Southwestern South Dakota Research Articles

Occurrence of the Red-bellied Snake (Storeria occipitomaculata) on the margins of a disjunct range

The Red-bellied Snake (Storeria occipitomaculata) can be found throughout much of eastern North America, though two notable disjunct populations exist in the Black Hills of southwestern South Dakota and the Central Platte River Valley in southcentral Nebraska, west of the species’ core range. While literature continues to be added on the Red-bellied Snake and its natural history, it remains largely understudied in Nebraska. Throughout much of this species’ range, it is considered associated with woodland and wetland habitat features. On 28 September 2021, we detected one Red-bellied Snake near a treeless playa wetland in the Rainwater Basins ecoregion of southcentral Nebraska. Using a Grubbs Test to determine significant outliers, we found that this record was further from the Platte River than other previous accounts of this species in the state. This observation suggests this species may be found in other portions of the Rainwater Basins and considerably further from the Platte River than previously believed. Our observation along with other recent work indicates that Red-bellied Snakes may persist in herbaceous habitats lacking established woodland that include sufficient wetland features to support their primary food sources, including gastropods and other soft-bodied invertebrates. Due to the fragmentation of suitable habitats in the Rainwater Basins, coupled with the low dispersal of Red-bellied Snakes, populations persisting in the region are likely to be isolated.

Methane seeps as refugia during ash falls in the Late Cretaceous Western Interior Seaway of North America

Abstract Methane seeps host rich biotic communities, forming patchy yet highly productive ecosystems across the global ocean. Persistent hydrocarbon emissions fuel chemosynthetic food webs at seeps. Methane seeps were abundant in the Western Interior Seaway of North America during the Late Cretaceous. This area also experienced intermittent ash falls, which negatively impacted the marine fauna. We propose that methane seeps acted as refugia during these environmental perturbations. We report a laterally continuous bentonite within the upper Campanian Baculites compressus Zone of the Pierre Shale in southwestern South Dakota (USA) that fortuitously cuts across a methane seep deposit. We compare the macroinvertebrate record below and above the bentonite at seep and non-seep sites. Our results reveal that the paleocommunity (measured by abundance and diversity) was largely unaffected by the ash fall at the seep site, whereas it was significantly altered at the non-seep site. Thus, methane seeps in the Western Interior Seaway may have provided refuges or served as oases in the aftermath of severe environmental perturbations.

LATE PLEISTOCENE PINE MARTEN (MARTES; MUSTELIDAE) FROM THE BLACK HILLS, SOUTH DAKOTA

Two species of pine martens (Mustelidae, Martes americana, M. caurina) inhabit northern North America, with both species overlapping their distributions in the northwest of the USA and Canada. One extinct form (M. nobilis), larger than extant species, is known predominantly from Late Pleistocene cave deposits in the Intermountain West. Here we report on the skeletal remains of pine marten recovered from 2 caves in Wind Cave National Park, Black Hills, southwestern South Dakota. Only introduced marten populations occur in the region today, highlighting the significance of the records for understanding the biotic history of the region. One complete skeleton of Martes recovered from Wind Cave radiocarbon dates to approximately 11,100 calibrated years BP, whereas the other fossil remains from the nearby Persistence Cave date to between 12,000 and 42,000 y old based on associated 14C dates. These remains represent the 1st fossil record of Martes from the Black Hills. Both forms of recovered pine martens, characterizing extinct and extant morphologies, were recovered in the caves but as yet are not understood to be sympatric in the local community.

Trace-element and Sr and Nd isotopic geochemistry of Cretaceous bentonites in Wyoming and South Dakota tracks magmatic processes during eastward migration of Farallon arc plutons

