Native Ungulates Research Articles

Body mass estimation in Early Miocene native South American ungulates: a predictive equation based on 3D landmarks

AbstractSouth American native ungulates include extinct taxa that evolved within the geographical context given by the isolation of South America during most of the Cenozoic. The ungulates (orders Notoungulata, Litopterna and Astrapotheria) of the Santa Cruz Formation (late Early Miocene) are particularly interesting for paleobiological studies due to their diversity, richness and quality of preservation of the specimens. The body mass estimation of extinct species is one of the basic biological attributes for paleobiological reconstructions. The most common way to estimate body mass from fossils is using linear regression. Here, we used geometric morphometric techniques in order to estimate their body mass. We used regressions based on centroid size of 3D craniomandibular landmark configurations, including extant ungulates (their size and ecological relatives). Cases were weighted to maximize the taxonomic evenness. A broad body size range was recorded. The highest predictive power is obtained with those functions derived from the highest taxonomic and ecological diversity. The highest taxonomic richness corresponds to masses below 100 kg. Among Notoungulata, typotheres (Hegetotheriidae + Interatheriidae) vary from 1 to less than 10 kg, while the smaller toxodontid reached 100 kg and the larger 500 kg. Litoptern proterotheriid body masses vary from 10 to 50 kg, and macraucheniids surpass 100 kg. The astrapotheres (Astrapotheria) reached (or even surpassed) 1000 kg, being the only megamammal in the Santacrucian ungulate assemblage.

Differences in Vegetation and Native Ungulate use between Exclosures and Cattle Grazed Plots in Sheep River Provincial Park, Alberta

Cattle grazing can cause significant changes in quality and quantity of forage available to the wildlife. The effects of livestock on native ungulates are still unclear, and range from positive to negative depending on the season. The objectives of our study were to determine the impact of cattle grazing on the vegetation biomass and quality by comparing twenty-four livestock exclosures and corresponding grazed plots. Use of exclosures by bighorn sheep and elk were evaluated. Furthermore, we compared proportion of live vegetation and forbs from 1994-95 to 2005-06 to investigate long-term changes in the vegetation quality and biomass. As predicted, higher vegetation biomass and lower quality was found inside the exclosures during some of the months. The proportion of live vegetation found within an area was negatively correlated with acid detergent fiber (ADF) and positively correlated with crude protein indicating higher net energy and nutritional value. More forbs were found in the lightly grazed areas. Number of fecal groups did not differ significantly between exclosures and grazed plots. The number of sheep groups sighted was higher in grazed plots than exclosures during the summer, but not during the winter. The proportion of live vegetation and biomass did not change between 1994-95 and 2005-06, but more forbs were found in 2005-06 than before. Overall, most of our results corresponded well with previous studies. Care must be taken to ensure that nutritional requirements of native ungulates are met during the winter, as a decrease in vegetation biomass due to cattle grazing was more pronounced than the increase in quality during this time.

Have wet meadow restoration projects in the Southwestern U.S. been effective in restoring geomorphology, hydrology, soils, and plant species composition?

