Pavlacky Jr. D.C.,Rocky Mountain Bird Observatory |
Blakesley J.A.,Rocky Mountain Bird Observatory |
White G.C.,Colorado State University |
Hanni D.J.,Rocky Mountain Bird Observatory |
Lukacs P.M.,University of Montana
Journal of Wildlife Management | Year: 2012
sOccupancy estimation is an effective analytic framework, but requires repeated surveys of a sample unit to estimate the probability of detection. Detection rates can be estimated from spatially replicated rather than temporally replicated surveys, but this may violate the closure assumption and result in biased estimates of occupancy. We present a new application of a multi-scale occupancy model that permits the simultaneous use of presence-absence data collected at 2 spatial scales and uses a removal design to estimate the probability of detection. Occupancy at the small scale corresponds to local territory occupancy, whereas occupancy at the large scale corresponds to regional occupancy of the sample units. Small-scale occupancy also corresponds to a spatial availability or coverage parameter where a species may be unavailable for sampling at a fraction of the survey stations. We applied the multi-scale occupancy model to a hierarchical sample design for 2 bird species in the Black Hills National Forest: brown creeper (Certhia americana) and lark sparrow (Chondestes grammacus). Our application of the multi-scale occupancy model is particularly well suited for hierarchical sample designs, such as spatially replicated survey stations within sample units that are typical of avian monitoring programs. The model appropriately accounts for the non-independence of the spatially replicated survey stations, addresses the closure assumption for the spatially replicated survey stations, and is useful for decomposing the observation process into detection and availability parameters. This analytic approach is likely to be useful for monitoring at local and regional scales, modeling multi-scale habitat relationships, and estimating population state variables for rare species of conservation concern. © 2011 The Wildlife Society. Copyright © The Wildlife Society, 2011.
Pool D.B.,Rocky Mountain Bird Observatory |
Panjabi A.O.,Rocky Mountain Bird Observatory |
Macias-Duarte A.,Rocky Mountain Bird Observatory |
Macias-Duarte A.,University of Sonora |
Solhjem D.M.,Parks and Tourism
Biological Conservation | Year: 2014
Grasslands are one of the most imperiled ecosystems worldwide. Conversion to cropland and desertification, including shrub encroachment, are primary factors behind the loss of temperate grasslands across the globe. Governments and conservation organizations in North America have identified the highest priority grasslands from Canada to Mexico in an effort to conserve grassland biodiversity, particularly migratory birds. Twenty-nine of 33 (88%) grassland-obligate bird species breeding in western North America's Great Plains are migratory and 90% of these overwinter in the Chihuahuan Desert. The 2.7. M. ha Valles Centrales is a region of northern Mexico comprised of desert shrublands, mountains and grassland valleys. It supports wintering populations of 28 migratory grassland bird species from the Great Plains, in addition to threatened and endangered species in Mexico such as Aplomado Falcon (Falco femoralis), Pronghorn (Antilocapra americana mexicana) and others. Using remote sensing, we documented a 6.04% annual rate of cropland expansion in the Valles Centrales from 2006 to 2011, resulting in a loss of 69,240. ha of valley-bottom grasslands and shrub lands. Open grasslands are the principle habitat for most declining, grassland-obligate bird species. Expansion of center-pivot irrigated cropland was the primary driver of grassland loss. The area cleared for agriculture, as determined via remote sensing, exceeded the amount of land that had been permitted for land-use change to cropland, according to government records, by >2000%. As a consequence of this habitat loss, we estimate the winter carrying capacity for 28 species of grassland birds in this region has been reduced by approximately 355,142 individual birds. At the current rate, the ongoing expansion of ground-water irrigated cropland could eliminate the remaining low-slope valley bottom grasslands from the Valles Centrales region by 2025. Cumulative grassland losses in the Chihuahuan Desert could have severe impacts on global populations of declining migratory grassland birds, as well as several threatened and endangered species. Our findings demand an urgent call to action by governments and responsible resource management agencies to work with the agricultural sectors to address land use change, sustainable agriculture and grassland ecosystem services in this globally-important region for grassland birds and biodiversity. © 2013 Elsevier Ltd.
