Jacob Hennig

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Chapters

• Petersen, S., Scasta, J., Schoenecker, K., & Hennig, J. (2023). Feral equids. In Rangeland Wildlife Ecology and Conservation. doi:10.1007/978-3-031-34037-6_21
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  Feral horses (Equus ferus caballus) and burros (E. asinus)inNorth America, often referred to as free-roaming, free-ranging, or wild horses and burros, are introduced species that are currently increasing in arid and semi-arid rangelands. They differ from all other North American mammals by being the only feral species protected by federal law. These equids inhabit areas featuring rough topography, limited net primary productivity, and extreme weather conditions, and have potential to cause long-term ecosystem impacts. In this chapter, we review the historical and modern context of feral equids on North American rangelands including their evolutionary past and introduction to the continent, their relation-ships to the environment, and challenges associated with their management. The management of feral equids is perhaps more scrutinized than any other species because their legal status, body size, physiology, foraging patterns, and local abun-dance directly interacts and competes with rangeland resource quality, impacts native wildlife populations, and conflicts with the multiple-uses of the land that they inhabit.

Journals/Publications

• Beck, J., Milligan, M., Smith, K., Street, P., Pratt, A., Kirol, C., Wanner, C., Hennig, J., Dinkins, J., Scasta, J., & Coates, P. (2024). Free‐roaming horses exceeding appropriate management levels affect multiple vital rates in greater sage‐grouse. Journal of Wildlife Management, 88, e22669.
• Hennig, J. D., Beck, J. L., & Scasta, J. D. (2024). Feral horses and pronghorn: a test of the forage maturation hypothesis in an arid shrubland. Animal Behaviour, 210, 55-61.
• Schoenecker, K. A., King, S., Hennig, J. D., Cole, M. J., Scasta, J. D., & Beck, J. L. (2024). Effects of telemetry collars on two free-roaming feral equid species. PLOS ONE, 19(5), e0303312.
• Duchardt, C., Augustine, D., Porensky, L., Beck, J., Hennig, J., Pellatz, D., Scasta, J., Connell, L., & Davidson, A. (2023). Disease and weather induce rapid shifts in a rangeland ecosystem mediated by a keystone species (Cynomys ludovicianus). Ecological Applications, 33(1). doi:10.1002/eap.2712
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  Habitat loss and changing climate have direct impacts on native species but can also interact with disease pathogens to influence wildlife communities. In the North American Great Plains, black-tailed prairie dogs (Cynomys ludovicianus) are a keystone species that create important grassland habitat for numerous species and serve as prey for predators, but lethal control driven by agricultural conflict has severely reduced their abundance. Novel disease dynamics caused by epizootic plague (Yersinia pestis) within prairie dog colonies have further reduced prairie dog abundances, in turn destabilizing associated wildlife communities. We capitalized on a natural experiment, collecting data on prairie dog distributions, vegetation structure, avian abundance, and mesocarnivore and ungulate occupancy before (2015–2017) and after (2018–2019) a plague event in northeastern Wyoming, USA. Plague decimated black-tailed prairie dog populations in what was then the largest extant colony complex, reducing colony cover in the focal area from more than 10,000 ha to less than 50 ha. We documented dramatic declines in mesocarnivore occupancy and raptor abundance post-plague, with probability of occupancy or abundance approaching zero in species that rely on prairie dogs for a high proportion of their diet (e.g., ferruginous hawk [Buteo regalis], American badger [Taxidea taxus], and swift fox [Vulpes velox]). Following the plague outbreak, abnormally high precipitation in 2018 hastened vegetation recovery from prairie dog disturbance on colonies in which constant herbivory had formerly maintained shortgrass structure necessary for certain colony-associates. As a result, we observed large shifts in avian communities on former prairie dog colonies, including near-disappearance of mountain plovers (Charadrius montanus) and increases in mid-grass associated songbirds (e.g., lark bunting [Calamospiza melanocorys]). Our research highlights how precipitation can interact with disease-induced loss of a keystone species to induce drastic and rapid shifts in wildlife communities. Although grassland taxa have co-evolved with high spatiotemporal variation, fragmentation of the remaining North American rangelands paired with higher-than-historical variability in climate and disease dynamics are likely to destabilize these systems in the future.