Wet meadows occur in numerous locations throughout the American Southwest, but in many cases have become heavily degraded. Among other things they have frequently been overgrazed and have had roads built through them, which have affected the hydrology of these wetland ecosystems. Because of the important hydrologic and ecological functions they are believed to perform, there is currently significant interest in wet meadow restoration. Several restoration projects have been completed recently or are underway in the region, sometimes at considerable expense and with minimal monitoring. The objective of this review was to evaluate the effects of wet meadow restoration projects in the southwestern United States on geomorphology, hydrology, soils and plant species composition. A secondary objective was to determine the effects of wet meadow restoration projects on wildlife. Electronic databases, internet search engines, websites and personal contacts were used to find articles of relevance to this review. Articles were filtered by title, abstract and full text. Summary information for each of the articles remaining after the filtering process was compiled and used to assess the quality of the evidence presented using two different approaches. Our searches yielded 48 articles, of which 25 were published in peer-reviewed journals, 14 were monitoring or project reports, and 9 were published in conference proceedings or are unpublished theses or manuscripts. A total of 26 operational-scale restoration projects were identified. A wide range of restoration techniques were employed, ranging from small-scale manipulations of stream channels (e.g., riffle structures) to large scale pond-and-plug projects. Other common restoration techniques included fencing to exclude livestock (and sometimes also native ungulates), other forms of grazing management, seeding, and transplanting seedlings. Most of the articles reported that restoration was fully or partially effective, at least in the short-term. However, the relative lack of high quality quantitative data, and especially data extending more than two years after project implementation, greatly limits our ability to determine how effective restoration has truly been in practice. While caution is warranted due to data quality limitations, progress has been made over the past 20 years in wet meadow restoration. In particular, important contributions have been made in restoring the highly degraded wet meadow systems that are characterized by deep, wide and relatively straight gullies. There is evidence, for example, that the pond-and-plug approach is an effective technique for restoring many aspects of these systems, albeit at the cost of creating new features (ponds) that are not necessarily natural features of wet meadows. There is a need to allocate additional effort to project documentation, including better-designed and longer-lasting monitoring programs. One approach that might help is for practitioners to work with scientists from government agencies, local universities and colleges, and other organizations. When this type of collaboration has happened in the past it appears to have been effective. Many important lessons could have been learned, and mistakes avoided, if more effort had been put into documenting both successes and failures of past projects.

Diseases of red deer introduced to Patagonia and implications for native ungulates

The red deer (Cervus elaphus) invasion in Patagonia has been continuing for nearly a century, with occurrence in all habitats between 34°S and 55°S. Their distribution, movement patterns and locally high densities raise concerns over their potential epidemiological role in maintaining disease reservoirs or transmitting diseases such as foot-and-mouth disease or tuberculosis, with potential severe health and economical impacts at the interface of humans, livestock or native wildlife. Among adult females collected by rifle and radio-collared deer that died naturally, no ectoparasites were found (n = 73). Fasciola hepatica was encountered in three surveys at prevalences ranging from 9% to 50% (n = 108). Taenia ovis krabbei was identified, and Cysticerus tenuicollis was found at a prevalence of 8% (n = 12). Ostertagia sp., Bunostomum sp. and Dictyocaulus sp. had a prevalence of 75%, 25% and 13% (n = 9), respectively. Several gastrointestinal parasites reported at low prevalence in endangered Patagonian huemul (Hippocamelus bisulcus) are common in livestock and considered commensals in domestic ruminants. Sympatry of huemul with livestock is commonplace, whereas with red deer it occurs in <2% of known populations, in which case there were 1.2 red deer, but 25.2 livestock per huemul, making livestock the determining epidemiological factor regarding disease transmission or reservoir. As red deer have been coexisting with livestock for >100 years in Argentina, both red deer and livestock play epidemiological roles for shared diseases. Research, conservation and management efforts should be directed towards livestock herd health programs or restriction of free livestock movements, particularly if diseases are shown to have an impact on recruitment of endangered natives. Livestock are routinely researched and inspected at slaughter and thus provide a proxy for diseases afflicting co-existing ungulates. Testing for antibodies to foot-and-mouth disease viral antigen was negative (n = 41). A tentative diagnosis of mycobacterial infection was based on typical visceral lesions. Antler damage occurred on 73% of shed antlers, with 36% having major breaks of tines and main beams, possibly indicating mineral imbalances. One male had both antlers, including pedicles with portions of frontal, parietal and occipital bones, broken off the skull, causing his death. The prevalence of 0.9% of campylognathia (n = 776) indicates that the disease is unlikely to be inheritable, because the founding stock of 20 animals would have had a prevalence of at least 5%. Among deer, handedness of scoliosis related significantly to the hemisphere where specimens originated (P < 0.001, n = 131). Coriolis forces are known to affect early stages of development, such as the innervation pattern of the mammalian vestibular system, or the plane of bilateral symmetry. It is, therefore, conceivable that the networks processing these environmental cues, or the mechanisms responsible for compensation, are malfunctioning and thus result in a preponderance of facial scoliosis in accordance to the earth’s rotation.

