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At least 325 records · Page 18Linked to original sources

USGS2022

Automating sandhill crane counts from nocturnal thermal aerial imagery using deep learning

Population monitoring is essential to management and conservation efforts for migratory birds, but traditional low-altitude aerial surveys with human observers are plagued by individual observer bias and risk to flight crews. Aerial surveys that use remote sensing can reduce bias and risk, but manual counting of wildlife in imagery is laborious and may be cost-prohibitive. Therefore, automated methods for counting are critical to cost-efficient application of remote sensing for wildlife surveys covering large areas. We conducted nocturnal surveys of sandhill cranes ( Antigone canadensis ) during spring migration in the Central Platte River Valley of Nebraska, USA, using midwave thermal infrared sensors. We developed a framework for automated counting of sandhill cranes from thermal imagery using deep learning, assessed and compared the performance of two automated counting models, and quantified the effect of spatial resolution on counting accuracy. Aerial thermal imagery data were collected in March 2018 and 2021; 40 images were analyzed. We applied two deep learning models: an object detection approach, Faster R-CNN and a recently developed pixel-density estimation approach, ASPDNet. Model performance was determined using data independent of the training imagery. The effect of spatial resolution was quantified with a beta regression on relative error. Our results showed model accuracy of 9% mean percent error for ASPDNet and 18% for Faster R-CNN. Most error was related to the undercounting of sandhill cranes. ASPDNet had < 50% of the error of Faster R-CNN as measured by mean percent error, root-mean-squared error and mean absolute error. Spatial resolution affected accuracy of both models, with error rate increasing with coarser resolution, particularly with Faster R-CNN. Deep learning models, particularly pixel-density estimators, can accurately automate counting of migratory birds in a dense, aggregate setting such as nocturnal roosting sites.

Nebraska↗

USGS2017

Demographic consequences of nest box use for Red-footed Falcons Falco vespertinus in Central Asia

Nest box programs are frequently implemented for the conservation of cavity-nesting birds, but their effectiveness is rarely evaluated in comparison to birds not using nest boxes. In the European Palearctic, Red-footed Falcon Falco vespertinus populations are both of high conservation concern and are strongly associated with nest box programs in heavily managed landscapes. We used a 21-year monitoring dataset collected on 753 nesting attempts by Red-footed Falcons in unmanaged natural or semi-natural habitats to provide basic information on this poorly known species; to evaluate long-term demographic trends; and to evaluate response of demographic parameters of Red-footed Falcons to environmental factors including use of nest boxes. We observed significant differences among years in laying date, offspring loss, and numbers of fledglings produced, but not in egg production. Of these four parameters, offspring loss and, to a lesser extent, number of fledglings exhibited directional trends over time. Variation in laying date and in numbers of eggs were not well explained by any one model, but instead by combinations of models, each with informative terms for nest type. Nevertheless, laying in nest boxes occurred 2.10 ± 0.70 days earlier than in natural nests. In contrast, variation in both offspring loss and numbers of fledglings produced were fairly well explained by a single model including terms for nest type, nest location, and an interaction between the two parameters (65% and 81% model weights respectively), with highest offspring loss in nest boxes on forest edges. Because, for other species, earlier laying dates are associated with more fit individuals, this interaction highlighted a possible ecological trap, whereby birds using nest boxes on forest edges lay eggs earlier but suffer greater offspring loss and produce lower numbers of fledglings than do those in other nesting settings. If nest boxes increase offspring loss for Red-footed Falcons in heavily managed landscapes where populations are at greater risk, or for the many other species of rare or endangered birds supported by nest box programs, these processes could have important demographic and conservation consequences.

