest in populations sympatric with both pumas and wolves because managers reduced female harvest in areas with abundant or diverse carnivores. Mortality from native carnivores peaked in late winter and early spring, while harvest-induced mortality peaked in autumn. The strong peak in harvest-induced mortality during the autumn hunting season decreased as the number of native carnivore species increased. Synthesis and applications. Elevated baseline adult female elk mortality from wolves in years with high winter precipitation could affect elk abundance as winters across the western US become drier and wolves recolonize portions of the region. In the absence of human harvest, wolves had additive, although limited, effects on mortality. However, human harvest, and its apparent use by managers to offset predation, primarily controls overall variation in adult female mortality. Altering harvest quotas is thus a strong tool for offsetting impacts of carnivore recolonization and shifting weather patterns on elk across western North America.

Colorado;Idaho;Montana;Utah;Washington;Wyoming↗

USGS2013

Mount Rainier National Park and Olympic National Park elk monitoring program annual report 2011

Fiscal year 2011 was the first year of implementing an approved elk monitoring protocol in Mount Rainier (MORA) and Olympic (OLYM) National Parks in the North Coast and Cascades Network (NCCN) (Griffin et al. 2012). However, it was the fourth and second year of gathering data according to protocol in MORA and OLYM respectively; data gathered during the protocol development phase followed procedures that are laid out in the protocol. Elk monitoring in these large wilderness parks relies on aerial surveys from a helicopter. Summer surveys are intended to provide quantitative estimates of abundance, sex and age composition, and distribution of migratory elk in high elevation trend count areas. An unknown number of elk is not detected during surveys; however the protocol estimates the number of missed elk by applying a model that accounts for detection bias. Detection bias in elk surveys in MORA is estimated using a double-observer sightability model that was developed using survey data from 2008-2010 (Griffin et al. 2012). That model was developed using elk that were previously equipped with radio collars by cooperating tribes. At the onset of protocol development in OLYM there were no existing radio-collars on elk. Consequently the majority of the effort in OLYM in the past 4 years has been focused on capturing and radio-collaring elk and conducting sightability trials needed to develop a double-observer sightability model in OLYM. In this annual report we provide estimates of abundance and composition for MORA elk, raw counts of elk made in OLYM, and describe sightability trials conducted in OLYM. At MORA the North trend count area was surveyed twice and the South once (North Rainier herd, and South Rainier herd). We counted 373 and 267 elk during two replicate surveys of the North Rainier herd, and 535 elk in the South Rainier herd. Using the model, we estimated that 413 and 320 elk were in the North and 652 elk were in the South trend count areas during the time of the respective surveys. At OLYM, the Core and Northwest trend count areas were completely surveyed, as were portions of the Quinault. In addition, we surveyed 10 survey units specifically to get resight data. Two-hundred and forty eight elk were counted in the Core, 19 in the Northwest, and 169 in the Quinault. We conducted double-observer sightability trials associated with 14 collared elk groups for use in developing the double-observer sightability model for OLYM.

Washington↗

USGS2010

Mount Rainier National Park and Olympic National Park Elk Monitoring Program Annual Report 2010

Fiscal year 2010 was the third year of gathering data needed for protocol development while simultaneously implementing what is expected to be the elk monitoring protocol at Mount Rainier (MORA) and Olympic (OLYM) national parks in the North Coast and Cascades Network (NCCN). Elk monitoring in these large wilderness parks relies on aerial surveys from a helicopter. Summer surveys are planned for both parks and are intended to provide quantitative estimates of abundance, sex and age composition, and distribution of migratory elk in high elevation trend count areas. Spring surveys are planned at Olympic National Park and are intended to provide quantitative estimates of abundance of resident and migratory elk on low-elevation winter ranges within surveyed trend count areas. An unknown number of elk is not detected during surveys. The protocol under development aims to estimate the number of missed elk by applying a model that accounts for detection bias. Detection bias in elk surveys in MORA will be estimated using a double-observer sightability model that was developed based on data from surveys conducted in 2008-2010. The model was developed using elk that were previously equipped with radio collars by cooperating tribes. That model is currently in peer review. At the onset of protocol development in OLYM there were no existing radio- collars on elk. Consequently double-observer sightability models have not yet been developed for elk surveys in OLYM; the majority of the effort in OLYM has been focused on capturing and radio collaring elk to permit the development of sightability models for application in OLYM. As a result, no estimates of abundance or composition are included in this annual report, only raw counts of the numbers of elk seen in surveys. At MORA each of the two trend count areas (North Rainier herd, and South Rainier herd) were surveyed twice. 290 and 380 elk were counted on the two replicates in the North Rainier herd, and 621 and 327 elk counted on the two replicate South Rainier counts. At Olympic National Park, each of three spring trend count areas was surveyed once in March 2010. 27 elk were observed in the South Fork Hoh trend count area, 137 elk were observed in the Hoh trend count area, and 131 elk were observed in the Queets trend count area. In September 2010, 18 elk were captured and fitted with radio collars as part of a contracted animal capture, eradication and tagging of animals (ACETA) operation. These animals will be available to contribute double-observer sightability data in future spring and summer surveys. There were no summer surveys for elk in OLYM in 2010.

Washington↗