Behavioural response of free-ranging guanacos (Lama guanicoe) to land-use change: habituation to motorised vehicles in a recently created reserve

Context Guanacos, the only native ungulates inhabiting Patagonian arid lands, are perceived by local people as a threat to livestock production and, consequently, uncontrolled hunting and harassment are widespread across the region. In 2005, a traditional sheep ranch (RSP) was converted into a wildlife reserve, offering the opportunity to assess changes in guanaco tolerance to motorised vehicles after harassment ceased. Aims The aims of the present study were to address factors influencing guanaco flight response on RSP, to assess inter-annual variation in flight responses after management changed and to compare guanaco response to cars among the RSP population, neighbouring ranches with traditional management and a southern population (C2B) that has had effective protection since the early 1970s. Methods Field surveys using available roads at RSP were conducted during a 4-year period to assess inter-annual changes in guanaco flight probability. Current estimates of flight probability at RSP were then compared with point estimates obtained from neighbouring ranches and the C2B population. Results We found that flight probability at RSP decreased as groups were located farther from the transect line and groups with at least one juvenile were more likely to flee than were adult-only groups. Flight probability decreased progressively during the study and significant differences with initial conditions emerged during the fourth year of monitoring. The current flight response observed at RSP is consistent with an intermediate state between neighbouring ranches and C2B population. Key conclusion Our results support the hypothesis that guanacos can become rapidly habituated to vehicles if harassment ceases and subsequent traffic acts as a neutral stimulus for enough time. Implications Finally, we discuss how our results may be helpful for other recently created reserves and ecotourism oriented projects.

Contrasting feeding patterns of native red deer and two exotic ungulates in a Mediterranean ecosystem

Context Ungulates have been widely introduced in multiple ecosystems throughout the world due to their value as food and for sport hunting. The identification of foraging preferences of exotic and native ungulates living in sympatry is, therefore, becoming increasingly important in order to assess potential impacts of introduced animals on the host ecosystem. Aims To describe species-specific foraging strategies and infer resource selection overlap between native and exotic ungulates. Methods We compared the trophic ecology of three sympatric ungulate species living in a Mediterranean landscape: the native Iberian red deer Cervus elaphus hispanicus, and two exotic bovids, the European mouflon Ovis orientalis musimon and the aoudad Ammotragus lervia. We simultaneously determined herbivore diet through analyses of botanical content in faeces and assessed the nutritional content of these diets. Key results Higher selection of shrubs by deer was sustained throughout the year, while bovids showed seasonal shifts in forage selection. Both bovids displayed a selective dietary strategy directed towards a higher overall nutritional quality than that of deer. Divergent exploitation patterns between the studied cervid and bovids might be related to body mass and physiological adaptations to overcome secondary defence compounds of shrubs, and were largely affected by seasonal changes in the nutritional value of available vegetation. Ecological theory suggests that diet overlap should be greater between similar-sized species. Indeed, both exotics showed similar, sometimes overlapping, dietary patterns that could lead to potential competition in the use of resources. Native red deer preferences only showed some overlap with those of exotic mouflon under constrained summer conditions. Conclusions Dietary overlap between deer and mouflon and between aoudad and mouflon during limiting summer conditions could entail a potential competitive interaction under more even densities of the study species, since a concurrent habitat overlap between those pairs of species has previously been reported. Implications The outcomes of our study suggest the need for an integration of habitat and ungulate management. Management actions in Mediterranean rangelands should be directed towards protecting habitat conditions so that biodiversity is enhanced along with the presence of sustainable communities of large herbivores. Management directed towards ungulates should maintain moderate stocking rates and monitor and control introduced and native populations.

Quebrada Fiera (Mendoza), un importante centro paleobiogeográfico en el Oligoceno tardío de América del Sur