Abstract Bentonite beds, which are clay deposits produced by the submarine alteration of volcanic tephra, preserve millions of years of volcanic products linked to magmatic systems for which records are otherwise lost through erosion and alteration. Cretaceous strata from the Bighorn Basin, Wyoming, and southwestern South Dakota contain bentonites that originated from arc magmatism produced by subduction of the Farallon plate. We analyzed the bulk major- and trace-element geochemistry, and the 87Sr/86Sr (n = 87) and 143Nd/144Nd (n = 26) isotopic compositions of individual bentonite beds from these areas spanning 40 m.y. of volcanism to recover signals of magmatic processes and to attempt to trace bentonite geochemical and isotopic signatures to contemporaneous Cordilleran plutonic rocks. Using multiple immobile elements (e.g., Zr, TiO2, Nb, Ta, and rare earth elements), distinct temporal trends show variations in the effects of mineral fractionation and changes in crustal thickness. Bentonite Sr and Nd isotopic compositions allow ash beds to be correlated with specific batholithic complexes in Idaho and western Montana. With this data set, we observed the following: (1) The volcanic arc migrated across the 0.706 isopleth between 115 and 105 Ma; (2) between 105 and 95 Ma, magmatism stalled in central Idaho and was supported through significant MASH (mixing-assimilation-storage-homogenization) processing; (3) by 85 Ma, a shallowing subduction angle resulted in the eastward migration of the volcanic front into western Montana while volcanism in Idaho diminished; and (4) around 75 Ma, evidence of Idaho volcanism is lost. Montana plutonism continued with significant assimilation of radiogenic basement and regional centers of local magma emplacement (i.e., Pioneer batholith).

Hydrogeological controls of arsenic and uranium dissolution into groundwater of the Pine Ridge Reservation, South Dakota

AbstractThis study integrates geochemical modeling, spatial analysis and several statistical methods including principal component analysis, multivariate regression and cluster analysis to investigate hydrogeologic controls of arsenic and uranium contamination within groundwater of the Arikaree aquifer on the Pine Ridge Reservation (PRR). Located in southwestern South Dakota, the PRR is largely rural and many people rely on domestic supply wells completed in the Arikaree aquifer as their primary drinking water source. Locally, the White River Group, which unconformably underlies the Arikaree Group, is enriched in arsenic and uranium related to volcanic ash deposits and acts as a geogenic metal source. Geochemical data from over 250 groundwater samples were obtained through collaboration with the Oglala Sioux Tribe. Cluster spatial statistics analyses delineated four regions of statistically significant variations in groundwater chemistry that represent upgradient, intermediate, and downgradient portions of the Arikaree aquifer. Groundwater evolves as it flows through the Arikaree aquifer with increasing alkalinity, sodium, and pH along flow paths. These chemical changes are likely due to dissolution of carbonate minerals and volcanic ash. Thermodynamic calculations suggest increasing supersaturation of the groundwater with respect to calcite; thus, volcanic ash dissolution may be an important secondary source of alkalinity. Elevated alkalinity and pH levels were found to be the driving factors of arsenic and uranium mobility, and downgradient sections of the aquifer in the northern portions of the PRR are most likely to be impacted by metal(loid) contamination, with 73% of the wells in this grouping failing a USEPA maximum contaminant level for arsenic, uranium, and/or gross alpha.

Whitneyan (Middle Oligocene) Rodents from Obritsch Ranch (Stark County, North Dakota) and a Review of Whitneyan Rodent Fossil Record

Until recently, few well-described rodent faunae from the Whitneyan North American Land Mammal Age [NALMA] were known, hindering studies of rodent diversity, biogeography, and evolutionary patterns during the Oligocene. This study describes a new Whitneyan rodent assemblage from the Obritsch Ranch paleontological locality in the Little Badlands region of North Dakota. Specimens were collected from three stratigraphically restricted sampling intervals within the middle to upper Brule Formation, resulting in the recognition of fourteen rodent species, five of which are elsewhere known to first appear in Whitneyan faunae. Described is one new species, the eomyid Paradjidaumo obritschorum, and the first cranial material of the heteromyid rodent ProharrymysKorth and Branciforte, 2007. The rodent fauna from the upper two sampling intervals at Obritsch Ranch and the uppermost fauna recently described from the nearby Fitterer Ranch paleontological locality share four taxa in common with the late Whitneyan Blue Ash local fauna from southwestern South Dakota, indicating these two North Dakota rodent faunae are also from the late Whitneyan. Increasing knowledge of Whitneyan rodent faunae in North America reveals unusually high survivorship of rodent species from the older Orellan NALMA into the Whitneyan NALMA and much geographic variation in the diversity, distribution, and relative abundance of different rodent families between individual Whitneyan rodent faunae. Those factors help explain prior difficulties in differentiating Orellan and Whitneyan rodent faunae and in identifying biostratigraphically useful rodent taxa for the Whitneyan. Overall, Whitneyan rodent faunae from North America display an increase in the diversity of aplodontiids, cricetids, and sciurids and a decrease in eomyid and ischyromyid diversity relative to the Orellan.

