377 research outputs found

    Winter and Spring Ecology of Gray Partridge in East Central South Dakota

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    Gray partridge (Perdix perdix) habitat utilization, home range, and food habits were studied in Brookings County, South Dakota during winter and spring of 1979 and 1980. Habitat utilization and food habits data were analyzed in 2-month periods; winter (December 22-February 21), early spring (February 22-April 21), and late spring (April 22-June 21). Habitat utilization was determined through radio telemetry, roadside surveys, and incidental observations. Chi-square analysis was used to determine habitat selection of partridge. Home range was determined to via radio telemetry data. Food habits were analyzed with percent volume and frequency of occurrence methods. In winter partridge utilized pasture in a year with deep snow (56 cm) and row crops in a year with less snow (4 cm). Partridge may have been able to locate food more easily in a pasture than in a stubble field in a year with deep snow. In early spring during dispersal, pair formation, and selection of nesting territories, partridge utilized a greater variety of habitat types. Partridge utilized row crops and idle areas for this period in 1980. Birds utilized idle areas in late spring during the nesting period in both years. An unknown sex grey partridge had a home range of 60 ha during early spring. Two paired birds had home ranges of 10 ha and 17 ha, and an unpaired male had a home range of 224 ha in late spring. Home range was studied in 1980 only. Avian predators accounted for the majority of identified depredations on radio-tagged birds. Green vegetation and corn were the most important food items eaten by gray partridge according to percent volume and percent occurrence methods. Sunflower seeds and oats were also important. Green and yellow foxtail (Setaria viridis, S. lutescens) represented the highest volumes and perent occurences for weed seeds. Insects were an important food in late spring. Ants (Hymenoptera) and beetles (Coleoptera) represented the most commonly utilized insects

    Shorebird Breeding Biology in Wetlands of the Playa Lakes, Texas, USA

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    Wetlands in the Playa Lakes Region of Texas are important habitats for North American wintering waterfowl and migrant shorebirds. However, shorebird breeding biology has been overlooked in characterizing the region’s ecological importance. In 1998 and 1999, American Avocet (Recurvirostra americana), Black-necked Stilt ( Himantopus mexicanus ), Killdeer (Charadrius vociferous), and Snowy Plover (C. alexandrinus) breeding ecology were studied in playas, saline lakes, and riparian wetlands in the Playa Lakes Region of Texas. Chronology of nest initiation, clutch sizes, and hatching success for 298 Snowy Plover, 111 American Avocet, 43 Killdeer, and 26 Blacknecked Stilt clutches were measured. All four species nested in saline lakes, American Avocet and Killdeer also nested in playas, and Snowy Plover nested on riparian wetlands. American Avocet had higher hatching success in 1999 (52%) than 1998 (8%), because of more suitable hydrological conditions and lower predation. Hatching success was higher in 1998 than 1999 for Killdeer (1998, 63%; 1999, 21%) and Snowy Plover (1998, 47%; 1999, 33%) due to failures caused by flooding and hail in 1999. In other regions, clutch predation limits shorebird productivity, but hatching success in the Playa Lakes Region appears to be limited by unpredictable precipitation patterns and wetland hydroperiod. As such, breeding shorebird conservation and management should focus upon maintaining wetland hydrological integrity

    Northern Bobwhite Densities in Burned and Unburned Redberry Juniper Rangelands

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    We estimated northern bobwhite (Colinus virginianus) densities in 4- and 8-year-old burned and unburned redberry juniper (Juniperus pinchottii) dominated pastures. The 4-year-old burned (800 ha), 8-year-old burned (1,200 ha), and unburned (1,200 ha) treatment sites had 8.6, 14.4, and 22.3% woody canopy coverage, respectively. Fall bobwhite densities were estimated from 122 flushes of quail coveys on 592.8 km of transects. Data histograms indicated that bobwhite were harder to detect in the unburned area than in the 8-year-old burn or the 4-year-old burn. Probability detection functions were smaller in the old burn than the new burn (P = 0.05) or unburned area (P = 0.02). Bobwhite densities of 43.3, 55.1, and 60.5 birds/100 ha in the 4-year-old burn, 8-year-old burn, and unburned sites, respectively, were similar (P \u3e 0.10). Prescribed burning to control redberry juniper and manage bobwhite should be designed to maintain intermittent shrub coverage

