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Wildlife capture, and the data collection associated with it, has led to major advancements in ecology that are integral to decision making pertaining to wildlife conservation. Capturing wildlife, however, can cause lethal and non-lethal risks to animals. Understanding the factors that contribute to the level of risk involved in wildlife capture is therefore important for the development and implementation of the safest and most effective methodologies. We used data from 736 animal captures of 389 individuals for 2 subspecies of female bighorn sheep (Rocky Mountain bighorn [Ovis canadensis canadensis], Sierra Nevada bighorn sheep [O. c. sierrae]) in Wyoming and California, USA, in 2002–2020 to evaluate the degree and extent of time that capture via helicopter net-gunning affects survival. We compared pre- and post-capture survival during a 10-week window centered on a capture event, and post-capture survival between captured animals and animals that were monitored but not captured during the 10-week window. Additionally, we evaluated the effects of handling techniques (number of times captured, season of capture event, handling time, chase time, and body temp) and biological factors (age and nutritional condition) on probability of capture mortality. Mean daily survival was 0.9992 during a 5-week pre-capture window, dropped to 0.9864 on the day of capture, and rebounded within 3 days of capture to pre-capture levels and that of sheep that were not captured. Overall, direct mortality resulting from capture was 1.36%, with 0.54% mortality occurring within the 3 days following a capture event for an overall 1.90% capture-related mortality. The only handling and biological metrics that influenced the probability of capture mortality were rectal temperature and nutritional condition; high initial rectal temperatures and poor body condition were associated with increased risk of mortality in the days following capture. Overall, helicopter net-gunning imposed low and short-term risk to survival of female bighorn sheep. To reduce bias in survival estimates, we recommend using a 3-day censorship window for post-capture mortalities as opposed to the common practice of a 2–5-week censor window. Helicopter net-gunning, including annual or seasonal recaptures, remains an effective and comparatively safe technique for capture and associated data collection of bighorn sheep.

The Laramide belt of the North American Cordillera is a thick-skinned orogen that continues to garner attention due to many unresolved ambiguities, particularly in the subsurface. Recent seismic studies provide a better understanding of Laramide tectonism at deep crustal levels. However, mechanisms for deformation accommodation in the upper crust remain unclear. A structural/tectonic analysis of Precambrian fabrics and structural grain of basement-cored Laramide arches and uplifts in Wyoming using only previously collected data, along with a hypothesis on the potential role of these features in Laramide orogenesis, is presented. This work provides evidence for the presence of Neoarchean convergence zones dominantly directed from the SW-NE toward the Wyoming Province forming NNW anisotropies. In addition, regional compressional forces from convergence formed WNW- and NE-striking conjugate shears. Precambrian basement fabrics characterize all three directions of major anisotropy, and they likely have a complex history of deformation since the Precambrian, most recently, during the Laramide orogeny. This Precambrian deformation system was likely a fundamental tectonic control in Laramide arch/uplift formation in Wyoming. During the Laramide orogeny, reactivation of anisotropies occurred throughout Laramide contraction, forming somewhat symmetrical, but discrete zones of transpression, displaced along a SW-NE-directed Laramide deformational front. Reverse-left oblique-slip faults developed from reactivation of WNW fabrics and, where connected, acted as relay zones, facilitating major arch development along NNW-striking faults. Internal controls for Laramide orogenesis in the upper crust are likely related to these basement anisotropies, which may link the evolution of foreland arches at deeper crustal levels to surface structures.

