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At least 163 records · Page 9Linked to original sources
USGS2000

The Cooperative Wildlife Research Unit and wildlife education: Historic development, future challenges

In 1932, J. N. 'Ding' Darling proposed a 3-year tripartite arrangement between the Iowa Fish and Game Commission, Iowa State University, and himself to establish the first Cooperative Wildlife Research Unit. Three years later, the Cooperative Wildlife Research Unit Program was broadened to include 9 land-grant colleges representing recognized ecoregions in the United States. In 1960, the Units were given statutory recognition by Public Law 86-686 that also included provision for establishing Cooperative Fishery Units. The Cooperative Research Unit idea has evolved to 39 Units in 2000. Today, the main cooperators of the Unit program are the land-grant university, the state fish and game or conservation agency, the U.S. Geological Survey, and the Wildlife Management Institute. The Cooperative Units mission, as stated in Public Law 86-686, remains: 'To facilitate cooperation between the Federal Government, colleges and universities, and private organizations for cooperative unit programs of research and education relating to fish and wildlife and for other purposes.' Graduate research and education continue to be the program's primary missions. In any given year >600 graduate and post-graduate students are involved. Post-graduate employment of Unit-afffiliated students is >90%. Perhaps the primary benefit to the education process is the Units' formal connection to the state cooperator and to their federal agency that might not otherwise be available to university faculty and students. Units are conduits to state and federal funding for research projects conducted by university faculty and students. The CRU program is well positioned to educate a multitalented, ethnically diverse cadre of graduate students who will be prepared not only for their first professional job but also for their career by having been instilled with a desire for life-long professional accomplishment.

Wildlife Society Bulletin↗
USGS1999

The northern pintail in North America: status and conservation needs of a struggling population

The number of northern pintails (Anas acuta) in North America continues to be low despite sub- stantially improved wetland habitat conditions as recorded by the May Breeding Population and Habitat Survey (May Survey, United States Fish and Wildlife Service [USFWS] 1998; Figure 1). In 1993-97, following extended drought during the 1980s and early 1990s, favorable precipitation pat- terns returned to the critical waterfowl nesting areas of the northern Great Plains of the United States (U.S.) and Canada (USFWS 1997), the area known as the Prairie Pothole Region (PPR, Bellrose 1980). Historically, when the number of wetlands (May ponds) counted on the May Survey increased in the PPR, pintail breeding populations (BPOP) also increased (e.g., Smith 1970). However, even though May ponds attained record high levels 1996 and 1997, the expected increase in pintail populations did not occur (Figure 1). Even after a 30% increase in the BPOP between 1996 and 1997, pintails remained 19% below the long-term average and 36% below the North American Waterfowl Management Plan (NAWMP) goal of 5.6 million (USFWS et al. 1994); additionally, peaks and lows in pintail BPOP have been successively lower since 1955-56 (Figure 1). In contrast, all other PPR-nest- ing dabbling ducks (tribe Anatini) rebounded in the 1990s to levels that exceeded objectives set by NAWMP (USFWS 1997). The minimal recovery of pintails is perplexing, given the very large popula- tions attained during previous periods of abundant May ponds (Figure 1).

Wildlife Society Bulletin↗
USGS1990

Ecology, behavior, and conservation of the Poo-uli (Melamprosops phaeosoma)