FAUNAL ASSOCIATIONS IN COLD-METHANE SEEP DEPOSITS FROM THE UPPER CRETACEOUS PIERRE SHALE, SOUTH DAKOTA

Study of ancient cold-methane seep deposits provides insight into the changes in seep communities over the lifetime of a seep, which are otherwise difficult to observe in modern settings. We studied 24 cold-methane seep deposits in the Upper Cretaceous (Campanian) Pierre Shale of southwestern South Dakota. These deposits were subdivided into three categories depending on their physical characteristics: (1) those with a single main conduit, few secondary pipes and concretionary bodies, and no carbonate cap, implying strong advective flow to the sediment-water interface; (2) those with a single main conduit, a moderate number of secondary pipes and concretionary bodies, and a small carbonate cap, implying both advective and diffusive flow to the sediment-water interface; and (3) those with a single main conduit, a high number of secondary pipes and concretionary bodies, and a broad carbonate cap, implying extensive flow, but dampening at the sediment-water interface due to the presence of the large carbonate cap. We analyzed the faunal composition at all 24 seeps. The number of species ranges from five to 20. All of the seeps are dominated by baculitid ammonites, inoceramids, and lucinids (“foundation” organisms). These species are the same as those in time-equivalent non-seep sites in the Pierre Shale and are not seep-obligate. However, in seep categories 2 and 3, the number and kind of secondary organisms increases in association with the development of the large carbonate cap. These organisms include oysters, gastropods, echinoids, sponges, crinoids, and scaphitid ammonites. We infer that these organisms appear because (1) the carbonate hardground provides a more diverse habitat allowing attachment and encrustation and (2) the bottom waters are better oxygenated and/or the level of hydrogen sulfide is reduced because the methane rich fluids are diverted away from the carbonate cap, thus providing a more suitable habitat for organisms such as scaphitid ammonites that require a well-oxygenated environment. However, even at these seeps, the number of secondary organisms usually does not exceed that of foundation organisms.

Biostratigraphy of the Campanian-Maastrichtian, Mid-Maastrichtian, and Cretaceous-tertiary boundaries in the Raton Basin: Implications for models of early Laramide tectonism and for the origin of the enigmatic Disturbed Zone

The Campanian-Maastrichtian stage boundary is placed within the upper part of the Pierre Shale about 100 m below the base of the Trinidad Sandstone at Berwind Canyon, Colorado. Correlation of ammonite biostratigraphy with palynostratigraphy places this boundary near the top of the Vermejo Formation in the southwestern part of the Raton Basin, northeastern New Mexico. The informal mid-Maastrichtian boundary should be placed at the level of the Trinidad Sandstone at Berwind Canyon, although it should be placed at the level of the Vermejo-Raton unconformity in northeastern New Mexico based upon palynostratigraphy. High-resolution megafloral biostratigraphy of the K-T boundary is also discussed. Chronostratigraphic and paleoenvironmental indicator species reveal differential sedimentation rates across the basin. The magnitude of the Vermejo-Raton unconformity varies primarily in a north-south direction across the Raton Basin and was greatest in northeastern New Mexico and least in south-central Colorado, which may affect interpretations of the early Laramide history of the Raton Basin. The results of this study preclude correlation of the basal part of the Vermejo Formation with the Disturbed Zone of southwestern South Dakota.

Polycotylus latipinnis Cope (Plesiosauria, Polycotylidae), a nearly complete skeleton from the Niobrara Formation (early Campanian) of southwestern South Dakota

