Geology topics

Abigail J. Darrah

Publications and source records attributed to Abigail J. Darrah.

11 recordsLinked to original sources

USGS2026

Co-producing coastal bird research on the Gulf Coast through structured decision making (SDM) and constructed value of information (CVoI)

Conservation practitioners face the complex challenge of addressing global biodiversity threats within social-ecological systems with multiple jurisdictions, numerous interest groups, and changing environmental conditions. Bridging the research-to-implementation gap between scientists and managers, which integrates diverse perspectives that represent the variety of considerations impacting management outcomes can help to inform efficient and effective conservation. Avian conservation programs along the U.S. Gulf Coast exemplify these challenges, as management decisions must address diverse threats to declining coastal bird populations across large breeding, wintering, and migratory ranges while facing uncertainty surrounding the efficacy of large-scale strategies. This provides opportunities for improving management through co-produced research with structured decision making (SDM). We present a case study that demonstrates the application of co-production principles and SDM to collaboratively develop high-priority research questions informing effective avian conservation and management. Additionally, we applied a constructed value of information (CVoI) framework to identify and prioritize which uncertainties to reduce and better understand how research questions impact management actions. The integration of SDM’s five-step decision making framework ensured key principles of co-production were met, while co-production enhanced SDM outcomes by incorporating diverse perspectives and knowledge bases. CVoI further allowed participants to collectively determine final high-priority research questions in the face of complexity and uncertainty. Together, these approaches supported co-produced knowledge-generation, strategic hypothesis prioritization, and identification of research questions most likely to improve conservation decisions. This case study from the U.S. Gulf Coast demonstrates how co-produced research through SDM offers a broadly applicable approach for navigating ecological complexity and bridging the research-to-implementation gap in avian conservation.

Gulf Coast↗

USGS2025

Effectiveness of stewardship and management strategies to conserve coastal bird populations in the northern Gulf of Mexico: A literature review

Shorebirds, seabirds, and wading birds (hereafter coastal birds) have experienced considerable losses over the last century and require proactive conservation management to stabilize or grow populations. Habitat loss and/or degradation and human disturbance are among the most urgent threats faced by coastal bird populations. Identifying effective conservation management techniques to mitigate these threats is of great interest in the northern Gulf of Mexico (nGoM), a region that provides important habitat during the entire life cycle of resident birds and an essential breeding, wintering, and stopover site for migratory birds. A suite of 35 coastal birds have been identified as priority species for multi-scale conservation monitoring in this region by the Gulf of Mexico Avian Monitoring Network (GoMAMN). This review focuses on impacts of human disturbance and anthropogenic habitat loss and/or degradation on coastal birds and effectiveness of the management strategies implemented to mitigate them, with the goal of informing nGoM management. Our review found that human disturbance was best alleviated by simultaneously deploying complementary stewardship techniques (e.g., signs, fencing, steward patrols, education and community involvement, and beach closures to humans, dogs, and vehicles). However, the relative efficacy of each individual technique is unclear given that only 13% of human disturbance management studies and 38% of habitat management studies have been conducted in the nGoM region. Given the nature of coastal bird habitat and associated risks from sea level rise and human development, most habitat management studies encouraged strategic applications of beach renourishment, limitations on beach raking, as well as site- and species-specific restoration strategies. Studies demonstrated that successful management of coastal birds in the nGoM combined these approaches, employing complementary and adaptive strategies over extended periods.

Journal of Field Ornithology↗

USGS2024

Utilizing artificial nesting platforms as a management tool: Enhancing breeding productivity of Western Flycatchers (Empidonax difficilis occidentalis) in southwestern Colorado and southern Arizona, USA