Pavlacky D.C.,University of Queensland |
Pavlacky D.C.,Rocky Mountain Bird Observatory |
Possingham H.P.,University of Queensland |
Lowe A.J.,University of Adelaide |
And 4 more authors.
Journal of Animal Ecology | Year: 2012
Local extinctions in habitat patches and asymmetric dispersal between patches are key processes structuring animal populations in heterogeneous environments. Effective landscape conservation requires an understanding of how habitat loss and fragmentation influence demographic processes within populations and movement between populations. We used patch occupancy surveys and molecular data for a rainforest bird, the logrunner (Orthonyx temminckii), to determine (i) the effects of landscape change and patch structure on local extinction; (ii) the asymmetry of emigration and immigration rates; (iii) the relative influence of local and between-population landscapes on asymmetric emigration and immigration; and (iv) the relative contributions of habitat loss and habitat fragmentation to asymmetric emigration and immigration. Whether or not a patch was occupied by logrunners was primarily determined by the isolation of that patch. After controlling for patch isolation, patch occupancy declined in landscapes experiencing high levels of rainforest loss over the last 100years. Habitat loss and fragmentation over the last century was more important than the current pattern of patch isolation alone, which suggested that immigration from neighbouring patches was unable to prevent local extinction in highly modified landscapes. We discovered that dispersal between logrunner populations is highly asymmetric. Emigration rates were 39% lower when local landscapes were fragmented, but emigration was not limited by the structure of the between-population landscapes. In contrast, immigration was 37% greater when local landscapes were fragmented and was lower when the between-population landscapes were fragmented. Rainforest fragmentation influenced asymmetric dispersal to a greater extent than did rainforest loss, and a 60% reduction in mean patch area was capable of switching a population from being a net exporter to a net importer of dispersing logrunners. The synergistic effects of landscape change on species occurrence and asymmetric dispersal have important implications for conservation. Conservation measures that maintain large patch sizes in the landscape may promote asymmetric dispersal from intact to fragmented landscapes and allow rainforest bird populations to persist in fragmented and degraded landscapes. These sink populations could form the kernel of source populations given sufficient habitat restoration. However, the success of this rescue effect will depend on the quality of the between-population landscapes. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.
Cariveau A.B.,Rocky Mountain Bird Observatory |
Pavlacky Jr. D.C.,Rocky Mountain Bird Observatory |
Bishop A.A.,U.S. Fish and Wildlife Service |
Lagrange T.G.,Nebraska Game and Parks Commission
Wetlands | Year: 2011
Many isolated wetlands that fill by rainfall, such as playas, have been affected by sedimentation in heavily modified agricultural landscapes. Conservation plantings and buffers reduce sedimentation in wetlands but also may reduce the frequency of inundation. We studied the effects of surrounding landcover on the responses of playas in southwestern Nebraska to heavy rain events using aerial photography, ground surveys, and GIS landscape analyses. Using a generalized linear mixed model, we found that playas in rangeland were more likely to become inundated than playas in cropland, and both were more likely to become inundated than playas in fields enrolled in USDA's Conservation Reserve Program (CRP), typified by tall, dense grasses. Inundation was also positively related to rainfall amount and playa size. Our results highlight the significance of maintaining playas in native prairie and underscore the importance of planting and managing appropriate mixes of native shortgrass and/or mixed-grass prairie species surrounding playas to mimic the vegetative structure of native prairie. In light of historic wetland losses, a reduction in the probability of flooding for individual playas in CRP must be weighed against the protection from sedimentation that buffers afford wetlands in cropland and other beneficial influences of CRP in the landscape. © 2011 Society of Wetland Scientists.
