Ecological Disturbance Through Patch-Burn Grazing Influences Lesser Prairie-Chicken Space Use

Across portions of the western Great Plains in North America, natural fire has been removed from grassland ecosystems, decreasing vegetation heterogeneity and allowing woody encroachment. The loss of fire has implications for grassland species requiring diverse vegetation patches and structure or patches that have limited occurrence in the absence of fire. The lesser prairie-chicken (Tympanuchus pallidicinctus) is a declining species of prairie-grouse that requires heterogeneous grasslands throughout its life history and fire has been removed from much of its occupied range. Patch-burn grazing is a management strategy that re-establishes the fire-grazing interaction to a grassland system, increasing heterogeneity in vegetation structure and composition. We evaluated the effects of patch-burn grazing on lesser prairie-chicken space use, habitat features, and vegetation selection during a 4-year field study from 2014–2017. Female lesser prairie-chickens selected 1- and 2-year post-fire patches during the lekking season, ≥4-year post-fire patches during the nesting season, and year-of-fire and 1-year post-fire patches during post-nesting and nonbreeding seasons. Vegetation selection during the lekking season was not similar to available vegetation in selected patches, suggesting that lesser prairie-chickens cue in on other factors during the lekking season. During the nesting season, females selected nest sites with greater visual obstruction, which was available in ≥4-year post-fire patches; during the post-nesting season, females selected sites with 15–25% bare ground, which was available in the year-of-fire, 1-year post-fire, and 2-year post-fire patches; and during the nonbreeding season they selected sites with lower visual obstruction, available in the year-of-fire and 1-year post-fire patches. Because lesser prairie-chickens selected all available time-since-fire patches during their life history, patch-burn grazing may be a viable management tool to restore and maintain lesser prairie-chicken habitat on the landscape. © 2021 The Wildlife Society.     

Flower production of Aster tripolium is affected by behavioral differences in livestock species and stocking densities: the role of activity and selectivity

Semi-natural grasslands are an important habitat for endangered plant and animal species. In grasslands, low-intensity livestock grazing is frequently applied as a tool for nature conservation. We aim to investigate how different livestock species in various densities influence the state and flower production of a single plant species by selective defoliation and/or trampling. We hypothesized that (1) moderate stocking densities would cause more damage than low, and that (2) horses would cause more damage than cattle due to their higher activity. The experiment took place in a salt marsh in the Netherlands where grazing treatments with horses and cattle in two stocking densities were installed. Damage to individual Aster tripolium plants and number of flower heads were recorded at the end of the grazing season in late September. We found (1) more damage and fewer flower heads in moderate stocking densities compared to low densities. However, a reduction of flower heads by higher stocking densities was less clear with cattle. No clear difference (2) between livestock species was found, due to opposite trends in moderate and low densities. At low stocking densities, cattle caused more damage by selective defoliation. At moderate densities, horses caused more damage, because of their higher mobility, which led to damage by trampling. We conclude that the response of Aster to grazing is strongly affected by behavioral differences between livestock species. Grazing experiments and management schemes for semi-natural grasslands should therefore not only consider stocking densities, but also livestock species to reach desired conservation goals.     

The Predicted Influence of Climate Change on Lesser Prairie-Chicken Reproductive Parameters

