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Geology topics

Joshua J. Millspaugh

Publications and source records attributed to Joshua J. Millspaugh.

10 recordsLinked to original sources
USGS2024

Leveraging local wildlife surveys for robust occupancy trend estimation

Natural resource agencies are frequently tasked with monitoring populations of at-risk species to ensure management activities do not negatively affect the viability of wildlife populations. Typically, these monitoring efforts evaluate trends in a population’s abundance, occupancy, or geographic distribution. Often, surveys provide local information, but results are generally not incorporated into broad-scale monitoring efforts that focus on range-wide population changes due to their variable nature in both spatial extent and effort. We investigated whether aggregating these local (hereafter “variable”) surveys can generate enough statistical power to estimate broad-scale population trends using simulations of declining populations of fishers ( Pekania pennati ) over a 10-year time horizon. Our simulations included three population sizes which we refer to as abundant, common, and rare ( N 0 = 700, 350, and 100 individuals, respectively) with each declining at a rapid and moderate pace ( λ = 0.933, and 0.977, respectively). For each population, we simulated variable surveys using an occupancy framework to subsample the population with parameters that mimic combining multiple independent monitoring efforts which vary annually in location, and effort. Regardless of spatial consistency of annual sampling, there was minimal variation in statistical power under both high and low detection probability simulations. However, when sampling effort varied each year, statistical power was lower for most populations and sampling scenarios when compared to consistent sampling effort unless some baseline level of sampling effort was reliably achieved in all years. In many cases, adding low-level consistent baseline sampling to variable surveys resulted in statistical power close to that of consistent sampling efforts. Our results suggest statistical power is driven by annual consistency in the proportion of landscape sampled rather than spatial consistency in sampling locations. This result indicates that current variable surveys could be leveraged and combined to detect population declines for at-risk species at broad-scales if a baseline proportion of landscape is robustly sampled. The level of baseline sampling is highly dependent on population size and magnitudes of population change. In simulations with a common or abundant population experiencing a rapid decline, a baseline survey effort of at least 5% of the landscape in combination with variable surveys resulted in statistical power consistently above the standard threshold of 0.80 for occupancy monitoring. Leveraging existing local efforts to achieve high detection probability and baseline sampling would reduce financial and logistical burdens of broad-scale wildlife monitoring efforts.

Idaho, Montana↗
USGS2019

Developing a decision-support process for landscape conservation design

Planning for sustainable landscapes is hampered by uncertainty in how species will respond to conservation actions amidst impacts from landscape and climate change. Planning decisions, including tradeoffs among competing species objectives, are complex. We developed a decision-support framework that integrates dynamic-landscape metapopulation models (DLMPs) and structured decision making (SDM) to help guide landscape conservation design. With this framework, we demonstrated that planning for viable populations across broad scales can be achieved under global change. Furthermore, the integration of DLMPs with SDM enabled decisions to be more objective and transparent, and thus, more defensible.

Report↗
USGS2018

Integrating physiological stress into the movement ecology of migratory ungulates: A spatial analysis with mule deer

Rapid climate and human land-use change may limit the ability of long-distance migratory herbivores to optimally track or “surf” high-quality forage during spring green-up. Understanding how anthropogenic and environmental stressors influence migratory movements is of critical importance because of their potential to cause a mismatch between the timing of animal movements and the emergence of high-quality forage. We measured stress hormones (fecal glucocorticoid metabolites; FGMs) to test hypotheses about the effects of high-quality forage tracking, human land use, and use of stopover sites on the physiological state of individuals along a migratory route. We collected and analyzed FGM concentrations from 399 mule deer (Odocoileus hemionus) samples obtained along a 241 km migratory route in western Wyoming, USA, during spring 2015 and 2016. In support of a fitness benefit hypothesis, individuals occupying areas closer to peak forage quality had decreased FGM levels. Specifically, for every 10-day interval closer to peak forage quality, we observed a 7% decrease in FGMs. Additionally, we observed support for both an additive anthropogenic stress hypothesis and a hypothesis that stopovers act as physiological refugia, wherein individuals sampled far from stopover sites exhibited 341% higher FGM levels if in areas of low landscape integrity compared to areas of high landscape integrity. Overall, our findings indicate that the physiological state of mule deer during migration is influenced by both anthropogenic disturbances and their ability to track high-quality forage. The availability of stopovers, however, modulates physiological responses to those stressors. Thus, our results support a recent call for the prioritization of stopover locations and connectivity between those locations in conservation planning for migratory large herbivores.