Studies of the population density, habitat structure, foraging behavior, and activity budgets of the Poo-uli (Melamprosops phaeosoma) were conducted intermittently between 1973 and 1985 in a 50-ha study area in the upper Hanawi watershed, island of Maui, Hawaii. Poo-uli have apparently declined in density on this site by 80% from 1975 to 1981 and by 90% from 1975 to 1985. During this period, pig activity, as indexed by ground cover disturbance, increased 473%. Compared to values in the range of the Poo-uli, pig activity was 9-24 times greater in two adjacent out-of-range areas. Poo-uli most frequently foraged from 4-7 m height on ohia (Metrosideros polymorpha), olapa (Cheirodendron trigynum), ohelo (Vaccinium calycinum), and kanawao (Broussaisia arguta) in decreasing frequency; feeding on kanawao was significantly more frequent than random expectation. Chief food items were land snails and insects. Most prey were captured on branches from under moss, lichen, and bark by gleaning, probing, and pecking. Birds spent 48% of their daylight hours foraging and 30% quietly perching. Poo-uli frequently formed small mixed-species flocks, usually with Maui Creepers (Puroreomyza montana), that probably facilitated predator avoidance and foraging efficiency. The major limiting factors at present appear to be habitat modification from feral pigs (Sus scrofa), predation, avian disease, interspecific competition from the introduced garlic snail (Oxychilus alliarius), and possibly gene pool impoverishment. Control of pigs is recommended.

The Wilson Bulletin↗
USGS2017

Engaging the user community for advancing societal applications of the Surface Water Ocean Topography mission

Scheduled for launch in 2021, the Surface Water and Ocean Topography (SWOT) mission will be a truly unique mission that will provide high-temporal-frequency maps of surface water extents and elevation variations of global water bodies (lakes/reservoirs, rivers, estuaries, oceans, and sea ice) at higher spatial resolution than is available with current technologies (Biancamaria et al. 2016; Alsdorf et al. 2007). The primary instrument on SWOT is based on a Ka-band radar interferometer (KaRIN), which uses radar interferometery technology. The satellite will fly two radar antennas at either end of a 10-m (33 ft) mast, allowing it to measure the elevation of the surface along a 120-km (75 mi)-wide swath below. The availability of high-frequency and high-resolution maps of elevations and extents for surface water bodies and oceans will present unique opportunities to address numerous societally relevant challenges around the globe (Srinivasan et al. 2015). These opportunities may include such diverse and far-ranging applications as fisheries management, flood inundation mapping/risk mitigation/forecasting, wildlife conservation, global data assimilation for improving forecast of ocean tides and weather, reservoir management, climate change impacts and adaptation, and river discharge estimation, among others. Although SWOT is a research mission and not scheduled for launch for another 4 years, there is a need to build engagement within the application community now and to explore how best to advance the societal relevance and benefits of the SWOT mission from concept to reality. The SWOT Applications Working Group organized a workshop on 5–6 April 2017 at the U.S. Geological Survey (USGS) headquarters in Reston, Virginia. The goal of the workshop was to understand and communicate how the applications community can use SWOT data to address problems of profound societal relevance.

Bulletin of the American Meteorological Society↗
USGS1973

Value and validity of earth resources observations from space

Observations of the earth from space can provide overall repetitive views in various regions of the electromagnetic spectrum. Data from such surveys can be used as the basis for more detailed observations from aircraft and on the ground to guide resource exploration, development, and conservation activities. The value of earth resource observations from space has been demonstrated by the practical use of photographs from the Gemini and Apollo spaceflights and particularly by a series of multispectral photographs taken during the flight of Apollo 9. The analysis of those photographs has shown that the performance of the planned Earth Resources Technology Satellite will meet the needs of the resource and environmental community for small-scale repetitive images of the earth in the visible and solar infrared portions of the spectrum and has provided a limited base of material for earth scientists to work with in order to ready themselves for the ERTS data. The validity of earth resource observations from space can be derived by analogy from the successively closer observations of the moon, culminating in repeated physical sampling of the moon's surface. The method of inductive reasoning and analysis used for the moon is the opposite of the normal deductive analysis used on the earth. Adoption of the inductive methods and reasoning for earth observations will provide a framework of broad observations and conclusions leading to the identification of target areas for more detailed observation and will, in time, reduce the costs and time required for surveys dealing with resource and environmental problems.