• Hennig, J., & Schoenecker, K. (2023). Comparing methods to estimate feral burro abundance. Wildlife Society Bulletin, 47(4). doi:10.1002/wsb.1495
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  Obtaining precise and unbiased estimates of feral burro (Equus asinus) abundance in the western United States is challenging due to their cryptic pelage and the rugged terrain they inhabit. Management agencies employ helicopter-based, simultaneous double-observer sightability surveys (hereafter denoted as DOS) to estimate abundance of burros; but the DOS method routinely produces negatively biased estimates due to residual heterogeneity in detection probability. Consequently, testing alternative methods to improve upon current procedures is warranted. Residual heterogeneity in DOS surveys can be minimized by including radio-collared individuals in the population. Alternatively, if distance measurements are recorded, residual heterogeneity can also be reduced via a mark-recapture distance sampling (MRDS) approach. Aerial infrared (IR) surveys offer a safer alternative than helicopter-based surveys because they can be flown at a higher altitude and require fewer observers in the aircraft. Further, IR surveys using a distance sampling approach have been shown to generate accurate and precise estimates of feral horse (E. caballus) populations. Accordingly, we compared results of surveys using aerial IR distance sampling, the standard DOS survey, a DOS survey incorporating detections of radio-collared individuals, and an MRDS analysis of a feral burro population with a known minimum population size in central Utah, winter 2015–2016 and spring 2016. The minimum number of burros known alive during the winter and spring surveys were 236 and 136, respectively. The average detection probability of IR surveys was P = 0.88 (SE = 0.16) and distance models produced estimates of 127 burros (95% CIs = 99–175) for the winter survey, and 94 burros (CIs = 72–134) for the spring survey. Mean detection probability of the standard DOS surveys was P = 0.78 (SE = 0.09), and model-generated abundance estimates were 155 burros (CIs = 133–227) in winter, and 92 burros (CIs = 79–139) in spring. Incorporating detections of radio-collared individuals in the DOS survey resulted in a decreased detection probability (P = 0.46; SE = 0.06) and increased abundance estimates to 267 (CIs = 169–571) and 155 (CIs = 128–263) for winter and spring, respectively. Mark-recapture distance sampling produced a mean detection probability of P = 0.48 (SE = 0.12) and resulted in estimates of 282 (CIs = 178–385) and 169 (CIs = 73–310) burros in winter and spring, respectively. Our study demonstrated that aerial IR surveys conducted using standard distance sampling can produce precise estimates of burro population sizes; however, estimates were negatively biased relative to the known population size. Small sample size limits generalization of our results, but the IR-based distance approach did not improve upon DOS surveys. Accounting for residual heterogeneity through use of radio-collars and mark-recapture distance sampling eliminated the negative bias from the standard DOS survey but decreased survey precision. Managers will need to decide whether unbiased but less precise abundance estimates are preferable compared to a more precise, but biased, estimate.
• Hennig, J., Duchardt, C., Esmaeili, S., Fuhlendorf, S., Beck, J., Francisco, T., & Scasta, J. (2023). A crossroads in the rearview mirror: the state of United States feral equid management in 2023. BioScience, 73(6). doi:10.1093/biosci/biad033
• Hennig, J., Scasta, J., Pratt, A., Wanner, C., & Beck, J. (2023). Habitat selection and space use overlap between feral horses, pronghorn, and greater sage-grouse in cold arid steppe. Journal of Wildlife Management, 87(1). doi:10.1002/jwmg.22329
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  Populations of feral horses (Equus ferus caballus) in the western United States have increased during the past decade, consequently affecting co-occurring wildlife habitat. Feral horses may influence 2 native wildlife species, greater sage-grouse (Centrocercus urophasianus; sage-grouse) and pronghorn (Antilocapra americana) through mechanisms of habitat alteration and competition. Wyoming, USA, contains the largest populations of pronghorn and sage-grouse of any state and also has the highest degree of range overlap between feral horses and these species. Consequently, the effects that horses may have on pronghorn and sage-grouse populations in Wyoming have implications at local, state, and population-wide levels. Managers need information concerning habitat selection and space use overlap among these species to develop appropriate management strategies; yet this information is absent for most feral horse management areas. To address this knowledge need, we attached global positioning system (GPS) transmitters to horses, pronghorn, and sage-grouse within the greater Bureau of Land Management–Adobe Town Herd Management Area in southern Wyoming and northern Colorado, USA, between 2017 and 2021 to evaluate habitat selection and space use of all species during 3 biologically relevant seasons: spring (Apr–Jun; sage-grouse breeding, nesting, and early-brood rearing; pronghorn late gestation and early parturition), summer (Jul–Oct; sage-grouse summer and late-brood rearing; pronghorn late parturition and breeding), and winter (Nov–Mar; non-breeding season). Feral horses selected flatter slopes and shorter mean shrub height across all seasons and were closer to water in spring and summer. Pronghorn habitat selection was similar to horses, but they also avoided oil and gas well pads year-round. During spring, sage-grouse selected greater herbaceous cover, flatter slopes, and areas farther from well pads. In summer, sage-grouse selected greater mean shrub height, flatter slopes, and were closer to water. In winter, sage-grouse selected flatter slopes and areas with greater vegetation production during the preceding summer. Our results indicate strong year-round overlap in space use between horses and pronghorn, whereas overlap between horses and sage-grouse is greatest during the summer in this region. Consequently, managers should recognize the potential for horses to influence habitat quality of pronghorn and sage-grouse in the region.