Esta contribución se centra en los principales resultados obtenidos en los últimos años sobre la fauna oligocena de Quebrada Fiera (Mendoza, Argentina) y las investigaciones en curso. La asociación faunística de Quebrada Fiera está aportando datos nuevos sobre la distribución y la evolución de los mamíferos sudamericanos de la Edad mamífero Deseadense. Recientemente, se han dado a conocer los restos de dos familias de notoungulados, Notohippidae y Archaeohyracidae. En el primer caso, se reconoció un género nuevo, mientras que los arqueohirácidos se identifican en su gran mayoría como la especie presente en Salla (Bolivia). Los estudios en curso sobre otras familias de ungulados nativos (Hegetotheriidae, Interatheriidae, Leontinidae, Homalodotheriidae, Toxodontidae, ?Proterotheriidae y Pyrotheriidae), así como de los restos de metaterios, xenartros y roedores recuperados en Quebrada Fiera, ampliarán el conocimiento detallado de esta fauna. De forma preliminar, el conjunto faunístico aparece como una mezcla de taxones; por un lado, con afinidades patagónicas y, por otro, relacionados con especies conocidas en latitudes bajas (Bolivia), al mismo tiempo que cuenta con representantes exclusivos como Mendozahippus (Notohippidae). El avance de las investigaciones permitirá comprender mejor el papel del área de Mendoza en las distribuciones paleobiogeográfica y bioestratigráfica de los mamíferos sudamericanos del Oligoceno tardío.

Griphotherion peiranoi, gen. et sp. nov., a new Eocene Notoungulata (Mammalia, Meridiungulata) from northwestern Argentina

ABSTRACT Griphotherion peiranoi, a new genus and species of notoungulate from northwestern Argentina, is presented here. The material studied consists of a nearly complete skull and part of the postcranial skeleton, recovered in the Lumbrera Formation (Eocene) at the locality of El Simbolar (Salta Province, northwestern Argentina). The specimen was evaluated in terms of a matrix of 28 craniodental characters and compared with 11 typotherian genera. Additionally, characters of the new taxon were compared to those included in a previously published data matrix that includes several native South American ungulates. The particular features present in the specimen indicate unequivocally that this is a new notoungulate taxon; nevertheless, due to its distinctiveness, we opted not to place the novel taxon in any of the known families of Notoungulata. The results of the analyses performed indicate that G. peiranoi is closely related to Mesotheriidae, Hegetotheriidae, and Archaeohyracidae. These families represent the ‘rodent-like’ notoungulates that evolved during the Late Paleogene and the Neogene. This new record contributes to our knowledge of the Eocene notoungulate fauna of northwerstern Argentina. It also supports the broader perspective that this region played an important role as an area of origin and diversification for several lineages of this remarkable order of endemic South American ungulates.

The role of large predators in maintaining riparian plant communities and river morphology

Studies assessing the potential for large predators to affect, via trophic cascades, the dynamics of riparian plant communities and the morphology of river channels have been largely absent in the scientific literature. Herein, we consider the results of recent studies involving three national parks in the western United States: Yellowstone, Olympic, and Zion. Within each park, key large predators were extirpated or displaced in the early 1900s and subsequent browsing pressure by native ungulates initiated long-term declines in recruitment (i.e., growth of seedlings/sprouts into tall saplings and trees) of palatable woody species and impairment of other resources. Channel responses to browsing-suppressed riparian vegetation included increased widths of active channels via accelerated bank erosion, erosion of floodplains and erraces, increased area of unvegetated alluvium, channel incision, and increased braiding. A reduced frequency of overbank flows indicated these rivers have become increasingly disconnected from historical floodplains because of channel widening/incision. Results from Zion National Park also identified major biodiversity affects (e.g., reduced abundance of plant and animal species). Although these studies were conducted in national parks, results may have implications concerning riparian plant communities, biodiversity, and channel morphology for streams and rivers draining other public lands in the western US. It is on these lands that native and introduced ungulates have often heavily utilized riparian areas, largely in the absence of key predators, with significant consequences to plant communities and channels.

