Natural Resources Management and Policy Commons^™

Effects Of Pregnancy Prevention On Brucella Abortus Shedding In American Bison (Bison Bison), Pauline Nol, Rebecca Frey, Morgan Wehtje, Jack C. Rhyan, Patrick Ryan Clarke, Matthew Mccollum, Christine Quance, Douglas C. Eckery, Suelee Robbe-Austerman

United States Department of Agriculture Wildlife Services: Staff Publications

Products of parturition are the predominant source of Brucella abortus for transmission in bison (Bison bison). Our objective was to assess whether preventing pregnancy in Brucella-seropositive bison reduced B. abortus shedding. Brucella-seropositive and -seronegative bison from Yellowstone National Park, Wyoming, USA were used in a replicated experiment. Each of two replicates (rep1, rep2) included a group of seropositive females treated with a single dose of gonadotropin-releasing hormone-based immunocontraceptive (Treatment rep1, n = 15; Treatment rep2, n = 20) and an untreated group (Control rep1, n = 14; Control rep2, …

Internal And External Factors Affect Pair Mate Proximity In Captive Coyotes, Canis Latrans, Alexandra Turano, Stacey P. Brummer, Jeffrey T. Schultz, Julie Young, Sara M. Freeman

United States Department of Agriculture Wildlife Services: Staff Publications

No abstract provided.

Toxoplasma Gondii Survey In Waterfowl And Gulls From Eight Usa States, Sawsan Ammar, Tania J. Dawant, Janetta Kelly, Graham Hickling, Justin Brown, Kyle R. Van Why, Rebecca Poulson, Chunlei Su, Richard W. Gerhold Jr.

United States Department of Agriculture Wildlife Services: Staff Publications

Sera from 391 waterbirds from eight USA states were tested for Toxoplasma gondii antibodies using the modified agglutination test. Fifteen different waterbird species (26.6%; n = 104) were seropositive. Of the adults, 25.4% (n = 52) showed a significantly higher T. gondii seroprevalence compared with juveniles (13.4%; n = 17); however, sex was not a significant factor.

Increased Bat Activity At Urban Water Sources: Implications For Cross-Species Transmission Of Bat Rabies To Mesocarnivores, Lias A. Hastings, Carol L. Chambers, David L. Bergman, Tad C. Theimer

United States Department of Agriculture Wildlife Services: Staff Publications

We examined the potential for urban water sources, specifically golf course ponds, to act as centers for rabies transmission from bats to mesocarnivores in the arid southwestern United States where surface water is often limited. Because residential housing can act as den and roost sites for both mesocarnivores and bats, we also examined the effect of housing density around water sources on activity. Using ultrasonic acoustic recorders to assess bat activity and camera traps to estimate mesocarnivore activity, we compared 14 pairs of wet and dry locations over two years by surveying twice during the summer, once prior to summer …

Experimental Assessment Of Laser Scarecrows For Reducing Avian Damage To Sweet Corn, Sean T. Manz, Kathryn E. Sieving, Rebecca N. Brown, Page E. Klug, Bryan M. Kluever

United States Department of Agriculture Wildlife Services: Staff Publications

Background

Birds damage crops, costing millions of dollars annually, and growers utilize a variety of lethal and nonlethal deterrents in an attempt to reduce crop damage by birds. We experimentally tested laser scarecrows for their effectiveness at reducing sweet corn (Zea mays) damage. We presented 18 captive flocks of free-flying European starlings (Sturnus vulgaris) with fresh sweet corn ears distributed on two plots where laser and control treatments were alternated each day and allowed each flock to forage over 5 days. In 16 trials, fresh sweet corn ears were mounted on wooden sticks distributed from 0 …

Unraveling Parasite Identification In Invasive And Endangered Squirrel Species: Potential For Parasite Spillover, Deandra Jones, Patricia S. Stock, Emilie Lefoulon, Maria V. Mazzamuto, W. Eugene Hall, David L. Bergman, John L. Kaprowski

United States Department of Agriculture Wildlife Services: Staff Publications

Invasive species can impact ecosystem health by introducing parasites during their establishment in new areas. However, the dynamics of parasite loads between invasive and native species remain poorly understood. In the 1940s, Abert’s squirrels (Sciurus aberti) were introduced to the Pinaleño Mountains in southeastern Arizona where they now co-occur with endemic endangered Mt. Graham red squirrels (Tamiasciurus fremonti grahamensis). The study aimed to identify and quantify parasites in both Abert’s and Mt. Graham red squirrels, with a focus on investigating possible parasite spillover between these two species and examining how host-related factors affect parasite presence. PCR …

