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At least 1,387 records · Page 77Linked to original sources

USGS2021

Life-history theory provides a framework for detecting resource limitation: A test of the Nutritional Buffer Hypothesis

For ungulates and other long-lived species, life-history theory predicts that nutritional reserves are allocated to reproduction in a state-dependent manner because survival is highly conserved. Further, as per capita food abundance and nutritional reserves decline (i.e., density dependence intensifies), reproduction and recruitment become increasingly sensitive to weather. Thus, the degree to which weather influences vital rates should be associated with proximity to nutritional carrying capacity—a notion that we refer to as the Nutritional Buffer Hypothesis. We tested the Nutritional Buffer Hypothesis using six moose ( Alces alces ) populations that varied in calf recruitment (33–69 calves/100 cows). We predicted that populations with high calf recruitment were nutritionally buffered against the effects of unfavorable weather, and thus were below nutritional carrying capacity. We applied a suite of tools to quantify habitat and nutritional condition of each population and found that increased browse condition, forage quality, and body fat were associated with increased pregnancy and calf recruitment, thereby providing multiple lines of evidence that declines in calf recruitment were underpinned by resource limitation. From 2001 to 2015, recruitment was more sensitive to interannual variation in weather (e.g., winter severity, drought) and plant phenology (e.g., duration of spring) for populations with reduced browse condition, forage quality, and body fat, suggesting these populations lacked the nutritional reserves necessary to buffer demographic performance against the effects of unfavorable weather. Further, average within-population calf recruitment was determined by regional climatic variation, suggesting that the pattern of reduced recruitment near the southern range boundary of moose stems from an interaction between climate and resource limitation. When coupled with information on habitat, nutrition, weather, and climate, life-history theory provides a framework to estimate nutritional limitation, proximity to nutritional carrying capacity, and impacts of climate change for ungulates.

Colorado, Utah, Wyoming↗

USGS2015

Value of information in natural resource management: technical developments and application to pink-footed geese

The “value of information” (VOI) is a generic term for the increase in value resulting from better information to guide management, or alternatively, the value foregone under uncertainty about the impacts of management (Yokota and Thompson, Medical Decision Making 2004; 24 : 287). The value of information can be characterized in terms of several metrics, including the expected value of perfect information and the expected value of partial information. We extend the technical framework for the value of information by further developing the relationship between value metrics for partial and perfect information and describing patterns of their performance. We use two different expressions for the expected value of partial information to highlight its relationship to the expected value of perfect information. We also develop the expected value of partial information for hierarchical uncertainties. We highlight patterns in the value of information for the Svalbard population of the pink-footed goose ( Anser brachyrhynchus ), a population that is subject to uncertainty in both reproduction and survival functions. The framework for valuing information is seen as having widespread potential in resource decision making, and serves as a motivation for resource monitoring, assessment, and collaboration.

Svalbard↗

USGS2020

Fatty acid-based diet estimates suggest ringed seal remain the main prey of southern Beaufort Sea polar bears despite recent use of onshore food resources

Polar bears ( Ursus maritimus ) from the southern Beaufort Sea (SB) subpopulation have traditionally fed predominantly upon ice‐seals; however, as the proportion of the subpopulation using onshore habitat has recently increased, foraging on land‐based resources, including remains of subsistence‐harvested bowhead whales ( Balaena mysticetus ) and colonial nesting seabirds has been observed. Adipose tissue samples were collected from this subpopulation during the springs of 2013–2016 and analyzed for fatty acid signatures. Diet estimates were generated for the proportional consumption of ringed seal ( Pusa hispida ), bearded seal ( Erignathus barbatus ), and beluga whale ( Delphinapterus leucas ), relative to onshore foods, including bowhead whale remains and seabird, as represented by black guillemot ( Cepphus grylle mandtii ) nestlings and eggs. Quantitative fatty acid signature analysis (QFASA) estimated that the ice‐obligate prey, ringed seal, remained the predominant prey species of SB polar bears (46.4 ± 1.8%), with much lower consumption of bearded seal (19.6 ± 2.0%), seabird (17.0 ± 1.2%), bowhead whale (15.0 ± 1.4%), and hardly any beluga whale (2.0 ± 0.5%). Adult and subadult females appeared to depend more on the traditional ringed seal prey than adult and subadult males. Diet estimates of SB polar bears showed significant interannual variability for all prey ( F 12, 456 = 3.17, p < .001). Longer‐term estimates suggested that both types of onshore prey, bowhead whale remains and seabird, have represented a moderate proportion of the food resources used by SB polar bears since at least the start of the 21st Century.