ABSTRACTA nearly complete skeleton of Polycotylus latipinnis (SDSM 23020) from the upper Niobrara Formation (early Campanian) of South Dakota (U.S.A) greatly improves information for this formerly poorly known taxon. Specimens SDSM 23020 and YPM 1125 (paratype P. latipinnis) exhibit numerous postcranial characters that distinguish Polycotylus, in particular presacral vertebral count, nature of chevron facets, unique ilia, and highly derived paddles including five epipodial ossifications and increased hyperphalangy. Greater vertebral and phalangeal counts of Polycotylus are accompanied by exceptional foreshortening; thus, the relative body and limb proportions are likely similar to less derived polycotylids, with fewer, more elongate vertebrae and phalanges. The complete skull, derived among polycotylids, has short temporal fenestrae, elongate frontals, exceptionally slender parasphenoid with prominent cultriform process, and exceptionally long extensions of the angulars and splenials within the mandibular symphysis. Cladistic analysis indicates that Polycotylus nests firmly within derived Polycotylidae as a potential sister taxon to Dolichorhynchops osborni and Trinacromerum, despite a ‘primitive’ presacral vertebral count. Future improvements in available data, in particular better information regarding basal polycotylids, and refinement of character selection to nullify homoplasy could significantly alter the tree structure to show distinct subgroups within Polycotylidae. North American polycotylids with elongate temporal fenestrae, elongate podials, and relatively long vertebrae are confined to occurrences of late Cenomanian and earliest Turonian age, whereas polycotylids distinctly foreshortened in these respects are restricted to post-Turonian occurrences. Ilium morphology is highly variable among polycotylids and, in addition to taxonomic utility, may be in part attributable to sexual dimorphism.Citation for this article: Schumacher, B. A., and J. E. Martin. 2015. Polycotylus latipinnis Cope (Plesiosauria, Polycotylidae), a nearly complete skeleton from the Niobrara Formation (early Campanian) of southwestern South Dakota. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1031341.

Geochemical evidence (C and Sr isotopes) for methane seeps as ammonite habitats in the Late Cretaceous (Campanian) Western Interior Seaway

Methane seeps in the Upper Cretaceous Pierre Shale of the U.S. Western interior contain a rich fauna including ammonites (Baculites, Hoploscaphites, Didymoceras, Placenticeras, Solenoceras), bivalves (Lucina), gastropods, sponges, and crinoids. Occasionally, the shell material in the seeps is very well preserved, retaining the original mineralogy and microstructure. We explored two such seeps from the upper Campanian Didymoceras cheyennense and overlying Baculites compressus Zones (74.7–73.5 Ma) in southwestern South Dakota. Light values of δ13C in the micritic limestones (–11 to –47 ‰) confirm the impact of anaerobic oxidation of methane on the isotopic composition of the dissolved inorganic carbon reservoir. At the seep from the D. cheyennense Zone, δ13C values in well-preserved specimens of Hoploscaphites and Baculites are significantly lighter than those measured in specimens from approximately age-equivalent non-seep deposits. In addition, the 87Sr/86Sr ratio is elevated in the authigenic carbonates and ammonite shells compared with the coeval marine value. This suggests that seep fluids imprinted with a radiogenic Sr signature, perhaps derived from isotopic exchange with granitic deposits at depth associated with the Black Hills uplift, are transported through the surficial sediments into the overlying water. The persistence of these isotopic tracers of seep fluids in the ammonite shells suggests that these mobile animals were likely demersal and were living in close proximity to the seep. A more restricted data set on a single baculite and nautilid from the seep in the B. compressus Zone shows less divergence of δ13C and 87Sr/86Sr relative to non-seep values, suggesting that fluid transport was not as strong at that seep.

Cephalopods from the Badlands National Park area, South Dakota: Reassessment of the position of the Cretaceous/Paleogene boundary

Terry et al. (2001) proposed that the Fox Hills Formation in the area of Badlands National Park, southwestern South Dakota, USA, contains the Cretaceous/Paleogene (K/Pg) boundary, marked by a thick layer of contorted bedding called the Disturbed or Disrupted Zone (DZ). Examination of the ammonites from just below this layer yields Hoploscaphites nicolletii (Morton, 1842), H. spedeni (Landman and Waage, 1993), Discoscaphites gulosus (Morton, 1834), D. conradi (Morton, 1834), and Sphenodiscus lobatus (Tuomey, 1856). The abundance of Discoscaphites and the presence of a coarsely ornamented specimen of H. spedeni suggest that this assemblage corresponds to the upper part of the H. nicolletii Zone in the type area of the Fox Hills Formation. No ammonites are present above the DZ, but previous analyses of the dinoflagellates from just below, within, and above the DZ by Palamarczuk et al. (2004) are consistent with the ammonite results. Together, these fossils indicate that the interval just below and above the DZ represents the upper part of the lower upper Maastrichtian (≈ middle upper Maastichtian). Belemnites are present in the strata just below the DZ and occur as guards either isolated in the matrix or associated with fragmentary ammonites in concretions composed of soft sandy marl. The belemnites are assigned to Belemnitella bulbosaMeek and Hayden, 1857a, and B. badlandsensis n. sp., which is characterized by an unusually large fissure angle. The distribution of ammonites and lithofacies at this time reveals that the western shoreline of the Western Interior Seaway trended northeast–southwest across western South Dakota and adjacent parts of North Dakota. Based on an examination of the oxygen isotopes of the belemnites and scaphites in this area, the seawater temperature was nearly constant along the coast, approximately 17–20 °C. A comparison of the contact between the Pierre Shale and Fox Hills Formation at various localities in the Western Interior Basin indicates that this contact rises in the section toward the east, reflecting the final retreat of the Seaway during the late Maastrichtian.