Elevated sensitivity: riparian vegetation in upper mountain zones is especially vulnerable to livestock grazing

AbstractQuestion: Riparian zones provide ecologically rich interfaces between land and flowing water, and are favoured areas for grazing by native ungulates and livestock. Overgrazing can degrade riparian vegetation. Will sensitivity and vulnerability to grazing increase in upper mountain zones because of the harsh physical environment?Location: We compared the impact of cattle grazing along natural elevational corridors provided by two first‐order creeks in the Rocky Mountains of Alberta, Canada.Methods: Substrate and vegetation characteristics were assessed in quadrats within transects positioned in ungrazed or lightly grazed, versus moderately to heavily grazed sites extending from the alpine down through the subalpine, montane, parkland and prairie zones.Results: Analyses revealed that 18 of 19 substrate and vegetation characteristics varied along the elevational profile (17 P<0.05; 1 P<0.1). Fifteen differed with grazing (12 P<0.05; 3 P<0.1), which was associated with coarser substrate with lower pH, reduced diversity and density of shrubs and trees, reduced vegetation cover, increased percent cover and species of weeds and changes in proportions of particular plants such as increasing yarrow (Achillea millefolium) and decreasing mountain valerian (Valeriana sitchensis). Significant grazing × elevation interactions for seven characteristics (5 P<0.05; 2 P<0.1) indicated greater impacts at higher elevations.Conclusions: This study revealed that the upper elevations were heavily affected, despite their shorter, seasonally restricted grazing history. This indicates that riparian zones in upper mountain environments are particularly vulnerable to livestock grazing.

Is competition with livestock detrimental for native wild ungulates? A case study of chital (Axis axis) in Gir Forest, India

Abstract:Livestock graze Indian forests to varying extents but their impact on wild native ungulates is rarely understood. Negative impacts of sympatric livestock on chital (Axis axis) demography and food availability were assessed and compared in the Gir Forest, India, at different spatio-temporal scales. No difference in average group size (mean ± SE) (7.11 ± 0.8 indiv.) (short-term response), fawn to doe ratio (0.43 ± 0.03) (short- to medium-term response), chital density (44.8 ± 7.1 indiv. km−2) (medium- to long-term response), and rate of population increase (r= 0.07 ± 0.014) (long-term response) was found between areas sympatric and livestock-free at the larger spatial scale of Gir Forest. Instead, chital density was correlated with rainfall (r= 0.92). After controlling for confounding factors of rainfall, vegetation community, terrain and lion density, chital density was 62% higher for livestock-free compared with sympatric areas but other demographic parameters showed no statistical difference. Peak above-ground biomass was greater in livestock-free (3255 ± 209 kg ha−1) compared to sympatric areas (1438 ± 152 kg ha−1), but chital food was more abundant in moderately grazed areas compared to livestock-free areas. Overall, long-term livestock grazing has depressive effects on chital but in the short term habitat productivity and suitability overrides the depressive effects of sympatric livestock.

Lack of feral livestock interference with native guanaco during the dry season in a South American desert

Analyzing coexistence of exotic and native ungulates in arid areas is important from both a theoretical and a species conservation perspective. We assess the habitat use patterns and possible interference between guanaco (Lama guanicoe) and feral livestock (donkey and cattle) in arid environments of South America. To determine habitat use and niche overlap between exotic and native ungulate species, ten sites with different habitats and six natural waterholes were selected. Plots (20 at each site, ten around each waterhole) were randomly set up and characterized by environmental variables and relative use by cattle, donkey and guanaco through faecal pellet counts. Aggregation, niche breadth and niche overlap of the three herbivores were analyzed at habitat level (mesoscale). A direct redundancy analysis was used to examine the relationships between abundance of herbivore faeces and environmental variables at microscale. Mesoscale analyses showed (i) an extensive use of the area by all three species, with guanaco having the highest niche breadth followed by donkey and cattle and (ii) a large, broad guanaco–donkey and donkey–cattle habitat overlap. However, results at a finer scale showed high spatial aggregation of feral livestock species and an independent use of territory by guanacos. This study is the first to provide information about habitat partitioning between guanacos and feral livestock in the hyper-arid Monte Desert biome and points to an apparent lack of negative effects on the native ungulate.

