Geology topics

Dustin L. Toy

Publications and source records attributed to Dustin L. Toy.

14 recordsLinked to original sources

USGS2025

Not all spatially structured populations are metapopulations: Re-examining paradigms for a threatened shorebird

For at-risk species, understanding population vital rates is imperative for developing informed conservation strategies and population models. Managers often assume that species that are spatially distributed among patches of suitable habitat meet the criteria of a metapopulation. Metapopulation dynamics are determined not only by within-patch birth and death processes but also by between-patch dispersal movements of individuals that are infrequent but critical to maintaining population viability across space and time. To conserve and manage such species, an understanding of all these vital rates, including connectivity, is required. The degree to which the northern Great Plains piping plover ( Charadrius melodus ) breeding population functions as a metapopulation depends, in part, on the rate of movement among patchily distributed breeding areas. Here, we examined annual adult survival and breeding dispersal probabilities for 2582 individuals at two spatial scales within the northern Great Plains piping plover breeding population between 2014 and 2019. Inconsistent with a metapopulation structure, annual survival varied minimally among breeding regions but did vary across years. We also found that breeding dispersal probabilities were temporally variable, high, and unbalanced at both spatial scales examined, suggesting high connectivity in contrast to metapopulation dynamics. Further, we detected context-dependent effects of reproductive success on dispersal decisions. Individuals were more likely to disperse from the northern Missouri River to the US Alkali Wetlands following nest failure due to inundation or severe storms (including in the year prior to dispersal), whereas dispersal from the US Alkali Wetlands to the northern Missouri River decreased following successful nest attempts. Individuals also decreased dispersal from the US Alkali Wetlands to the northern Missouri River in response to renesting attempts in both the year of interest and the year prior to dispersal. Our results contradict the paradigm that northern Great Plains piping plovers are structured as a metapopulation and instead suggest a patchily distributed, likely panmictic, population. Our findings have implications for the conservation and management of this listed species and are also a general reminder that in the absence of robust knowledge of movement, spatial variation in birth and death processes across patches should not be conflated with a metapopulation structure.

Montana, North Dakota, South Dakota↗

USGS2024

Assessing trade-offs in developing a landscape-scale nest monitoring programme for a threatened shorebird

Effective monitoring of wildlife species requires thorough planning and development of survey programmes that can address management and conservation objectives. Decisions about monitoring programmes include where to survey, survey design and how much effort to allocate at survey sites are typically predicated on limited budgets and available resources. When the scope of inference requires monitoring on a broad spatial scale, predictions of habitat distribution or suitability may be useful for identifying potential survey sites. We focused on a threatened but widely distributed shorebird, the piping plover ( Charadrius melodus ), which is actively monitored across some, but not all of its range. Our objective was to use piping plover habitat distribution maps, which vary annually, to assess the effectiveness of multiple monitoring programme scenarios and their associated costs. In the breeding range, efforts to improve productivity for species of conservation concern often focus on improving probabilities of nest survival. Consequently, collecting adequate nesting data is crucial for obtaining accurate and precise estimates of nest survival and for evaluating the effectiveness of management actions. By simulating the nest monitoring process, we evaluated how much area, where and how often to survey each site when estimating nest survival and detecting effects of potential management actions. As expected, precision increased and bias decreased around nest survival estimates with greater survey coverage and nest visit frequency. We also identified monitoring programmes with negative net values where survey costs outweighed statistical benefits. Although we applied our simulation framework to evaluate nest monitoring designs for piping plovers, it could be extended to assess whether different monitoring programmes can detect changes in the distribution of other species or occupancy of habitats over time.