The Southern High Plains is anticipated to experience significant changes in temperature and precipitation due to climate change. These changes may influence the lesser prairie-chicken (Tympanuchus pallidicinctus) in positive or negative ways. We assessed the potential changes in clutch size, incubation start date, and nest survival for lesser prairie-chickens for the years 2050 and 2080 based on modeled predictions of climate change and reproductive data for lesser prairie-chickens from 2001–2011 on the Southern High Plains of Texas and New Mexico. We developed 9 a priori models to assess the relationship between reproductive parameters and biologically relevant weather conditions. We selected weather variable(s) with the most model support and then obtained future predicted values from climatewizard.org. We conducted 1,000 simulations using each reproductive parameter’s linear equation obtained from regression calculations, and the future predicted value for each weather variable to predict future reproductive parameter values for lesser prairie-chickens. There was a high degree of model uncertainty for each reproductive value. Winter temperature had the greatest effect size for all three parameters, suggesting a negative relationship between above-average winter temperature and reproductive output. The above-average winter temperatures are correlated to La Niña events, which negatively affect lesser prairie-chickens through resulting drought conditions. By 2050 and 2080, nest survival was predicted to be below levels considered viable for population persistence; however, our assessment did not consider annual survival of adults, chick survival, or the positive benefit of habitat management and conservation, which may ultimately offset the potentially negative effect of drought on nest survival.     

Survival and habitat use in translocated and resident greater prairie-chickens

Translocation, or the purposeful movement of organisms from one location to another for conservation, is currently being used to bolster populations of the endangered greater prairie-chicken (Tympanuchus cupido). We used radiotelemetry to compare survival between 58 resident birds and 54 newly translocated greater prairie-chickens that were sourced from a location more than 325 km away. Model averaged survival estimates were lower in translocated birds (0.42; 95% CI: 0.17–0.66) than in resident prairie-chickens (0.65; 95% CI: 0.46–0.79) through the breeding season. Habitat, sex and year were each included in at least 1 of the top 4 models, but the model averaged confidence intervals for each parameter encompassed zero. Survival of both resident and translocated prairie-chickens increased throughout the breeding season. Both translocated and resident prairie-chickens selected for core prairie habitat over agriculture, and birds tended to avoid surrounding private grasslands and wooded areas. We suggest that future translocation projects account for reduced survival of translocated birds when determining the appropriate release cohort sizes and sex ratios. We also recommend that future management for greater prairie-chicken habitat focus on the expansion of core protected patches of prairie to promote elevated survival and better chances of conservation success.     

Similar Bird Communities Across Grazing Systems in the Nebraska Sandhills

Much of the remaining native rangeland in the Great Plains in the United States is privately owned and managed for beef production, and this single priority for land use may be contributing to declining avian biodiversity through a loss of structural heterogeneity. One proposed solution is to use multiple grazing systems across ranches, under the assumption that this approach will increase heterogeneity of vegetation structure and avian diversity across the landscape. We tested the relationship between grazing systems and avian diversity in the Nebraska Sandhills during 2014 and 2015 on a landscape that included 11 management units containing 5 different grazing systems. We used multivariate models to examine the relationship of bird diversity and communities to grazing systems at the management unit scale, and we used simulations to combine empirical data from ≥1 grazing system into virtual landscapes to test the hypothesis that multiple grazing systems would result in greater heterogeneity. The 5 most common avian species made up 84% of observations (28 species), and songbird richness was 5–6 species/7.06 ha at 53% of our plots. Variation in each of the diversity measures (Shannon diversity range = 0.41–2.2, Simpson's diversity range = 0.24–0.88) was best explained by the previous dormant season's stocking rate, and richness declined by about 1 species/plot with an increase in 1 animal unit month (AUM)/ha. Songbird community structure showed the most variance between management unit, but grazing system explained little community variation. None of the simulated landscapes consistently had greater structural heterogeneity of visual obstruction reading, litter depth, and cover of bare ground than others, and there was a limited level of heterogeneity overall in the simulated landscapes. In contrast to our predictions, a variety of grazing systems did not increase heterogeneity of vegetation structure across the landscape. Thus, conservation practitioners should encourage the use of other strategies to create structural heterogeneity, such as prescribed fires and extreme stocking rates, which will support a diverse grassland songbird community (i.e., a greater variety of bird species) across the landscape. © 2020 The Wildlife Society.     