Moses M.R.,New Mexico State University |
Moses M.R.,Rocky Mountain Bird Observatory |
Frey J.K.,New Mexico State University |
Roemer G.W.,New Mexico State University
Oecologia | Year: 2012
Modest increases in global temperature have been implicated in causing population extirpations and range shifts in taxa inhabiting colder environs and in ectotherms whose thermoregulation is more closely tied to environmental conditions. Many arid-adapted endotherms already experience conditions at their physiological limits, so it is conceivable that they could be similarly affected by warming temperatures. We explored how climatic variables might influence the apparent survival of the banner-tailed kangaroo rat (Dipodomys spectabilis), a rodent endemic to the Chihuahuan Desert of North America and renowned for its behavioral and physiological adaptations to arid environments. Relative variable weight, strength of variable relationships, and other criteria indicated that summer, diurnal land surface temperature (SD_LST) was the primary environmental driver of apparent survival in these arid-adapted rodents. Higher temperatures had a negative effect on apparent survival, which ranged from 0. 15 (SE = 0. 04) for subadults to 0. 50 (SE = 0. 07) for adults. Elevated SD_LST may negatively influence survival through multiple pathways, including increased water loss and energy expenditure that could lead to chronic stress and/or hyperthermia that could cause direct mortality. Land surface temperatures are predicted to increase by as much 6. 5°C by 2099, reducing apparent survival of adults to ~0. 15 in some regions of the species' range, possibly causing a shift in their distribution. The relationship between SD_LST and survival suggests a mechanism whereby physiological tolerances are exceeded resulting in a reduction to individual fitness that may ultimately cause a shift in the species' range over time. © 2011 Springer-Verlag.
Ramsdell C.P.,Virginia Polytechnic Institute and State University |
Sorice M.G.,Virginia Polytechnic Institute and State University |
Dwyer A.M.,Rocky Mountain Bird Observatory
Environmental Conservation | Year: 2016
Financial incentives have become a core component of private lands conservation programmes because of their ability to motivate stewardship behaviour. Concern exists about the durability of stewardship behaviours after payments end. Payments for performance may impact farmers' current and future engagement with an incentive programme to protect an at-risk ground-nesting grassland bird. Farmer motivations for participating in the programme, as well as their intention to continue the programme if the financial incentive no longer existed, were quantified. Although farmers did not report a high level of current involvement in the programme, most reported they would continue at a similar or higher level of engagement if the payments ended. These outcomes were related to their perception that their participation was driven by their internal motivation to help rather than the desire to obtain the financial reward. The perception that their behaviour was self-directed was positively influenced by the flexibility surrounding landowners' engagement with the programme, a feeling of competence and achievement, and a feeling of connectedness to the organization implementing the programme. The success of conservation incentive programmes over the long term can be enhanced by explicitly accounting for the needs of landowners in programme design and administration. © 2015 Foundation for Environmental Conservation.
Macias-Duarte A.,University of Sonora |
Panjabi A.O.,Rocky Mountain Bird Observatory
Auk | Year: 2013
Grassland bird populations have shown persistent declines over the past four decades in North America. Possible explanations for the declines include decreased winter survival because of habitat deterioration. To address this hypothesis, we evaluated the relationship between habitat structure and winter survival of Vesper Sparrows (Pooecetes gramineus) in Chihuahuan Desert grasslands of northern Mexico. We radiotagged and monitored the survival of 102 individuals during the winters of 2009 and 2010. We obtained visual estimates of vegetation structure and composition at every individual's radiotelemetry location. We used an exponential regression model to estimate daily survival rates and determine the association between habitat structure and survival. We estimated a daily winter survival probability of 99.1% (95% confidence interval: 97.4-99.7%) for Vesper Sparrows in both years. Our survival analysis suggests that habitat structure is an important predictor of winter survival. Average grass height and shrub height were positively related to Vesper Sparrow survival. Our results suggest that grassland bird populations may be negatively affected by poor grassland conditions during the winter and that low winter survival may be an important factor in population declines. Winter habitat conditions in the Chihuahuan Desert grasslands are shaped primarily by grazing and climate, highlighting the need to improve range management, especially in Mexico, as a means to reverse persistent population declines of grassland birds. Copyright © 2013 by The American Ornithologists' Union.