Hydrological Sciences Bulletin↗
USGS2024

True metabolizable energy of foods consumed by lesser scaup (Aythya affinis)

The energy derived from available foods is an important factor used in conservation planning for migratory species. Estimating true metabolizable energy (TME) of available foods has become a common method for resource managers to increase reliability in energetic carrying-capacity estimates. Lesser scaup ( Aythya affinis ; hereafter scaup), have experienced a population decline concurrent with suspected decreases in foraging habitat quality and quantity at spring stopover sites in the upper Midwest, USA. Unfortunately, few TME estimates are available for common diet items of scaup. We estimated nitrogen-adjusted TME (TME N ) of 5 common foods of scaup by conducting feeding trials on wild females and males. True metabolizable energy varied by food taxa, but not by pretrial body mass or sex. Mean TME N (kcal/g[dry] ± SE) was greatest for wild millet ( Echinochloa crus-galli ; 2.20 ± 0.14), followed by chironomids ( Chironomus spp.; 1.41 ± 0.49), amphipods ( Gammarus spp .; 1.33 ± 0.23 ) , planorbid snails (Planorbidae; 0.17 ± 0.07), and fingernail clams (Sphaeriidae; −0.79 ± 0.27). Our results, combined with scaup diet literature indicated that the management of spring staging areas for high-energy invertebrates (i.e., chironomids and amphipods) would provide improved opportunity for energy acquisition during migration. Further study could help determine if the acclimation of scaup to particular diets, especially bivalves, increases their TME N values.

Wildlife Society Bulletin↗
USGS2013

A meta-analysis of lesser prairie-chicken nesting and brood-rearing habitats: implications for habitat management

The distribution and range of lesser prairie-chicken ( Tympanuchus pallidicinctus ) has been reduced by >90% since European settlement of the Great Plains of North America. Currently, lesser prairie-chickens occupy 3 general vegetation communities: sand sagebrush ( Artemisia filifolia ), sand shinnery oak ( Quercus havardii ), and mixed-grass prairies juxtaposed with Conservation Reserve Program grasslands. As a candidate for protection under the Endangered Species Act, there is a need for a synthesis that characterizes habitat structure rangewide. Thus, we conducted a meta-analysis of vegetation characteristics at nest sites and brood habitats to determine whether there was an overall effect (Hedges' d ) of habitat selection and to estimate average (95% CI) habitat characteristics at use sites. We estimated effect sizes (d i ) from the difference between use (nests and brood sites) and random sampling sites for each study ( n = 14), and derived an overall effect size (d ++ ). There was a general effect for habitat selection as evidenced by low levels of variation in effect sizes across studies and regions. There was a small to medium effect (d ++ ) = 0.20-0.82) of selection for greater vertical structure (visual obstruction) by nesting females in both vegetation communities, and selection against bare ground (d ++ = 0.20-0.58). Females with broods exhibited less selectivity for habitat components except for vertical structure. The variation of d ++ was greater during nesting than brooding periods, signifying a seasonal shift in habitat use, and perhaps a greater range of tolerance for brood-rearing habitat. The overall estimates of vegetation cover were consistent with those provided in management guidelines for the species.

Wildlife Society Bulletin↗
USGS2021

Field methods for translocating female greater sage-grouse (Centrocercus urophasianus) with their broods

Greater sage-grouse ( Centrocercus urophasianus ) have experienced considerable range contraction and reduced abundance in response to habitat loss and degradation. Translocation is a conservation action that is often used to reintroduce extirpated populations or augment existing small populations. Translocations have had limited success in restoring viable populations of sage-grouse; a lack of success is attributed to long-distance post-release movements away from release sites, reduced survival, and lack of reproductive success of translocated individuals. Translocating female sage-grouse with their chicks (brood translocation) is a technique aimed at promoting breeding area fidelity and reproduction and may be beneficial to population restoration efforts. Furthermore, the ability to capture, relocate, and release individuals while minimizing translocation-induced loss increases the overall probability of restoration success. Accordingly, we developed a protocol to translocate female sage-grouse and their broods simultaneously, using a delayed-release system that included a custom release box and acclimation pen. We tested our protocol across 2 separate restoration projects in North Dakota and California during 2017–2019 with a total of 38 translocated females and 196 chicks. We successfully released 174/196 chicks (88.8%) from 32/38 (84.2%) broods. Our protocol builds on existing translocation methods used to translocate sage-grouse and will likely prove to be a critical technique in restoring sage-grouse populations.