Ecological Solutions and Evidence↗

USGS2023

Estimating population viability of the northern Great Plains piping plover population considering updated population structure, climate change, and intensive management

One challenge in wildlife conservation is understanding how various threats and management actions may influence long-term population viability. This is particularly evident when there is considerable uncertainty regarding population structure and vital rates. Reassessment of current knowledge and population trends is necessary for listed species to improve management actions that benefit conservation. We present an updated population viability analysis for northern Great Plains piping plovers ( Charadrius melodus circumcinctus ) based on the latest scientific data on survival, fecundity, and connectivity. Further, we explore the consequences of potential management actions and the stochastic effects of global climate change on population viability through changes in survival and fecundity. Our results predict elevated risks of extinction after 50 years (0.088 – 0.373) compared to previous predictions (0.033) based on assumed conditions of low connectivity among four major breeding groups structured as a metapopulation. We explored eight scenarios based on empirically-derived, higher connectivity rates and found that the northern Great Plains population never had a mean predicted population growth rate greater than one (0.946 – 0.996). Two scenarios that simulated a reduction in adult survival showed higher extinction probabilities (0.267 – 0.373), whereas two other scenarios that simulated an increase in fecundity exhibited lower extinction probabilities (0.088 – 0.103). These results indicate that viability of the northern Great Plains population of piping plovers could be improved with management actions that increase fecundity as long as adult survival is not simultaneously reduced. Lastly, breeding groups appeared to function less independently when connectivity rates were higher, as the breeding population was divided evenly among breeding groups. This indicates that the presumed metapopulation structure of our study system may need to be re-evaluated, and that empirically-based estimates of connectivity are essential to assessing population viability of mobile species that exhibit a spatially structured distribution.

Frontiers in Bird Science↗

USGS2023

Conspecific density and habitat quality affect breeding habitat selection: Support for the social attraction hypothesis

Breeding habitat selection is a critical component of the annual cycle because of its effect on fitness. Multiple theories of habitat selection can be differentiated by their responses to the quantity of habitat, conspecific density, and habitat quality. Here, we use network analysis to understand the characteristics of fine-scale breeding habitat selected by both immigrant and returning adult piping plovers ( Charadrius melodus ) to test five hypotheses of habitat selection. Between 2014 and 2019, we recorded 2034 uniquely marked adults breeding at 326 breeding locations with 1240 successive breeding events. Among adults, immigration events (i.e., individuals that moved to a new breeding location) were detected as often as fidelity to the same breeding location. We found support for the social attraction hypothesis for both immigrants and returners, indicating that adult plovers use social cues for settlement decisions. Adult plovers selected habitats with intermediate levels of conspecific density and high habitat quality, as assessed by con- and heterospecific nest survival, with no effect from the amount of available habitat. We also simulated the loss of breeding habitat and identified highly connected breeding locations, which occurred mostly on the riverine habitat type, which have important implications for habitat conservation for this listed species. Our results highlight the role of conspecifics at identifying high-quality breeding habitat regardless of whether individuals return to the same breeding site or immigrate to new areas.

North Dakota, South Dakota↗

USGS2023

Data integration reveals dynamic and systematic patterns of breeding habitat use by a threatened shorebird

Incorporating species distributions into conservation planning has traditionally involved long-term representations of habitat use where temporal variation is averaged to reveal habitats that are most suitable across time. Advances in remote sensing and analytical tools have allowed for the integration of dynamic processes into species distribution modeling. Our objective was to develop a spatiotemporal model of breeding habitat use for a federally threatened shorebird (piping plover, Charadrius melodus ). Piping plovers are an ideal candidate species for dynamic habitat models because they depend on habitat created and maintained by variable hydrological processes and disturbance. We integrated a 20-year (2000–2019) nesting dataset with volunteer-collected sightings (eBird) using point process modeling. Our analysis incorporated spatiotemporal autocorrelation, differential observation processes within data streams, and dynamic environmental covariates. We evaluated the transferability of this model in space and time and the contribution of the eBird dataset. eBird data provided more complete spatial coverage in our study system than nest monitoring data. Patterns of observed breeding density depended on both dynamic (e.g., surface water levels) and long-term (e.g., proximity to permanent wetland basins) environmental processes. Our study provides a framework for quantifying dynamic spatiotemporal patterns of breeding density. This assessment can be iteratively updated with additional data to improve conservation and management efforts, because reducing temporal variability to average patterns of use may cause a loss in precision for such actions.

