Reproductive ecology of interior least tern and piping plover in relation to Platte River hydrology and sandbar dynamics

Historical and contemporary use of large, economically important rivers by threatened and/or endangered species in the United States is a subject of great interest to a wide range of stakeholders. In a recent study of the Platte River in Nebraska, Farnsworth et al. (2017) (hereinafter referred to as “the authors” or “Farnsworth et al.”) used distributions of nest initiation dates taken mostly from human-created, off-channel habitats and a model of emergent sandbar habitat to evaluate the hypothesis that least terns (Sternula antillarum) and piping plovers (Charadrius melodus) are physiologically adapted to initiate nests concurrent with the cessation of spring river flow rises. The authors conclude that (1) these species are not now, nor were they in the past, physiologically adapted to the hydrology of the Platte River, (2) habitats in the Platte River did not, and cannot support reproductive levels sufficient to maintain species subpopulations, (3) the gap in local elevation between peak river stage and typical sandbar height, in combination with the timing of the average spring flood, creates a physical environment which limits opportunities for successful nesting and precludes persistence by either species, and (4) the presence of off-channel habitats, including human-created sand and gravel mines, natural lakes, and a playa wetland, allowed the species to expand into the Platte River basin

Learning from Conservation Planning for the U.S. National Wildlife Refuges

The U.S. National Wildlife Refuge System has nearly completed its first round of unit-level, comprehensive conservation plans (CCPs) and will soon begin required revisions. Laws and policies governing refuge planning emphasize ecological integrity, landscape-scale conservation, and adaptive management. We evaluated 185 CCPs completed during 2005–2011, which cover 324 of 555 national wildlife refuges. We reviewed CCP prescriptions addressing 5 common conservation issues (habitat and game, nongame, imperiled, and invasive species) and 3 specialized topics (landscape-scale conservation, climate change, and environmental quality). Common conservation issues received prescriptions in \u3e90% of CCPs. Specialized topics received more variable treatment. Prescriptions for aquatic connectivity, water quantity, and climate change impacts increased over the study period. Except for climate change, direct actions were the most common type of management prescription, followed by plans or studies. Most CCPs stated a commitment to adaptive management and prescribed monitoring for common conservation objectives; other aspects of planning for adaptive management were often lacking, despite strong support for adaptive management in the conservation planning literature. To better address refuge-specific threats, we recommend that revised plans explicitly match identified refuge issues with prescriptions, particularly for under-represented concerns such as novel pests and pathogens. We recommend incorporating triggers into monitoring frameworks and specifying actions that will occur when threshold values are reached to improve support for adaptive management. Revised CCPs should better reflect work that refuges already undertake to extend conservation objectives beyond their borders and better engage with regional conservation efforts to continue this work. More thorough landscape-scale threat assessments and explicit prioritization of planned actions would further improve conservation effectiveness. Excellent examples of all recommended practices exist within the CCPs we examined; sharing best planning practices would improve planning efficiency within the refuge system

Estimating offsets for avian displacement effects of anthropogenic impacts

Biodiversity offsetting, or compensatory mitigation, is increasingly being used in temperate grassland ecosystems to compensate for unavoidable environmental damage from anthropogenic developments such as transportation infrastructure, urbanization, and energy development. Pursuit of energy independence in the United States will expand domestic energy production. Concurrent with this increased growth is increased disruption to wildlife habitats, including avian displacement from suitable breeding habitat. Recent studies at energy-extraction and energy-generation facilities have provided evidence for behavioral avoidance and thus reduced use of habitat by breeding waterfowl and grassland birds in the vicinity of energy infrastructure. To quantify and compensate for this loss in value of avian breeding habitat, it is necessary to determine a biologically based currency so that the sufficiency of offsets in terms of biological equivalent value can be obtained. We describe a method for quantifying the amount of habitat needed to provide equivalent biological value for avifauna displaced by energy and transportation infrastructure, based on the ability to define five metrics: impact distance, impact area, pre-impact density, percent displacement, and offset density. We calculate percent displacement values for breeding waterfowl and grassland birds and demonstrate the applicability of our avian-impact offset method using examples for wind and oil infrastructure. We also apply our method to an example in which the biological value of the offset habitat is similar to the impacted habitat, based on similarity in habitat type (e.g., native prairie), geographical location, land use, and landscape composition, as well as to an example in which the biological value of the offset habitat is dissimilar to the impacted habitat. We provide a worksheet that informs potential users how to apply our method to their specific developments and a framework for developing decision-support tools aimed at achieving landscape-level conservation goals

Maximizing the ecological contribution of conservation banks

In 1995, California established the first conservation banking program in the United States to provide a new financial mechanism to conserve wildlife and natural communities in rapidly developing regions. Conservation banks are lands protected and managed for conservation of species of concern. Developers may purchase species credits from a conservation bank to offset adverse impacts of development at another site. Conservation banks facilitate pooling of mitigation resources from multiple development projects to protect planned habitat reserves of greater ecological value than can be achieved with project-byproject mitigation. In this study, we conducted the first ever assessment of the ecological performance of the California Conservation Banking Program. Specifically, we investigated to what extent conservation banks contribute to achieving regional conservation objectives.We hypothesized that conservation banks within a region should have similarly high ecological values if they are appropriately evaluated and prioritized based on principles of conservation planning. We created a new ecological value metric to evaluate and rank conservation banks and used it to compare potential conservation banks or reserves within a region. We found the ecological value of banks within regions varied and concluded that maximizing the ecological contribution of conservation banks requires prioritization of lands for potential bank sites and reserves. Our analysis identified circumstances where conservation banking is not an appropriate mitigation mechanism to protect rare species and natural communities. We concluded that limited funding for conservation planning should be directed toward regions where species of concern are wide-ranging, biodiversity is highly variable, threats to species of concern are highly varied, and there are many potential conservation bank sites. © 2013 The Wildlife Society