The spatial distribution of animals has consequences for nutrition, predator–prey dynamics, spread of diseases, and population dynamics in general. Animals must establish a home range to secure adequate resources to fuel their energy needs. Home ranges, therefore, are temporally and spatially dynamic, given the changing requirements of an animal and the availability of resources on the landscape. We used data from two populations of bighorn sheep with contrasting population dynamics following pneumonia epizootics and different habitat quality on their summer range to test the hypothesis that the distribution and size of home ranges are influenced by environmental conditions and reproductive status. We used a combination of data from 768 vegetation transects and remotely sensed metrics to index forage quality of consecutive biweekly home ranges for 27 bighorn sheep, June–August 2019–2021. There were population differences in home range dynamics that were consistent with resource limitations in the population declining in abundance. Animals in both populations increased the size of their home range through the summer in association with declining forage quality indexed by plant phenology. Furthermore, animals in the Whiskey Mountain population without offspring had home ranges more than twice the size of animals with offspring, whereas there were no differences in the home range size between animals with and without offspring in Jackson. We demonstrated that limitations young offspring impose on space use of a mother may have consequences for animals living where larger home ranges are needed to secure adequate resources—sheep on Whiskey Mountain had to travel 1000 m from escape terrain to access the same amount of biomass that the Jackson sheep could access directly adjacent to escape terrain. Forage quality and availability influence movement and space use. In the presence of disease, movement and space use may influence pathogen transmission and persistence. Thus, forage availability may play an indirect role in population dynamics in the presence of disease, which is another line of evidence for how environmental and nutritional conditions may influence population dynamics when coping with disease.

Biotic invasions in the fossil record provide natural experiments for testing hypotheses of niche stability, speciation, and the assembly and diversity of regional biotas. We compare ecological parameters (preferred environment, occupancy, median abundance, rank abundance) of genera shared between faunal provinces during the Richmondian Invasion in the Late Ordovician on the Laurentian continent. Genera that spread from one faunal province to the other during the invasion (invading shared genera) have high Spearman rank correlations (>0.5) in three of four ecological parameters, suggesting a high level of niche stability among invaders. Genera that existed in both regions prior to and following the invasion (noninvading shared genera) have low correlations (<0.3) and suggest niche shift between lineages that diverged at least 8 Myr earlier. Niche shift did not accumulate gradually over this time interval but appears to have occurred in a pulse associated with the onset of the Taconic orogeny and the switch from warm-water to cool-water carbonates in southern Laurentia.

Penstemon caryi is a narrow-range endemic angiosperm found primarily on sparsely vegetated limestone outcrops in the Bighorn and Pryor Mountains of north-central Wyoming and south-central Montana. A former candidate for listing under the Endangered Species Act, and currently a species of concern in these states, P. caryi is potentially threatened by habitat loss due to encroaching anthropogenic activities, such as limestone quarrying and road construction. In an effort to assess the capacity of P. caryi to withstand habitat loss and degradation, we used simple sequence repeats (SSRs) and amplified fragment length polymorphism (AFLP) markers to examine genetic diversity and differentiation of P. caryi populations from the Pryor Mountains of Montana and the southern Bighorn Mountains of Wyoming. Our analyses revealed overall moderate to high levels of genetic diversity in P. caryi, but with relatively lower levels of diversity in populations from the Pryor Mountains. There are fewer known individuals of Penstemon caryi in Montana, and because the examined populations from Montana exhibited less genetic diversity than those from Wyoming, populations from Montana may face an increased risk of population decline and extirpation. Both the AFLP and SSR data sets found population structure between different regions (Montana vs. Wyoming), while AFLP markers identified further subdivision between Wyoming populations. Despite moderate to high levels of genetic diversity, P. caryi is still a species at risk due to impending environmental stresses such as global climate change and human encroachment, which may be especially troublesome given its narrow distribution and the specificity of its habitat preferences.

