Active adaptive management is the centerpiece of a major species recovery program now underway on the central Platte River in Nebraska. The Platte River Recovery Implementation Program initiated on ...January 1, 2007 and is a joint effort between the states of Colorado, Wyoming, and Nebraska; the U.S. Department of the Interior; waters users; and conservation groups. This program is intended to address issues related to endangered species and loss of habitat along the Platte River in central Nebraska by managing land and water resources and using adaptive management as its science framework. The adaptive management plan provides a systematic process to test hypotheses and apply the information learned to improve management on the ground, and is centered on conceptual models and priority hypotheses that reflect different interpretations of how river processes work and the best approach to meeting key objectives. This framework reveals a shared attempt to use the best available science to implement experiments, learn, and revise management actions accordingly on the Platte River. This paper focuses on the status of adaptive management implementation on the Platte, experimental and habitat design issues, and the use of decision analysis tools to help set objectives and guide decisions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Migratory birds like endangered whooping cranes (Grus americana) require suitable nocturnal roost sites during twice annual migrations. Whooping cranes primarily roost in shallow surface water ...wetlands, ponds, and rivers. All these features have been greatly impacted by human activities, which present threats to the continued recovery of the species. A portion of one such river, the central Platte River, has been identified as critical habitat for the survival of the endangered whooping crane. Management intervention is now underway to rehabilitate habitat form and function on the central Platte River to increase use and thereby contribute to the survival of whooping cranes. The goal of our analyses was to develop habitat selection models that could be used to direct riverine habitat management activities (i.e., channel widening, tree removal, flow augmentation, etc.) along the central Platte River and throughout the species' range. As such, we focused our analyses on two robust sets of whooping crane observations and habitat metrics the Platte River Recovery Implementation Program (Program or PRRIP) and other such organizations could influence. This included channel characteristics such as total channel width, the width of channel unobstructed by dense vegetation, and distance of forest from the edge of the channel and flow-related metrics like wetted width and unit discharge (flow volume per linear meter of wetted channel width) that could be influenced by flow augmentation or reductions during migration. We used 17 years of systematic monitoring data in a discrete-choice framework to evaluate the influence these various metrics have on the relative probability of whooping crane use and found the width of channel unobstructed by dense vegetation and distance to the nearest forest were the best predictors of whooping crane use. Secondly, we used telemetry data obtained from a sample of 38 birds of all ages over the course of seven years, 2010-2016, to evaluate whooping crane use of riverine habitat within the North-central Great Plains, USA. For this second analysis, we focused on the two metrics found to be important predictors of whooping crane use along the central Platte River, unobstructed channel width and distance to nearest forest or wooded area. Our findings indicate resource managers, such as the Program, have the potential to influence whooping crane use of the central Platte River through removal of in-channel vegetation to increase the unobstructed width of narrow channels and through removal of trees along the bank line to increase unforested corridor widths. Results of both analyses also indicated that increases in relative probability of use by whooping cranes did not appreciably increase with unobstructed views ≥200 m wide and unforested corridor widths that were ≥330 m. Therefore, managing riverine sites for channels widths >200 m and removing trees beyond 165 m from the channel's edge would increase costs associated with implementing management actions such as channel and bank-line disking, removing trees, augmenting flow, etc. without necessarily realizing an additional appreciable increase in use by migrating whooping cranes.
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The Platte River Recovery Implementation Program (PRRIP) and its partners invested substantial resources in creating and managing off-channel nesting habitat for Interior Least Terns (Sternula ...antillarum athalassos) and Piping Plovers (Charadrius melodus) along the central Platte River in Nebraska. Among other things, management activities implemented at nesting sites to increase nest and brood survival have included tree removal, construction of a water barrier surrounding the nesting areas, installation of predator fences, and predator trapping. We used 15 years of data at off-channel sites along the central Platte River to assess the influence of several biotic and abiotic variables on the survival of Interior Least Tern and Piping Plover nests and broods. We observed high survival rates for Interior Least Tern and Piping Plover nests and broods as two-thirds of Interior Least Tern and three-quarters of Piping Plover nests were successful and three-quarters of all Interior Least Tern and Piping Plover broods were successful. We found productivity of Interior Least Terns and Piping Plovers was reduced during both the nesting and brood-rearing stages by weather-related variables rather than variables the PRRIP can manage. As such, we conclude habitat management activities implemented at off-channel sites to date are sufficient for maintaining high levels of productivity for Interior Least Terns and Piping Plovers along the central Platte River.
