Geology topics

Corey Class

Publications and source records attributed to Corey Class.

3 recordsLinked to original sources

USGS2026

Nutritional and reproductive dynamics of moose near their southern range limit

Understanding the relationships between nutrition and life-history characteristics can provide insight into the factors limiting populations. Moose ( Alces alces ) at their southern range periphery are subject to nutritional constraints because of marginal climatic and habitat conditions, but how these limitations influence vital rates remains a point of uncertainty. We examined the nutritional and reproductive dynamics of moose at the fringes of their range in southeast Wyoming, USA. We used an individual-based approach to evaluate the nutritional condition (i.e., body fat) of female moose by recapturing the same individuals each autumn and spring to measure body fat, pregnancy, recruitment of offspring, and survival. Like other temperate ungulates, we anticipated that moose would accumulate body fat over summer and use those reserves to support survival and reproduction over winter. Throughout the annual cycle, we expected that body fat, an integrated measure of energetic gains and losses, would influence pregnancy, recruitment, and adult survival. Contrary to expectations, body fat varied by less than 1.5 percentage points between autumn and spring. Despite relatively low seasonal fluctuations, body fat was positively associated with probability of pregnancy and adult survival but did not influence recruitment of young. Moreover, age influenced probability of pregnancy and overwinter survival. We demonstrate clear signs of nutritional limitation and unexpectedly absent relationships between body fat and recruitment that may be unique to moose living at the fringes of their range, highlighting environmental constraints on reproduction at distributional limits. By investigating the connections between nutrition and reproduction in southern moose, we provide insight into how vital rates can be used to monitor demographic performance for at-risk populations.

Wyoming↗

USGS2026

Moose indifferent to canopy loss from forest disturbance by bark beetles

Conifer forests have experienced widespread disturbance following the infestation of bark beetles ( Dendroctonus spp.). Tree mortality and resulting canopy loss have altered forest composition in ways that could affect moose ( Alces alces ), including potential benefits from increased understory forage and drawbacks through the loss of refuge from heat and deep snow. We examined the behavioral response of moose to beetle-killed forest, comparing resource selection before (2005–2006) and after (2015–2017) disturbance in southeast Wyoming, USA. To evaluate selection, we created a land cover classification layer at 0.5-m resolution using machine learning to delineate dead conifers, as well as aspen and willows that were underrepresented in existing land cover products. By measuring resource selection in a fractional cover framework, we found that moose showed strikingly similar resource selection before and after beetle disturbance. Moose during both periods selected willows and aspen while avoiding conifer forest and shrubs throughout the year. Moose in the post-beetle periods avoided conifer forest more strongly the more conifer forest made up their home range. The same pattern emerged for beetle-killed conifer: the more beetle-kill in a home range, the stronger the avoidance of beetle-kill. Our findings indicate that forest disturbance caused by bark beetles does not appreciably alter habitat quality for moose, and moose continue to employ similar patterns of resource selection regardless of forest changes in the early stages of the post-beetle infestation. Our work supports the importance of riparian and deciduous land cover in sustaining moose populations in the face of widespread forest disturbances.

Wyoming↗

USGS2024

Ungulate migrations of the Western United States, volume 4

Broadly distributed across the Western United States, ungulates (hooved mammals) play an important role in ecosystem function by affecting vegetation communities and forming the prey base for large carnivores. Additionally, ungulates provide economic benefits to regional communities through tourism and hunting and hold cultural significance for many Tribal communities. Many ungulates migrate seasonally between distinct summer and winter ranges to take advantage of spatially and temporally variable food sources and avoid threats such as predators and deep snow. Increasingly, these migrations are threatened by the growing human footprint and associated subdivisions, energy development, and increased traffic volume. Efforts to study ungulate populations and conserve their migrations received support in recent years from the U.S. Department of the Interior Secretarial Order No. 3362, which provided Federal support for enhancing habitat quality for ungulates across the Western States. In response to Secretarial Order No. 3362, the U.S. Geological Survey (USGS) established the Corridor Mapping Team, a collaboration among USGS and participating State and Federal wildlife management agencies and numerous Tribal Nations. Together, the Corridor Mapping Team maps ungulate migrations throughout the Western United States in the USGS “Ungulate Migrations of the Western United States” report series. This report (volume 4) details migrations and seasonal ranges from 31 new herds throughout nine Western States. Additionally, this report includes updates to two herds published in previous reports. Including this report, the report series has provided the mapped migrations and seasonal ranges of 182 unique herds and has provided a map-based inventory of the documented ungulate migrations across the Western United States for biologists, managers, policy makers, and conservation practitioners. This report also discusses how the mapping efforts associated with the Corridor Mapping Team can be used to guide management and policy regarding renewable energy development and ungulate disease, specifically chronic wasting disease, in the Western United States.

Arizona, California, Colorado, New Mexico, Nevada,↗