California, North Dakota, Wyoming↗
USGS2000

Protection of fish spawning habitat for the conservation of warm temperate reef fish fisheries of shelf-edge reefs of Florida

We mapped and briefly describe the surficial geology of selected examples of shelf-edge reefs (50–120 m deep) of the southeastern United States, which are apparently derived from ancient Pleistocene shorelines and are intermittently distributed throughout the region. These reefs are ecologically significant because they support a diverse array of fish and invertebrate species, and they are the only aggregation spawning sites of gag ( Mycteroperca microlepis ), scamp ( M. phenax ), and other economically important reef fish. Our studies on the east Florida shelf in the Experimental Oculina Research Reserve show that extensive damage to the habitat-structuring coral Oculina varicosa has occurred in the past, apparently from trawling and dredging activities of the 1970s and later. On damaged or destroyed Oculina habitat, reef-fish abundance and diversity are low, whereas on intact habitat, reef-fish diversity is relatively high compared to historical diversity on the same site. The abundance and biomass of the economically important reef fish was much higher in the past than it is now, and spawning aggregations of gag and scamp have been lost or greatly reduced in size. On the west Florida shelf, fishers have concentrated on shelf-edge habitats for over 100 yrs, but fishing intensity increased dramatically in the 1980s. Those reefs are characterized by low abundance of economically important species. The degree and extent of habitat damage there is unknown. We recommend marine fishery reserves to protect habitat and for use in experimentally examining the potential production of unfished communities.

Florida↗
USGS2002

Source of solutes to the coastal sabkha of Abu Dhabi

An ascending-brine model is proposed to address the observed isotope geochemistry, solute composition, and solute and water fluxes in the coastal sabkha of the Emirate of Abu Dhabi. Mass-balance measurements document that >95% of the solutes are derived from ascending continental brines; minor amounts are derived from rainfall and from groundwater entering from upgradient areas. Nearly 100% of the annual water loss is from evaporation and not lateral discharge. Direct rainfall on the sabkha and subsequent recharge to the underlying aquifer account for ~ 90% of the annual water input to the system; the remaining 10% comes from both lateral and ascending groundwater flow. Thus, the water and solutes in this system are from different sources. Solute concentrations of conservative (i.e., nonreactive) elements in the coastal, sabkha-covered aquifer are consistent with the fluid pore volumes of ascending brine calculated from hydrologic properties. Calcium to sulfate ratios and sulfur isotopes are consistent with this source of solute from the underlying Tertiary formations. Recharging rainwater dissolves halite and other soluble minerals on the surface, causing the solution to become more dense and sink to the bottom of the aquifer where it vertically mixes with less dense ascending brines. Solutes are returned to the surface by capillary forces and recycled or lost from the system by eolian or fluvial processes. Thus, the system becomes vertically mixed, consistent with the presence of tritium throughout the aquifer; but there is essentially no horizontal mixing of seawater with groundwater. The observed seawater solutes in the supratidal zone come from interstitial seawater trapped by the rapid progradation of the sediments into the Arabian Gulf and are not refluxed or laterally mixed. The ascending-brine model contrasts significantly with both the seawater-flooding and evaporative-pumping models previously proposed as a source of solutes to the coastal sabkha of the Emirate of Abu Dhabi. Use of these earlier models leads to incorrect conclusions and raises serious questions about their applicability in the evaluation of sabkhat in the geologic record.