Ibis↗

USGS2003

Short-term bird response to harvesting switchgrass for biomass in Iowa

The Conservation Reserve Program (CRP) provides habitat for grassland birds, but as contracts expire, some CRP fields might be returned to rowcrop production. One alternative to returning CRP fields to rowcrops is to produce switchgrass ( Panicum virgatum ) for use as a biomass fuel. Because the biomass is harvested during the fall and winter, breeding birds would not be directly affected by mowing the fields bur might be influenced by changes in vegetation structure resulting from the harvest. We evaluated bird abundances and nest success in totally harvested, partially harvested (alternating cut and uncut strips), and nonharvested CRP switchgrass fields in southern Iowa, USA, in 1999 and 2000. Species richness did not differ among harvest treatments. Abundances of most species (16 of 18) were not affected by the harvesting of switchgrass fields, and strip width did not affect bird numbers in strip-harvested fields. Grasshopper sparrows ( Ammodramus savannarum ) were more abundant in harvested portions of fields, and more sedge wrens ( Cistothorus platensis ) were recorded in nonharvested areas. The residual vegetation in nonharvested areas provided nest cover for species that begin nesting early in the season (e.g., northern harrier [Circus cyaneus] and ring-necked pheasant [ Phasianus colchicus ]). Nest success rates of grasshopper sparrows and common yellowthroats ( Geothlypis trichas ) were similar to those reported by other studies in switchgrass fields and might be sufficient to maintain stable populations. In general, switchgrass biomass fields create breeding habitat for some grassland birds, and a mixture of harvested and nonharvested fields would be more beneficial to grassland birds than totally harvesting or partially harvesting all switchgrass fields.

Iowa↗

USGS2025

Aggregating three sources of long-term trends of swallows and martins to identify priority conservation areas in the Great Lakes region

1. Long-term monitoring of bird populations across scales is important in evaluating conservation targets and creating effective conservation strategies. For nearly six decades, the Breeding Bird Survey (BBS) has served as the primary broad-scaled source of relative abundance trends of swallows and martins in North America. Recently, however, it has become possible to obtain breeding population trends using semi-structured eBird community science data. Moreover, weather surveil-lance radar data of swallow and martin roosting populations yield a third complementary source of trend information. 2. Using results from these three approaches, we propose a novel method of spatially combining estimates of percent change per year into a probability of directional agreement and/or disagreement that describes (1) the direction of the trend within a given region, (2) the amount of evidence associated with the estimate and (3) how much uncertainty surrounds it. We focus our efforts on an area of high Hirundinidae concentration in the North American Great Lakes region and predict trends from 2012 to 2022. 3. We found a high probability of agreement between all three sources about ob-served declines in swallow and martin trends in the region surrounding Lake Ontario and to the west of Lake Michigan. Focusing future research on these regions could improve our understanding of these declines and help build more targeted conservation initiatives. 4. Synthesis and applications. Our data integration methodology allows managers to identify regions that accumulate evidence of concerning trends across multiple wildlife monitoring schemes. These regions can thus be prioritized in conservation and management efforts. This approach can be generalized to other sources of long-term monitoring data of different species, at different stages of their annual cycle, in any geographic location.

Great Lakes region↗

USGS2004

How we can learn more about the Cerulean Warbler ( Dendroica cerulea )

A sense of urgency attends the study of species of concern, like the Cerulean Warbler ( Dendroica cerulea ). Sharpened by Robbins et al. (1992) and Hamel (1992), such concern prompted the U.S. Department of the Interior, Fish and Wildlife Service (USFWS) to commission a status assessment of the Cerulean Warbler (Hamel 2000a). Shortly after the status review was published, a petition (Ruley 2000) was delivered to the USFWS urging that the species be listed as “threatened” under the Endangered Species Act of 1973. The account of the Cerulean Warbler in the Birds of North America series also appeared that year (Hamel 2000b). Substantial attention is currently focused on the species, and the Cerulean Warbler Technical Group (CWTG) was formed in 2002 (see Appendix). This overview consists of two parts. The first, prepared primarily by P.B.H., attempts to summarize current knowledge and suggest productive avenues to pursue in our efforts to understand the biology and conserve populations of Cerulean Warblers. The second, written by D.K.D. and P.D.K., is a summary of the structure and priorities of the CWTG, an organization that can spur and facilitate research and conservation action directed at this species and serve as a model for conservation of other forest birds (Appendix). Further information on Cerulean Warblers and activities of the Cerulean Warbler Technical Group can be found on the CWTG website (see Acknowledgments).