Montana, North Dakota, South Dakota↗

USGS2022

Implications of habitat-driven survival and dispersal on recruitment in a spatially structured piping plover population

Natal survival and dispersal have important consequences for populations through the movement of genes and individuals. Metapopulation theory predicts either balanced natal dispersal among regions or source–sink dynamics, which can dramatically change population structure. For species reliant on dynamic, early-successional habitats, availability and location of habitat will shift from year to year, requiring primiparous individuals to locate an appropriate breeding habitat. We estimated hatch-year survival to adulthood and natal dispersal rates between two breeding groups of Northern Great Plains piping plovers ( Charadrius melodus ) from four cohorts ( n = 2669 total individuals; 2014–2017). Hatch-year survival to adulthood was slightly higher for individuals hatched on the Missouri River than on the US Alkali Wetlands but declined over time. Individuals hatched on the US Alkali Wetlands were more likely to disperse to breed on the Missouri River (0.33 [0.20, 0.48]) than vice versa (0.17 [0.11, 0.24]). When more habitat was available at the natal site than in the prior year, natal dispersal rates increased. However, despite higher recruitment rates as a result of higher natal fidelity, the Missouri River showed lower total recruitment with a declining trend in the number of recruits, largely due to differences in abundance between breeding groups. Overall, unbalanced, high natal dispersal rates within the Northern Great Plains indicate high connectivity among distinct regions with different water regimes on the Missouri River and on the US Alkali Wetlands driven by fluctuating availability of habitat. Our results suggest that plovers in the Northern Great Plains take advantage of dynamic habitats where they are available in a broad geographic area, which is consistent with a spatially structured panmictic population rather than a true metapopulation, but further research on adult breeding dispersal is needed to clarify population structure.

North Dakota, South Dakota↗

USGS2021

Experimental evaluation of predator exclosures on nest, chick, and adult survival of piping plovers

Species of conservation concern often receive intensive management to improve vital rates and facilitate recovery. Piping plovers ( Charadrius melodus ) are federally listed in the United States and concerns over nest depredation have prompted widespread use of plover-permeable predator exclosures placed around nests (0.5–2-m radius). While effectiveness of exclosures for improving nest survival has been demonstrated, concerns remain about decreased chick survival (through predator cueing or density-dependent processes) or increased vulnerability of adults to predation (ambush as adult leaves exclosure). Either one of these concerns could demographically outweigh the benefits of increased nest survival. During 2014–2016, we conducted an experiment designed to evaluate survival of uniquely identified nests ( n = 418), chicks ( n = 453), and adults ( n = 367) at wetlands across the Northern Great Plains, USA. We assigned wetlands ( n 2014 = 26, n 2015 = 28, n 2016 = 25) into 2 groups: wetlands in which half of the nests received exclosures and wetlands in which none of the nests received exclosures. Exclosed nests had greater cumulative survival (0.73 [85% CI = 0.70–0.77]) than unexclosed nests at treatment wetlands (0.58 [0.54–0.62]) or unexclosed nests at control wetlands (0.52 [0.49–0.56]). Survival to fledging was highest for chicks hatched from exclosed nests (0.51 [0.47–0.56]), and similar between chicks hatched from unexclosed nests at treatment (0.34 [0.30–0.39]) and control (0.37 [0.32–0.42]) wetlands. Cumulative survival of adults during incubation varied by exclosure status, but adults associated with exclosed nests (0.90 [0.88–0.93]) and unexclosed nests at treatment wetlands (0.89 [0.86–0.92]) had greater survival than those associated with unexclosed nests at control wetlands (0.75 [0.64–0.84]). Adult annual survival rates varied by year (0.79–0.95) but not by exclosure status. The positive influence of exclosures on nest survival was not offset by a reduction in chick or adult survival, indicating that exclosures are a viable tool for piping plover conservation.