The 2.95-2.82 Ga quartzofeldspathic gneisses and granitoids in the Bighorn, western Owl Creek, and northeastern Wind River uplifts in the central Wyoming Province include low-K tonalite - trondhjemite - granodiorite (TTG) and high-K granodiorite-granite (GG) rocks. Both types of granitoids were intruded contemporaneously, although TTGs are more abundant in the older gneisses. The TTG suite consists of calcic to marginally calc-alkalic rocks that straddle the boundaries between metaluminous and peraluminous and between ferroan and magnesian compositions. Rare-earth element (REE) patterns of these rocks may be highly fractionated with low heavy rare-earth element (HREE) contents and modest to absent Eu anomalies but may also be less strongly HREE depleted. These rocks do not represent first-generation continental crust: most have unradiogenic Nd and radiogenic 207Pb/204Pb isotopic compositions that require the incorporation of isotopically evolved sources. The GG suite has compositions that are transitional between Archean TTG and modern, continental margin calc-alkalic rocks. The GG suite is characterized by higher alkali contents relative to CaO than the TTG suite and higher K/Na ratios but exhibits a similar range in REE patterns. The Nd, Sr, and Pb isotopic compositions of the GG suite are slightly less variable but lie within the range of those of the TTG suite. We interpret them as having a source similar to that of the TTG, perhaps forming by partial melting of preexisting TTG. The shift from TTG-dominated to GG-dominated continental crust was a gradual transition that took place over several hundred million years. Clearly subduction-related calc-alkalic magmatism is not recognized in the Wyoming Province prior to 2.67 Ga.

In December 2008, near Flaming Gorge Reservoir in northeastern Utah, a 2 ½-year-old male Rocky Mountain bighorn sheep (Ovis canadensis canadensis) was reported in poor body condition with bloody lesions covering the muzzle area. The sheep was euthanized, and samples were submitted to the Utah Veterinary Diagnostic Laboratory in Logan, Utah. The gross and microscopic lesions confirmed the diagnosis of contagious ecthyma (CE). This is the first documented report of CE in bighorn sheep from Utah.

An isolated ramus of the pterygotid eurypterid Jaekelopterus cf. howelli from the Early Devonian (Pragian) Beartooth Butte Formation (Cottonwood Canyon, north-western Wyoming) is described. Pterygotid taxonomy and synonymy is briefly discussed with the genera Pterygotus, Acutiramus and Jaekelopterus shown to be potential synonyms. The use of cheliceral denticulation patterns as a generic-level character is discouraged in light of variations within genera and its unsuitability as a major characteristic in the other eurypterid families.

The Bighorn Mountains of the central Wyoming Province expose a large tract of Archean crust that has been tectonically inactive and at relatively high crustal levels since ∼2.7 Ga. Seven sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon and titanite age determinations on samples of the main lithologic units provide a geochronological framework for the evolution of this area. The oldest, precisely dated magmatic event occurred at 2950±5 Ma, when diorite to granite dykes and sills intruded an older gneiss complex exposed in the central and southern Bighorn Mountains. Rocks as old as 3.25 Ga may be present in this gneissic basement, as indicated by the oldest dates obtained on areas of zircon grains that are interpreted as inherited cores. A tonalitic gneiss was intruded into the gneiss complex at 2886±5 Ma. Deformation of the central and southern gneisses preceded the intrusion of the Bighorn batholith, a tonalitic to granitic intrusion that occupies the northern portion of the uplift. This composite batholith was intruded over the period 2.86-2.84 Ga. Ca. 3.0-2.8 Ga crust is also present in the Beartooth Mountains, the Washakie block of the northeastern Wind River Range, the Owl Creek Mountains, and the northern Granite Mountains, but late Archean deformation and plutonism has obscured much of the earlier history in the southern portion of this area. The entire area, referred to as the Beartooth-Bighorn Magmatic Zone, has been undeformed since 2.6 Ga. Proterozoic extension was focused in those parts of the Wyoming Province outside of this domain.

In December 2008, near Flaming Gorge Reservoir in northeastern Utah, a 2 ½-year-old male Rocky Mountain bighorn sheep (Ovis canadensis canadensis) was reported in poor body condition with bloody lesions covering the muzzle area. The sheep was euthanized, and samples were submitted to the Utah Veterinary Diagnostic Laboratory in Logan, Utah. The gross and microscopic lesions confirmed the diagnosis of contagious ecthyma (CE). This is the first documented report of CE in bighorn sheep from Utah.