Abu Dhabi↗
USGS2000

Protection of fish spawning habitat for the conservation of warm-temperature reef-fish fisheries of shelf-edge reefs of Florida

We mapped and briefly describe the surficial geology of selected examples of shelf-edge reefs (50–120 m deep) of the southeastern United States, which are apparently derived from ancient Pleistocene shorelines and are intermittently distributed throughout the region. These reefs are ecologically significant because they support a diverse array of fish and invertebrate species, and they are the only aggregation spawning sites of gag ( Mycteroperca microlepis ), scamp ( M. phenax ), and other economically important reef fish. Our studies on the east Florida shelf in the Experimental Oculina Research Reserve show that extensive damage to the habitat-structuring coral Oculina varicosa has occurred in the past, apparently from trawling and dredging activities of the 1970s and later. On damaged or destroyed Oculina habitat, reef-fish abundance and diversity are low, whereas on intact habitat, reef-fish diversity is relatively high compared to historical diversity on the same site. The abundance and biomass of the economically important reef fish was much higher in the past than it is now, and spawning aggregations of gag and scamp have been lost or greatly reduced in size. On the west Florida shelf, fishers have concentrated on shelf-edge habitats for over 100 yrs, but fishing intensity increased dramatically in the 1980s. Those reefs are characterized by low abundance of economically important species. The degree and extent of habitat damage there is unknown. We recommend marine fishery reserves to protect habitat and for use in experimentally examining the potential production of unfished communities.

Florida↗
USGS2017

Assessment of frequency and duration of point counts when surveying for golden eagle presence

We assessed the utility of the recommended golden eagle ( Aquila chrysaetos ) survey methodology in the U.S. Fish and Wildlife Service 2013 Eagle Conservation Plan Guidance. We conducted 800-m radius, 1-hr point-count surveys broken into 20-min segments, during 2 sampling periods in 3 areas within the Intermountain West of the United States over 2 consecutive breeding seasons during 2012 and 2013. Our goal was to measure the influence of different survey time intervals and sampling periods on detectability and use estimates of golden eagles among different locations. Our results suggest that a less intensive effort (i.e., survey duration shorter than 1 hr and point-count survey radii smaller than 800 m) would likely be inadequate for rigorous documentation of golden eagle occurrence pre- or postconstruction of wind energy facilities. Results from a simulation analysis of detection probabilities and survey effort suggest that greater temporal and spatial effort could make point-count surveys more applicable for evaluating golden eagle occurrence in survey areas; however, increased effort would increase financial costs associated with additional person-hours and logistics (e.g., fuel, lodging). Future surveys can benefit from a pilot study and careful consideration of prior information about counts or densities of golden eagles in the survey area before developing a survey design. If information is lacking, survey planning may be best served by assuming low detection rates and increasing the temporal and spatial effort.

Idaho, New Mexico, Wyoming↗
USGS1977

Conservation committee report. Falconry: Effects on raptor populations and management in North America

The art of falconry in North America, practiced by a few individuals for many years, attracted little attention until the 1960?s. Presently about 2800 falconers are licensed in the United States with less than one half considered to be active. While interest in this art is expected to increase, we believe growth will be slow, probably 5 to 10% per year, due to rigorous demands on time and equipment required and restrictive regulations.....Many different species of raptors have been used in falconry. Presently 6 species are commonly used, especially the Red-tailed Hawk and American Kestrel. Present evidence suggests that only 2 races of the Peregrine Falcon are threatened in North America, and declines may have occurred in local populations of other species. Declines in populations of Peregrines are attributed to pesticide contamination of food chains. Apparent declines in other populations of raptors are also attributed to pesticides and locally to changes in land use and possibly indiscriminate shooting. Removal of raptors from wild populations for falconry has not had documentable adverse effects except possibly at local nesting sites. Continuation of the art of falconry under the framework of the recent federal regulations is not expected to have measurable impacts on region-wide populations. Management of raptors is poorly developed and relatively unexplored. Captive breeding of raptors holds much promise for production of birds both for re-establishment and as a source of birds for falconry. Falconers have contributed much to the continued improvement of the Cornell University Peregrine program in terms of breeding stocks and technique development.