• Hennig, J., Rigsby, W., Stam, B., & Scasta, J. (2022). Distribution of Salers cows in contrasting rangeland pastures relative to established slope and water guidelines. Livestock Science, 257. doi:10.1016/j.livsci.2022.104843
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  Topographical constraints, particularly steep slopes and far distances to water, have persistently challenged livestock distribution globally. Information gained from global positioning system (GPS) tracking devices have accelerated knowledge of cattle (Bos taurus) use of complex topography to potentially challenge established guidelines. In northern Wyoming, USA, we deployed 5 GPS collars on multiparous Salers cows with calves from July to November 2018–2019. Cattle rotated between 2 contrasting rangeland pastures: the Basin pasture (Foothills Shrublands and Low Mountains ecoregion; mean slope of 17.7% (range: 0.87–111.01%)) and Mountain pasture (transitioning to Absaroka-Gallatin Volcanic Mountain ecoregion; mean slope of 24.4% (range: 0.26–125.11%)). We estimated mean and maximum slope use and distances from water, along with daily distances traveled for each GPS-collared cow per pasture per year. We also generated utilization distributions with Brownian bridge movement models to compare mean slope and distances to water among quartiles of predicted use, and compared stocking rate adjustments per pasture between standard and GPS location derived methods. Mean daily distance traveled was 5126.5 km and 5011.6 km in the Basin and Mountain pastures, respectively, and average distance to water was
• Hennig, J., Schoenecker, K., Cain, J., Roemer, G., & Laake, J. (2022). Accounting for residual heterogeneity in double-observer sightability models decreases bias in burro abundance estimates. Journal of Wildlife Management, 86(5). doi:10.1002/jwmg.22239
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  Feral burros (Equus asinus) and horses (E. ferus caballus) inhabiting public land in the western United States are intended to be managed at population levels established to promote a thriving, natural ecological balance. Double-observer sightability (MDS) models, which use detection records from multiple observers and sighting covariates, perform well for estimating feral horse abundances, but their effectiveness for use in burro populations is less understood. These MDS models help minimize detection bias, yet bias can be further reduced with models that account for unmodeled variation, or residual heterogeneity, in detection probability. In populations containing radio-marked individuals, residual heterogeneity can be estimated with MDS models by including a covariate that corresponds to the marked status of a group (MH models). Another approach is to use information from detections missed by both observers to account for the characteristics that make groups more or less likely to be detected, or recaptured, by the second observer (MR models). We used aerial survey data from 3 burro populations (Sinbad Herd Management Area, UT [2016–2018], Lake Pleasant Herd Management Area, AZ [2017], and Fort Irwin National Training Center, CA [2016–2017]) to develop MDS models applicable for feral burros in the southwestern United States. Our objectives were to quantify precision and bias of standard MDS surveys for feral burros and to examine which model type for incorporating residual heterogeneity (MH or MR) would result in the least-biased estimates of burro populations relative to the minimum number known alive (MNKA) within the Sinbad Herd Management Area. Standard MDS model estimates achieved a mean coefficient of variation of 0.08, while underestimating MNKA by an average of 27.1%. Accounting for residual heterogeneity through recapture probability in MR models resulted in estimates closer to MNKA than MH models (9.5% vs. 16.5% less than MNKA). Our results indicate that MDS models can achieve precise enough estimates to monitor feral burro populations, but they routinely produce negatively biased estimates. We encourage the use of radio-collars to reduce bias in future burro surveys by accounting for residual heterogeneity through MR models.