Investigations of breeding ecology of interior least tern (Sternula antillarum athalassos) and piping plover (Charadrius melodus) in the Platte River basin in Nebraska, USA, have embraced the idea ...that these species are physiologically adapted to begin nesting concurrent with the cessation of spring floods. Low use and productivity on contemporary Platte River sandbars have been attributed to anthropomorphically driven changes in basin hydrology and channel morphology or to unusually late annual runoff events. We examined distributions of least tern and piping plover nest initiation dates in relation to the hydrology of the historical central Platte River (CPR) and contemporary CPR and lower Platte River (LPR). We also developed an emergent sandbar habitat model to evaluate the potential for reproductive success given observed hydrology, stage–discharge relationships, and sandbar height distributions. We found the timing of the late‐spring rise to be spatially and temporally consistent, typically occurring in mid‐June. However, piping plover nest initiation peaks in May and least tern nest initiation peaks in early June; both of which occur before the late spring rise. In neither case does there appear to be an adaptation to begin nesting concurrent with the cessation of spring floods. As a consequence, there are many years when no successful reproduction is possible because emergent sandbar habitat is inundated after most nests have been initiated, and there is little potential for successful renesting. The frequency of nest inundation, in turn, severely limits the potential for maintenance of stable species subpopulations on Platte River sandbars. Why then did these species expand into and persist in a basin where the hydrology is not ideally suited to their reproductive ecology? We hypothesize the availability and use of alternative off‐channel nesting habitats, like sandpits, may allow for the maintenance of stable species subpopulations in the Platte River basin.
We examined distributions of central Platte River interior least tern and piping plover nest initiation dates in relation to the hydrology of the historical central Platte River and contemporary central and lower Platte River and developed an emergent sandbar habitat model to evaluate the potential for reproductive success given observed hydrology, stage–discharge relationships, and sandbar height distributions. We found there was a limited potential for reproductive success on Platte River sandbars which would suggest the availability and use of alternative off‐channel nesting habitats like sandpits may have allowed the species to expand into and persist in a basin where the hydrology is not ideally suited to their reproductive ecology. Our results refute John William Hardy's concept of the physiological adaptation of interior least tern to begin nesting concurrent with recession of the spring rise that has been embraced in Platte River literature and expanded to include piping plover.