The Auk↗

USGS2014

Assessment of bird response to the Migratory Bird Habitat Initiative using weather-surveillance radar

In response to the Deepwater Horizon oil spill in spring 2010, the Natural Resources Conservation Service implemented the Migratory Bird Habitat Initiative (MBHI) to provide temporary wetland habitat for migrating and wintering waterfowl, shorebirds, and other birds along the northern Gulf of Mexico via managed flooding of agricultural lands. We used weather-surveillance radar to conduct broad regional assessments of bird response to MBHI activities within the Mississippi Alluvial Valley and the West Gulf Coastal Plain. Across both regions, birds responded positively to MBHI management by exhibiting greater relative bird densities within sites relative to pre-management conditions in prior years and relative to surrounding non-flooded agricultural lands. Bird density at MBHI sites was generally greatest during winter for both regions. Unusually high flooding in the years prior to implementation of the MBHI confounded detection of overall changes in remotely sensed soil wetness across sites. The magnitude of bird response at MBHI sites compared to prior years and to non-flooded agricultural lands was generally related to the surrounding landscape context: proximity to areas of high bird density, amount of forested wetlands, emergent marsh, non-flooded agriculture, or permanent open water. However, these relationships varied in strength and direction between regions and seasons, a finding which we attribute to differences in seasonal bird composition and broad regional differences in landscape configuration and composition. We detected greater increases in relative bird use at sites in closer proximity to areas of high bird density during winter in both regions. Additionally, bird density was greater during winter at sites with more emergent marsh in the surrounding landscape. Thus, bird use of managed wetlands could be maximized by enrolling lands located near areas of known bird concentration and within a mosaic of existing wetlands. Weather-radar observations provide strong evidence that MBHI sites located inland from coastal wetlands impacted by the oil spill provided wetland habitat used by a variety of birds.

Gulf Of Mexico;Mississippi Alluvial Valley;West Gu↗

USGS2021

Status of endemic reed-warblers of the Mariana Islands, with emphasis on conservation strategies for the endangered Nightingale Reed-warbler

Insular species, particularly birds, experience high levels of speciation and endemism. Similarly, island birds experience extreme levels of extinction. Based on a 2012 taxonomic assessment, historically there were four reed-warbler species in the Mariana Islands, the Guam Reed-warbler Acrocephalus luscinia (Guam), the Nightingale Reed-warbler Acrocephalus hiwae (Saipan and Alamagan), the Aguijuan Reed-warbler A. nijoi (Aguiguan or Aguijuan), and the Pagan Reed-warbler A. yamashinae (Pagan). Between 2008 and 2010 we surveyed for three of these species on Alamagan, Aguiguan, and Pagan. Our results indicate that reed-warblers are extinct on Aguiguan, likely extinct on Pagan, and only the Nightingale Reed-warbler on Alamagan and Saipan remains. We estimated the global population at between 1,019 and 6,356 birds (95% CI; mean estimate 3,688), which has declined by more than 1,000 birds since the first quantitative surveys were conducted in 1982, i.e. a 24% decline in 28 years. Camp et al . ( 2009 ) describe the status of the Nightingale Reed-warbler on Saipan, which has also declined. We estimated the Alamagan population to be between 428 and 1,762 birds in 2010 (mean estimate 946). Thus, the Alamagan population is ~25 % of the global population, and it has declined slightly since 2000. This decline was not significant but is concerning, especially given a similar decline on Saipan. Restoration and protection of tall-stature native and secondary forest could benefit the Alamagan population, as would similar conservation on Saipan that includes wetland habitat. After suitable restoration of forest and wetland habitats on Aguiguan, Guam and Pagan, individuals from Alamagan and Saipan could serve as founder populations. Careful consideration of the extent and habitat preference of individuals translocated to Tinian, where an unknown reed-warbler species previously occurred, is warranted.