Paleoproterozoic transpressional shear zone, eastern Black Hills, South Dakota: Implications for the late tectonic history of the southern Trans-Hudson Orogen

Paleoproterozoic rocks in the Black Hills of southwestern South Dakota record deformation associated with accretion of Proterozoic terranes from the south and suturing of the Wyoming and Superior cratons (ca. 1780–1715 Ma). Folding associated with suturing of these Precambrian terranes is well documented. However, penetrative fabrics related to shearing are characterized in only a few localities. The research presented herein identifies and characterizes a ≥4-km-wide, pervasive, thick-skinned shear zone, which deforms the regional-scale folding in the Black Hills portion of the Wyoming craton. Shearing is bracketed between ca. 1740 Ma (post regional-F2 folding) and ca. 1715 Ma (intrusion of the Harney Peak Granite). This high-strain zone is characterized by narrow anastomosing shear zones (m-scale) in the Paleoproterozoic rocks in the east-central Black Hills near Rockerville, South Dakota. The shear zones converge to form a km-wide zone of deformation in Paleoproterozoic and Archean rocks to the north near Nemo, South Dakota. Kinematic indicators such as composite foliations, microfolding, and asymmetric mantled porphyroclasts from within the shear zone support left-lateral, east-side-up transpression. Furthermore, strain associated with the shearing is coupled to vertically plunging, isoclinal F3 folds, commonly identified only as hinge areas preserved between strongly sheared limbs, within and adjacent to the shear zone in the study area. Correlation of this deformational event from the Paleoproterozoic rocks in the east-central Black Hills to older Paleoproterozoic and Archean rocks to the north has implications for these structures to have formed during a basement-involved deformational event. Evidence that stresses associated with this ∼1740–1715 Ma event were transferred inboard to the Wyoming Province is present to the southwest in the Hartville Uplift and Laramie Mountains of southeastern Wyoming. In both locations, structures with similar timing and kinematics overprint Cheyenne-Belt deformation. The regional extent and thick-skinned nature of these structures are interpreted to signify the change to continent-continent collisional tectonics during the final suturing of the Wyoming and Superior Provinces.

Genetic diversity in a reintroduced swift fox population

Swift fox (Vulpes velox) were historically dis- tributed in southwestern South Dakota including the region surrounding Badlands National Park (BNP). The species declined during the mid-1800s, largely due to habitat loss and poisoning targeted at wolves (Canis lupus) and coyotes (Canis latrans). Only a small population of swift foxes near Ardmore, which is located in Fall River County, South Dakota, persisted. In 2003, a reintroduction program was initiated at BNP with swift foxes translocated from Colo- rado and Wyoming. Foxes released in the years 2003, 2004 and 2005 were translocated from Colorado (BNP-Colo- rado) whereas in 2006, released foxes were translocated from Wyoming (BNP-Wyoming). Our objective was to evaluate genetic diversity and structure of the restored swift fox population in the area surrounding BNP com- pared to source fox populations in an area of Colorado and Wyoming, as well as the local swift fox population neighboring BNP near Ardmore in Fall River County, South Dakota. A total of 400 swift foxes (28 released in 2003, 28 released in 2004, 26 released in 2005, 26 released in 2006, 252 wild-born foxes, 40 individual foxes from the Ardmore area of South Dakota) was genotyped using twelve microsatellite loci. We report mean gene diversity values of 0.778 (SD = 0.156) for the BNP-Colorado pop- ulation, 0.753 (SD = 0.165) for the BNP-Wyoming pop- ulation, 0.751 (SD = 0.171) for the BNP population, and 0.730 (SD = 0.166) for the Fall River population. We also obtained Fst values ranging from 0.014 to 0.029 for pair- wise comparisons of fox populations (BNP, Fall River, BNP-Wyoming, BNP-Colorado). We conclude that the reintroduced fox population around BNP has high genetic diversity comparable to its source populations in Colorado and Wyoming. Although genetic diversity indicates that the reintroduction was successful, additional time is necessary to fully evaluate long-term genetic maintenance and in- terconnectivity among these populations.