Lesser Prairie-Chicken Survival in Varying Densities of Energy Development

Anthropogenic features increasingly affect ecological processes with increasing human demand for natural resources. Such effects also have the potential to vary depending on the sex and age of an individual because of inherent behavioral and life experience differences. For the lesser prairie-chicken (Tympanuchus pallidicinctus), studies on male survival are limited because most previous research has been focused on females. To better understand patterns of lesser prairie-chicken survival in habitat with varying levels of anthropogenic infrastructure associated with oil and natural gas development, we monitored survival of 178 radio-tagged male and female lesser prairie-chickens in eastern New Mexico, USA, from 2013 to 2015. We examined the relationships of shrub cover, proximity to and density of anthropogenic features (i.e., utility poles), displacement of natural vegetation by anthropogenic features (i.e., area of roads and well pads), and individual demographics (i.e., sex, age) with lesser prairie-chicken survival. Furthermore, we categorized the probable cause of mortality and examined its relationship with oil and gas development intensity (indexed by utility pole density) within 1,425 m of an individual's mortality site or final observed location. We predicted that survival would be lower for individuals exposed to greater levels of anthropogenic features, and that males and subadults would be more negatively affected than females and adults because of increased exposure to predators during the lekking season and naiveté. Relationships between survival and utility pole density, sex, and age were supported in our top-ranked models, whereas models including other anthropogenic and natural features (i.e., roads, well pads, shrub cover) received little support. We predicted a substantial decrease in adult and subadult male survival with increasing densities of utility poles. The relationship between survival and utility pole density for females was weaker and not as clearly supported as for males. We did not find a detectable difference in utility pole counts among probable mortality causes. Our findings highlight the importance of including male lesser prairie-chickens in research and conservation planning, and the negative effect that high densities of anthropogenic features can have on lesser prairie-chicken survival. © 2021 The Wildlife Society.     

Effect of cattle grazing a species-rich mountain pasture under different stocking rates on the dynamics of diet selection and sward structure

Although stocking rate is a key management variable influencing the structure and composition of pastures, only few studies have simultaneously analysed the seasonal patterns of pasture use by cattle, and the adjustments the animals make to maintain intake of a high-quality diet over the grazing season. Therefore, over a 3-year study, we recorded diet selection, plot use and impact of heifers on sward structure and quality under three different stocking rates (0.6, 1.0 and 1.4 livestock units (LU) per ha) in a species-rich mountain pasture of central France. Measurements were made on three occasions between early June and the end of September each year. Overall, heifers selected for bites dominated by legumes or forbs, and against reproductive grass, whatever the stocking rate or season. Selection for tall mixed (P < 0.05), short mixed (P < 0.05) and short pure grass bites (P < 0.01) was more pronounced in plots grazed at the lowest stocking rate. Although heifers' selection for short patches decreased at the end of the season (P < 0.001), they continued to graze previously grazed areas, thus exhibiting a typical 'patch grazing' pattern, with the animals that grazed at the lowest stocking rate tending to better maintain their selection for short patches in September (treatment × period: P = 0.078). Neither diet quality nor individual animal performance were affected by the different stocking rate treatments despite high variability in the quantity and quality of herbage offered and differences in diet selection. However, at the 1.4 LU per ha stocking rate, the quantity of forage available per animal at the end of the season, 0.79 t dry matter (DM) per ha of green leaves with the median of sward height at 4.6 cm, approached levels limiting cattle's ability to compensate for the effects of increasing stocking rate. In plots grazed at 0.6 LU per ha, the total herbage biomass remained higher than 3 t DM per ha with more than 30% of plot area still covered by reproductive grass patches at the end of the grazing season, which in the medium term should affect the botanical composition of these pastures. Sward heterogeneity was high in plots grazed at 1.0 LU per ha, with sufficient herbage availability (1.1 t DM per ha of green leaves) to maintain animal performance, and more than 15% of plot area was kept at a reproductive stage at the end of the grazing season. Hence, it could represent the optimal balance to satisfy both livestock production and conservation management objectives.     