    Shorebird Habitat Use and Nest-site Selection in the Playa Lakes Region

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    Wetlands in the Playa Lakes Region (PLR) provide important habitats for wintering waterfowl, cranes, and both migrant and breeding shorebirds. Playa Lakes Region wetlands experience naturally fluctuating hydroperiods but are exposed to anthropogenic stresses, which are exacerbated during summer and may influence PLR wetland occupancy and selection by breeding shorebirds. We examined wetland-scale habitat use and nest-site selection of the 4 dominant shorebirds (American avocets [Recurvirostra americana], black-necked stilts [Himantopus mexicanus], killdeer [Charadrius vociferus], snowy plovers [C. alexandrinus]) nesting in playas, saline lakes, and in both created and riparian wetlands in the PLR of Texas, USA. All 4 species nested in saline lakes. Only avocets and kill deer nested in playas, and snowy plovers nested in riparian wetlands. No nests were found in created wetlands. Wetland habitat changed (P \u3c 0.001) during the breeding season, while water habitats generally decreased. Used (i.e., shorebirds found nesting) wetlands had more (P \u3c 0.05) mudflats than non-used (i.e., shorebirds not found nesting) wetlands, which had more (P \u3c 0.05) dry habitats. Used and non-used wetlands had similar (P \u3e 0.05) amounts of water habitats. Nests were located close to vegetation on bare dry ground and dry ground with vegetation. Because water is ephemeral in PLR wetlands, shorebirds must select—in a somewhat predictive manner upon arrival—wetlands with suitable nest-site and brood-rearing habitat. Although surface water is necessary for nesting, its presence is not adequate for delineating suitable PLR wetland habitat for breeding shorebirds. Our findings that created wetlands cannot compensate for regional wetland losses in habitat or function highlights the need for conservation of natural PLR wetlands

    Breeding Biology of an Interior Least Tern (Sterna Antillarum Athalassos) Colony in Childress County of North Texas

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    This study documented nest success, nest initiation chronology and nest site selection for interior least terns (Sterna antillarum athalassos) along the Prairie Dog Town Fork of the Red River in Childress County, Texas during 1998. Terns experienced a 65% nest success rate (Mayfield estimate 71 %) and clutch sizes ranged from 1 3 eggs (x = 2.25) for 20 nests. Seventy percent of all nests were initiated during the first 20 days of June, which coincided with the highest number of adult terns observed on the study site. All nests were found on gravel/sand bars in the river basin; 25% were placed on gravel and 75% were placed on sand. Sixty-five percent of tern nests were located within 15 cm of driftwood and/or rocks, but nests were not more frequently associated with objects than random sites (P \u3e 0.05). Nests were generally \u3e 10 m from vegetative cover and 200 m from surface water. However, habitat variables (i.e., distances to upland, mudflat, water and vegetative cover) did not vary (P \u3e 0.05) between nests and random sites nor between successful and nonsuccessful nests. This colony of interior least terns was last documented in the mid-1980s and evidently has some degree of stability. Conservation efforts should focus on protecting, restoring and enhancing riparian wetland habitats in the High and Rolling Plains of Texas for this endangered species