Natural resource manager perceptions of agency performance on climate change

An important precursor to the adoption of climate change adaptation strategies is to understand the perceived capacity to implement and operationalize such strategies. Utilizing an importance–performance analysis (IPA) evaluation framework, this article presents a comparative case study of federal and state land and natural resource manager perceptions of agency performance on factors influencing adaptive capacity in two U.S. regions (northern Colorado and southwestern South Dakota). Results revealed several important findings with substantial management implications. First, none of the managers ranked the adaptive capacity factors as a low priority. Second, managers held the perception that their agencies were performing either neutrally or poorly on most factors influencing adaptive capacity. Third, gap analysis revealed that significant improvements are required to facilitate optimal agency functioning when dealing with climate change-related management issues. Overall, results suggest that a host of institutional and policy-oriented (e.g., lack of clear mandate to adapt to climate change), financial and human resource (e.g., inadequate staff and financial resources), informational (e.g., inadequate research and monitoring programs) and contextual barriers (e.g., sufficient regional networks to mitigate potential transboundary impacts) currently challenge the efficient and effective integration of climate change into decision-making and management within agencies working in these regions. The IPA framework proved to be an effective tool to help managers identify and understand agency strengths, areas of concern, redundancies, and areas that warrant the use of limited funds and/or resource re-allocation in order to enhance adaptive capacity and maximize management effectiveness with respect to climate change.

Dinoflagellate cysts from the upper Campanian Pierre Shale and Bearpaw Shale of the U.S. Western Interior

The Upper Cretaceous Pierre Shale and Bearpaw Shale contain rich assemblages of dinoflagellates. We analyzed nine samples from the Baculites compressus – B. cuneatus Zones in Montana, South Dakota, and Colorado. According to the ammonite zonation of the Western Interior of North America, these zones represent the middle part of the upper Campanian. Dinoflagellate cysts include Alterbidinium acutulum, Cordosphaeridium fibrospinosum, Hystrichodinium pulchrum, Isabelidinium cooksoniae, Laciniadinium firmum , members of the Microdinium group Odontochitina operculata, Oligosphaeridium pulcherrimum, Palaeohystrichophora infusorioides, Palaeoperidinium pyrophorum, Phelodinium tricuspe , members of the Spiniferites group, Spongodinium delitiense , and Xenascus ceratioides . Variation in species composition among samples may indicate slight differences in environment and/or age. The environment and proximity of samples to the paleoshoreline was evaluated based on the ratio of marine to terrestrial palynomorphs and the relative abundance of dinoflagellate cysts versus other organic-walled remains. Our results suggest that the samples from Colorado were deposited in a nearshore environment, the samples from southwestern South Dakota and Montana in an offshore environment, and the sample from eastern South Dakota in an offshore environment far from shore. These results agree with previous interpretations about the position of the shoreline based on the distribution of litho- and biofacies.

Distribution Records and Comments on Fleas in Southwestern South Dakota

From October 2003 through April 2006, we collected 565 fleas incidental to a distribution survey of mammals in southwestern South Dakota. Sixty-one specimens, representing 18 species of mammals, possessed 20 species of fleas. The geographic distributions of these flea species revealed 8 new records for the Black Hills and its adjacent grasslands. Four species—Megarthroglossus divisus, Stenoponia americana, Odontopsyllus dentatus, and Amaradix euphorbi—constitute new records for South Dakota, thus increasing the state's known flea fauna to 42 species. Hunters, trappers, and field biologists should be aware that serosurveillance during the 1990s revealed the presence of sylvatic plague and tularemia in the Black Hills area.

Antipredatory Defense of Neonatal Pronghorn (Antilocapra americana) by Yearling Male Pronghorn in Southwestern South Dakota

ABSTRACT. Antipredatory defense of pronghorn (Antilocapra americana) neonates (≤1 month old) by adult females (>18 months old) is well documented throughout the geographic range of this species. However, reports of male pronghorn defending neonates against predators are limited to a single study in northwestern Wyoming where occurrences were documented of adult males assisting female pronghorn in defending neonates against coyotes (Canis latrans). To our knowledge, defense of neonatal pronghorn by yearling males (12–18 months old) has not been reported previously for this species. We report occurrences of antipredatory defense of neonatal pronghorn by yearling males in southwestern South Dakota.