The effect of horse, cattle and sheep grazing on the diversity and abundance of land snails in nutrient-poor calcareous grasslands

Livestock grazing is a common management practise in semi-natural grasslands in Central Europe. Different types of livestock (horses, cattle, sheep) and grazing intensity are known to affect the richness and composition of plant species. However, knowledge of grazing-dependent effects on invertebrates is limited. We examined the influence of horse, cattle and sheep grazing on the richness, abundance and composition of land snail species in 21 calcareous nutrient-poor grassland areas in the northwestern Jura Mountains, Switzerland. Grazing by different livestock species did not affect the species richness, abundance and species composition of land snails. Furthermore, the number of open-land species and the ratio of large- to small-sized snail species or individuals did not differ among the three pasture types. However, independent of livestock species, grazing intensity negatively influenced the snail fauna. Snail species richness, abundance and number of Red list species decreased with increasing grazing intensity. Grazing intensity also affected the occurrence of individual snail species (Truncatellina cylindrica, Cecilioides acicula, Candidula unifasciata and Trichia plebeia). To preserve the snail fauna in nutrient-poor grasslands, pastures can be stocked with horses, cattle or sheep. However, both maximum stocking rate (number of livestock units per hectare) and grazing duration (number of grazing days per year) must be carefully defined for the proper management of the pastures.     

Simulating Strategic Implementation of the CRP to Increase Greater Prairie-Chicken Abundance

The Conservation Reserve Program (CRP) has the potential to influence the distribution and abundance of grasslands in many agricultural landscapes, and thereby provide habitat for grassland-dependent wildlife. Greater prairie-chickens (Tympanuchus cupido pinnatus) are a grassland-dependent species with large area requirements and have been used as an indicator of grassland ecosystem function; they are also a species of conservation concern across much of their range. Greater prairie-chicken populations respond to the amount and configuration of grasslands and wetlands in agriculturally dominated landscapes, which in turn can be influenced by the CRP; however, CRP enrollments and enrollment caps have declined from previous highs. Therefore, prioritizing CRP reenrollments and new enrollments to achieve the greatest benefit for grassland-dependent wildlife seems prudent. We used models relating either lek density or the number of males at leks to CRP enrollments and the resulting landscape structure to predict changes in greater prairie-chicken abundance related to changes in CRP enrollments. We simulated 3 land-cover scenarios: expiration of existing CRP enrollments, random, small-parcel (4,040 m²) addition of CRP grasslands, and strategic, large-parcel (80,000 m²) addition of CRP grasslands. Large-parcel additions were the average enrollment size in northwestern Minnesota, USA, within the context of a regional prairie restoration plan. In our simulations of CRP enrollment expirations, the abundance of greater prairie-chickens declined when grassland landscape contiguity declined with loss of CRP enrollments. Simulations of strategic CRP enrollment with large parcels to increase grassland contiguity more often increased greater prairie-chicken abundance than random additions of the same area in small parcels that did not increase grassland contiguity. In some cases, CRP enrollments had no or a negative predicted change in greater prairie-chicken abundance because they provided insufficient grassland contiguity on the landscape, or increased cover-type fragmentation. Predicted greater prairie-chicken abundance increased under large-parcel and small-parcel scenarios of addition of CRP grassland; the greatest increases were associated with large-parcel additions. We suggest that strategic application of the CRP to improve grassland contiguity can benefit greater prairie-chicken populations more than an opportunistic approach lacking consideration of the larger landscape context. Strategic implementation of the CRP can benefit greater prairie-chicken populations in northwestern Minnesota, and likely elsewhere in landscapes where grassland continuity may be a limiting factor. © 2020 The Wildlife Society.     