Artificial nesting substrates have been added around the world for many cavity-nesting bird species, but this has not been undertaken as extensively for crevice-nesting birds. The Western Cordilleran Flycatcher ( Empidonax difficilis occidentalis ) is a migratory, crevice-nesting flycatcher that is nest-site limited, breeding in higher elevation riparian habitats throughout intermountain western North America. We tested the effectiveness of multiple artificial nesting platform types that this flycatcher would accept for nesting, and then utilizing the successful design established an experimental array of platforms in southwestern Colorado and southern Arizona. From 2008 to 2022 we documented Cordilleran Flycatcher breeding and the influence of nesting platforms on productivity of young and adult numbers. Breeding behaviors did not differ significantly between natural nest sites and platform nests, except that the nestling period was an average of 16.73 (+/- 0.98) days on platforms as compared to 15.92 (+/- 0.71) on human structures and 15.67 (+/- 0.48) days in natural locations. Platform nests had lower predation rates and greater rates of successful fledging when compared to natural locations. At both study locations platform nests doubled the number of young fledged each year. In Colorado, where Western Cordilleran Flycatchers were initially absent from areas, adult numbers increased following introduction of platforms, but in Arizona adult flycatcher numbers were not affected. Our findings demonstrate that the addition of artificial nesting platforms can enhance productivity and numbers of Western Cordilleran Flycatchers, and we hope that our findings will prove useful for the conservation of other crevice-nesting bird species.

Arizona, Colorado↗

USGS2021

Brood provisioning rates and fledgling behavior of Cordilleran Flycatchers in southwestern Colorado

The behavior of young songbirds after fledging is one of the least understood phases of the breeding cycle, although parental provisioning rates and movement of fledglings are key to understanding life history evolution. We studied Cordilleran Flycatchers ( Empidonax occidentalis ) at two sites in southwestern Colorado, USA, from 2012 to 2017. We banded and sexed breeding adults to determine the relative contributions of males and females to nestling and fledgling care, and attached radio-transmitters to nestlings to facilitate observations of brood behavior after fledging. Females made 60% and 78% of total observed feedings of nestlings and fledglings, respectively. Parental provisioning rates increased with nestling age, and per-nestling provisioning rates increased with brood size. Parental provisioning rates declined just before fledging, then increased just after fledging. Fledging times of individuals in broods were asynchronous and concentrated during the late afternoon and early evening. Males stopped caring for fledglings before females even though this species is single-brooded, with some late-season broods being abandoned by males. Broods spent the first three weeks after fledging within 400 m of nests, after which they began to disperse. Most aspects of the breeding biology of Cordilleran Flycatchers in our study, including the duration of nestling and fledging periods, female-dominated provisioning, and movement patterns of fledglings, were similar to those of other Empidonax species. However, the times when young fledged were not concentrated in the morning as reported in most other songbirds, and this result warrants additional study of the timing of fledging in ecologically and taxonomically similar species. The increased per-nestling provisioning rate with increasing brood size was unexpected, and additional study is needed to determine if this increase results from a trade-off between adult annual survival and productivity favoring increased provisioning of young in larger broods, or from the existence of high-quality individuals where larger clutches and higher provisioning rates are linked.

Colorado↗

USGS2018

Influences of the invasive tamarisk leaf beetle (Diorhabda carinulata) on avian diets along the Dolores River in Southwestern Colorado USA

The tamarisk leaf beetle ( Diorhabda carinulata ), introduced from Eurasia in 2001 as a biological control agent for the invasive plant Tamarix ramosissima , has spread widely throughout the western USA. With D. carinulata now very abundant, scientists and restoration managers have questioned what influence this introduced arthropod might have upon the avian component of riparian ecosystems. From 2009 through 2012 we studied the consequences of biological invasions of the introduced tamarisk shrub and tamarisk leaf beetles on the diets of native birds along the Dolores River in southwestern Colorado, USA. We examined avian foraging behavior, sampled the arthropod community, documented bird diets and the use of invasive tamarisk shrubs and tamarisk leaf beetles by birds. We documented D. carinulata abundance, on what plants the beetles occurred, and to what degree they were consumed by birds as compared to other arthropods. We hypothesized that if D. carinulata is an important new avian food source, birds should consume beetles at least in proportion to their abundance. We also hypothesized that birds should forage more in tamarisk in the late summer when tamarisk leaf beetle larvae are more abundant than in early summer, and that birds should select beetle-damaged tamarisk shrubs. We found that D. carinulata composed 24.0 percent (± 19.9–27.4%) and 35.4% biomass of all collected arthropods. From the gut contents of 188 birds (25 passerine species), only four species ( n = 11 birds) contained tamarisk leaf beetle parts. Although D. carinulata comprised one-quarter of total insect abundance, frequency of occurrence in bird gut contents was only 2.1% by abundance and 3.4% biomass. Birds used tamarisk shrubs for foraging in proportion to their availability, but foraging frequency did not increase during the late summer when more tamarisk leaf beetles were present and birds avoided beetle-damaged tamarisk shrubs. Despite D. carinulata being the most abundant arthropod in the environment, these invasive beetles were not frequently consumed by birds and seem not to provide a significant contribution to avian diets.