Coyotes In The Great Basin Desert Do Not Exhibit A Spatial Response Following The Removal Of Anthropogenic Water Sources, Nadine A. Pershyn, Eric M. Gese, Erica F. Stuber, Bryan M. Kluever

United States Department of Agriculture Wildlife Services: Staff Publications

Coyote (Canis latrans) range expansion into desert ecosystems has highlighted the role of anthropogenic water sources in arid ecosystems. Despite hypotheses that additional water facilitated this expansion, previous studies reported that coyotes did not exhibit a spatial or dietary response to removal of anthropogenic water. We used GPS data to examine if coyotes responded to water removal at a finer spatial scale than previously investigated. Our integrated step selection analysis did not find evidence that coyotes adjusted their distance to water following water removal. Vegetation was an important factor in habitat selection of coyotes, with riparian and agricultural …

Frequency And Vehicle Damage Costs Of Wild Pig‑Vehicle Collisions In The United States, 2015–2022, Sophie C. Mckee, Jeremiah L. Psiropoulos, John J. Mayer

United States Department of Agriculture Wildlife Services: Staff Publications

The increasing frequency of wildlife-vehicle collisions (WVCs) is a globally recognized problem that can severely impact both the animals and humans involved in these accidents. Introduced wild pigs (Sus scrofa) have been present in various parts of the USA for centuries, but no study on wild pig-vehicle collisions (WPVCs) has been conducted on a national scale for the USA Using data provided by State Farm, we derived the number of vehicle collisions with wild pigs by state in the USA over the 2015–2022 period and the associated vehicle damage costs. In 2022, we estimated that a total of …

An Estimate Of The Marginal Annual Economic Contribution Of Wild-Pig Hunting In Texas, Sophie C. Mckee, Keith M. Carlisle, John Tomeček, Stephanie A. Shwiff, Rachael Connally, Maureen Frank, Mike Bodenchuk, Nicole Didero

United States Department of Agriculture Wildlife Services: Staff Publications

Context

Wild-pig (Sus scrofa) hunting is a culturally significant recreational and commercial activity in Texas, but the overall impacts are contested. Except for one 1980s study, there has been no research to formally quantify any economic benefits of wild-pig hunting in Texas, which is an important component for weighing the costs and benefits of wild-pig presence in the state.

Aims and methods

To fill that research gap, we surveyed a sample of resident and non-resident 2018–2019 hunting-license holders in Texas about various topics related to their wild-pig hunting activities, including expenditures

Key results

On the basis of the …

Use Of Nest Boxes By European Starlings (Sturnus Vulgaris): Effects Of Perceived Nest Predation Risk, Bradley F. Blackwell, Morgan B. Pfeiffer, Joshua L. Hoblet, Bruce N. Buckingham

United States Department of Agriculture Wildlife Services: Staff Publications

The European starling (Sturnus vulgaris) has expanded beyond its native Eurasian range, exploiting both natural cavities and human structures for nesting. We hypothesized that starling exposure to enhanced risk of nest predation at nest boxes (surrogates for nest sites in other structures), due to predator access, would negatively affect occupancy (establishment of a nest and ≥ 1 egg) and subsequent nest success. We also hypothesized that starlings would show no distinction in occupancy between nest boxes relative to the presence/absence of old nest material (i.e., material from the previous season), conditions that can contribute to nest predation risk. …

Steps Towards Operationalizing One Health Approaches, Kim M. Pepin, Keith M. Carlisle, Dean Anderson, Michael G. Baker, Richard B. Chipman, Jackie Benschop, Nigel P. French, Suzie Greenhalgh, Scott Mcdougall, Petra Muellner, Emil Murphy, Dion R. J. Neale, Michael J. Plank, David T. S. Hayman

United States Department of Agriculture Wildlife Services: Staff Publications

One Health recognizes the health of humans, agriculture, wildlife, and the environment are interrelated. The concept has been embraced by international health and environmental authorities such as WHO, WOAH, FAO, and UNEP, but One Health approaches have been more practiced by researchers than national or international authorities. To identify priorities for operationalizing One Health beyond research contexts, we conducted 41 semi-structured interviews with professionals across One Health sectors (public health, environment, agriculture, wildlife) and institutional contexts, who focus on national-scale and international applications. We identify important challenges, solutions, and priorities for delivering the One Health agenda through government action. Participants …

Discrimination Among Similarly Colored Goose Species In Federal Harvest Surveys, Joshua L. Dooley, Paul F. Doherty Jr., David L. Otis, Gary C. White, Daniel R. Taylor, Doreen L. Griffin, Syephen C. Chandler, Stephanie M. Catino, Kathy K. Fleming, Robert V. Raftovich, Antoinette J. Piaggio