The importance of grazing regime in the provision of breeding habitat for grassland birds: The case of the endangered little bustard (Tetrax tetrax)

In Mediterranean dry grasslands, grazing by domestic animals is an important agricultural activity on dry grasslands. Several bird species occur in these grazed habitats and are now experiencing a near continuous decline. We investigated the impact of livestock grazing on the threatened little bustard (Tetrax tetrax L.). The study was conducted at the NATURA 2000 Site/Important Bird Area of Cabrela, Portugal. Our main goals were to investigate responses of little bustard territorial males and breeding females to different livestock management practices, namely pasture types, stocking rates and sward structure. Bird distribution was surveyed using car and foot surveys. Data on grazing was supplied by land managers every 10 days from February to June through field interviews. Generalised additive models and model averaging were used to compute predictive models. Results indicate that higher probabilities of occurrence were found in long-term pastures and under light-moderate grazing conditions (stocking rates around 0.4 LU/ha). Conversely, lower probabilities of occurrence were found in ungrazed or heavy grazed fields. Males occurred mostly in large fields, but this variable seemed to be less important for females. On the other hand, green plant cover and the vegetation height were good predictors for the occurrence of females but not for males. Females used mostly pastures with vegetation height around 20–25 cm. Our results suggest that grazing management plans that aim to conserve little bustard populations should consider (1) the maintenance of the larger long-term pastures and (2) the use of light-moderate stocking rates (0.2–0.6 LU/ha).     

The Parasitic Eyeworm Oxyspirura petrowi as a Possible Cause of Decline in the Threatened Lesser Prairie-Chicken (Tympanuchus pallidicinctus)

Lesser prairie-chickens (Tympanuchus pallidicinctus) have been declining range wide since the early 1900''s despite efforts to establish conservation and improve their habitat. In early 2014, the lesser prairie-chicken was listed as a threatened species under the U.S Endangered Species Act and the need to find out why they are declining is more important than ever. Nine hunter shot lesser prairie-chickens were donated and sampled for the presence or absence of the eyeworm Oxyspirura petrowi, a known parasite that can cause damage to the eye of its host, and common environmental contaminants. Eyeworm infection was found in 7 of 9 birds (78% infection rate) with an infection range between 0–16 O. petrowi per bird. Breast, liver, and fat tissue samples from the lesser prairie-chickens were analyzed for the frequency of 20 organochlorine pesticides. Femurs and livers were also tested on these birds for metal contaminants. Pesticides were found in several samples above the detection limits but were still in the low ng/g range. Notable was the ubiquitous presence of endrin aldehyde across all tissues. One femur showed 5.66 µg/g of lead (Pb) but this is still relatively low. No liver samples had elevated mercury (Hg) above detection limits. The presence of these organochlorines is consistent with the historic use of pesticides in this region. With pesticide and metals found in such low levels and parasitic nematode infections at rather high levels, it is recommended that these parasites be further evaluated as a contributing factor to the decline of the lesser prairie-chicken.     

Density and habitat preferences of male little bustard across contrasting agro-pastoral landscapes in Sardinia (Italy)

The little bustard Tetrax tetrax has undergone severe range contraction within Europe due to abandonment of traditional agro-pastoral activities. Previous studies of habitat selection have mainly focused on extensive cereal and cropland mosaics, while the species’ ecology in pastoral landscapes is understood less well, and data are completely lacking from the Sardinian population. We conducted distance sampling surveys of displaying males across three contrasting landscapes in Sardinia and modelled habitat preference at both the landscape and local (within pastures and recent fallows) scale. Abbasanta, with a balance of pasture and cropland, the greatest isolation from roads and shortest vegetation, supported the highest little bustard densities (95%CI 2.7–3.4 males/100 ha). Significantly lower densities were found in two landscapes with lower isolation from roads and taller vegetation within grasslands: Campeda (0.1–0.2 males/100 ha), comprising cropland and pasture in similar proportions to those found at Abbasanta, and Campidano (0.3–0.4 males/100 ha) that was dominated by cereal agriculture. At the landscape level, males preferred pastures and recent fallows over arable lands. At the local scale, within grasslands, probability of occurrence was greater with shorter vegetation, more legume and green herb cover and at points remote from roads. Shorter vegetation in grasslands resulted from high grazing pressure, and habitat suitability for breeding males depends strongly on extensively grazed grasslands. Conservation efforts for this species should focus on maintaining traditional agro-pastoral practices which maintain large areas of extensively grazed pastures and recent fallows located far from roads.     