Colorado↗

USGS2017

Riparian bird density decline in response to biocontrol of Tamarix from riparian ecosystems along the Dolores River in SW Colorado, USA

Biocontrol of invasive tamarisk ( Tamarix spp.) in the arid Southwest using the introduced tamarisk beetle ( Diorhabda elongata ) has been hypothesized to negatively affect some breeding bird species, but no studies to date have documented the effects of beetle-induced defoliation on riparian bird abundance. We assessed the effects of tamarisk defoliation by monitoring defoliation rates, changes in vegetation composition, and changes in density of six obligate riparian breeding bird species at two sites along the Dolores River in Colorado following the arrival of tamarisk beetles. We conducted bird point counts from 2010 to 2014 and modeled bird density as a function of native vegetation density and extent of defoliation using hierarchical distance sampling. Maximum annual defoliation decreased throughout the study period, peaking at 32–37% in 2009–2010 and dropping to 0.5–15% from 2011–2014. Stem density of both tamarisk and native plants declined throughout the study period until 2014. Density of all bird species declined throughout most of the study, with Song Sparrow disappearing from the study sites after 2011. Blue Grosbeak, Yellow-breasted Chat, and Yellow Warbler densities were negatively related to defoliation in the previous year, while Lazuli Bunting exhibited a positive relationship with defoliation. These findings corroborate earlier predictions of species expected to be sensitive to defoliation as a result of nest site selection. Tamarisk defoliation thus had short-term negative impacts on riparian bird species; active restoration may be needed to encourage the regrowth of native riparian vegetation, which in the longer-term may result in increased riparian bird density.

Colorado↗

USGS2017

Importance of the 2014 Colorado River Delta pulse flow for migratory songbirds: Insights from foraging behavior

The Lower Colorado River provides critical riparian areas in an otherwise arid region and is an important stopover site for migrating landbirds. In order to reverse ongoing habitat degradation due to drought and human-altered hydrology, a pulse flow was released from Morelos Dam in spring of 2014, which brought surface flow to dry stretches of the Colorado River in Mexico. To assess the potential effects of habitat modification resulting from the pulse flow, we used foraging behavior of spring migrants from past and current studies to assess the relative importance of different riparian habitats. We observed foraging birds in 2000 and 2014 at five riparian sites along the Lower Colorado River in Mexico to quantify prey attack rates, prey attack maneuvers, vegetation use patterns, and degree of preference for fully leafed-out or flowering plants. Prey attack rate was highest in mesquite (Prosopis spp.) in 2000 and in willow (Salix gooddingii) in 2014; correspondingly, migrants predominantly used mesquite in 2000 and willow in 2014 and showed a preference for willows in flower or fruit in 2014. Wilson’s warbler (Cardellina pusilla) used relatively more low-energy foraging maneuvers in willow than in tamarisk (Tamarix spp.) or mesquite. Those patterns in foraging behavior suggest native riparian vegetation, and especially willow, are important resources for spring migrants along the lower Colorado River. Willow is a relatively short-lived tree dependent on spring floods for dispersal and establishment and thus spring migrants are likely to benefit from controlled pulse flows.

Arizona, California↗

USGS2016

Effects of drought and fire on bird communities of the Kofa National Wildlife Refuge, Arizona