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The Flow-Sediment-Mechanical approach is one of two management strategies presented in the Platte River Recovery Implementation Program's (Program) Adaptive Management Plan to create and maintain ...suitable riverine habitat (≥200 m wide unobstructed channels) for whooping cranes (Grus americana). The Program's Flow-Sediment-Mechanical management strategy consists of sediment augmentation, mechanical vegetation clearing and channel widening, channel consolidation, and short duration high flow releases of 142–227 m3/s for three to five days in two out of three years in order to increase the unvegetated width of the main channel and, by extension, create and maintain suitable habitat for whooping crane use. We examined the influence of a range of hydrologic and physical metrics on total unvegetated channel width (TUCW) and maximum unobstructed channel width (MUOCW) during the period of 2007–2015 and applied those findings to assess the performance of the Flow-Sediment-Mechanical management strategy for creating and maintaining whooping crane roosting habitat. Our investigation highlights uncertainties that are introduced when exploring the relationship between physical process drivers and species habitat metrics. We identified a strong positive relationship between peak flows and TUCW and MUOCW within the Associated Habitat Reach of the central Platte River. However, the peak discharge magnitude and duration needed to create highly favorable whooping crane roosting habitat within our study area are much greater than short duration high flow releases, as currently envisioned. We also found disking in combination with herbicide application to vegetated portions of the channel are effective for creating and maintaining highly favorable unobstructed channel widths for whooping cranes in all but the very driest years. As such, resource managers could prioritize the treatment of mid-channel islands that are vegetated to increase the suitability of roosting habitat for whooping cranes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Given the high productivity of Interior Least Terns (Sternula antillarum athalassos) and Piping Plovers (Charadrius melodus) on constructed off-channel nesting sites along the central Platte River in ...Nebraska, USA, and the possibility of creating similar habitats at other locations in their breeding range, understanding how these species use off-channel nesting habitats is important. We used data collected along the central Platte River in Nebraska, USA, over a 15-year period (2001-2015), and a discrete-choice modeling framework to assess the effects of physical site attributes and inter- and intraspecific associations on off-channel nest-site selection by Interior Least Terns and Piping Plovers. We found that Piping Plovers avoided nesting near each other, whereas colonial Interior Least Terns selected nest sites near those of conspecifics. In addition, the relative probability of use for both species was maximized when distance to the nearest predator perch was ≥ 150 m and elevation above the waterline was ≥ 3 m . Probability of use for nesting by Interior Least Terns increased as distance to water increased, whereas the probability of use by Piping Plovers was maximized when distance to water was ~50 m. Our results suggest that important features of constructed, off-channel nesting sites for both species should include no potential predator perches within 150 m of nesting habitat and nesting areas at least 3 m above the waterline. Efficient site designs for Interior Least Terns would be circular, maximizing the area of nesting habitat away from the shoreline, whereas an effective site design for Piping Plovers would be more linear, maximizing the area of nesting habitat near the waterline. An efficient site design for both species would be lobate, incorporating centralized nesting habitat for Interior Least Terns and increased access to foraging areas for nesting and brood-rearing Piping Plovers. Dada la alta productividad de Sternula antillarum y Charadrius melodus en sitios de anidación construido fuera del canal a lo largo del tramo central del río Platte en Nebraska, USA y la posibilidad de crear hábitats similares en otras localidades en sus rangos de reproductión, es importante comprender como estas especies usan estos hábitats de anidación fuera del canal. Utilizamos información colectada a lo largo del tramo central del río Platte en Nebraska, USA, a lo largo de un periodo de 15 años (2001-2015) y un marco de modelamiento por selección discreta para determinar el efecto de los atributos fisicos y asociaciones inter e intra-específicas en la selección de sitios de anidación fuera del canal por Sternula antillarum y Charadrius melodus. Encontramos que individuos de Charadrius melodus evitan anidar cerca los unos de los otros, mientras que los individuos de Sternula antilUrum, al ser de anidación colonial, seleccionaron los nidos cerca de con-específicos. Adicionalmente, la probabilidad relativa del uso por las dos especies fue maximizada cuando la distancia a la percha del depredador más cercano fue ≥ 150 m y la elevación por encima de la superficie del agua fue ≥ 3 m. La probabilidad de uso para anidación por Sternula antillarum incrementó con la distancia a la superficie del agua mientras que la probabilidad de uso por Charadrius melodus es maximizad cuando la distancia al agua es ~50 m. Nuestros resultados sugieren, que para ambas especies, las características importantes de los sitios de anidación fuera del canal construidos artificialmente no deben incluir perchas para depredadores dentro de 150 m del hábitat de anidación y tener áreas de anidación por lo menos 3 metros por encima de la superficie del agua. Un diseño eficiente para Sternula antillarum debe ser circular, maximizando el área del hábitat de anidación lejos de la costa mientras que un diseño efectivo para Charadrius melodus deb ser más lineal, maximizando el área del hábitat de anidacion cerca de la superficie del agua. Un diseño de los sitios de anidación que sea eficiente para las dos especies, debe ser lobulado, incorporando hábitat de anidación centralizado para Sternulla antillarum y con mayor acceso a las áreas de forrajeo para anidación y crianza de las nidadas en Charadrius melodus.
