Long-Term Climate Trends and Northern Bobwhite Populations in South Texas

Because climate change and its associated weather changes may influence population trends of birds, we analyzed northern bobwhite (Colinus virginianus; bobwhite hereafter) age ratios and abundance in relation to climate trends during 1908-1997 in south Texas. Weather variables included regional mean temperature maxima for June, July, and August, and precipitation totals for autumn (Sep-Nov), winter (Dec-Feb), spring (Mar-May), and summer (Jun-Aug). Long-term temporal trends for these weather variables were estimated with a linear regression. Yearly weather data were used to predict bobwhite age ratios (juv/ad in autumn and winter) and abundance between 1908 and 1997 using neural network models. We compared these predictions with data available from various bobwhite surveys in south Texas over the period 1940-1999. Means for daily maximum temperature during summer declined at rates between 1.6 and 2.3°C/century. No temporal trends were detected for seasonal precipitation (1908-1997), age ratios (1940-1999), or abundance (1977-1998). Neural models developed independently to predict bobwhite age ratios and bobwhite abundance from weather data produced predictions that were consistent with each other. Years with high age ratios tended to coincide with or precede years of high abundance

Assessing Landscape Constraints on Species Abundance: Does the Neighborhood Limit Species Response to Local Habitat Conservation Programs?

Landscapes in agricultural systems continue to undergo significant change, and the loss of biodiversity is an ever-increasing threat. Although habitat restoration is beneficial, management actions do not always result in the desired outcome. Managers must understand why management actions fail; yet, past studies have focused on assessing habitat attributes at a single spatial scale, and often fail to consider the importance of ecological mechanisms that act across spatial scales. We located survey sites across southern Nebraska, USA and conducted point counts to estimate Ring-necked Pheasant abundance, an economically important species to the region, while simultaneously quantifying landscape effects using a geographic information system. To identify suitable areas for allocating limited management resources, we assessed land cover relationships to our counts using a Bayesian binomial-Poisson hierarchical model to construct predictive Species Distribution Models of relative abundance. Our results indicated that landscape scale land cover variables severely constrained or, alternatively, facilitated the positive effects of local land management for Ring-necked Pheasants

Public Access for Pheasant Hunters: Understanding an Emerging Need

Ring‐necked pheasant (Phasianus colchicus; i.e., pheasant) hunting participation is declining across North America, reflecting a larger downward trend in American hunting participation and threatening benefits to grassland conservation and rural economies. To stabilize and expand the pheasant hunting population, we must first identify factors that influence pheasant hunter participation. We used an extensive in‐person hunter survey to test the hypothesis that hunter demographics interact with social‐ecological traits of hunting locations to affect hunter decisions, outcomes, and perceptions. We built a series of Bayesian mixed effects models to parse variation in demographics, perceptions, and hunt outcomes of pheasant hunters interviewed at public access hunting sites across 3 regions in Nebraska, USA, that varied in pheasant abundance and proximity to urban population centers. Among pheasant hunters in Nebraska, access to private lands was negatively related to the human population density of a pheasant hunter’s home ZIP code and the distance a hunter had traveled to reach a hunting location. Pheasant hunters interviewed closer to metropolitan areas tended to be more urban and travel shorter distances, and their parties were more likely to include youth but less likely to include dogs. Hunter satisfaction was positively associated with seeing and harvesting pheasants and hunting with youth. Whereas youth participation and the number of pheasants seen varied by study region, hunter satisfaction did not differ across regions, suggesting that hunters may calibrate their expectations and build their parties based on where they plan to hunt. The variation in hunter demographics across hunting locations and disconnects between social and ecological correlates of hunter satisfaction suggests that diverse pheasant hunting constituencies will be best served by diverse pheasant hunting opportunities

Translating statistical species-habitat models to interactive decision support tools

Understanding species-habitat relationships is vital to successful conservation, but the tools used to communicate species-habitat relationships are often poorly suited to the information needs of conservation practitioners. Here we present a novel method for translating a statistical species-habitat model, a regression analysis relating ring-necked pheasant abundance to landcover, into an interactive online tool. The Pheasant Habitat Simulator combines the analytical power of the R programming environment with the user-friendly Shiny web interface to create an online platform in which wildlife professionals can explore the effects of variation in local landcover on relative pheasant habitat suitability within spatial scales relevant to individual wildlife managers. Our tool allows users to virtually manipulate the landcover composition of a simulated space to explore how changes in landcover may affect pheasant relative habitat suitability, and guides users through the economic tradeoffs of landscape changes. We offer suggestions for development of similar interactive applications and demonstrate their potential as innovative science delivery tools for diverse professional and public audience

Global variability in leaf respiration in relation to climate, plant functional types and leaf traits

• Leaf dark respiration (Rdark) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. • Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark. • Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8–28°C). By contrast, Rdark at a standard T (25°C, Rdark25) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark25 at a given photosynthetic capacity (Vcmax25) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark25 values at any given Vcmax25 or [N] were higher in herbs than in woody plants. • The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs)