• Scasta, J., Thacker, E., Hennig, J., & Hoopes, K. (2022). Dehydration and mortality of feral horses and burros: a systematic review of reported deaths. Human-Wildlife Interactions, 16(2). doi:10.26077/v8qe-4h13
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  Water is a requirement for all organisms, including equids. Dehydration-caused mortality of feral horses (Equus ferus caballus) is often cited as a cause of concern and as justification for management of feral horses, yet a paucity of information exists on the matter. We conducted a systematic review from September 1, 2020 through January 15, 2021 of available news reports of feral horse and burro (E. asinus) dehydration mortalities and public interventions to save horses using a public search engine with a priori defined search term combinations and additional snowball sampling. We found 15 uniquely reported mortality incidents representing 744 horse in the United States and Australia that occurred between 1976 and 2019; no similar reports for burros were found. Mortalities occurred during hotter and drier than normal conditions with occurrences escalating through the summer and fall. The number of horses per dehydration mortality event ranged from 1–191 with a mean of 50 horses. Mortalities occurred on a wide range of land jurisdictions including private lands, tribal lands, national forests, national parks, and Bureau of Land Management lands. Increasing feral horse populations in western North America and Australia, coupled with the drought forecasts over the next century, simply cannot be ignored. This study represents the first global and longitudinal assessment of feral horse dehydration mortalities
• Boyce, P., Hennig, J., Brook, R., & McLoughlin, P. (2021). Causes and consequences of lags in basic and applied research into feral wildlife ecology: the case for feral horses. Basic and Applied Ecology, 53, 154-163.
• Dinkins, J., Duchardt, C., Hennig, J., & Beck, J. (2021). Changes in hunting season regulations (1870s–2019) reduce harvest exposure on greater and Gunnison sage-grouse. PLoS ONE, 16(10 October). doi:10.1371/journal.pone.0253635
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  Hunter harvest is a potential factor contributing to population declines of sage-grouse (Centrocercus spp.). As a result, wildlife agencies throughout western North America have set increasingly more conservative harvest regulations over the past 25 years to reduce or eliminate hunter success and concomitant numbers of harvested greater (C. urophasianus) and Gunnison (C. minimus) sage-grouse. Sage-grouse hunting has varied widely over time and space, which has made a comprehensive summary of hunting management challenging. We compiled data on harvest regulations among 11 western U.S. states and 2 Canadian provinces from 1870–2019 to create a timeline representative of hunting regulations. We compared annual harvest boundaries and area-weighted average hunting regulations, 1995–2018, relative to administrative boundaries and areas of high probability of sage-grouse occupation. We also summarized estimated numbers of birds harvested and hunters afield, 1995–2018, across both species’ ranges. From 1995–2018, there was a 30% reduction in administrative harvest boundaries across the greater sage-grouse range compared to a 16.6% reduction in area open to harvest within 8 km from active leks. Temporary closures occurred in response to wildfires, disease outbreaks, low population numbers, and two research projects; whereas, permanent closures primarily occurred in small populations and areas on the periphery of the species distribution. Similarly, area-weighted possession limits and season length for greater sage-grouse decreased 52.6% and 61.0%, respectively, while season start date stayed relatively stable (mean start date ~259 [mid-September]). In contrast, hunting of the now federally-threatened Gunnison sage-grouse ended after 1999. While restrictions in harvest regulations were large in area, closures near areas of high greater sage-grouse occupancy were relatively smaller with the same trend for Gunnison sage-grouse until hunting ceased. For greater sage-grouse, most states reduced bag and possession limits and appeared to adhere to recommendations for later and shorter hunting seasons, reducing potential for additive mortality.
• Esmaeili, S., Jesmer, B., Albeke, S., Aikens, E., Schoenecker, K., King, S., Abrahms, B., Buuveibaatar, B., Beck, J., Boone, R., Cagnacci, F., Chimeddorj, B., Cross, P., Dejid, N., Enkhbyar, J., Fischhoff, I., Ford, A., Jenks, K., Hemami, M., , Hennig, J., et al. (2021). Body size and digestive system shape resource selection by ungulates: A cross-taxa test of the forage maturation hypothesis. Ecology Letters, 24(10). doi:10.1111/ele.13848
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  The forage maturation hypothesis (FMH) states that energy intake for ungulates is maximised when forage biomass is at intermediate levels. Nevertheless, metabolic allometry and different digestive systems suggest that resource selection should vary across ungulate species. By combining GPS relocations with remotely sensed data on forage characteristics and surface water, we quantified the effect of body size and digestive system in determining movements of 30 populations of hindgut fermenters (equids) and ruminants across biomes. Selection for intermediate forage biomass was negatively related to body size, regardless of digestive system. Selection for proximity to surface water was stronger for equids relative to ruminants, regardless of body size. To be more generalisable, we suggest that the FMH explicitly incorporate contingencies in body size and digestive system, with small-bodied ruminants selecting more strongly for potential energy intake, and hindgut fermenters selecting more strongly for surface water.