The ecology of Canada Yew (Taxus canadensisMarsh.): A review

Canada yew (Taxus canadensis Marsh.) is a shade-tolerant evergreen shrub native to the understories of the boreal and deciduous forests of northeastern North America. Canada yew has a relatively unique growth form, with low sprawling branches capable of forming dense clusters of stems. Historic accounts suggest that before Euro-American settlement, Canada yew was a common plant across its range in many forest types and that it was locally abundant or dominant in 5%–20% of forest stands in the northern part of its range. Canada yew’s range has declined during the last century as a result of browsing by native ungulates, fire, intensive forest management, and clearing of land for agriculture and other development. It is considered uncommon throughout most of its present North American range, except for often isolated populations in areas that remain free from heavy browsing pressure by moose and deer (e.g., islands, areas with heavy snow cover, or areas naturally low in ungulate abundance). Its decline has likely resulted in changes to abiotic and biotic conditions, including structure and composition of understory vegetation and concomitant effects on understory vertebrates. Increasing white-tailed deer populations and reduced snowfall as a result of climate change in eastern North America threaten to extirpate this species from additional parts of its range in the next century. Suggestions for future research are discussed.

Response of native ungulates to drought in semi‐arid Kenyan rangeland

AbstractThe distribution and abundance of native ungulates were measured on commercially managed, semi‐arid rangeland in central Kenya over a 3‐year period that encompassed severe drought and above‐average rainfall. Native ungulate biomass density averaged 5282 kg km−2 over the study and was dominated by elephant (Loxodonta africana), impala (Aepyceros melampus) and dik‐dik (Madoqua kirkii). Biomass density of domestic cattle (Bos taurus) averaged 2280 kg km−2 during the study. Responses of native ungulates to severe drought were variable. Impala densities were similar to or greater than densities for similar habitat in protected areas, and varied from 12 to 16 km−2 during and following the drought to 24–29 km−2 following above‐average rainfall. Dik‐dik densities were also greater than densities reported for protected areas and were surprisingly stable throughout the study despite the wide annual fluctuations in rainfall. Elephant migrated out of the region during drought but were present at high densities (2.9–5.2 km−2) during wet seasons, consistent with telemetry studies emphasizing the importance of Acacia bushland habitat on commercial rangelands for the migratory portion of the Laikipia–Samburu elephant population. Results show that substantial densities of native browsing and mixed‐feeding ungulates can occur on rangeland managed for commercial beef production and suggest that the capacity for ungulates to move over large spatial scales (>100 km2) and to shift distributions in response to locally variable thunderstorms may be important for sustaining these populations.

African wild ungulates compete with or facilitate cattle depending on season

AbstractSavanna ecosystems are vital for both economic and biodiversity values. In savannas worldwide, management decisions are based on the concept that wildlife and livestock compete for grassland resources[1-4], yet there are virtually no experimental data to support this assumption[1]. Specifically, the critical assessment of whether or not wild ungulates alter livestock performance (e.g., weight gain, reproduction or survival) has rarely been carried out, although diminished performance is an essential prerequisite for inferring competition[1]. Here we use a large-scale experiment in a semi-arid savanna in Kenya to show that wild ungulates do depress cattle performance (weight gain) during the dry season, indicating a competitive effect, but enhance cattle performance during the wet season, signifying facilitation. This is the first experimental demonstration of either competitive or facilitative effects of an assemblage of native ungulates on domestic livestock in a savanna ecosystem, and a unique demonstration of a rainfall-dependent shift in competition-facilitation balance within any herbivore guild. These results are critical for better understanding and management of wildlife-livestock coexistence in savanna ecosystems globally, and especially in the African savanna biome which crucially hosts the last remnants of an intact large herbivore fauna.

Habitat Interference by Axis Deer on White‐Tailed Deer

Abstract: Many studies of interactions between exotic and native ungulates have not had temporal and spatial controls nor have they considered the types of competitive interactions that would allow coexistence. For exotic axis deer (Axis axis) and native white‐tailed deer (Odocoileus virginianus) to coexist one species should be superior at interference competition and the other species should be superior at exploitative competition. We generated and tested predictions, based on body size and diet breadth, about habitat selection by white‐tailed deer in the presence and absence of axis deer, dominance relationships, and time at sites provisioned with high quality forage. We conducted our study in treatment (axis and white‐tailed deer) and control (white‐tailed deer only) areas when both species were present and after axis deer were removed. We conducted vehicle surveys to determine habitat use of both species. At provisioned feeding sites we recorded aggressive behaviors and amount of time species spent at feeding sites alone and together. In the treatment area white‐tailed deer selection for wooded habitat increased 2.1 times after axis deer were removed, whereas habitat selection by white‐tailed deer was constant in the control area over the same time. At feeding sites axis deer were dominant to white‐tailed deer; both species spent a significantly greater amount of time alone than at feeders together, but amount of time that individuals of each species spent at feeders did not differ. Axis deer were superior at interference competition, but white‐tailed deer were not superior at exploitative competition; thus, species coexistence is unlikely. Whether white‐tailed deer are negatively impacted by axis deer at spatial scales larger than our experiment probably depends on abundance of axis deer at larger spatial scales. Experiments of species interactions with temporal and spatial controls that consider types of competitive interactions increase a manager's understanding of when and how native ungulates may be negatively impacted by exotic ungulates.