Long-Term Agricultural Land-Use Trends In Nebraska, 1866–2007

Although landscape changes from anthropogenic causes occur at much faster rates than those from natural processes (e.g., geological, vegetation succession), human perception of such changes is often subjective, inaccurate, or nonexistent. Given the large-scale land-use changes that have occurred throughout the Great Plains, the potential impacts of land-use changes on ecological systems, and the insight gained from knowledge of land-use trends (e.g., to compare to wildlife population trends), we synthesized information related to land-use trends in Nebraska during 1866–2007. We discussed and interpreted known and potential causes of short- and long-term land-use trends based on agricultural and weather data; farm policies and programs; and local, state, and global events. During the study period, mean farm size steadily increased, whereas number of farms rapidly increased until about 1900, remained stable until about 1930, then rapidly decreased. Total area of cropland in Nebraska increased until the 1930s, but then showed long-term stability with large short-term fluctuations. Crop diversity was highest during 1955–1965, then slowly decreased; corn was always a dominant crop, but sorghum and oats were increasingly replaced by soybeans after the 1960s. Land-use changes were affected by farm policies and programs attempting to stabilize commodity supply and demand, reduce erosion, and reduce impacts to wildlife and ecological systems; direct and indirect effects of war (e.g., food demand, pesticides, fertilizers); technological advances (e.g., mechanization); and human population growth and redistribution. Although these causes of change will continue to affect Nebraska’s landscape, as well as that of other Great Plains states, new large-scale trends such as increasing energy demands (e.g., biofuels) may contribute to an already highly modified landscape

Greater prairie-chicken nest success and habitat selection in southeastern Nebraska

Greater prairie-chickens (Tympanuchus cupido pinnatus) are reported to benefit from grasslands created through the Conservation Reserve Program (CRP). Prairie-chicken population size increased noticeably in southeastern Nebraska after \u3e15% of county-level landscapes were converted to CRP grasslands. But, the mechanisms behind the increase in population size are not well understood, and managers and policy makers could benefit from evidence of CRP’s relative contribution to populations of prairie-chickens. Therefore, our objectives were to characterize the relations of vegetation structure and composition with prairie-chicken nest-site selection and nest survival rates at both the macrohabitat (within landscape of study site) and microhabitat (at the nest) level. We radio-marked female prairie-chickens at a study site with \u3e15% of land enrolled in CRP in Johnson County in southeastern Nebraska. We monitored 90 nests during 2006–2007, 36 (40%) of which were successful. We compared nest sites’ macro- and microhabitat characteristics with random points using discrete choice analyses, and we used logistic exposure analyses to assess the effect of habitat and other variables on nest survival. Prairie-chickens were 5.70 (95% CI: 2.60–12.48) times more likely to select cool-season CRP fields, and 5.05 (95% CI: 2.17–11.72) times more likely to select warm-season CRP fields for nesting relative to selecting rangeland. Prairie-chickens selected nest sites, relative to sites available in fields selected for nesting, with abundant grass cover and moderate levels of forb cover and standing litter. Females also selected sites at upper elevations. Nest survival was influenced by macrohabitat, microhabitat, and temporal variables; nest survival was greater in CRP fields and greatest for nests with abundant grass cover and forb cover and moderate levels of residual litter. Nest survival peaked, temporally, with nests initiated in late May. The size of the prairie-chicken population in southeastern Nebraska has increased since the landscape was modified under CRP, and the reproductive benefits that our study demonstrates could support such population-level responses. We would expect the population to continue to benefit from management that provides high quality, diverse grasslands

Chapter 18- Chick Survival of Greater Prairie-Chickens

Chick survival during the first three weeks of life is a critical stage in the demography of Greater Prairie-Chickens (Tympanuchus cupido), but little information is available. Biologists often estimate brood success using periodic flushes of radio-marked females, but it is impossible to determine mortality factors if chicks are not radio-marked. We used sutures to attach 0.5-g transmitters to 1- to 2-day-old chicks in Johnson County, Nebraska, during 2008. Our objectives were to (1) assess causes of mortality of 0- to 21-day-old chicks, (2) estimate daily survival probability for 0- to 21-day-old chicks, and (3) evaluate the effect of applying transmitters with suture attachment to chicks. We monitored a total of 221 prairie chicken chicks from 20 broods. We radio-marked 27 chicks from 10 broods of radio-marked females (one to five chicks per brood). The chicks were located twice per day to ensure that they were within a 10-m radius of the female. Our limited sample showed a weak effect of radio-marking on the survival of prairie chicken chicks (β= –0.54; SE= 0.33). Forty-two (19%; 95% CI: ±5%) of the 221 chicks in our sample survived to day 21, confirming low rates of productivity observed in hunter wing surveys and brood flushes of radio-marked females in a concurrent study. All radio-marked chicks in our sample died (13% exposure; 87% predators) before 21 days of age. Survival of chicks increased with age, and survival decreased during periods with high precipitation. Daily and 21-day survival rate estimates for all chicks in our sample were 0.926 (95% CI: 0.915–0.937) and 0.193 (95% CI; 0.155–0.255), respectively. Predation appeared to be the most critical factor for chick survival, so management of landscapes to reduce risk from predators may have a positive effect on Greater Prairie-Chicken populations