Executive Summary The U.S. Government created the Kofa National Wildlife Refuge (Kofa NWR) in 1939 in response to a citizen campaign to improve desert bighorn sheep populations in Arizona. The Kofa NWR is mountainous and remote, and its management by the U.S. Fish and Wildlife Service (FWS) keeps anthropogenic disturbance levels low. As such, Partners In Flight (PIF) listed the Kofa NWR as one of its Sonoran Desert portfolio sites in its Desert Bird Conservation Plan (McCreedy and others, 2009). Research presented here demonstrates that bird communities within a well-managed and remote Sonoran Desert portfolio site can nonetheless be negatively affected by human-caused stressors like fire and Brown-headed Cowbird ( Molothrus ater ) parasitism, which originate from beyond the Kofa NWR’s boundaries. In chapter 1, we examine how avian productivity can be influenced by timing of nest initiation. We demonstrate that (1) late nesting dates are correlated with low winter precipitation levels, a condition expected to occur in greater frequency in coming decades due to climate change (Seager and others, 2007) and that (2) late nesting dates result in decreased productivity, due to higher rates of nest depredation and, in the case of an open-cup nesting species, higher rates of brood parasitism experienced later in the breeding season. The brood parasite, the Brown-headed Cowbird, appears to forage and roost on agricultural lands north of the Kofa NWR’s boundary. From that location, they commute to the refuge to parasitize other passerine bird nests. Drought and subsequent loss in primary production have been correlated with decreased productivity for birds that breed in arid habitats (Preston and Rotenberry, 2006; Chase and others, 2005; Johnson and others, 2002; Morrison and Bolger, 2002; Brown and Li, 1996; Anderson and Anderson, 1973), yet drought’s standing as a threat to bird populations has been underestimated in recent regional conservation planning efforts (McCreedy and others, 2009; Latta and others, 1999). In chapter 2, we examine the effects of the King Valley fire on breeding and migrant birds within the Kofa NWR. This fire was caused by incendiary weapons testing within Yuma Proving Ground, south of the Kofa NWRboundary (Esque and others, 2013). We found large differences in spring migrant and breeding species abundance and richness between bird count stations within the 2005 King Valley fire zone and bird count stations immediately outside the fire perimeter. Habitat loss to fire, and the subsequent slow regeneration of a Sonoran Desert flora that is not well adapted to fire disturbance, is a recognized threat to bird populations (McCreedy and others, 2009; Latta, 1999), and of all Sonoran Desert wildlife, birds may be the most impacted by loss of perennial Sonoran Desert vegetation to fire (Esque and Schwalbe, 2002). We conclude that decreases in both breeding and migrant use of washes within burned areas will likely persist into the long term (>25 years) due to slow return rates of xeroriparian woodlands lost in the fire.

Arizona↗

USGS2014

Exposure pathways and biological receptors: baseline data for the canyon uranium mine, Coconino County, Arizona

Recent restrictions on uranium mining within the Grand Canyon watershed have drawn attention to scientific data gaps in evaluating the possible effects of ore extraction to human populations as well as wildlife communities in the area. Tissue contaminant concentrations, one of the most basic data requirements to determine exposure, are not available for biota from any historical or active uranium mines in the region. The Canyon Uranium Mine is under development, providing a unique opportunity to characterize concentrations of uranium and other trace elements, as well as radiation levels in biota, found in the vicinity of the mine before ore extraction begins. Our study objectives were to identify contaminants of potential concern and critical contaminant exposure pathways for ecological receptors; conduct biological surveys to understand the local food web and refine the list of target species (ecological receptors) for contaminant analysis; and collect target species for contaminant analysis prior to the initiation of active mining. Contaminants of potential concern were identified as arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, thallium, uranium, and zinc for chemical toxicity and uranium and associated radionuclides for radiation. The conceptual exposure model identified ingestion, inhalation, absorption, and dietary transfer (bioaccumulation or bioconcentration) as critical contaminant exposure pathways. The biological survey of plants, invertebrates, amphibians, reptiles, birds, and small mammals is the first to document and provide ecological information on .200 species in and around the mine site; this study also provides critical baseline information about the local food web. Most of the species documented at the mine are common to ponderosa pine Pinus ponderosa and pinyon–juniper Pinus–Juniperus spp. forests in northern Arizona and are not considered to have special conservation status by state or federal agencies; exceptions are the locally endemic Tusayan flameflower Phemeranthus validulus, the long-legged bat Myotis volans, and the Arizona bat Myotis occultus. The most common vertebrate species identified at the mine site included the Mexican spadefoot toad Spea multiplicata, plateau fence lizard Sceloporus tristichus, violetgreen swallow Tachycineta thalassina, pygmy nuthatch Sitta pygmaea, purple martin Progne subis, western bluebird Sialia mexicana, deermouse Peromyscus maniculatus, valley pocket gopher Thomomys bottae, cliff chipmunk Tamias dorsalis, black-tailed jackrabbit Lepus californicus, mule deer Odocoileus hemionus, and elk Cervus canadensis. A limited number of the most common species were collected for contaminant analysis to establish baseline contaminant and radiological concentrations prior to ore extraction. These empirical baseline data will help validate contaminant exposure pathways and potential threats from contaminant exposures to ecological receptors. Resource managers will also be able to use these data to determine the extent to which local species are exposed to chemical and radiation contamination once the mine is operational and producing ore. More broadly, these data could inform resource management decisions on mitigating chemical and radiation exposure of biota at high-grade uranium breccia pipes throughout the Grand Canyon watershed.