Bird Conservation International↗

USGS2026

Biome-scale spatial patterns of avian abundance reveal proactive conservation opportunities in North American grasslands

North American grassland birds have experienced steeper population declines than any other avian guild, yet conservation efforts remain largely reactive and fragmented. We used nearly four decades of North American Breeding Bird Survey data to identify biome-scale spatial patterns (clustering) of grassland bird abundance for the Great Plains. Our results reveal an ecological core in the north-central Plains where community-level abundance is either increasing by >100% or remains high and stable, providing a strategic roadmap for a “Defend the Core” conservation approach. This approach flips the script from reactive triage centered on isolated population fragments to a proactive strategy of maintaining large-scale ecosystem integrity. Conversely, we found that population losses are more spatially clustered than wins, reflecting the relentless, one-way movement of woody encroachment and agricultural conversion. This asymmetry supports prioritizing intact landscapes, as current restoration rates are often outpaced by the scale of habitat loss. Notably, we found that community-level spatial clustering is a more robust indicator of biome condition than trends of individual flagship species, suggesting that managing for ecosystem integrity provides a more effective multi-species umbrella. Given our results, there is an opportunity for operationalizing a Great Plains Conservation Design that is ecosystem-centric and rooted in the sustainability of the private-land cattle production that maintains these open spaces. By leveraging avian abundance as a biological sensor, managers and producers can deploy a shared vision that matches the spatial scale of the threats, moving from reactive triage to proactive defense of core working grasslands in North America.

Great Plains biome↗

USGS2017

Rapid colonization of a Hawaiian restoration forest by a diverse avian community

Deforestation of tropical forests has led to widespread loss and extirpation of forest bird species around the world, including the Hawaiian Islands which have experienced a dramatic loss of forests over the last 200–800 years. Given the important role birds play in forest ecosystem functions via seed dispersal and pollination, a bird community's response to forest restoration is an important measure of the success of such conservation actions. We evaluated the bird response to reforestation at an important bird sanctuary, Hakalau Forest National Wildlife Refuge, Hawai′i Island, using 26 years of bird count data. We show that most species from within the diverse avian community increased significantly, but species colonized the restoration forest at different rates. Distance from intact forest and time since restoration were both important predictors of colonization rate, interacting such that for most species it took more time to colonize areas farther from the intact forest. In addition, both forest cover and understory diversity helped to explain bird densities, but the effect varied among species, suggesting that different habitat requirements may help drive variation in colonization rates. This article provides the first detailed evaluation of how a diverse community of birds has responded to one of the largest, ongoing reforestation projects in Hawai′i.

Hawai′i↗

USGS2004

Differential parasitism of seed-feeding Cydia (Lepidoptera: Tortricidae) by native and alien wasp species relative to elevation in subalpine Sophora (Fabaceae) forests on Mauna Kea, Hawaii

Alien parasitic wasps, including accidental introductions and purposefully released biological control agents, have been implicated in the decline of native Hawaiian Lepidoptera. Understanding the potential impacts of alien wasps requires knowledge of ecological parameters that influence parasitism rates for species in their new environment. Sophora seed-feeding Cydia spp. (Lepidoptera: Tortricidae) were surveyed for larval parasitoids to determine how native and alien wasps are partitioned over an elevation gradient (2200-2800 m) on Hawaii Island, Hawaii. Parasitism rate of native Euderus metallicus (Eulophidae) increased with increased elevation, while parasitism rate by immigrant Calliephialtes grapholithae (Ichneumonidae) decreased. Parasitism by Pristomerus hawaiiensis (Ichneumonidae), origins uncertain, also decreased with increased elevation. Two other species, Diadegma blackburni (Ichneumonidae), origins uncertain, and Brasema cushmani (Eupelmidae), a purposefully introduced biological control agent for pepper weevil, did not vary significantly with elevation. Results are contrasted with a previous study of this system with implications for the conservation of an endangered bird species that feed on Cydia larvae. Interpretation of results is hindered by lack of knowledge of autecology of moths and wasps, origins, phylogeny, systematics, competitive ability, and physiological limitations of each wasp species. These factors should be incorporated into risk analysis for biological control introductions and invasive species programs. ?? 2004 Kluwer Academic Publishers.