The Wilson Bulletin↗
USGS1953

Geology of the west-central part of the Gunnison Plateau, Utah

A detailed study of the west-central part of the Gunnison Plateau, Utah, has disclosed stratigraphic and structural relations important in the geological history of central Utah. The area mapped includes the eastern half of the Axtell No. 2 quadrangle, Manti area (U. S. Dept. of Agriculture, Soil Conservation Service). The bedrock ranges in age from the Arapien shale (Upper Jurassic) to the Green River formation (Eocene). The North Horn formation (Cretaceous-Tertiary), the Flagstaff limestone (Paleocene-Eocene), and the Green River formation (Eocene) successively overlap the Arapien shale and the Indianola group in the northern part of the area. In the southern part of the area, the North Horn formation and the Flagstaff limestone successively overlap the Price River conglomerate with angular discordance. The latter relation establishes a post-Price River and pre-North Horn orogenic movement in central Utah. A conspicuous west-dipping monocline, broken by many high-angle faults and a graben, extends along most of the western margin of the area. This structure is similar to the monocline and graben in the Wasatch Plateau to the east. At one point in the northern part of the area, the North Horn and the overlying Flagstaff oppose the Arapien shale across a high-angle fault. The Green River formation extends across the fault and overlaps the Arapien. This relation suggests faulting between Flagstaff and Green River time because the Colton formation, which normally occurs between the Flagstaff and Green River, cannot be differentiated in this immediate area. Numerous small intrusive masses of monzonite porphyry of post-Upper Jurassic age occur in the Arapien shale.

Utah↗
USGS2000

A time-dependent probabilistic seismic-hazard model for California

For the purpose of sensitivity testing and illuminating nonconsensus components of time-dependent models, the California Department of Conservation, Division of Mines and Geology (CDMG) has assembled a time-dependent version of its statewide probabilistic seismic hazard (PSH) model for California. The model incorporates available consensus information from within the earth-science community, except for a few faults or fault segments where consensus information is not available. For these latter faults, published information has been incorporated into the model. As in the 1996 CDMG/U.S. Geological Survey (USGS) model, the time-dependent models incorporate three multisegment ruptures: a 1906, an 1857, and a southern San Andreas earthquake. Sensitivity tests are presented to show the effect on hazard and expected damage estimates of (1) intrinsic (aleatory) sigma, (2) multisegment (cascade) vs. independent segment (no cascade) ruptures, and (3) time-dependence vs. time-independence. Results indicate that (1) differences in hazard and expected damage estimates between time-dependent and independent models increase with decreasing intrinsic sigma, (2) differences in hazard and expected damage estimates between full cascading and not cascading are insensitive to intrinsic sigma, (3) differences in hazard increase with increasing return period (decreasing probability of occurrence), and (4) differences in moment-rate budgets increase with decreasing intrinsic sigma and with the degree of cascading, but are within the expected uncertainty in PSH time-dependent modeling and do not always significantly affect hazard and expected damage estimates.

California↗
USGS2016

A strategy for recovering continuous behavioral telemetry data from Pacific walruses