Using cattle for conservation objectives in a Scots pine Pinus sylvestris forest: results of two trials

It has been argued that large ungulates play a key role in natural forest dynamics, but in Britain, the largest native ungulates (aurochs and elk) are extinct. Cattle could have some similar effects, and are widely used, but rarely tested, for nature conservation management. Here, we test conservation management with cattle at a native Scots pine Pinus sylvestris forest in Scotland. Our hypotheses were that cattle impacts would (a) increase the abundance of an understorey shrub of conservation importance, bilberry Vaccinium myrtillus; and (b) increase Scots pine seedling establishment. Two cattle trials were established, one for each objective, based on a 14-ha plot within the forest, and a 6.1-ha plot at the forest edge. Cattle were introduced for 2 months to both plots, giving an approximately 100- to 150-fold increase in ungulate biomass per hectare when compared to background deer abundance. The ground layer vegetation in both treatment and matched control plots was monitored before and after treatment, and subsequently over a 4-year period. At the within-forest trial, bilberry percent-cover, 4 years after treatment, was 1.9 times higher in the cattle area than in the control (95% confidence limits 1.6–2.3). Bilberry percent-cover increases were directly related to the degree of trampling impact on heather Calluna vulgaris, as recorded immediately after the trial. At the forest-edge trial, there were vegetation changes in the cattle plot that were considered favourable to pine seedling establishment: reduced moss/litter depth and vegetation percent-cover, and increased ground-level light incidence. However, too few new pine seedlings were found for formal analysis, partly due to unexpectedly low seed-fall. Nevertheless, the potential for cattle to create conditions that would subsequently promote pine regeneration was illustrated by the observation of large numbers of new, young pine seedlings at the within-forest cattle plot. We recommend that managers and researchers collaborate to develop further trials like the ones reported here, to give an improved understanding of the conditions under which cattle can yield nature conservation benefits in woodlands.

Changes in vigilance, grazing behaviour and spatial distribution of bighorn sheep due to cattle presence in Sheep River Provincial Park, Alberta

The physical presence of livestock can influence the behaviour of native ungulates. Behavioural data on bite rates and vigilance of Rocky Mountain bighorn sheep were collected during the summer and fall of 2006 in Sheep River Provincial Park, Alberta. Spatial distributions of bighorn sheep and domestic cattle were recorded using daily censuses and GPS collar locations during the same time period. We hypothesized that the presence of cattle would induce a negative behavioural response in bighorn sheep and cause avoidance behaviour. As predicted, foraging bite rates decreased and vigilance rates increased when cattle were located nearby. Vigilance in females was higher than in males. The average distances between bighorn sheep and cows were found to be smaller than expected at random, and minimal distances were not affected by the presence of cows. The sheep were found in the same general areas used by cattle. The cattle presence was shown to influence distribution and behaviour of bighorn sheep, although not in the way we expected.