• Hennig, J., Beck, J., Duchardt, C., & Derek Scasta, J. (2021). Variation in sage-grouse habitat quality metrics across a gradient of feral horse use. Journal of Arid Environments, 192. doi:10.1016/j.jaridenv.2021.104550
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  Feral horse (Equus ferus caballus) grazing can alter arid shrubland habitat in the western United States to the detriment of sympatric wildlife species, including the greater sage-grouse (Centrocercus urophasianus). To date, studies of horse-influenced habitat alteration have only occurred in a few locations and have infrequently represented gradients of horse use. We investigated whether greater sage-grouse habitat quality metrics were negatively associated with feral horse use in southcentral Wyoming, USA. We also tested whether utilization distributions generated from feral horses tracked with global position system transmitters were correlated with dung pile density, our index of horse use. Dung pile density did not vary among utilization distribution levels, indicating utilization distributions were a poor predictor of cumulative horse use. Bare ground increased with dung pile density (β = 0.06, 85% CI = 0.04–0.18), and grass height exhibited a threshold response and began to decline after 638 piles/ha. Other habitat metrics including percent shrub cover, native perennial grass cover, and visual obstruction were better explained by topographic and temporal variation. Our results suggest that herd size reduction may limit soil erosion potential and improve desired herbaceous structure, though additional management actions regarding feral horse use are needed to sustain high-quality greater sage-grouse habitat.
• Hennig, J., Beck, J., Gray, C., & Scasta, J. (2021). Temporal Overlap Among Feral Horses, Cattle, and Native Ungulates at Water Sources. Journal of Wildlife Management, 85(6). doi:10.1002/jwmg.21959
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  Feral horse (Equus ferus caballus) populations on public rangelands in the western United States threaten forage production for livestock and wildlife habitat. Interference competition between feral horses and heterospecifics at watering sources can have negative effects on livestock and wildlife. Researchers have documented altered timing and behavior of wild ungulates at water sources when horses were present. The few studies examining these interactions have infrequently occurred within areas specifically managed for feral equids and have not occurred in sites with cattle. We used motion-sensitive cameras at 8 watering sources to document watering activity patterns and construct indices of temporal overlap among feral horses, cattle, elk (Cervus canadensis), mule deer (Odocoileus hemionus), and pronghorn (Antilocapra americana) within the Adobe Town Herd Management Area in southern Wyoming, USA, between June and September 2018 and 2019. Feral horses, cattle, and pronghorn exhibited a high degree of temporal overlap (>79%) in water use, with feral horses and pronghorn exhibiting the highest estimated percent overlap (88.1%, 95% CI = 86.5–89.6%). Mule deer and elk watering activity also overlapped with horses and cattle but to a lesser degree (
• Hennig, J., Schoenecker, K., Terwilliger, M., Holm, G., & Laake, J. (2021). Comparison of aerial thermal infrared imagery and helicopter surveys of bison (Bison bison) in grand canyon national park, USA. Sensors, 21(15). doi:10.3390/s21155087
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  Aerial thermal infrared (TIR) surveys are an attractive option for estimating abundances of large mammals inhabiting extensive and heterogeneous terrain. Compared to standard helicopter or fixed‐wing aerial surveys, TIR flights can be conducted at higher altitudes translating into greater spatial coverage and increased observer safety; however, monetary costs are much greater. Further, there is no consensus on whether TIR surveys offer improved detection. Consequently, we performed a study to compare results of a TIR and helicopter survey of bison (Bison bison) on the Powell Plateau in Grand Canyon National Park, USA. We also compared results of both surveys to estimates obtained using a larger dataset of bison helicopter detections along the entire North Rim of the Grand Canyon. Observers in the TIR survey counted fewer individual bison than helicopter observers (101 to 127) and the TIR survey cost was 367% higher. Additionally, the TIR estimate was 18.8% lower than the estimate obtained using a larger dataset, while the comparative helicopter survey was 9.3% lower. Despite our small sample size, we found that helicopter surveys are currently the best method for estimating bison abundances in dense canopy cover sites due to ostensibly more accurate estimates and lower cost compared to TIR surveys. Additional research will be needed to evaluate the efficacy of these methods, as well as very high resolution satellite imagery, for bison populations in more open landscapes.