Dispersal movements of subadult cougars from the Black Hills: the notions of range expansion and recolonization

Dispersal plays a vital role in cougar (Puma concolor) population ecology, creating genetic viability and maintaining gene flow between populations. The naturally recolonized cougar population in the Black Hills is at the edge of the species' range in North America and completely surrounded by the grasslands of the Northern Great Plains. Our objective was to document dispersal movements and possible range expansion of subadult cougars captured within the Black Hills ecosystem of southwestern South Dakota and eastern Wyoming. Twenty‐four (n = 14 males, n = 10 females) subadult cougars were captured in the Black Hills. Independence of cougars from females averaged 13.5 months (range = 10–16 months) from parturition; dispersal occurred 1–3 months post independence. Males dispersed (mean = 274.7 km SE 88.3) farther than females (mean = 48.0 km SE 10.9), with females exhibiting 40% philopatry. We documented several (n = 6) long‐distance dispersal movements (>250 km) of male cougars and hypothesize that males making long‐distance movements were in search of available mates. The long‐distance cougar dispersal movements documented by our study indicate that range expansion and habitat recolonization are occurring and further suggest proactive efforts to increase public knowledge of cougar ecology in areas where cougars are recolonizing previously occupied range.

Growth of Male White-Tailed Deer: Consequences of Maternal Effects

Identifying maternal effects on offspring is critical to interpreting population dynamics, but the duration of maternal effects and which life-history traits they influence is not well understood. We quantified growth and development of male white-tailed deer (Odocoileus virginianus) originating from the Black Hills in southwestern South Dakota and from eastern South Dakota in a controlled environment with high-quality nutrition. Despite being in good nutritional condition, males from the Black Hills ceased rapid growth 41 days earlier, were 29% smaller at asymptotic body mass, and grew significantly smaller antlers than males from eastern South Dakota. Females from eastern South Dakota were 14.9 kg larger than females from the Black Hills, yet birth mass of male offspring was similar for females from the 2 regions. Male offspring of 1stgeneration deer from the Black Hills attained a 30% larger asymptotic body mass and grew significantly larger antlers than their sires. Body mass and antler size of 2nd-generation males of Black Hills origin approached that of 1st-generation males from eastern South Dakota at maturity. Suppression in growth of 1st-generation males of the Black Hills and increased growth by their offspring supported an influence of maternal and grandmaternal condition during gestation on subsequent growth of offspring and highlighted the significance of nutrition during gestation. These intergenerational effects indicate that measures of animal condition and population performance might reflect past rather than current conditions, and illustrate the potential for time lags in responses of populations to improved environmental conditions.

Design to monitor trend in abundance and presence of American beaver (Castor canadensis) at the national forest scale

Wildlife conservationists design monitoring programs to assess population dynamics, project future population states, and evaluate the impacts of management actions on populations. Because agency mandates and conservation laws call for monitoring data to elicit management responses, it is imperative to design programs that match the administrative scale for which management decisions are made. We describe a program to monitor population trends in American beaver (Castor canadensis) on the US Department of Agriculture, Black Hills National Forest (BHNF) in southwestern South Dakota and northeastern Wyoming, USA. Beaver have been designated as a management indicator species on the BHNF because of their association with riparian and aquatic habitats and its status as a keystone species. We designed our program to monitor the density of beaver food caches (abundance) within sampling units with beaver and the proportion of sampling units with beavers present at the scale of a national forest. We designated watersheds as sampling units in a stratified random sampling design that we developed based on habitat modeling results. Habitat modeling indicated that the most suitable beaver habitat was near perennial water, near aspen (Populus tremuloides) and willow (Salix spp.), and in low gradient streams at lower elevations. Results from the initial monitoring period in October 2007 allowed us to assess costs and logistical considerations, validate our habitat model, and conduct power analyses to assess whether our sampling design could detect the level of declines in beaver stated in the monitoring objectives. Beaver food caches were located in 20 of 52 sampled watersheds. Monitoring 20 to 25 watersheds with beaver should provide sufficient power to detect 15-40% declines in the beaver food cache index as well as a twofold decline in the odds of beaver being present in watersheds. Indices of abundance, such as the beaver food cache index, provide a practical measure of population status to conduct long-term monitoring across broad landscapes such as national forests.