Journal of Insect Conservation↗

USGS2019

Impacts of saltwater intrusion on wetland prey production and composition in a historically freshwater marsh

Sea level rise is a fundamental driver of ecosystem change and has the potential to shift the spatial distributions of habitats more rapidly than species can adapt. Rapid sea level rise and associated saltwater intrusion have negative impacts on coastal environments, including loss of habitat for species such as sea turtles and shorebirds. In Florida’s largest wetland, the Everglades, the availability of small fishes that are prey for wading birds serve as an indicator of ecosystem health. In the southwestern part of the ecosystem, sea level rise and a reduction in freshwater flow have converted formerly freshwater marsh into an estuarine mangrove-dominated landscape. In this study, we sampled fish communities in this southwest portion of the Everglades exposed to a range of saline conditions. Biomass of native fishes was highest at a salinity value of approximately 25 parts per thousand, while non-native biomass decreased with increasing salinity. Applying salinity change scenarios, we determined that a 10% reduction from the salinity levels recorded in this study would be optimal for biomass of native fishes. The baseline data we collected on non-native fishes at the site will be useful for monitoring as restoration progresses and for managers working on invasive species control. This region has been actively undergoing ecosystem restoration for the last decade, but restored freshwater flow closer to historical conditions is still years away. Without increased freshwater inflow from hydrologic restoration, rising sea levels and saltwater intrusion may provide conservation challenges for wading birds and their prey-base fishes.

Florida↗

USGS2024

Molecular sexing of birds using quantitative PCR (qPCR) of sex-linked genes and logistic regression models

The ability to sex individuals is an important component of many behavioural and ecological investigations and provides information for demographic models used in conservation and species management. However, many birds are difficult to sex using morphological characters or traditional molecular sexing methods. In this study, we developed probabilistic models for sexing birds using quantitative PCR (qPCR) data. First, we quantified distributions of gene copy numbers at a set of six sex-linked genes, including the sex-determining gene DMRT1 , for individuals across 17 species and seven orders of birds ( n = 150). Using these data, we built predictive logistic models for sex identification and tested their performance with independent samples from 51 species and 13 orders ( n = 209). Models using the two loci most highly correlated with sex had greater accuracy than models using the full set of sex-linked loci, across all taxonomic levels of analysis. Sex identification was highly accurate when individuals to be assigned were of species used in model building. Our analytical approach was widely applicable across diverse neognath bird lineages spanning millions of years of evolutionary divergence. Unlike previous methods, our probabilistic framework incorporates uncertainty around qPCR measurements as well as biological variation within species into decision-making rules. We anticipate that this method will be useful for sexing birds, including those of high conservation concern and/or subsistence value, that have proven difficult to sex using traditional approaches. Additionally, the general analytical framework presented in this paper may also be applicable to other organisms with sex chromosomes.

Molecular Ecology Resources↗

USGS2000

Turnover and dispersal of prairie falcons in southwestern Idaho

We studied Prairie Falcon (Falco mexicanus) breeding dispersal, natal dispersal, and turnover at nesting areas in the Snake River Birds of Prey National Conservation Area (NCA) from 1971- 95. Of 61 nesting areas where falcons identified one year were known to be present or absent the following year, 57% had a different falcon. This turnover rate was 2-3 times higher than that reported elsewhere for large falcons, and may have been related to high nesting densities in the NCA. Turnover at nesting areas was independent of nesting success in the previous year, but was significantly higher for females nesting on large cliffs. Mean distance between natal and breeding locations for 26 falcons banded as nestlings and later encountered as nesting adults was 8.9 km. Natal dispersal distances were similar for males and females, but more than twice as many males marked as nestlings were later encountered nesting in the NCA. Fourteen adult falcons found on different nesting areas in successive years moved an average of 1.5 km between nesting areas; males dispersed significantly farther than females. Natal and breeding dispersal distances in the NCA were lower than those reported for Prairie Falcons in other study areas. Only four falcons banded as nestlings were found outside NCA boundaries during the breeding period, and only one of these birds was known to be occupying a nesting area. We encountered no falcons banded outside the NCA occupying nesting areas in the NCA during this study.