• Scasta, J., Hennig, J., & Calkins, C. (2021). Feral horse cause-specific mortality relative to mustering (gathering) and individual demographic attributes in the USA. Wildlife Research, 48(8). doi:10.1071/WR20157
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  Context: Mustering (gathering) feral horses (Equus ferus caballus) often cause mortalities, yet cause-specific details are lacking. Aims: Given the need to optimise horse welfare, we analysed public horse muster data from the USA to understand specific causes of mortalities. Methods: We coded 393 individual horse mortality reports for 92 cause-specific mortality terms (keywords informing the deciphering of specific causes of mortality classified as anatomical, causal or conditional) and demographic details (age, sex, and body condition). Data were derived from 50 musters across seven states with at least one horse mortality. Musters were coded for type (helicopter or bait), emergency or regular planned efforts, and number of horses mustered and shipped daily. Key Results: More horses were euthanased than died naturally (330 (84.0%) and 39 (9.9%) respectively), and more horses had chronic than acute conditions (317 (80.7%) and 76 (19.3%) respectively), with both trends holding for both sexes and across ages. Body condition scores (BCS) for female horses were skewed low, whereas male horse BCS data were more normally distributed. Female horses had lower BCS than did male horses (P < 0.001). On average, each horse mortality had two cause-specific mortality terms, ranging from 1 to 7. Only 57 horses (14.5%) had terms describing anatomy, cause and condition, concurrently. Phi coefficients (φ; indicators of fidelity and constancy) for cause-specific terms were related to demographic or muster attributes and were analysed with post hoc ANOVA tests of estimated marginal means to allow for ranking. Female horses were most often described as emaciated, weak, and starving, whereas male horses were described as lame, arthritic, blind or dangerous. Bait trapping and emergency musters included horses that were starving, dehydrated and weak. Conclusions: Generally, disorders associated with legs and feet, eyes, necks and nutrition were the most prevalent cause-specific mortality issues. Using a machine learning approach, validation and test accuracy were high for predicting euthanasia versus natural mortalities, but low for predicting acute versus chronic mortalities. Individual horse demographics or daily muster features had a greater relative influence than did capture type or emergency status in both comparisons. Implications: These results provide practical insight for potential cause-specific mortalities relative to demographics and muster techniques.
• Hennig, J., Scasta, J., Beck, J., Schoenecker, K., & King, S. (2020). Systematic review of equids and telemetry collars: Implications for deployment and reporting. Wildlife Research, 47(5). doi:10.1071/WR19229
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  Abstract: Data from animals equipped with global positioning system collars have advanced our understanding of vertebrates, but this technology has rarely been employed to study feral equids. Hesitation to equip feral equids with telemetry collars in the USA can often be attributed to safety concerns stemming from one study from the 1980s, where injuries were sustained by feral horses (Equus ferus caballus) equipped with radio-collars. Improvements in collar design over the ensuing quarter-century may have decreased risk of collar-related complications; however, telemetry-based studies on feral equids continue to be limited. In the present review, studies from wild and feral equids worldwide were systematically reviewed to better understand the mortality and injury risk in application of telemetry collars to equids. Our goals were to: (1) report the number of individual equids fitted with telemetry collars (1979-2017); and (2) document the number of individual equids that reportedly died or suffered injuries from collars or other sources. A comparative review of elk (Cervus canadensis), mule deer (Odocoileus hemionus) and pronghorn (Antilocapra americana) was also conducted to evaluate the relative risk of collar-related complications among equids and routinely collared North American ungulates. In total, 1089 wild and feral telemetered equids were identified across 48 studies. Of these, 87 (8.0%) were reported to have died, with only one (0.09%) mortality attributable to a collar. Comparatively, 23.0% (1095) of 4761 elk, mule deer and pronghorn fitted with telemetry collars were found to have died in the same number of studies, though no mortalities were reported to be related to the collar. Although wild and feral equids did not experience increased natural mortality compared with the other ungulates, studies have not provided sufficient information to assess relative risk of collar-related complications. Explicit reporting and discussion of telemetry collar impacts in future publications of all animal species are recommended, especially equids, to improve understanding of how telemetry collars can affect study individuals.