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Wide channels with short bank vegetation, access to nearby foraging habitat, shallow water areas (<30 cm deep), and absence of disturbance features are factors commonly associated with suitable roost ...sites for Sandhill Cranes (Antigone canadensis). However, since channel width has typically been evaluated independently of channel depth and flow, it is possible that use of narrow channels is not limited so much by a requirement for wider channels but by deeper water that flows through these narrow channels. We used a discrete-choice modeling framework and 9 years of roost location data to evaluate the influence of channel-width measures and flow per linear unit of channel width on roost-site selection by Sandhill Cranes. Roost-site selection was influenced by maximum unvegetated channel width and flow per unit length of total unvegetated channel width of all channels. The relative selection ratio increased as maximum unvegetated channel width increased to 131 m for small groups (≤500 cranes) and 275 m for large groups (>5000 cranes), but the ratio was statistically similar across a wide range of maximum unobstructed channel widths. Medium-sized Sandhill Crane groups (501–5000 cranes) were less influenced by in-channel vegetated islands, and these groups selected channels based on wide total unvegetated channel widths. Our results also suggest that flows ≤39.05 m3/s (cms; 1379 cfs) in channels that are 275 m in unvegetated width maximize selection ratios for medium and large crane groups, so flows above this level may not improve Sandhill Crane roosting habitat conditions during the spring migration and staging season within the central Platte River. While Sandhill Cranes stage within the central Platte River valley for a longer time interval in the spring, Whooping Cranes (Grus americana) also use the Platte River as a stopover point. Both species share similar indices for roosting habitat, such as unobstructed channel width and shallow water depths. The results of our investigation could be used to identify a range of flows and channel width configurations expected to generate the highest amount of suitable habitat for Sandhill Cranes roosting along the central Platte River.
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Implementation of the Platte River Recovery Implementation Program's adaptive management plan has proceeded with the understanding that management uncertainties, expressed as hypotheses, encompass ...complex physical and ecological responses. Adaptive management in the Platte River ecosystem relies on a combination of monitoring of physical and biological responses to management treatments, predictive modeling, and retrospective analyses. Given the abundance and diversity of fishes inhabiting waterways decreases with groundwater extractions and flow alterations, we used existing interior least tern productivity data and flow data collected from the Central Platte River area for retrospective analyses to assess the influence of forage fish availability on productivity during the brood-rearing season. Our analyses suggest that low flows during the least tern brood-rearing season do not have a negative relationship with interior least tern productivity. As such, we used this indirect line of evidence to build empirical support to assess the forage fish-related hypotheses in the Platte River Recovery Implementation Program's adaptive management plan, and we concluded forage fish abundance does not limit interior least tern productivity on the Central Platte River.
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Active adaptive management is the centerpiece of a major species recovery program now underway on the central Platte River in Nebraska. The Platte River Recovery Implementation Program initiated on ...January 1, 2007 and is a joint effort between the states of Colorado, Wyoming, and Nebraska; the U.S. Department of the Interior; waters users; and conservation groups. This program is intended to address issues related to endangered species and loss of habitat along the Platte River in central Nebraska by managing land and water resources and using adaptive management as its science framework. The adaptive management plan provides a systematic process to test hypotheses and apply the information learned to improve management on the ground, and is centered on conceptual models and priority hypotheses that reflect different interpretations of how river processes work and the best approach to meeting key objectives. This framework reveals a shared attempt to use the best available science to implement experiments, learn, and revise management actions accordingly on the Platte River. This paper focuses on the status of adaptive management implementation on the Platte, experimental and habitat design issues, and the use of decision analysis tools to help set objectives and guide decisions. PUBLICATION ABSTRACT
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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