Alaska↗

USGS2021

Multiple coping strategies maintain stability of a small mammal population in a resource-restricted environment

In semi-arid environments, aperiodic rainfall pulses determine plant production and resource availability for higher trophic levels, creating strong bottom-up regulation. The influence of climatic factors on population vital rates often shapes the dynamics of small mammal populations in such resource-restricted environments. Using a 21-year biannual capture–recapture dataset (1993 to 2014), we examined the impacts of climatic factors on the population dynamics of the brush mouse ( Peromyscus boylii ) in semi-arid oak woodland of coastal-central California. We applied Pradel's temporal symmetry model to estimate capture probability ( p ), apparent survival ( φ ), recruitment ( f ), and realized population growth rate ( λ ) of the brush mouse and examined the effects of temperature, rainfall, and El Niño on these demographic parameters. The population was stable during the study period with a monthly realized population growth rate of 0.993 ± SE 0.032, but growth varied over time from 0.680 ± 0.054 to 1.450 ± 0.083. Monthly survival estimates averaged 0.789 ± 0.005 and monthly recruitment estimates averaged 0.175 ± 0.038. Survival probability and realized population growth rate were positively correlated with rainfall and negatively correlated with temperature. In contrast, recruitment was negatively correlated with rainfall and positively correlated with temperature. Brush mice maintained their population through multiple coping strategies, with high recruitment during warmer and drier periods and higher survival during cooler and wetter conditions. Although climatic change in coastal-central California will likely favor recruitment over survival, varying strategies may serve as a mechanism by which brush mice maintain resilience in the face of climate change. Our results indicate that rainfall and temperature are both important drivers of brush mouse population dynamics and will play a significant role in predicting the future viability of brush mice under a changing climate.

California↗

USGS2018

Resource competition model predicts zonation and increasing nutrient use efficiency along a wetland salinity gradient

A trade-off between competitive ability and stress tolerance has been hypothesized and empirically supported to explain the zonation of species across stress gradients for a number of systems. Since stress often reduces plant productivity, one might expect a pattern of decreasing productivity across the zones of the stress gradient. However, this pattern is often not observed in coastal wetlands that show patterns of zonation along a salinity gradient. To address the potentially complex relationship between stress, zonation, and productivity in coastal wetlands, we developed a model of plant biomass as a function of resource competition and salinity stress. Analysis of the model confirms the conventional wisdom that a trade-off between competitive ability and stress tolerance is a necessary condition for zonation. It also suggests that a negative relationship between salinity and production can be overcome if (1) the supply of the limiting resource increases with greater salinity stress or (2) nutrient use efficiency increases with increasing salinity. We fit the equilibrium solution of the dynamic model to data from Louisiana coastal wetlands to test its ability to explain patterns of production across the landscape gradient and derive predictions that could be tested with independent data. We found support for a number of the model predictions, including patterns of decreasing competitive ability and increasing nutrient use efficiency across a gradient from freshwater to saline wetlands. In addition to providing a quantitative framework to support the mechanistic hypotheses of zonation, these results suggest that this simple model is a useful platform to further build upon, simulate and test mechanistic hypotheses of more complex patterns and phenomena in coastal wetlands.

Louisiana↗

USGS2019

Antipredator response diminishes during periods of resource deficit for a large herbivore

The starvation-predation hypothesis predicts that, during resource shortages, prey forego antipredator behavior and forage as much as possible to avoid starvation, even when risk of predation is high. We tested this hypothesis using GPS locations collected simultaneously from moose (Alces alces) and wolves (Canis lupus) in the Greater Yellowstone Ecosystem of North America. We assessed shifts in the speed, displacement, and habitat selection of moose 24 hours following encounter with wolves (0–1500 m distance). We examined whether the strength of antipredator behaviors would weaken as winter progressed and the nutritional condition of moose declined. Moose responded to wolf encounters by increasing their rate of movement in early winter, but only within 500 m distance. Importantly, these responses attenuated as winter progressed. Moose did not avoid their preferred foraging habitat (riparian areas) following encounters with wolves at any distance, and instead they more strongly selected riparian areas, especially in early winter. Our findings support theoretical predictions that resource deficits should dampen prey antipredator behavior, and suggest that nutritional condition of prey may buffer against run-away risk effects in food webs involving large mammalian predators and prey.