Habitat, Fish Species, and Fish Assemblage Associations of the Topeka Shiner in West-Central Iowa

Our goal was to identify habitat, fish species, and fish assemblages associated with the occurrence of Topeka Shiners Notropis topeka in stream and off-channel habitat (OCH) of west-central Iowa. Fish assemblages and habitat characteristics were estimated in 67 stream and 27OCHsites during 2010–2011. Topeka Shiners were sampled in 52% of OCH sites, but in only 9% of stream sites, which supports the hypothesis that OCH is an important component of their life history. Fish assemblages containing Topeka Shiners were different from those that did not contain Topeka Shiners in OCH sites, but this was not evident in stream sites. Results from logistic regression models suggested that Topeka Shiner presence was associated with increased submerged vegetation and abundance of Fathead Minnow Pimephales promelas. Contrary to the findings of other studies, the abundance of large piscivorous fishes was not associated with the occurrence of Topeka Shiners. Our results provide new information about the biology and life history of the Topeka Shiner that will guide habitat restoration and other recovery efforts

Extreme site fidelity as an optimal strategy in an unpredictable and homogeneous environment

1. Animal site fidelity structures space use, population demography and ultimately gene flow. Understanding the adaptive selection for site fidelity patterns provides a mechanistic understanding to both spatial and population processes. This can be achieved by linking space use with environmental variability (spatial and temporal) and demographic parameters. However, rarely is the environmental context that drives the selection for site fidelity behaviour fully considered. 2. We use ecological theory to understand whether the spatial and temporal variability in breeding site quality can explain the site fidelity behaviour and demographic patterns of Gunnison sage‐grouse (Centrocercus minimus). We examined female site fidelity patterns across multiple spatial scales: proximity of consecutive year nest locations, space‐use overlap within and across the breeding and brooding seasons, and fidelity to a breeding patch. We also examined the spatial and temporal variability in nest, chick, juvenile and adult survival. 3. We found Gunnison sage‐grouse to be site faithful to their breeding patch, area of use within the patch and generally where they nest, suggesting an “Always Stay” site fidelity strategy. This is an optimal evolutionary strategy when site quality is unpredictable. Further, we found limited spatial variability in survival within age groups, suggesting little demographic benefit to moving among patches. We suggest Gunnison sage‐grouse site fidelity is driven by the unpredictability of predation in a relatively homogeneous environment, the lack of benefits and likely costs to moving across landscape patches and leaving known lek and breeding/brooding areas. 4. Space use and demography are commonly studied separately. More so, site fidelity patterns are rarely framed in the context of ecological theory, beyond questions related to the win‐stay:lose‐switch rule. To move beyond describing patterns and understand the adaptive selection driving species movements and their demographic consequences require integrating movement, demography and environmental variability in a synthetic framework. 5. Site fidelity theory provides a coherent framework to simultaneously investigate the spatial and population ecology of animal populations. Using it to frame ecological questions will lead to a more mechanistic understanding of animal movement, spatial population structuring and meta‐population dynamics

Sage‐Grouse Breeding and Late Brood‐Rearing Habitat Guidelines in Utah

Delineation, protection, and restoration of habitats provide the basis for endangered and threatened species recovery plans. Species recovery plans typically contain guidelines that provide managers with a scientific basis to designate and manage critical habitats. As such, habitat guidelines are best developed using data that capture the full diversity of ecological and environmental conditions that provide habitat across the species’ range. However, when baseline information, which fails to capture habitat diversity, is used to develop guidelines, inconsistencies and problems arise when applying those guidelines to habitats within an ecologically diverse landscape. Greater sage‐grouse (Centrocercus urophasianus; sage‐ grouse) populations in Utah, USA, reflect this scenario—published range‐wide habitat guidelines developed through a literature synthesis did not include data from the full range of the species. Although all sage‐ grouse are considered sagebrush obligates (Artemisia spp.), the species occupies a diversity of sagebrush communities from shrub‐dominated semideserts in the southwest to more perennial grass‐dominated sagebrush‐steppe in the northeast portions of their distribution. Concomitantly, local ecological site and environmental conditions may limit the ability of managers to achieve broader range‐wide habitat guidelines. We combined microsite habitat vegetation parameters from radiomarked sage‐grouse nest and brood locations with state‐wide spatially continuous vegetation, climatic, and elevation data in a cluster analysis to develop empirically based sage‐grouse habitat guidelines that encompass the range of ecological and environmental variation across Utah. Using this novel approach, we identified 3 distinct clusters of sage‐grouse breeding (i.e., nesting and early brood‐rearing) and late brood‐rearing habitats in Utah. For each cluster, we identified specific vegetation recommendations that managers can use to assess sage‐grouse breeding and late brood‐rearing habitat. Our results provide relevant guidelines to Utah’s sage‐grouse populations and are feasible given the unique ecological variation found therein. This approach may have application to other species that occupy diverse habitats and physiographic regions