Colorado, Wyoming↗
USGS2016

Assessing the sensitivity of avian species abundance to land cover and climate

Climate projections for the Midwestern United States predict southerly climates to shift northward. These shifts in climate could alter distributions of species across North America through changes in climate (i.e., temperature and precipitation), or through climate-induced changes on land cover. Our objective was to determine the relative impacts of land cover and climate on the abundance of five bird species in the Central United States that have habitat requirements ranging from grassland and shrubland to forest. We substituted space for time to examine potential impacts of a changing climate by assessing climate and land cover relationships over a broad latitudinal gradient. We found positive and negative relationships of climate and land cover factors with avian abundances. Habitat variables drove patterns of abundance in migratory and resident species, although climate was also influential in predicting abundance for some species occupying more open habitat (i.e., prairie warbler, blue-winged warbler, and northern bobwhite). Abundance of northern bobwhite increased with winter temperature and was the species exhibiting the most significant effect of climate. Models for birds primarily occupying early successional habitats performed better with a combination of habitat and climate variables whereas models of species found in contiguous forest performed best with land cover alone. These varied species-specific responses present unique challenges to land managers trying to balance species conservation over a variety of land covers. Management activities focused on increasing forest cover may play a role in mitigating effects of future climate by providing habitat refugia to species vulnerable to projected changes. Conservation efforts would be best served focusing on areas with high species abundances and an array of habitats. Future work managing forests for resilience and resistance to climate change could benefit species already susceptible to climate impacts.

Ecosphere↗
USGS2013

American badgers selectively excavate burrows in areas used by black-footed ferrets: implications for predator avoidance

We evaluated how American badgers ( Taxidea taxus ) might exert selective pressure on black-footed ferrets ( Mustela nigripes ) to develop antipredator defenses. In a colony of black-tailed prairie dogs ( Cynomys ludovicianus ) in South Dakota, badgers concentrated their activities where burrow openings and prairie dogs were abundant, a selective behavior that was exhibited by ferrets in the same colony. Badgers excavated burrows more often when in areas recently used by a ferret, suggesting that badgers hunt ferrets or steal prey from ferrets, or both. We also conducted an analysis of survival studies for ferrets and Siberian polecats ( M. eversmanii ) released onto prairie dog colonies. This polecat is the ferret's ecological equivalent but evolved without a digging predator. Badgers accounted for 30.0% of predation on polecats and 5.5% of predation on ferrets. In contrast, both polecats and ferrets have evolutionary experience with canids, providing a plausible explanation for the similar relative impact of coyotes ( Canis latrans ) on them (65.0% and 67.1% of predation, respectively). We hypothesize that ferrets and badgers coexist because ferrets are superior at exploitation competition and are efficient at avoiding badgers, and badgers are superior at interference competition.

South Dakota↗
USGS2012

Black-footed ferret digging activity in summer

Black-footed ferrets (Mustela nigripes) excavate soil from prairie dog (Cynomys spp.) burrows, thereby creating characteristic soil deposits at burrow openings. These soil deposits have been observed only rarely in summer. We monitored adult ferrets during June–October of the years 2007 and 2008 on a 452-ha colony of black-tailed prairie dogs (Cynomys ludovicianus) in the Conata Basin, South Dakota. We located and identified ferret excavations during nighttime spotlight surveys for ferrets and daytime sampling of prairie dog burrow openings around locations where ferrets were located via spotlight. We accumulated 48 observations of in-process or recently completed ferret excavations during spotlight surveys (21 in 2007, 27 in 2008) and located 51 diggings during daytime burrow sampling (25 in 2007, 26 in 2008). We located diggings during 5.5% of spotlight observations, most frequently in July–August. These results collectively suggest ferrets may frequently excavate soil in summer, because prairie dogs frequently use soil to plug burrow openings and tunnels in defense against ferrets. Prairie dogs might frequently destroy soil deposits left by ferrets during summer, thereby reducing detection of diggings by biologists.