Wyoming↗

USGS2020

Trait‐based variation in host contribution to pathogen transmission across species and resource supplies

Two key knowledge gaps currently limit the development of more predictive and general models of pathogen transmission: (1) the physiological basis of heterogeneity in host contribution to pathogen transmission (reservoir potential) remains poorly understood, and (2) a general means of integrating the ecological dynamics of host communities has yet to emerge. If the traits responsible for differences in reservoir potential also modulate host community dynamics, these traits could be used to predict pathogen transmission as host communities change. In two greenhouse experiments, across 23 host species and two levels of resource supply, the reservoir potential of plant hosts increased significantly along the Leaf Economic Spectrum, a global axis of plant physiological trait covariation that features prominently in models of plant community ecology. This indicates that the traits of the Leaf Economic Spectrum underlie broad differences in reservoir potential across host species and resource supplies. Therefore, host traits could be used to integrate epidemiological models of pathogen transmission with ecological models of host community change.

Ecology↗

USGS2018

Anticipatory natural resource science and management for a changing future

Prolonged shifts in long‐term average climate conditions and increasing variability in short‐term weather conditions affect ecological processes, and represent a fundamental challenge for natural resource management. Recent and forthcoming advances in climate predictability may offer novel opportunities, but capitalizing on these opportunities will require focusing scientific research on understanding the links between climate and ecological responses over multiple timescales, fostering programmatic links among science and management agencies, and developing new and flexible decision‐making frameworks. Anticipating short‐ to near‐term climate conditions can help managers mitigate land degradation driven by unfavorable conditions and promote actions that make the most of favorable conditions. Similarly, anticipating long‐term, multidecadal climate trajectories can help managers to identify those species and communities that are most likely to remain viable throughout the 21st century. A focus on “anticipatory science and management” could substantially bolster natural resource planning and management but will require long‐term investment and widespread adoption.

Frontiers in Ecology and the Environment↗

USGS2022

Dynamic estimates of geologic CO2 storage resources in the Illinois Basin constrained by reinjectivity of brine extracted for pressure management

Geologic carbon storage (GCS) is likely to be an important part of global efforts to decarbonize the energy industry. Widespread deployment of GCS relies on strategies to maximize CO 2 injection rates while minimizing reservoir pressurization that could induce seismicity and/or fluid leakage into groundwater resources. Brine extraction from CO 2 storage formations with subsurface reinjection elsewhere could mitigate pressure buildup associated with GCS. Therefore, evaluation of CO 2 storage resources should consider the injectivity of produced brine in geologic layers above or below the CO 2 storage formation. For this study, a methodology was developed to estimate brine injectivity from formation depth and thickness using flow modeling and optimization techniques. The methodology was demonstrated in the Illinois Basin, where GCS in the Mt. Simon Sandstone is ongoing. Based on pressure constraints and considering only regions of the shallower units where salinity and sealing conditions were met, maximum brine injection rates were estimated within the Mt. Simon and three overlying hydrostratigraphic layers. Results indicate that a large area exists where CO 2 injectivity could be optimized by brine extraction and reinjection.

Illinois, Indiana↗

USGS2015

Climate change and water resources in a tropical island system: Propagation of uncertainty from statistically downscaled climate models to hydrologic models

Many tropical islands have limited water resources with historically increasing demand, all potentially affected by a changing climate. The effects of climate change on island hydrology are difficult to model due to steep local precipitation gradients and sparse data. This work uses 10 statistically downscaled general circulation models (GCMs) under two greenhouse gas emission scenarios to evaluate the uncertainty propagated from GCMs in projecting the effects of climate change on water resources in a tropical island system. The assessment is conducted using a previously configured hydrologic model, the Precipitation Runoff Modelling System (PRMS) for Puerto Rico. Projected climate data and their modelled hydrologic variables versus historical measurements and their modelled hydrologic variables are found to have empirical distribution functions that are statistically different with less than 1 year of daily data aggregation. Thus, only annual averages of the projected hydrologic variables are employed as completely bias‐corrected model outputs. The magnitude of the projected total flow decreases in the four regions covering Puerto Rico, but with a large range of uncertainty depending on the makeup of the GCM ensemble. The multi‐model mean projected total flow decreases by 49–88% of historical amounts from the 1960s to the 2090s for the high emissions scenarios and by 39–79% for the low emissions scenarios. Subsurface flow contributions decreased the least and groundwater flow contributions decreased the most across the island. At locations critical to water supply for human use, projected streamflow is shown to decrease substantially below projected withdrawals by 2099.