United States Department of Agriculture Wildlife Services: Staff Publications

Each year in the United States, fall‐winter (sport) harvests of goose species are estimated from federal surveys coordinated by the United States Fish and Wildlife Service, including the Migratory Bird Harvest Survey to estimate total goose harvest and the Parts Collection Survey (PCS) to estimate the species and age composition. For the PCS, randomly selected hunters collect tail and wing feathers of each goose shot during the hunting season, and then biologists determine the age class and species of each sample at organized events (Wingbees) in each of the 4 flyways (Pacific, Central, Mississippi, and Atlantic). For similarly colored goose …

Population Growth Rates Of Pronghorn: Influence Of Temporally And Spatially Explicit Conditions, Density Dependence, And Scale, Eric M. Gese, Cole A. Bleke, Shane B. Roberts, Paul Atwood, Patricia A. Terletzky

United States Department of Agriculture Wildlife Services: Staff Publications

Density-independent and density-dependent population regulation has long been a subject of investigation. We examined density-dependent and density-independent factors on growth rates of pronghorn (Antilocapra americana (Ord, 1815)) using a retrospective analysis of population survey data. Across Idaho, we found that as the proportion of the subpopulation harvested the previous year increased, growth rates increased. Similarly, as fawn recruitment increased, growth rates increased. We also found when the growth rate in the previous year increased, the growth rate the subsequent year decreased. When subpopulations were examined independently, we found that in a low-elevation desert subpopulation, growth rates were influenced by …

Effects Of Lethal Management On Gray Wolf Pack Persistence And Reproduction In Wisconsin, Usa, Alejandra Zubiria Perez, Kenneth F. Kellner, David M. Macfarland, Jennifer L. Price Tack, David B. Ruid, Glenn E. Stauffer, Jerold L. Belant

United States Department of Agriculture Wildlife Services: Staff Publications

Direct human-caused mortality accounts for about half of all large mammal mortality in North America. For social species like gray wolves (Canis lupus), the death of pack members can disrupt pack structure and cause pack dissolution, and mortality of breeding adults or wolves during reproduction and pup-rearing can decrease pup recruitment. We estimated minimum and maximum probability of wolf pack persistence in Wisconsin, USA, during biological years (15 April–14 April) 2011–2019 and evaluated the influence of pack size and legal harvest mortality on pack persistence during 2012–2014. Harvests comprised 75–161 mortalities within 194 monitored packs during 2012–2014, with …

Serological Response To Canine Distemper Vaccination In Wild Caught Raccoons (Procyon Lotor), Molly R. Selleck, Shylo R. Johnson, Amy T. Gilbert

United States Department of Agriculture Wildlife Services: Staff Publications

Canine distemper virus (CDV) is a well-known RNA virus that affects domestic dogs and all families of wild terrestrial carnivores. Spillover infections from wildlife to domestic animals are mitigated by preventive vaccination, but there is limited information on the off-label use of veterinary vaccines for wildlife like raccoons (Procyon lotor). Twenty wild-caught raccoons were inoculated with a commercial recombinant DNA canarypox-vectored CDV vaccine, applying a regimen of two serial doses by SC route with an interval of 25-28 days between doses. The CDV serum virus neutralizing antibody (VNA) baseline titers and the postvaccination titers were measured at fixed …

Kit Foxes Demonstrate Adaptive Compromise Characteristics Under Intraguild Predation Pressure By Coyotes In The Great Basin Desert, Nadine A. Pershyn, Eric M. Gese, Erica F. Stuber, Bryan M. Kluever

United States Department of Agriculture Wildlife Services: Staff Publications

Coyotes (Canis latrans) are believed to contribute to declining kit fox (Vulpes macrotis) numbers in the Great Basin desert through intraguild predation. Intraguild prey have been shown to exhibit adaptive compromise, whereby an animal increases selection for risky, but food-rich areas during times of food stress (i.e. winter). We evaluated the habitat selection of kit foxes in the Great Basin desert to elucidate if they demonstrated adaptive compromise as a method of coexisting with coyotes. We created 2nd order resource selection functions to analyze kit fox habitat selection associated with coyote relative probability of use (RPU), …

Effects Of Ungulate‐Proof Fencing On Space Use By Wild Pigs, Kelly Koriakin, D. Buck Jolley, Benjamin Smith, Kurt C. Vercauteren, Nathan P. Snow