Montana, North Dakota↗

USGS2021

Dispersal distance is driven by habitat availability and reproductive success in Northern Great Plains piping plovers

Background Dispersal is a critical life history strategy that has important conservation implications, particularly for at-risk species with active recovery efforts and migratory species. Both natal and breeding dispersal are driven by numerous selection pressures, including conspecific competition, individual characteristics, reproductive success, and spatiotemporal variation in habitat. Most studies focus on dispersal probabilities, but the distance traveled can affect survival, fitness, and even metapopulation dynamics. Methods We examined sources of variation in dispersal distances with 275 natal dispersal and 1335 interannual breeding events for piping plovers ( Charadrius melodus ) breeding in the Northern Great Plains between 2014 and 2019. Results Natal dispersal was on average longer (mean: 81.0 km, median: 53 km) than adult breeding movements (mean: 23.7 km, median: 1 km). Individuals moved the shortest distances when hatched, previously nested, or settling on river habitats. When more habitat was available on their natal area than in the year prior, hatch-year birds moved shorter distances to their first breeding location. Similarly, adults also moved shorter distances when more habitat was available at the settling site and when in closer proximity to other known nesting areas. Additionally, adult movement distance was shorter when successfully hatching a nest the year prior, retaining a mate, or initiating a current nest earlier. Conclusion Habitat availability appears to be associated with dispersal distance for both hatch-year and adult piping plovers. Conservation efforts that integrate dispersal distances may benefit from maintaining nesting habitat within close proximity to other areas for adults and a network of clustered sites spread out across a larger landscape for natal dispersal.

Montana, North Dakota, South Dakota↗

USGS2021

Spatial variation in population dynamics of northern Great Plains piping plovers

Metapopulation dynamics are determined not only by within-patch birth and death processes but also by between-patch movements of individuals (emigration and immigration). To conserve and manage a species that has a metapopulation structure, defined by local populations that are distributed among patches of suitable habitat, we need to understand each of these vital rates. For the federally listed northern Great Plains Charadrius melodus (Ord, 1824) (piping plover), managers assumed a metapopulation structure consisting of four breeding groups with low, balanced dispersal, which resulted in low extinction risk in a simulation-based viability study. The degree to which the northern Great Plains piping plover breeding population functions as a metapopulation depends on the rate of movement amongst breeding areas. Sources of variation in survival, dispersal probabilities, and dispersal distances were examined for hatch-year and adult piping plovers breeding in the northern Great Plains from 2014 to 2019 focusing on four management units (U.S. Alkali Wetlands, Lake Sakakawea, Garrison Reach of the Missouri River, and Lake Oahe). Additionally, renesting probabilities, renest reproductive success, and reproductive output were investigated from 2014 to 2016 in each of these areas to understand within-patch productivity. This report includes two major sections: (1) a presentation that includes the context, results, and implications of the study, followed by a detailed text methodology, and (2) an appendix that provides synthesized estimates of piping plover vital rates from throughout their range. River and alkali wetland habitats seem to be of higher quality than reservoir habitats, although alkali wetland habitats have lower annual survival, lower reproductive output, and lower fidelity probabilities than riverine habitats. Habitat availability drove dispersal probabilities and dispersal distances for hatch-year and adult piping plovers. Renesting propensity and renest reproductive success were generally low, suggesting that renesting is an uncommon and unproductive strategy to replace most lost reproductive attempts. Estimates indicated high connectivity between the U.S. Alkali Wetlands and the northern river units (Lake Sakakawea, Garrison Reach, Lake Oahe) of the Missouri River, suggesting that the assumed metapopulation structure and population viability may need to be reassessed.

Montana, North Dakota, South Dakota↗

USGS2021

Impacts of extreme environmental disturbances on piping plover survival are partially moderated by migratory connectivity

Effective conservation for listed migratory species requires an understanding of how drivers of population decline vary spatially and temporally, as well as knowledge of range-wide connectivity between breeding and nonbreeding areas. Environmental conditions distant from breeding areas can have lasting effects on the demography of migratory species, yet these consequences are often the least understood. Our objectives were to 1) evaluate associations between survival and extreme environmental disturbances at nonbreeding areas, including hurricanes, harmful algal blooms, and oil spills, and 2) estimate migratory connectivity between breeding and nonbreeding areas of midcontinental piping plovers ( Charadrius melodus ). We used capture and resighting data from 5067 individuals collected between 2002 and 2019 from breeding areas across the midcontinent, and nonbreeding areas throughout the Gulf of Mexico and southern Atlantic coasts of North America. We developed a hidden Markov multistate model to estimate seasonal survival and account for unobservable geographic locations. Hurricanes and harmful algal blooms were negatively associated with nonbreeding season survival, but we did not detect a similarly negative relationship with oil spills. Our results indicated that individuals from separate breeding areas mixed across nonbreeding areas with low migratory connectivity. Mixing among individuals in the nonbreeding season may provide a buffering effect against impacts of extreme events on any one breeding region. Our results suggest that understanding migratory connectivity and linking seasonal threats to population dynamics can better inform conservation strategies for migratory shorebirds.