South Dakota↗
USGS2012

Importance of lunar and temporal conditions for spotlight surveys of adult black-footed ferrets

Black-footed ferrets (Mustela nigripes) spend most daylight hours underground in prairie dog (Cynomys) burrows and exhibit aboveground movements primarily at night. Moonlight can influence the activity patterns of ferrets and, consequently, might influence the efficiency of spotlight surveys used by biologists to monitor ferret populations. We related detection of adult ferrets during postbreeding spotlight surveys to lunar and temporal conditions. We most frequently located ferrets during surveys in which the moon breached the horizon. The data suggested intersexual differences in response to moonlight. We located male ferrets most frequently during nights with greater moon illumination, but we did not detect a correlation between moon illumination and spotlight detection of female ferrets. In general, moonlight could facilitate aboveground navigation by ferrets. However, it seems activity under bright moonlight could be costly for female ferrets while they raise young. Detection of ferrets also varied among months. We detected female ferrets most frequently in August–September, when mothers increase hunting efforts to acquire prey for growing offspring (kits). Detection of adult female ferrets declined in October, when kits were likely independent of their mother. We located male ferrets most frequently in September–October, when males might increase activity to monitor female ferrets and male competitors. Consideration of lunar and temporal influences and standardization of postbreeding surveys could enhance site-specific assessment of reintroduction success and across-site assessment of species recoveiy progress. We suggest that postbreeding surveys for ferrets should be enhanced by concentrating efforts in August–September during moonlit nights when the moon is above the horizon.

Western North American Naturalist↗
USGS2012

Resource selection models are useful in predicting fine-scale distributions of black-footed ferrets in prairie dog colonies

Wildlife-habitat relationships are often conceptualized as resource selection functions (RSFs)—models increasingly used to estimate species distributions and prioritize habitat conservation. We evaluated the predictive capabilities of 2 black-footed ferret ( Mustela nigripes ) RSFs developed on a 452-ha colony of black-tailed prairie dogs ( Cynomys ludovicianus ) in the Conata Basin, South Dakota. We used the RSFs to project the relative probability of occurrence of ferrets throughout an adjacent 227-ha colony. We evaluated performance of the RSFs using ferret space use data collected via postbreeding spotlight surveys June–October 2005–2006. In home ranges and core areas, ferrets selected the predicted "very high" and "high" occurrence categories of both RSFs. Count metrics also suggested selection of these categories; for each model in each year, approximately 81% of ferret locations occurred in areas of very high or high predicted occurrence. These results suggest usefulness of the RSFs in estimating the distribution of ferrets throughout a black-tailed prairie dog colony. The RSFs provide a fine-scale habitat assessment for ferrets that can be used to prioritize releases of ferrets and habitat restoration for prairie dogs and ferrets. A method to quickly inventory the distribution of prairie dog burrow openings would greatly facilitate application of the RSFs.

South Dakota↗
USGS2011

The role of demographic compensation theory in incidental take assessments for endangered species

Many endangered species laws provide exceptions to legislated prohibitions through incidental take provisions as long as take is the result of unintended consequences of an otherwise legal activity. These allowances presumably invoke the theory of demographic compensation, commonly applied to harvested species, by allowing limited harm as long as the probability of the species' survival or recovery is not reduced appreciably. Demographic compensation requires some density-dependent limits on survival or reproduction in a species' annual cycle that can be alleviated through incidental take. Using a population model for piping plovers in the Great Plains, we found that when the population is in rapid decline or when there is no density dependence, the probability of quasi-extinction increased linearly with increasing take. However, when the population is near stability and subject to density-dependent survival, there was no relationship between quasi-extinction probability and take rates. We note however, that a brief examination of piping plover demography and annual cycles suggests little room for compensatory capacity. We argue that a population's capacity for demographic compensation of incidental take should be evaluated when considering incidental allowances because compensation is the only mechanism whereby a population can absorb the negative effects of take without incurring a reduction in the probability of survival in the wild. With many endangered species there is probably little known about density dependence and compensatory capacity. Under these circumstances, using multiple system models (with and without compensation) to predict the population's response to incidental take and implementing follow-up monitoring to assess species response may be valuable in increasing knowledge and improving future decision making.

Biological Conservation↗