• Doherty, K., Hennig, J., Dinkins, J., Griffin, K., Cook, A., Maestas, J., Naugle, D., & Beck, J. (2018). Understanding biological effectiveness before scaling up range-wide restoration investments for Gunnison sage-grouse. Ecosphere, 9(3). doi:10.1002/ECS2.2144
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  Imperiled species recovery is a high-stakes endeavor where uncertainty surrounding effectiveness of conservation actions can be an impediment to implementation at necessary scales, especially where habitat restoration is required. Gunnison sage-grouse (Centrocercus minimus) represents one such species in need of large-scale habitat restoration. It is a federally threatened sagebrush (Artemisia spp.) obligate bird with a limited range in Colorado and Utah. Threats to recovery of Gunnison sage-grouse include conifer expansion into sagebrush along with additional habitat loss and degradation attributed to human development and agricultural conversion. Recovery of Gunnison sage-grouse and other sensitive species can be aided by spatial tools that forecast plausible outcomes of conservation actions. We illustrate this by using a novel framework for predicting outcomes of proactive tree removal and subsequent sagebrush restoration for the Gunnison sage-grouse. To assess threats on Gunnison sage-grouse lek presence, we developed a spatially explicit breeding habitat model to compare active lek and random pseudo-absence locations from 2015. Models identified land cover, climatic, and abiotic variables at landscape-level scales (0.56 and 4 km) most important for predicting breeding habitat. Our model correctly differentiated between lek and pseudo-absence locations 94% of the time. All but one of the active leks (n = 94) were in areas with >0.65 probability of lek occurrence. Using this probability value as a threshold, we predicted 15% of the current grouse range as high-quality breeding habitat. Simulated removal of trees in areas with ≤30% tree canopy cover (0.56-km scale) increased extent of high-quality habitat fourfold (59%). Hypothetical restoration of sagebrush cover in the same areas increased habitat quality an additional 11%. Our breeding habitat model indicated that targeted tree removal and sagebrush restoration have potential to improve Gunnison sage-grouse breeding habitat. While our habitat treatment scenarios were not meant to be prescriptive, they highlight that considerable uplift in Gunnison sage-grouse breeding habitat may be possible across much of its range with cooperation from multiple stakeholders and illustrates the utility of this approach for predicting biological return on investment.
• Hennig, J., Beck, J., & Scasta, J. (2018). Spatial ecology observations from feral horses equipped with global positioning system transmitters. Human-Wildlife Interactions, 12, 75-84.
• Scasta, J., Hennig, J., & Beck, J. (2018). Framing contemporary U.S. wild horse and burro management processes in a dynamic ecological, sociological, and political environment. Human-Wildlife Interactions, 12(1).
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  The Wild Free-Roaming Horses and Burros Act (WFRHBA) of 1971 established all "unbranded or unclaimed" equids on U.S. public lands as "living symbols of the historic and pioneer spirit of the West." Today, > 72,000 feral horses (Equus ferus caballus) and burros (E. asinus; WHB) live on western U.S. public rangelands. The number of WHBs exceeds the Bureau of Land Management's maximum Appropriate Management Level (AML) of 26,715 by a factor of approximately 2.7 and has nearly doubled from 2007-2015. The AML was set to balance WHB numbers with rangeland health and support other uses such as wildlife habitat and livestock grazing. Thus, public land management agencies must manage WHB under the multiple-use context. This becomes more problematic when WHB populations go largely unmanaged and excessive equid grazing negatively impacts rangeland vegetation, native wildlife, and livestock forage. In addition, approximately 46,000 WHBs exist in off-range holding facilities, further straining federal budgets. Contemporary management actions are being constrained by: (1) litigation that has stymied federal government WFRHBA enforcement efforts, (2) public emotional concerns that lack reconciliation with the current situation, and (3) increasing complexity in the laws and subsequent amendments shaping WHB management policy. Collectively, these factors impede the implementation of concrete solutions to restore AML. Consequently, stakeholders are increasing polarized over how WHBs are or should be managed. While the ecological and animal health and welfare implications of unmanaged WHB populations are somewhat understood, publicly acceptable strategies to maintain healthy populations, healthy and functioning rangelands, and multiple uses that sustain wildlife and local communities remain unresolved.
• Chambers, J., Beck, J., Bradford, J., Bybee, J., Campbell, S., Carlson, J., Christiansen, T., Clause, K., Collins, G., Crist, M., Dinkins, J., Doherty, K., Edwards, F., Espinosa, S., Griffin, K., Griffin, P., Haas, J., Hanser, S., Havlina, D., , Henke, K., et al. (2017). Science framework for conservation and restoration of the sagebrush biome: Linking the department of the interior’s integrated rangeland fire management strategy to long-term strategic conservation actions. US Forest Service General Technical Report, 2017(360).