Biological Conservation↗

USGS2020

Asymmetric benefits of a heterospecific breeding association vary with habitat, conspecific abundance and breeding stage

Heterospecific breeding associations may benefit individuals by mitigating predation risk but may also create costs if they increase competition for resources or are more easily detectable by predators. Our understanding of the interactions among hetero‐ and conspecifics is often lacking in mixed species colonies. Here, we test how the presence of hetero‐ and conspecifics influence nest and chick survival for two listed (under the U.S. Endangered Species Act) migratory species breeding on the Missouri River, USA. We monitored 2507 piping plover Charadrius melodus nests and 3245 chicks as well as 1060 least tern Sternula antillarum nests and 1374 chicks on Lake Sakakawea, the Garrison River Reach and the Gavins Point Reach for varying years between 2007 and 2016. Piping plover nest and chick survival improved with the presence and abundance of least terns, but least terns only benefited from piping plover presence for certain study areas and breeding stages. Piping plover nest survival was also improved by the presence and abundance of conspecifics on the Garrison River Reach and was negatively influenced by conspecific presence on Lake Sakakawea. Least tern chick survival improved with the presence of other least terns only on the Gavins Point Reach. Ultimately, the heterospecific breeding association between plovers and terns is mutualistic but asymmetric and is moderated by habitat, abundance of conspecifics and breeding stage. Our results highlight that spatiotemporal variation in the interactions among individuals breeding in groups precludes simple generalizations and suggests that management focused on one species may restrict benefits to that focal species if nest site requirements for heterospecifics are not also included.

Nebraska, North Dakota, South Dakota↗

USGS2020

Low renesting propensity and reproductive success make renesting unproductive for the threatened Piping Plover (Charadrius melodus)

Upon reproductive failure, many bird species make a secondary attempt at nesting (hereafter, “renesting”). Renesting may be an effective strategy to maximize current and lifetime reproductive success, but individuals face uncertainty in the probability of success because reproductive attempts initiated later in the breeding season often have reduced nest, pre-fledging, and post-fledging brood survival. We evaluated renesting propensity, renesting intervals, and renest reproductive success of Piping Plovers ( Charadrius melodus ) by following 1,922 nests and 1,785 unique breeding adults from 2014 to 2016 in the Northern Great Plains of the United States. The apparent renesting rate for individuals was 25% for reproductive attempts that failed in the nest stage (egg laying and incubation) and only 1.2% for reproductive attempts when broods were lost. Renesting propensity declined if reproductive attempts failed during the brood-rearing stage, nests were depredated, reproductive failure occurred later in the breeding season, or individuals had previously renested that year. Additionally, plovers that nested on reservoirs were less likely to renest compared to other habitats. Renesting intervals declined when individuals had not already renested, were after-second-year adults without known prior breeding experience, and moved short distances between nest attempts. Renesting intervals also decreased if the attempt failed later in the season. Overall, reproductive success and daily nest survival were lower for renests than first nests throughout the breeding season. Furthermore, renests on reservoirs had reduced apparent reproductive success and daily nest survival unless the predicted amount of habitat on reservoirs increased within the breeding season. Our results provide important demographic measures for this threatened species and suggest that predation- and water-management strategies that maximize success of early nests would be more likely to increase productivity. Altogether, renesting appears to be an unproductive reproductive strategy to replace lost reproductive attempts for Piping Plovers breeding in the Northern Great Plains.