Puerto Rico↗

USGS2011

Evaluation of a black-footed ferret resource utilization function model

Resource utilization function (RUF) models permit evaluation of potential habitat for endangered species; ideally such models should be evaluated before use in management decision‐making. We evaluated the predictive capabilities of a previously developed black‐footed ferret ( Mustela nigripes ) RUF. Using the population‐level RUF, generated from ferret observations at an adjacent yet distinct colony, we predicted the distribution of ferrets within a black‐tailed prairie dog ( Cynomys ludovicianus ) colony in the Conata Basin, South Dakota, USA. We evaluated model performance, using data collected during post‐breeding spotlight surveys (2007–2008) by assessing model agreement via weighted compositional analysis and count‐metrics. Compositional analysis of home range use and colony‐level availability, and core area use and home range availability, demonstrated ferret selection of the predicted Very high and High occurrence categories in 2007 and 2008. Simple count‐metrics corroborated these findings and suggested selection of the Very high category in 2007 and the Very high and High categories in 2008. Collectively, these results suggested that the RUF was useful in predicting occurrence and intensity of space use of ferrets at our study site, the 2 objectives of the RUF. Application of this validated RUF would increase the resolution of habitat evaluations, permitting prediction of the distribution of ferrets within distinct colonies. Additional model evaluation at other sites, on other black‐tailed prairie dog colonies of varying resource configuration and size, would increase understanding of influences upon model performance and the general utility of the RUF.

South Dakota↗

USGS2017

Sandhill crane roost selection, human disturbance, and forage resources

Sites used for roosting represent a key habitat requirement for many species of birds because availability and quality of roost sites can influence individual fitness. Birds select roost sites based on numerous factors, requirements, and motivations, and selection of roosts can be dynamic in time and space because of various ecological and environmental influences. For sandhill cranes (Antigone canadensis) at their main spring-staging area along the Platte River in south-central Nebraska, USA, past investigations of roosting cranes focused on physical channel characteristics related to perceived security as motivating roost distribution. We used 6,310 roost sites selected by 313 sandhill cranes over 5 spring migration seasons (2003–2007) to quantify resource selection functions of roost sites on the central Platte River using a discrete choice analysis. Sandhill cranes generally showed stronger selection for wider channels with shorter bank vegetation situated farther from potential human disturbance features such as roads, bridges, and dwellings. Furthermore, selection for roost sites with preferable physical characteristics (wide channels with short bank vegetation) was more resilient to nearby disturbance features than more narrow channels with taller bank vegetation. The amount of cornfields surrounding sandhill crane roost sites positively influenced relative probability of use but only for more narrow channels < 100 m and those with shorter bank vegetation. We confirmed key resource features that sandhill cranes selected at river channels along the Platte River, and after incorporating spatial variation due to human disturbance, our understanding of roost site selection was more robust, providing insights on how disturbance may interact with physical habitat features. Managers can use information on roost-site selection when developing plans to increase probability of crane use at existing roost sites and to identify new areas for potential use if existing sites become limited.

Nebraska↗

USGS2025

Cultivating reciprocity and supporting Indigenous lifeways through the cultural transformation of natural resource management in North America