The Effects of Timing of Grazing on Plant and Arthropod Communities in High-Elevation Grasslands

Livestock grazing can be used as a key management tool for maintaining healthy ecosystems. However, the effectiveness of using grazing to modify habitat for species of conservation concern depends on how the grazing regime is implemented. Timing of grazing is one grazing regime component that is less understood than grazing intensity and grazer identity, but is predicted to have important implications for plant and higher trophic level responses. We experimentally assessed how timing of cattle grazing affected plant and arthropod communities in high-elevation grasslands of southwest Montana to better evaluate its use as a tool for multi-trophic level management. We manipulated timing of grazing, with one grazing treatment beginning in mid-June and the other in mid-July, in two experiments conducted in different grassland habitat types (i.e., wet meadow and upland) in 2011 and 2012. In the upland grassland experiment, we found that both early and late grazing treatments reduced forb biomass, whereas graminoid biomass was only reduced with late grazing. Grazing earlier in the growing season versus later did not result in greater recovery of graminoid or forb biomass as expected. In addition, the density of the most ubiquitous grassland arthropod order (Hemiptera) was reduced by both grazing treatments in upland grasslands. A comparison of end-of-season plant responses to grazing in upland versus wet meadow grasslands revealed that grazing reduced graminoid biomass in the wet meadow and forb biomass in the upland, irrespective of timing of grazing. Both grazing treatments also reduced end-of-season total arthropod and Hemiptera densities and Hemiptera biomass in both grassland habitat types. Our results indicate that both early and late season herbivory affect many plant and arthropod characteristics in a similar manner, but grazing earlier may negatively impact species of conservation concern requiring forage earlier in the growing season.     

Cattle grazing in CRP grasslands during the nesting season: effects on avian abundance and diversity

The Conservation Reserve Program (CRP) is a primary tool for restoring grassland in the United States, in part as wildlife habitat, which has benefited declining grassland bird populations. Among potential mid-contract management practices used to maintain early-successional CRP grasslands, cattle grazing had been prohibited and is currently disincentivized during the primary nesting season for birds (much of the growing season), despite the important role that large herbivores historically played in structuring grassland ecosystems. Conservative grazing of CRP grasslands could increase spatial heterogeneity in vegetation structure and plant diversity, potentially supporting higher densities of some grassland bird species and higher bird diversity. Our objective was to determine the effect of experimental cattle grazing on species-specific relative abundance and occupancy, species diversity, and community dissimilarity of grassland birds on CRP grasslands across the longitudinal extent of Kansas, USA (a 63.5-cm precipitation gradient) during the 2017–2019 avian breeding seasons. Fifty-three of 108 fields were grazed by cattle during the growing seasons of 2017 and 2018 and all fields were rested from grazing in 2019. For all analyses, we examined separate model sets for semiarid western versus more mesic eastern Kansas. Using data from line transect surveys, we modeled relative abundances of 5 songbird species: grasshopper sparrow (Ammodramus savannarum), dickcissel (Spiza americana), eastern meadowlark (Sturnella magna), western meadowlark (Sturnella neglecta), and brown-headed cowbird (Molothrus ater). Grazing had delayed yet positive effects on abundances of grasshopper sparrow in western Kansas, and eastern meadowlark in eastern Kansas, but negative effects on dickcissel abundance in western Kansas and especially on burned fields in eastern Kansas. Somewhat counterintuitively, brown-headed cowbirds in western Kansas were more abundant on ungrazed versus grazed fields in the years after grazing began. In addition, we modeled multi-season occupancy of 3 gamebird species (ring-necked pheasant [Phasianus colcicus], northern bobwhite [Colinus virginianus], mourning dove [Zenaida macroura]) and Henslow's sparrow (Centronyx henslowii); grazing did not affect occupancy of these species. In eastern Kansas, species diversity was highest in grazed, unburned fields. In western Kansas, bird communities in grazed and ungrazed fields were dissimilar, as determined from multivariate analysis. Though regionally variable, conservative stocking of cattle on CRP grasslands during the nesting season as a mid-contract management tool might increase bird species diversity by restructuring habitat that accommodates a greater variety of species and decreasing abundances of species associated with taller, denser stands of vegetation.     