    Application of a Geomorphic and Temporal Perspective to Wetland Management

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    The failure of managed wetlands to provide a broad suite of ecosystem services (e.g., carbon storage, wildlife habitat, ground-water recharge, storm-water retention) valuable to society is primarily the result of a lack of consideration of ecosystem processes that maintain productive wetland ecosystems or physical and social forces that restrict a manager’s ability to apply actions that allow those processes to occur. Therefore, we outline a course of action that considers restoration of ecosystem processes in those systems where off-site land use or physical alterations restrict local management. Upon considering a wetland system, or examining a particular management regime, there are several factors that will allow successful restoration of wetland services. An initial step is examination of the political/social factors that have structured the current ecological condition and whether those realities can be addressed. Most successful restorations of wetland ecosystem services involve cooperation among multiple agencies, acquisition of funds from non-traditional sources, seeking of scientific advice on ecosystem processes, and cultivation of good working relationships among biologists, managers, and maintenance staff. Beyond that, in on-site wetland situations, management should examine the existing hydrogeomorphic situation and processes (e.g., climatic variation, tides, riverine flood-pulse events) responsible for maintenance of ecosystem services within a given temporal framework appropriate for that wetland’s hydrologic pattern. We discuss these processes for five major wetland types (depressional, lacustrine, estuarine, riverine, and man-made impoundments) and then provide two case histories in which this approach was applied: Seney National Wildlife Refuge with a restored fen system and Bosque del Apache National Wildlife Refuge where riverine processes have been simulated to restore native habitat. With adequate partnerships and administrative and political support, managers faced with degraded and/or disconnected wetland processes will be able to restore ecosystem services for society in our highly altered landscape by considering wetlands in their given hydrogeomorphic setting and temporal stage

    Influence of Environmental Stress and Anthropogenic Disturbance on the Energy Expenditure of Wintering Northern Pintails (Anas acuta)

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    Winter conditions impose hardships on waterfowl, impacting how they apportion energy and time. Human disturbances may affect this energetic balance, influence lipid reserves, and potentially survival. Objectives of this study were to determine effects of environmental and anthropogenic factors on energetic expenditure (kcal/day) of Northern Pintails (Anas acuta) in behaviors commonly associated with a disturbance response (alert, locomotion, and flight) during winter 2008-2009 and 2009-2010 at Bosque del Apache National Wildlife Refuge in central New Mexico, USA. The refuge is a frequently visited ecotourism destination with over 170,000 visitors each winter. Thermoregulatory cost, time-of-winter, amount of natural and anthropogenic disturbances, and forage availability were examined to determine their influence on pintail energetic response (e.g., flight, locomotion, alert behavior). Average number of pintails ranged from 7,524-15,769. Using Akaike Information Criteria, the top-ranked model indicated that increased thermoregulatory cost, and by association decreased temperature, may cause a decline in energetic response of pintails to disturbances. Modeled values for energetic response had a mean (± SE) of 175 ± 11.5 kcal/day in year 1, and 111.7 ± 7.22 kcal/day in year 2. Neither the amount of disturbance nor forage availability strongly influenced energetic response. Results of this study raise questions about the efficacy of using behavior or energy expenditure data, alone, to assess anthropogenic disturbance effects on waterfowl

    Euclid at Threescore Years and Ten: The Twilight of Environmental and Land-Use Regulation?

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    Life, Liberty, and Whose Property lecture given by Loren A. Smith, Chief Judge, United States Court of Federal Claims. Is this the Twilight of Land Use Controls? lecture given by Charles M. Haar, Professor of Law at Harvard University Law. Capture and Counteraction: Self-Help and Environmental Zealots lecture given by James E. Krier, Earl Warren Delano Professor of Law, University of Michigan. Ecology and Aesthetics: Our Future and the Making of Things lecture given by William A. McDonough, Dean and Elson Professor, University of Virginia School of Architecture

    Linking Ecosystem Processes to Sustainable Wetland Management

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    The sustainability of ecosystems has become an explicitly stated goal of many natural resource agencies. Examples of sustainable ecosystem management, however, are uncommon because management goals often focus on specific deliverables rather than the processes that sustain ecosystems
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