Recent decades have seen increasing calls for implementing Indigenous Knowledges (IK) in natural resource management (NRM). However, efforts have been limited by the cultural incommensurabilities between (1) NRM institutions, which are rooted in worldviews that prioritize extraction for dominant cultures and assume dominance over nature and (2) Indigenous worldviews that prioritize kincentric reciprocity with the environment. This manuscript addresses how transforming NRM institutions enables management to better support Indigenous Knowledges and lifeways. This manuscript examines incommensurabilities between NRM institutional cultures and Indigenous cultures, with the value and lifeway of reciprocity as the focal point. Through synthesizing interdisciplinary scholarship and examples from author experiences, we explore how NRM institutions in North America can transform to honour and facilitate reciprocity, especially within efforts to implement IK and support Indigenous lifeways. NRM institutions are cultural products, and in North America were born of colonial histories and cultural roots connected to modern governance and power dynamics. These cultural foundations led to NRM approaches that prioritize maximizing economic growth while guarding against overexploitation. Kincentric reciprocal relations with the environment often emphasize interdependency with more-than-human kin, place-based holistic Knowledges grounded in cultural practices and communal responsibility to cultivate social-ecological abundance for present and future generations. Incommensurabilities between NRM institutional cultures and Indigenous cultures impede efforts to implement IK and support Indigenous lifeways as: (1) rigid institutional structures do not account for Indigenous worldviews and values but instead attempt to fit IK within dominant paradigms; (2) the siloing of NRM leads to the piecemealing and invalidation of IK at the expense of Knowledge Holders and (3) ineffective public engagement strategies limit the possibility of reciprocal relations between NRM institutions and communities throughout management processes. Incommensurabilities between NRM institutional cultures and Indigenous cultures impede efforts to implement IK and support Indigenous lifeways as: (1) rigid institutional structures do not account for Indigenous worldviews and values but instead attempt to fit IK within dominant paradigms; (2) the siloing of NRM leads to the piecemealing and invalidation of IK at the expense of Knowledge Holders and (3) ineffective public engagement strategies limit the possibility of reciprocal relations between NRM institutions and communities throughout management processes. Transforming NRM institutional cultures to better implement IK and support Indigenous lifeways is key for redressing long-standing issues and ensuring social-ecological resilience and abundance. Heavy investments of time, personnel and resources are necessary for transforming NRM institutions to appropriately cultivate reciprocal relations with Indigenous communities and lands. Strategies towards transformation include decentralization through decolonial frameworks, knowledge co-production and using place-based cultural evaluation processes to improve cultural alignment.

People and Nature↗

USGS2022

Endemic Guadalupe bass (Micropterus treculii) are supported by isotopically distinct resources in tributary versus mainstem river food webs

We used stable isotope analysis to investigate differences in Guadalupe bass ( Micropterus treculii ) resource use that might be associated with population-level variation in mainstem river versus tributary stream habitats. Guadalupe bass from mainstem sites had higher δ 13 C and δ 15 N values compared to those collected in tributaries, likely reflecting greater importance of algae as a basal resource and influences of urban wastewater in mainstem habitats. Documenting ecological variation across ecosystem types is important to inform fish conservation efforts, especially for species that occupy a range of stream sizes.

Texas↗

USGS2025

Dusky grouse seasonal resource selection in the Great Basin isolated mountain ranges of Nevada, USA

Dusky grouse Dendragapus obscurus are a montane forest grouse species with a paucity of information regarding their temporal and spatial resource use during critical times of high mortality and reproductive output. This lack of vital data may leave dusky grouse at risk of sub-optimal management in many areas of their distribution, especially in the isolated ‘sky island' mountain ranges of the Great Basin, where high elevation habitats are surrounded by sagebrush and salt desert shrubland flats. Many of these high elevation habitats are being altered and lost rapidly from increasing disturbance events and effects of climate change. Our objective was to evaluate dusky grouse resource selection in the Schell Creek, Duck Creek, and Egan ranges of White Pine County, Nevada, USA, during breeding, nesting, brood-rearing, and over winter to identify habitats of importance for concentrating conservation actions. We found that breeding male dusky grouse selected for aspen stands, nearness to water, and nearness to forest edges, while breeding female dusky grouse selected for mountain mahogany, aspen, and mountain shrub communities (i.e. sagebrush), and areas with high predicted probability of males. Nesting female dusky grouse selected for mountain shrub communities, intermediate elevation, low ruggedness, and high percent shrub cover. Brooding female dusky grouse selected for aspen and mountain shrub communities, nearness to water, high percent shrub cover, and intermediate elevation and ruggedness. Finally, wintering female dusky grouse selected for spruce–fir and pine conifer types, high elevation and ruggedness, and farther distances from forest edges, while selecting against high percent tree canopy cover. Our results suggest that dusky grouse presence may indicate aspen and conifer community health in the Great Basin mountain ranges. Conservation priority could be placed on these limited vegetation communities, especially given the slow regeneration and growth in the region due to the arid climate and xeric soils.