Montana, North Dakota, South Dakota↗

USGS2019

Demographic responses of least terns and piping plovers to the 2011 Missouri River flood—A large-scale case study

A catastrophic flood event on the Missouri River system in 2011 led to substantial changes in abundance and distribution of unvegetated sand habitat. This river system is a major component of the breeding range for interior Least terns ( Sternula antillarum ; “terns”) and piping plovers ( Charadrius melodus ; “plovers”), both of which are Federally listed ground-nesting birds that prefer open, unvegetated sand and gravel nesting substrates on sandbars and shorelines. The 2011 flood inundated essentially all tern and plover nesting habitat during 2011, but it had potential to generate post-flood habitat conditions that favored use by terns and plovers in subsequent years. We compared several tern and plover demographic parameters during the pre-flood and post-flood periods on the Garrison Reach and Lake Sakakawea, North Dakota, to determine how this event influenced these species (both species on the Garrison Reach, and plovers only on Lake Sakakawea). The principal parameters we measured (nest survival, chick survival, and breeding population) showed spatial and temporal variation typical of opportunistic species occupying highly variable habitats. There was little evidence that nest survival of least terns differed between pre- and post-flood. During 2012 when habitat was most abundant on the Garrison Reach and Lake Sakakawea, piping plover nest survival was higher than in any other year in the study, but returned to rates comparable to pre-flood years in 2013. Chick survival for terns on the Garrison Reach and plovers on Lake Sakakawea showed a similar pattern to plover nest survival, with the 2012 rate exceeding all other years of the study, and the remaining pre-flood and post-flood years being generally similar but slightly higher in post-flood years. However, plover chick survival on the Garrison Reach in 2012 was similar to pre-flood years, and increased annually thereafter to its highest rate in 2014. Although wide confidence intervals precluded firm conclusions about flood effects on breeding populations, the general pattern suggested lower populations of plovers but higher populations of least terns immediately after the flood. Despite near total absence of breeding habitat on either study area during the flood of 2011, populations of both species persisted after the flood due to their propensity to disperse and/or forgo breeding for at least a year. Tern and plover populations have similarly persisted and recovered after the flood, but their mechanisms for persistence likely differ. Data on tern dispersal is generally lacking, but they are thought to show little fidelity to their natal grounds, have a propensity to disperse potentially long distances, and routinely forgo breeding until their second year, thus a lost opportunity to breed in a given area may be easily overcome. Plovers exhibit stronger demographic ties to the general area in which they previously nested, yet they occupy much broader nesting habitat features than terns and exploit three major landforms in the Dakotas (free-flowing rivers, reservoir shorelines, and wetland shorelines). Consequently, dispersal to and from non-Missouri River habitats and potential to exploit non-traditional habitats likely sustained the Northern Great Plains population through the flood event. Terns and plovers normally occupy similar habitats on the Missouri River and both species experienced similar loss of a breeding season due to the flood. Persistence of these populations after the flood underscores the importance of understanding their unique demographic characteristics and the context within which the Missouri River operates.

North Dakota↗

USGS2017

Small high-definition video cameras as a tool to resight uniquely marked Interior Least Terns (Sternula antillarum athalassos)

Many bird species of conservation concern have behavioral or morphological traits that make it difficult for researchers to determine if the birds have been uniquely marked. Those traits can also increase the difficulty for researchers to decipher those markers. As a result, it is a priority for field biologists to develop time- and cost-efficient methods to resight uniquely marked individuals, especially when efforts are spread across multiple States and study areas. The Interior Least Tern ( Sternula antillarum athalassos ) is one such difficult-to-resight species; its tendency to mob perceived threats, such as observing researchers, makes resighting marked individuals difficult without physical recapture. During 2015, uniquely marked adult Interior Least Terns were resighted and identified by small, inexpensive, high-definition portable video cameras deployed for 29-min periods adjacent to nests. Interior Least Tern individuals were uniquely identified 84% (n = 277) of the time. This method also provided the ability to link individually marked adults to a specific nest, which can aid in generational studies and understanding heritability for difficult-to-resight species. Mark-recapture studies on such species may be prone to sparse encounter data that can result in imprecise or biased demographic estimates and ultimately flawed inferences. High-definition video cameras may prove to be a robust method for generating reliable demographic estimates.

Nebraska, North Dakota, South Dakota↗