Journal of Raptor Research↗

USGS2017

Mitigating future avian malaria threats to Hawaiian forest birds from climate change

Avian malaria, transmitted by Culex quinquefasciatus mosquitoes in the Hawaiian Islands, has been a primary contributor to population range limitations, declines, and extinctions for many endemic Hawaiian honeycreepers. Avian malaria is strongly influenced by climate; therefore, predicted future changes are expected to expand transmission into higher elevations and intensify and lengthen existing transmission periods at lower elevations, leading to further population declines and potential extinction of highly susceptible honeycreepers in mid- and high-elevation forests. Based on future climate changes and resulting malaria risk, we evaluated the viability of alternative conservation strategies to preserve endemic Hawaiian birds at mid and high elevations through the 21 st century. We linked an epidemiological model with three alternative climatic projections from the Coupled Model Intercomparison Project to predict future malaria risk and bird population dynamics for the coming century. Based on climate change predictions, proposed strategies included mosquito population suppression using modified males, release of genetically modified refractory mosquitoes, competition from other introduced mosquitoes that are not competent vectors, evolved malaria-tolerance in native honeycreepers, feral pig control to reduce mosquito larval habitats, and predator control to improve bird demographics. Transmission rates of malaria are predicted to be higher than currently observed and are likely to have larger impacts in high-elevation forests where current low rates of transmission create a refuge for highly-susceptible birds. As a result, several current and proposed conservation strategies will be insufficient to maintain existing forest bird populations. We concluded that mitigating malaria transmission at high elevations should be a primary conservation goal. Conservation strategies that maintain highly susceptible species like Iiwi ( Drepanis coccinea ) will likely benefit other threatened and endangered Hawai’i species, especially in high-elevation forests. Our results showed that mosquito control strategies offer potential long-term benefits to high elevation Hawaiian honeycreepers. However, combined strategies will likely be needed to preserve endemic birds at mid elevations. Given the delay required to research, develop, evaluate, and improve several of these currently untested conservation strategies we suggest that planning should begin expeditiously.

PLoS ONE↗

USGS2014

Resource selection and space use by sea ducks during the non-breeding season: Implications for habitat conservation planning in urbanized estuaries

Wide-ranging marine birds rely on multiple habitats for wintering, breeding, and migrating, and their conservation may be dependent on protecting networks of key areas. Urbanized estuaries are critical wintering and stopover areas for many declining sea ducks in North America; however, conservation measures within estuaries are difficult to establish given lack of knowledge about habitat use by these species and the variety of competing human interests. We applied hierarchical modeling to evaluate resource selection of sea ducks (surf scoters, Melanitta perspicillata) wintering in San Francisco Bay, California, USA, a large and highly urbanized estuary. We also examined their distribution, home range, and movements with respect to key habitat features and regions within the estuary. Herring roe was the strongest predictor of bird locations; however, eelgrass, water depth and salinity were also highly-ranked, with sea ducks using deeper areas of higher salinity associated with herring roe and eelgrass presence during mid-winter. Sea ducks were also strongly associated with ferry routes, suggesting these areas may contain resources that are too important to avoid and emphasizing the need to better understand water traffic effects. Movements and home range size differed between males and females in early winter but became more similar in late winter. Birds traveled farther and used several sub-bays in early winter compared to mid-winter when herring roe availability peaked in the Central Bay. Our findings identified key environmental variables, highlighted core use areas, and documented critical periods for consideration when developing conservation plans for sea ducks in urbanized estuaries.

California↗

USGS2026

Lead exposure of snakes near recreational and military shooting areas in a sagebrush steppe ecosystem