Implications of grazing and burning of grasslands on the sustainable use of francolins (Francolinus spp.) and on overall bird conservation in the highlands of Mpumalanga province, South Africa

We investigated the densities of the Redwing Francolinus levaillantii and Greywing Francolins F. africanus and the diversity of grassland birds in general along a land-use gradient in the highlands of Mpumalanga province, South Africa. Redwing Francolins cannot tolerate intensive grazing and frequent burning and are confined largely to unburnt, ungrazed grasslands. Their density and the species richness of grassland birds in general are negatively correlated with grazing intensity. Redwing populations drop to densities that cannot be utilised by hunters on a sustainable basis in grasslands that are grazed at even moderate levels or burned annually. Nineteen bird species (including five threatened species) were confined to essentially pristine grassland and were never observed in grazed/annually burned grasslands. The Greywing Francolin is more evenly distributed (although always at sub-utilisation densities) along the grassland land-use gradient, and its density is positively correlated with grazing intensity. There are two assemblages of grassland bird species that appear to be indicative of the intensity of habitat utilisation. Populations of grassland birds in the study area are becoming increasingly dependent on isolated patches of pristine grassland and are threatened by management involving annual burning and high stocking rates on a landscape scale.     

Configuration of daily grazing and searching of growing beef cattle in grassland: observational study

Many of the studies in Campos grasslands focus on management aspects such as the control of herbage allowance, and application of nutrients and/or overseeding with legumes. However, there is little literature on how the Campos grassland resource is utilised, especially regarding the grazing pattern and the relationship between pasture quantity and quality on daily grazing activities. The study of the ingestive behaviour in species-rich and heterogeneous native grasslands during daylight hours, and understanding how animals prioritise quality or quantity of intake in relation to pasture attributes, are important to comprehend the ingestive-digestive processes modulating the energy intake of animals and to achieve a better grazing management. Therefore, the objective was to describe and quantify the daily grazing behaviour of growing cattle grazing native pasture with different structures as a result of different management practices, and study the relationship of pasture attributes and intake through multivariate analysis. The study was carried out at the Faculty of Agronomy, Paysandú, Uruguay. Treatments were native grassland, overseeding with Trifolium pratense and Lotus tenuis + phosphorus, and native pasture + nitrogen-phosphorus. Grazing activities were discriminated into grazing, searching (defined when animals take 1–2 bites in one feeding station and then change to another feeding station and so on), ruminating and idling. The probability of time allocated to each activity was continuously measured during daylight hours (0700–1930) and was related to pasture structure and forage quality using regression tree models, while the bite rate was determined every 2 h. The diurnal pattern of growing cattle showed grazing and searching sessions, followed by ruminating and idling sessions. The length of sessions (as the probability of time allocated to each activity) varied throughout the day. The grazing probability was greater during afternoon than morning and midday (0.74 vs 0.45 vs 0.46, respectively), and it was associated with higher bite rate (34.2 bites/min). Regression tree models showed different grazing, searching and ruminating strategies according to pasture attributes. During the morning, animals modified grazing, searching, ruminating and idling strategies according to bite rate, crude protein in diet and herbage allowance. At midday, they only adjusted ruminating and idling, while during afternoon sessions, grazing activities were modified by pasture quantity attributes such as herbage mass and herbage allowance. By controlling the herbage allowance, herbage mass and pasture height, animals prioritise quality in the morning and quantity in the afternoon, integrating and modifying the grazing-searching and ruminating-idling pattern.     