Bartuszevige A.M.,Playa Lakes Joint Venture |
Pavlacky Jr. D.C.,Rocky Mountain Bird Observatory |
Burris L.,Colorado State University |
Herbener K.,Colorado State University
Wetlands | Year: 2012
Playa wetlands in the western Great Plains of the United States are an essential component of the ecological and hydrological systems in the region. However, these wetlands are threatened through culturally-accelerated sedimentation from the surrounding row-crop dominated landscape. As a consequence, conservation efforts have focused mainly on installing Conservation Reserve Program (CRP) grasslands around playas but these may impede water from reaching playa basins. Thus, better understanding of the factors that influence inundation is needed for effective conservation of playas. The objectives of this project were to investigate the effects of hydrological factors, landcover at local and watershed scales, and thresholds for playa inundation in a variety of landscape conditions. We used generalized linear mixed modeling to determine the landscape and hydrological factors that influence playa inundation. We found playa inundation was positively related to amount of rainfall in the previous 14 days, the variation in amount of rainfall, playa area and the slope of the surrounding landscape. After accounting for hydrological factors, we found CRP adjacent to the playa and CRP in the watershed had a larger influence on playa inundation than the landcover of Pasture orGrassland. There was a negative non-linear effect of CRP on playa inundation and evidence for a negative linear effect at the watershed scale. Playa conservation is an integral component of the Ogallala Initiative, and Farm Bill programs such as CRP are essential conservation tools thus it is imperative that we understand potential impacts of such programs in order to inform improvements. © Society of Wetland Scientists 2012.
Van Der Burg M.P.,University of Nebraska - Lincoln |
Bly B.,Nebraska Prairie Partners |
VerCauteren T.,Rocky Mountain Bird Observatory |
Tyre A.J.,University of Nebraska - Lincoln
Journal of Applied Ecology | Year: 2011
Wildlife managers are limited in the inferences they can draw about low density populations. These limits are imposed by biases in monitoring data not regularly accounted for. 2.We developed a Bayesian hierarchical model to correct biases arising from imperfect detection and spatial autocorrelation. Our analysis incorporated model selection uncertainty by treating model probabilities as parameters to be estimated in the context of model fitting. We fitted our model to count data from a monitoring programme for the mountain plover Charadrius montanus, a low density bird species in Nebraska, USA. 3.Our results demonstrated that previous accounts of the abundance and distribution of plovers in Nebraska were impacted by low detection probabilities (~5-20%). Uncorrected relative abundance estimates showed that the average number of birds per agricultural section increased over time, whereas corrected estimates showed that average abundance was stable. 4.Our method spatially interpolated relative abundance to produce distribution maps. These predictions suggested that birds were selecting some sites more frequently than others based on some habitat feature not explored in our study. Variation in mountain plover abundance appeared more heavily influenced by changes in the number of individuals occupying a few high quality sites, rather than from changes in abundance across many sites. Thus, conservation efforts may not be as efficient when focusing on low to moderate quality sites. 5.Synthesis and applications.Managers who must make decisions based on data-poor systems should adopt rigorous statistical approaches for drawing inferences. Spatial predictions provide information for deciding where to implement management, which is just as important as knowing what kind of management to apply. Our approach provides a step in the direction of making the biological signal in data-poor monitoring programmes more informative for conservation and management. © 2010 The Authors. Journal of Applied Ecology © 2010 British Ecological Society.
Phillips R.,U.S. Department of Agriculture |
West M.,U.S. Department of Agriculture |
Saliendra N.,U.S. Department of Agriculture |
Rundquist B.,University of North Dakota |
Pool D.,Rocky Mountain Bird Observatory
GIScience and Remote Sensing | Year: 2013
Canopy structural and chemical data are needed for senescent, mixed-grass prairie landscapes in autumn; yet data-driven models are lacking for rangelands dominated by non-photosynthetically active vegetation (NPV). We report how field data and aerial hyperspectral imagery were modeled to predict canopy attributes post growing-season using two approaches: (1) application of narrow spectral regions with Vegetation Indices (VIs) and (2) application of the full spectrum with Partial Least Squares Regression (PLSR). Analyses of the full spectrum using PLSR resulted in slightly lower root-mean-square error of prediction, as compared to VIs, which represent reflectance ratios for specific spectral bands. © 2013 Taylor and Francis Group, LLC.