Lead exposure has been documented in a multitude of bird and mammal species but less frequently in reptiles. Of the studies that have evaluated lead concentrations in reptiles, few have focused on snakes. We analyzed lead concentrations in liver and two types of bone from 24 gophersnakes ( Pituophis catenifer; Pc) and 12 Great Basin rattlesnakes ( Crotalus oreganus lutosus; Col) found dead along roads in the Morley Nelson Snake River Birds of Prey National Conservation Area in southwestern Idaho, U.S.A from 2018 to 2021. Because this area has been heavily impacted by both military and recreational activity, we also quantified lead concentrations in the soil near where the dead snakes were found. All soil samples had detectable lead (median: 12.53 µg/g; range: 0.07–16.77). Within individuals of both species, dry weight lead concentrations in liver generally were lower than those in bone (n samples < LOQ Liver: 9 of 13 ( Pc ), 9 of 10 ( Col ) (only a subset of individuals were in good enough condition to provide liver samples); Bone: 0 of 24 ( Pc ), 3 of 12 ( Col ). We did not detect any differences in lead concentrations between the species for either tissue type, nor between bone from the front (anterior) or back (posterior) of the snake skeleton. Additionally, we did not detect any correlation between lead concentration in soil collected at the roadkill sites and the tissue in the snakes. These data provide baseline information for lead exposure of two snake species in southwestern Idaho and demonstrate how lead is present in higher trophic levels within this ecosystem.

Idaho↗

USGS2026

Carcass size and ground substrate drive detection rates of avian carcasses by human surveyors and a dog team

Accurate avian mortality estimates are essential for understanding anthropogenic impacts to bird populations and informing conservation strategies. Carcass surveys are commonly conducted by human surveyors or by detection dogs, but the factors influencing surveyor detection abilities have not been fully explored. In this study, we conducted two years of detection trials in the semi-arid high desert of southern New Mexico, USA, testing 27 human surveyors and one conservation detection dog across 1096 trials with 238 carcasses representing 50 avian species. We directly compared detection abilities between surveyor types (human and dog) and identified key factors influencing detection probabilities. The conservation detection dog exhibited a significantly higher detection probability (mean = 0.87) than human surveyors (mean = 0.49, individuals ranged 0.25–0.71), consistent with previous studies. Detection probabilities for both surveyor types were influenced by carcass size and ground substrate; detection probability was higher for larger carcasses and areas with lower vegetative complexity. We discuss our results in the context of common tradeoffs faced by managers in designing carcass surveys and how guidance may vary under different scenarios. Broadly, our study provides valuable insight that can enhance wildlife mortality monitoring, ensuring more accurate mortality estimates to inform management and conservation efforts.

New Mexico↗

USGS2024

Season of grazing interacts with soil texture, selecting for associations of biocrust morphogroups

Livestock grazing, a widespread land use in semi-arid systems, is often placed in opposition to the perpetuation of biological soil crusts (“biocrusts”: lichens, mosses, and algal crusts including cyanobacteria) that live on the soil surface and provide ecosystem functions. The composition of biocrusts and vascular plants varies with climate, soils, and disturbance. In general, ruderal mosses and light algal crusts make up greater proportions of biocrusts in the presence of disturbance, although morphogroups of biocrusts respond differently to various disturbances. It is unknown if there are scenarios under which grazing can occur and ruderal components of biocrust could be maintained. We examine the hypothesis that soil surface texture-moisture interactions influence the ability of biocrusts to withstand trampling, reasoning that finer-textured soils are firmer (therefore serving as a better substrate for biocrusts) when dry and that coarser-textured are firmer when wet. We test these relationships within Birds of Prey, National Conservation Area (Boise, Idaho, USA). Results demonstrate two associations of biocrusts, dependent on season of grazing: one dominated by light algal crusts and lichens that frequently occurs with wet season grazing, and a second dominated by tall mosses and cup lichens that frequently occurs with dry season grazing. High cover of the invasive annual grass, Bromus tectorum (L.) was observed on sites with coarse-textured soils, and high sand content, that are grazed at relatively high intensities, creating unstable surfaces, and likely putting biocrusts at greater susceptibility to trampling. Results suggest that livestock management that accounts for soil texture and moisture could be used to maintain cover of ruderal biocrusts on fine-textured soils, that are grazed in the dry season, at low intensity. We discuss our findings in the context of managing for species of interest. Our findings are timely as varying the season of grazing is increasingly discussed as a means of favoring desirable native perennial grasses. Although ruderal morphogroups of biocrusts are not interpreted as having equivalent ecosystem functions compared to intact biocrusts, their contributions to soil stability, fertility, hydrology, and weed abatement could increase if they were more intentionally targeted by management.

Geoderma↗