Nevada↗

USGS2014

Competitive interactions and resource partitioning between northern spotted owls and barred owls in western Oregon

The federally threatened northern spotted owl ( Strix occidentalis caurina ) is the focus of intensive conservation efforts that have led to much forested land being reserved as habitat for the owl and associated wildlife species throughout the Pacific Northwest of the United States. Recently, however, a relatively new threat to spotted owls has emerged in the form of an invasive competitor: the congeneric barred owl ( S. varia ). As barred owls have rapidly expanded their populations into the entire range of the northern spotted owl, mounting evidence indicates that they are displacing, hybridizing with, and even killing spotted owls. The range expansion by barred owls into western North America has made an already complex conservation issue even more contentious, and a lack of information on the ecological relationships between the 2 species has hampered recovery efforts for northern spotted owls. We investigated spatial relationships, habitat use, diets, survival, and reproduction of sympatric spotted owls and barred owls in western Oregon, USA, during 2007–2009. Our overall objective was to determine the potential for and possible consequences of competition for space, habitat, and food between these previously allopatric owl species. Our study included 29 spotted owls and 28 barred owls that were radio-marked in 36 neighboring territories and monitored over a 24-month period. Based on repeated surveys of both species, the number of territories occupied by pairs of barred owls in the 745-km 2 study area (82) greatly outnumbered those occupied by pairs of spotted owls (15). Estimates of mean size of home ranges and core-use areas of spotted owls (1,843 ha and 305 ha, respectively) were 2–4 times larger than those of barred owls (581 ha and 188 ha, respectively). Individual spotted and barred owls in adjacent territories often had overlapping home ranges, but interspecific space sharing was largely restricted to broader foraging areas in the home range with minimal spatial overlap among core-use areas. We used an information-theoretic approach to rank discrete-choice models representing alternative hypotheses about the influence of forest conditions, topography, and interspecific interactions on species-specific patterns of nighttime resource selection. Spotted owls spent a disproportionate amount of time foraging on steep slopes in ravines dominated by old (>120 yr) conifer trees. Barred owls used available forest types more evenly than spotted owls, and were most strongly associated with patches of large hardwood and conifer trees that occupied relatively flat areas along streams. Spotted and barred owls differed in the relative use of old conifer forest (greater for spotted owls) and slope conditions (steeper slopes for spotted owls), but we found no evidence that the 2 species differed in their use of young, mature, and riparian-hardwood forest types. Mean overlap in proportional use of different forest types between individual spotted owls and barred owls in adjacent territories was 81% (range = 30–99%). The best model of habitat use for spotted owls indicated that the relative probability of a location being used was substantially reduced if the location was within or in close proximity to a core-use area of a barred owl. We used pellet analysis and measures of food-niche overlap to determine the potential for dietary competition between spatially associated pairs of spotted owls and barred owls. We identified 1,223 prey items from 15 territories occupied by spotted owls and 4,299 prey items from 24 territories occupied by barred owls. Diets of both species were dominated by nocturnal mammals, but diets of barred owls included many terrestrial, aquatic, and diurnal prey species that were rare or absent in diets of spotted owls. Northern flying squirrels ( Glaucomys sabrinus ), woodrats ( Neotoma fuscipes , N. cinerea ), and lagomorphs ( Lepus americanus , Sylvilagus bachmani ) were primary prey for both owl species, accounting for 81% and 49% of total dietary biomass for spotted owls and barred owls, respectively. Mean dietary overlap between pairs of spotted and barred owls in adjacent territories was moderate (42%; range = 28–70%). Barred owls displayed demographic superiority over spotted owls; annual survival probability of spotted owls from known-fate analyses (0.81, SE = 0.05) was lower than that of barred owls (0.92, SE = 0.04), and pairs of barred owls produced an average of 4.4 times more young than pairs of spotted owls over a 3-year period. We found a strong, positive relationship between seasonal (6-month) survival probabilities of both species and the proportion of old (>120 yr) conifer forest within individual home ranges, which suggested that availability of old forest was a potential limiting factor in the competitive relationship between these 2 species. The annual number of young produced by spotted owls increased linearly with increasing distance from a territory center of a pair of barred owls, and all spotted owls that attempted to nest within 1.5 km of a nest used by barred owls failed to successfully produce young. We identified strong associations between the presence of barred owls and the behavior and fitness potential of spotted owls, as shown by changes in movements, habitat use, and reproductive output of spotted owls exposed to different levels of spatial overlap with territorial barred owls. When viewed collectively, our results support the hypothesis that interference competition with barred owls for territorial space can constrain the availability of critical resources required for successful recruitment and reproduction of spotted owls. Availability of old forests and associated prey species appeared to be the most strongly limiting factors in the competitive relationship between these species, indicating that further loss of these conditions can lead to increases in competitive pressure. Our findings have broad implications for the conservation of spotted owls, as they suggest that spatial heterogeneity in vital rates may not arise solely because of differences among territories in the quality or abundance of forest habitat, but also because of the spatial distribution of a newly established competitor. Experimental removal of barred owls could be used to test this hypothesis and determine whether localized control of barred owl numbers is an ecologically practical and socio-politically acceptable management tool to consider in conservation strategies for spotted owls.