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  The Science Framework is intended to link the Department of the Interior’s Integrated Rangeland Fire Management Strategy with long-term strategic conservation actions in the sagebrush biome. The Science Framework provides a multiscale approach for prioritizing areas for management and determining effective management strategies within the sagebrush biome. The emphasis is on sagebrush (Artemisia spp.) ecosystems and Greater sage-grouse (Centrocercus urophasianus). The approach provided in the Science Framework links sagebrush ecosystem resilience to disturbance and resistance to nonnative, invasive plant species to species habitat information based on the distribution and abundance of focal species. A geospatial process is presented that overlays information on ecosystem resilience and resistance, species habitats, and predominant threats and that can be used at the mid-scale to prioritize areas for management. A resilience and resistance habitat matrix is provided that can help decisionmakers evaluate risks and determine appropriate management strategies. Prioritized areas and management strategies can be refined by managers and stakeholders at the local scale based on higher resolution data and local knowledge. Decision tools are discussed for determining appropriate management actions for areas that are prioritized for management. Geospatial data, maps, and models are provided through the U.S. Geological Survey (USGS) ScienceBase and Bureau of Land Management (BLM) Landscape Approach Data Portal. The Science Framework is intended to be adaptive and will be updated as additional data become available on other values and species at risk. It is anticipated that the Science Framework will be widely used to: (1) inform emerging strategies to conserve sagebrush ecosystems, sagebrush dependent species, and human uses of the sagebrush system, and (2) assist managers in prioritizing and planning on-the-ground restoration and mitigation actions across the sagebrush biome.
• Hennig, J., Benson, T., Stafford, J., Yetter, A., Hagy, H., & Stodola, K. (2017). An aerial grid-based sampling method to estimate nonbreeding duck abundance. Wildlife Society Bulletin, 41(4). doi:10.1002/wsb.807
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  Probability-based sampling designs for aerial surveys are useful for estimating wintering waterfowl abundances in large areas with contiguous habitat (e.g., Mississippi Alluvial Valley). The effectiveness of these approaches for estimating abundance of nonbreeding waterfowl in small areas with discontinuous habitat has rarely been assessed. Surveys conducted within riverine areas introduce sampling design difficulties because of discontinuous bottomland habitat and irregularity of flooding events. Therefore, we implemented and evaluated a generalizable grid-based, stratified random sampling design to estimate weekly duck abundance within the Wabash River floodplain in southeastern Illinois and southwestern Indiana, USA, during midwinter and early spring 2012 and 2013. We used aerial and ground-based counts to generate abundance estimates and evaluate within-week variation of counts. Peak duck abundance totaled 279,717 (SE = 69,101) in 2012 and 742,027 (SE = 296,563) in 2013. Dabbling ducks were the most abundant duck guild detected and abundance estimates for this group met our precision goal (CV ≤ 0.25) in 4 of 18 surveys = 0.33, range = 0.20–0.51). We compared the grid-based approach with a traditional aerial inventory and found that estimates from the grid-based approach were on average 75,175 (SE = 46,768) greater than inventory counts. Desired levels of precision were often not met, yet design improvements in 2013 notably increased precision, suggesting that further modifications may allow this method to be useful in riverine areas with discontinuous and ephemeral habitat. © 2017 The Wildlife Society.
• Chambers, J., Beck, J., Campbell, S., Carlson, J., Christiansen, T., Clause, K., Dinkins, J., Doherty, K., Griffin, K., Havlina, D., Henke, K., Hennig, J., Kurth, L., Maestas, J., Manning, M., Mayer, K., Mealor, B., McCarthy, C., Perea, M., & Pyke, D. (2016). Using resilience and resistance concepts to manage threats to sagebrush ecosystems, gunnison sage-grouse, and greater sage-grouse in their eastern range: A strategic multi-scale approach. US Forest Service General Technical Report, 2016(356).
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  This report provides a strategic approach developed by a Western Association of Fish and Wildlife Agencies interagency working group for conservation of sagebrush ecosystems, Greater sage-grouse, and Gunnison sage-grouse. It uses information on (1) factors that influence sagebrush ecosystem resilience to disturbance and resistance to nonnative invasive annual grasses and (2) distribution and relative abundance of sage-grouse populations to address persistent ecosystem threats, such as invasive annual grasses and wildfire, and land use and development threats, such as oil and gas development and cropland conversion, to develop effective management strategies. A sage-grouse habitat matrix links relative resilience and resistance of sagebrush ecosystems with modeled sage-grouse breeding habitat probabilities to help decisionmakers assess risks and determine appropriate management strategies at both landscape and site scales. Areas for targeted management are assessed by overlaying matrix components with Greater sage-grouse Priority Areas for Conservation and Gunnison sage-grouse critical habitat and linkages, breeding bird concentration areas, and specific habitat threats. Decision tools are discussed for determining the suitability of target areas for management and the most appropriate management actions. A similar approach was developed for the Great Basin that was incorporated into the Federal land use plan amendments and served as the basis of a Bureau of Land Management Fire and Invasives Assessment Tool, which was used to prioritize sage-grouse habitat for targeted management activities.