Tracking animal behavior and movement with telemetry sensors can offer substantial insights required for conservation. Yet, the value of data collected by animal-borne telemetry systems is limited by bandwidth constraints. To understand the response of Pacific walruses ( Odobenus rosmarus divergens ) to rapid changes in sea ice availability, we required continuous geospatial chronologies of foraging behavior. Satellite telemetry offered the only practical means to systematically collect such data; however, data transmission constraints of satellite data-collection systems limited the data volume that could be acquired. Although algorithms exist for reducing sensor data volumes for efficient transmission, none could meet our requirements. Consequently, we developed an algorithm for classifying hourly foraging behavior status aboard a tag with limited processing power. We found a 98% correspondence of our algorithm's classification with a test classification based on time–depth data recovered and characterized through multivariate analysis in a separate study. We then applied our algorithm within a telemetry system that relied on remotely deployed satellite tags. Data collected by these tags from Pacific walruses across their range during 2007–2015 demonstrated the consistency of foraging behavior collected by this strategy with data collected by data logging tags; and demonstrated the ability to collect geospatial behavioral chronologies with minimal missing data where recovery of data logging tags is precluded. Our strategy for developing a telemetry system may be applicable to any study requiring intelligent algorithms to continuously monitor behavior, and then compress those data into meaningful information that can be efficiently transmitted.

Wildlife Society Bulletin↗
USGS2014

Using sightability-adjusted brood-pair ratios to estimate waterfowl productivity

Historically, biologists used brood-pair ratios (BPRs) as an index to waterfowl productivity to help guide management decisions and evaluate conservation practices. However, BPRs are biased by imperfect detection probabilities, especially for broods. We conducted roadside surveys for breeding waterfowl pairs on 7–8 study sites in the springs of 2006–2008 in northeastern North Dakota, USA. Later each year, we conducted replicate counts of broods on the same wetlands and used mark–recapture methods to estimate sightability-adjusted BPRs (SA-BPRs). Traditional roadside brood surveys detected only 30–45% of the available broods, depending on species. We explored the potential for using SA-BPRs to measure hen success (i.e., the probability a female hatches ≥1 egg across all nesting attempts) for mallards (Anas platyrhynchos) and other upland-nesting dabbling ducks (Anas spp.). We found that SA-BPRs explained 40% of the variation in hen success over 5 species of dabbling ducks, and we were able to detect an effect of predator reduction on hen success in combined dabblers, but not in mallards alone. However, we found no relationship between SA-BPRs and mallard fledging rates (hen success × initial brood size × duckling survival). Our results suggest that SA-BPRs can provide a cost-effective alternative to traditional measures of productivity such as nesting success, but not to measures of duckling survival. Nevertheless, SA-BPRs may be useful in areas where traditional measures of waterfowl productivity are logistically or financially challenging.

Wildlife Society Bulletin↗
USGS2020

Validating deployment of aerially delivered toxic bait cartridges for control of invasive brown treesnakes

Aerial application of management tools can provide a cost‐effective means to conserve or control wildlife populations at the landscape scale. Large spatial scales, however, present difficulties when assessing in situ reliability and integrity of the devices themselves. We demonstrate application of a distance‐sampling density estimation approach to assess the performance of a newly developed toxicant bait system for the control of invasive brown treesnakes ( Boiga irregularis ). Bait cartridges were designed to open in flight to expose the toxicant‐laced bait and tangle in the forest canopy via a plastic ribbon component. Following application of 12,686 bait cartridges from an automated aerial delivery system over a 55‐ha site on Guam, USA, we employed distance sampling techniques to evaluate cartridge performance. We performed 22 line‐transect surveys for a total distance of 10.3 km, during which we recorded all observations of unopened bait cartridges, instances in which the ribbon did not remain attached to the cartridge capsule (i.e., ribbon failure), and carcasses of brown treesnakes and nontarget species. Too few undeployed bait cartridges ( n = 6), brown treesnake carcasses ( n = 1), or nontarget carcasses ( n = 0) were observed during surveys to support additional analysis. We detected 299 instances of ribbon failure. Using standard distance‐sampling analyses, we estimate that ribbon failure occurred in 3,376 ± 351 (estimate ± SE; 95% CL = 2,746–4,150) cartridges or 21.6–32.7% of the total applied. Our results demonstrate the utility of distance‐sampling density estimation techniques to validate performance and reliability of aerially applied management tools.

Wildlife Society Bulletin↗