Ontogenetic changes in innate immune function in captive and wild subspecies of prairie-chickens (Tympanuchus cupido spp.)

The Attwater's prairie-chicken (Tympanuchus cupido attwateri), a federally endangered grouse species, is currently experiencing high chick mortality in wild populations and the causes are unknown. We tested 3 indicators of innate immunity (hemaggluttination, serum lysozyme, and total immunoglobulin [IgY] levels) in the Attwater's prairie-chicken and a closely related sub-species, the greater prairie-chicken (Tympanuchus cupido pinnatus). Agglutination titers were approximately 25% higher in the juvenile and adult Attwater's prairie-chickens compared to equivalently aged greater prairie-chickens. Additionally, total IgY levels in wild-collected Attwater's prairie-chicken egg samples were 34% higher than IgY levels in captive greater prairie-chickens or Attwater's prairie-chicken eggs. These results suggest that differences in innate immune function exist between these sub-species and also among Attwater's prairie-chicken subpopulations that are exposed to different environmental conditions. © 2012 The Wildlife Society.     

Does Extensive Grazing Benefit Butterflies in Coastal Dunes?

Grazing at low stocking rates has become a common management practice in nature restoration projects in the Netherlands. However, detailed knowledge of grazing impact is often poor, in particular for invertebrates. This study addressed the impact of extensive grazing on butterflies. Butterflies are critical indicators of habitat quality for many plant and animal species. We compared monitoring data from 1992 to 1996 for calcareous coastal dune areas in the Netherlands with different management: 11 grazed areas, 7 ungrazed areas and 4 areas managed by annual cutting. Grazing typically concerned year‐round grazing by cattle and/or ponies, at low stocking rates (0.05–0.26 head ha^?1 yr^?1). Butterfly abundance was related to species composition and structure of the vegetation. Changes in butterfly abundance were positive in grazed and ungrazed areas compared to cut areas. Species richness was not affected by management, but individual species differed in their response. Species from open grassland benefited most from grazing, particularly Issoria lathonia (Queen of Spain Fritillary) and Lycaena phlaeas (Small Copper). No clear negative effects of grazing were observed, but species occurrence was not always positively related to the environmental characteristics associated with grazing. In the long run, even lower stocking rates might prove more beneficial to the butterfly community as a whole. Four of the more frequently observed species, I. lathonia, Hipparchia semele (Grayling), Pyrgus malvae (Grizzled Skipper) and Aricia agestis (Brown Argus), are listed as threatened to susceptible in the Netherlands. All were apparently favored by grazing. It is concluded that extensive grazing has good potential to enhance butterfly diversity in restoration projects.     

Genetic variation within and among fragmented populations of lesser prairie-chickens (Tympanuchus pallidicinctus)

As a result of recurrent droughts and anthropogenic factors, the range of the lesser prairie-chicken (Tympanuchus pallidicinctus) has contracted by 92% and the population has been reduced by approximately 97% in the past century, resulting in the smallest population size and most restricted geographical distribution of any North American grouse. We examined genetic variation through DNA sequence analysis of 478 base pairs of the mitochondrial genome and by assaying allelic variation at five microsatellite loci from lesser prairie-chickens collected on 20 leks in western Oklahoma and east-central New Mexico. Traditional population genetic analyses indicate that lesser prairie-chickens maintain high levels of genetic variation at both nuclear and mitochondrial loci. Although some genetic structuring among lesser prairie-chicken leks was detected within Oklahoma and New Mexico for both nuclear and mitochondrial loci, high levels of differentiation were detected between Oklahoma and New Mexico populations. Nested-clade analysis of mitochondrial haplotypes revealed that both historic and contemporary processes have influenced patterns of haplotype distributions and that historic processes have most likely led to the level of differentiation found between the Oklahoma and New Mexico populations.