Range Expansion of Barred Owls, Part II: Facilitating Ecological Changes

In Part I (Livezey, 2009), I presented the chronology and distribution of the range expansion of Barred Owls (Strix varia) from the late 1800s to the present. Here I explore what had prevented Barred Owls from expanding their range westward during recent millennia and what allowed them to do so during the past century. Using strength-of-evidence analysis, I evaluate the plausibility of the five ecological or behavioral changes proposed in the literature to have facilitated the range expansion. From this evaluation, three of these changes appear to be implausible, one appears to be plausible after modifying its location, and one appears to be very plausible. For the very plausible one, I score seven ecological changes that may have affected it using five strength-of-evidence criteria. Overall, it appears the historical lack of trees in the Great Plains acted as a barrier to the range expansion and recent increases in forests broke down this barrier. Increases in forest distribution along the Missouri River and its tributaries apparently provided Barred Owls with sufficient foraging habitat, protection from the weather, and, possibly, concealment from avian predators to allow Barred Owls to move westward. Decades later, increases in forests in the northern Great Plains allowed Barred Owls to connect their eastern and western distributions across southern Canada. These increases in forests evidently were caused by European settlers excluding fires historically set by Native Americans, suppressing fires and planting trees. They apparently were caused, to lesser degrees, by European settlers extirpating bison (Bison bison), overhunting elk (Cervus elaphus) and deer (Odocoileus spp.) and, in some areas, extirpating beaver (Castor canadensis) and replacing native ungulates with livestock. Accordingly, it appears the range expansion was prohibited for millennia by actions of Native Americans and recently facilitated by actions of European settlers.

Fire History in a Chaparral Ecosystem: Implications for Conservation of a Native Ungulate

Mature chaparral vegetation in the San Gabriel Mountains, California, resulting from long fire-return intervals (50–70 yr), has resulted in reduced visibility and availability and quality of forage, all of which are important attributes of mountain sheep (Ovis canadensis) habitat. Concomitantly, vegetation changes have decreased availability and quality of forage. We developed a resource-selection model to determine the effect of fire history on habitat use by mountain sheep, examined the hypotheses that habitat selection was associated with fire occurrence, and determined whether fire occurrence influenced the amount of potential habitat available to mountain sheep. The best model indicated that mountain sheep selected vegetation that had burned within 15 yr and avoided areas that had not burned within that time frame. We then used our model to quantify potential changes in mountain sheep habitat that have occurred over time based on fire conditions. We identified 390 km2 of mountain sheep habitat that existed in 2002 (when only 63 mountain sheep were tallied), 486 km2 in 1980 (when the mountain sheep population was at its highest), and 422 km2 in 2004 (just after a series of large wildfires). We also estimated that 615 km2 of suitable habitat would be available in a hypothetical situation in which the entire study area burned. Our results suggest that restoration of mountain sheep to their historical distribution in chaparral ecosystems will depend upon more frequent fires in areas formerly occupied by those specialized herbivores. La vegetación madura del chaparral en las Montañas San Gabriel, en California, resultado de largos intervalos de regreso del fuego (50–70 años), ha ocasionado reducida visibilidad, así como una baja disponibilidad y calidad de forraje los cuales son atributos importantes del hábitat de las ovejas de montaña (Ovis Canadensis). Asimismo, con los cambios en la vegetación, ha resultado en la disminución de la cantidad y calidad de forraje. Nosotros desarrollamos un modelo de selección de recursos para determinar el efecto histórico del fuego en el uso del hábitat por la oveja de montaña, y examinamos la hipótesis de que la selección del hábitat estaba asociada con la ocurrencia del fuego, la cual afecta al hábitat potencial disponible por las ovejas de montaña. El mejor modelo indicó que las ovejas de montaña seleccionaron vegetación se había quemado en los pasados 15 años, y evitaron áreas que no se habían quemado en ese que mismo periodo de tiempo. Usamos nuestro modelo para cuantificar los cambios potenciales en el hábitat de las ovejas de montaña que han ocurrido con el tiempo basándose en las condiciones del fuego. Identificamos 390 km2 del hábitat de las ovejas de montaña que existía en 2002 (cuando solamente hubo un incremento de 63 ovejas de montaña), 486 km2 en 1980 (cuando se tenía la población mas alta de ovejas de montaña), y 422 km2 (justo después de una serie de grandes incendios). Estimamos también que 615 km2 de hábitat sería apropiado, en una situación hipotética donde toda el área de estudio haya estado sujeta al fuego. Nuestros resultados sugieren que la re-introducción de la oveja de montaña a su distribución histórica en ecosistemas de chaparral dependerá de la ocurrencia de fuegos más frecuente en las áreas que originalmente estuvieron ocupadas por esos herbívoros especializados.