Oregon↗

USGS2026

Regional conservation planning tool: A spreadsheet model to support spatial prioritization and resource allocation decisions

Prioritization is a central component of natural resource management because conservation needs routinely exceed available resources. Waterfowl and wetland conservation programs in North America are at the forefront of landscape-scale prioritization and transboundary management decisions due to the migratory nature of ducks, geese, and swans. The growing availability of geographic information systems (GIS) and geospatial technologies has accelerated the development of multi-objective landscape prioritization models, including applications of structured decision making and multi-criteria decision analysis to spatial planning for waterfowl and wetlands at the continental scale. However, regional managers and conservationists could benefit from flexibility in downscaling continental tools, selecting objectives, and assigning weights for rapid production of spatial prioritization models at smaller spatial scales without extensive computer coding or GIS analysis. We developed a spatial value model that prioritizes landscapes at sub-continental scales (e.g., states and provinces, bird conservation regions, etc.) and provides flexibility for users to select waterfowl conservation objectives of interest and weights. Our model can be used for direct downscaling of an existing continental geospatial model or further customized with region-specific geospatial data. We illustrate how regional prioritization can vary with the spatial scale selected by the user. The spatial value modeling framework and the downscaling tool presented here could increase the use of multi-criteria decision analysis and linear value modeling in spatial landscape prioritization, while also providing flexibility for selecting scales, objectives, and weights. Our spreadsheet tool was developed specifically for use by regional biologists, conservationists, and managers and does not require knowledge of GIS software (although results can be exported from the spreadsheet for spatial analysis using GIS). Together, the model outputs and the accompanying spreadsheet tool provide a bridge between continental waterfowl conservation and regional implementation, enabling rapid, stakeholder-driven, value-explicit prioritization.

Wildlife Society Bulletin↗

USGS1979

Manganese nodule resources in the northeastern equatorial Pacific

Recent publication of maps at scale 1:1,000,000 of the northeastern equatorial Pacific region showing publicly available information on the nickel plus copper content of manganese nodules has made it possible to outline the prime area between the Clarion and Clipperton fracture zones which has been the focus of several recent scientific and commercial studies. The area, defined as that in which the nodules contain more than 1.8 percent nickel plus copper, is about 2o5 million km 2 . The available evidence suggests that about half of it contains nodules in concentration (reported in wet weight units) greater than 5 kg/m 2 and averaging 11.9 kg/m 2 . If we assume that 20 percent of the nodules in this area of 1.25 million km 2 are recoverable, its potential recoverable resources are about 2.1 billion dry metric tons of nodules averaging about 25 percent Mn, 1.3 percent Ni, 1.0 percent Cu, 0.22 percent Co, and 0.05 percent Mo—enough to support about 27 mining operations each producing an average of 75 million metric tons of nodules over their lifetimes. Estimates based on other plausible assumptions would be higher or lower, but of the same order of magnitude. Thus it seems probable that the magnitude of the potentially recoverable nodule resources of the Clarion-Clipperton prime area—the most promising now known—is at most in the range of several tens of the average-size operations postulated.

Book chapter↗