Arizona↗

USGS2010

Distribution and habitat use of king rails in the Illinois and Upper Mississippi River valleys

The migratory population of the king rail ( Rallus elegans ) has declined dramatically during the past 40 years, emphasizing the need to identify habitat requirements of this species to help guide conservation efforts. To assess distribution and habitat use of king rails along the Illinois and Upper Mississippi valleys, USA, we conducted repeated call-broadcast surveys at 83 locations in 2006 and 114 locations in 2007 distributed among 21 study sites. We detected king rails at 12 survey locations in 2006 and 14 locations in 2007, illustrating the limited distribution of king rails in this region. We found king rails concentrated at Clarence Cannon National Wildlife Refuge, an adjacent private Wetlands Reserve program site, and B. K. Leach Conservation Area, which were located in the Mississippi River floodplain in northeast Missouri. Using Program PRESENCE, we estimated detection probabilities and built models to identify habitat covariates that were important in king rail site occupancy. Habitat covariates included percentage of cover by tall (> 1 m) and short (<= 1 m) emergent vegetation, percentage of cover of woody vegetation, and interspersion of water and vegetation ( 2007 only) within 50 m of the survey location. Detection probability was 0.43 (SE = 0.12) in 2006 and 0.35 (SE = 0.03) in 2007 and was influenced by observer identity and percentage of cover by tall herbaceous vegetation. Site occupancy was 0.11 (SE = 0.04) in 2006 and 0.14 (SE = 0.04) in 2007 and was negatively influenced most by percentage of cover by woody vegetation. In addition, we found that interspersion of vegetation and water was positively related to occupancy in 2007. Thus, nesting king rails used wetlands that were characterized by high water-vegetation interspersion and little or no cover by woody vegetation. Our results suggest that biologists can improve king rail habitat by implementing management techniques that reduce woody cover and increase vegetation-water interspersion in wetlands.

Journal of Wildlife Management↗

USGS2010

Occupancy and habitat use of the Least Bittern and Pied-Billed Grebe in the Illinois and Upper Mississippi River Valleys

The Least Bittern ( Ixobrychus exilis ) and the Pied-billed Grebe ( Podilymbus podiceps ) are secretive marsh bird species that breed in the Illinois and Upper Mississippi River Valleys. Marsh bird surveys were conducted on public and private wetlands in this region during the breeding seasons of 2006 and 2007. Detection probability (ῥ) and site occupancy probability (ψ) were estimated for each species separately for each year. Candidate models including sampling and habitat covariates were compared using AIC( c ) to determine what variables had the greatest influence on ῥ and ψ. Average ῥ for Least Bitterns was 0.29 in 2006 and 0.18 in 2007, and varied throughout the 2007 survey season. Average ψ for Pied-billed Grebes was 0.44 in 2006 and 0.22 in 2007, and an observer effect was found in 2007. Overall ψ for Least Bitterns was 0.17 in 2006 and 0.14 in 2007. Least Bittern occupancy was positively related to tall emergent vegetation cover in both years and to water-vegetation interspersion in 2007, and was negatively related to woody vegetation cover in 2007. Overall ψ for Pied-billed Grebes was 0.21 in 2006 and 0.31 in 2007. Pied-billed Grebe occupancy was negatively related to woody vegetation cover in both years, and was positively related to areas of open water in 2006. Land managers targeting these species should provide wetlands free from woody vegetation with extensive areas of open water for Pied-billed Grebes, and tall emergent vegetation interspersed with small pools of water for Least Bitterns.

Waterbirds↗