United States Department of Agriculture Wildlife Services: Staff Publications

Wild pigs (Sus scrofa) are a highly adaptable species that have invaded many regions and cause significant damage throughout the world. Ungulate‐proof fencing is increasingly used in conjunction with other control techniques to manage wild pig populations. However, little is known about how fencing affects wild pig space use behaviors and whether any changes may be exploited to increase efficacy of control activities. Our goal was to understand how wild pigs altered their space use behaviors in response to newly constructed fencing. Specifically, we examined for changes in space use area (home range and core area), increases in …

Invasive Wild Pig (Sus Scrofa) Diets On Barrier Islands In The Southeastern United States, Vienna R. Canright, Antoinette J. Piaggio, James C. Beasley

United States Department of Agriculture Wildlife Services: Staff Publications

Background

Biological invasions are a leading cause of reductions in global biodiversity. Islands are particularly sensitive to invasions, which often result in cascading impacts throughout island communities. Wild pigs (Sus scrofa) are globally invasive and pose threats to numerous taxa and ecosystems, particularly for islands where they have contributed to declines of many endemic species. However, the impacts of wild pig diet on the flora and fauna remain understudied in many island systems.

Results

We used DNA metabarcoding of wild pig fecal samples to quantify the seasonal diet composition of wild pigs on three barrier islands in the …

Binding Affinity, Selectivity, And Pharmacokinetics Of The Oxytocin Receptor Antagonist L-368,899 In The Coyote (Canis Latrans), Sara M. Freeman, J. Leon Catrow, James Eric Cox, Alexandra Turano, Mckenna A. Rich, Hillary P. Ihrig, Naveena Poudyal, Cheng-Wei Tom Chang, Eric M. Gese, Julie K. Young, Aaron L. Olsen

United States Department of Agriculture Wildlife Services: Staff Publications

L-368,899 is a selective small-molecule oxytocin receptor (OXTR) antagonist originally developed in the 1990s to prevent preterm labor. Although its utility for that purpose was limited, L-368,899 is now one of the most commonly used drugs in animal research for the selective blockade of neural OXTR after peripheral delivery. A growing number of rodent and primate studies have used L-368,899 to evaluate whether certain behaviors are oxytocin dependent. These studies have improved our understanding of oxytocin’s function in the brains of rodents and monkeys, but very little work has been done in other mammals, and only a single paper in …

Records Of Fleas (Siphonaptera) From Delaware [Sampling, Distribution, Dispersal], Ashley C. Kennedy, Wil S. Winter, Alfred L. Gardner, Neal Woodman, Scarlett A. Shifflet, Sierra Redus, Jeffrey R. Newcomer, Ralph P. Eckerlin

United States Department of Agriculture Wildlife Services: Staff Publications

We present an annotated checklist of fleas (Siphonaptera) known to occur in the state of Delaware based on an examination of Siphonaptera collections at the University of Delaware and the Carnegie Museum of Natural History, as well as new specimens of fleas we collected from wildlife, other hosts, and tick flags. We review published records and compile them herein with our new records, which include 3 species previously unreported from Delaware. With these additions, there are now 18 flea species from 19 avian and mammalian hosts documented from Delaware.

Measuring Changes In Pork Demand, Welfare Effects, And The Role Of Information Sources In The Event Of An African Swine Fever Outbreak In The United States, Pratyoosh Kashyap, Jordan F. Suter, Sophie C. Mckee

United States Department of Agriculture Wildlife Services: Staff Publications

African swine fever (ASF) has never been detected in the United States, but the current global outbreak threatens to change that. Although ASF poses no known risk to human health and is not a food safety concern, little is known about the response in U.S. consumer demand in case of an outbreak. We use an online survey experiment, following the one-and-one-half-bound dichotomous choice contingent valuation approach to estimate changes in consumers’ willingness to pay for pork in case of an ASF outbreak. Using these estimates, we find that demand for unprocessed pork (processed pork) products in the U.S. is predicted …

Changing Fire Regimes And Nuanced Impacts On A Critically Imperiled Species, Jeremy T. Rockweit, Katie M. Dugger, Damon B. Lesmeister, Raymond J. Davis, Alan B. Franklin, J. Mark Higley

United States Department of Agriculture Wildlife Services: Staff Publications

Wildfire activity throughout western North America is increasing which can have important consequences for species persistence. Native species have evolved disturbance-adapted traits that confer resilience to natural disturbance provided disturbances operate within their historical range of variability. This resilience can erode as disturbance regimes change and begin operating outside this range. We assessed wildfire impacts during 1987–2018 on the northern spotted owl, an imperiled species with complex relationships with late and early seral forest in the Pacific Northwest, USA. We analyzed population- and individual-level wildfire impacts across the frequent-fire portion of the owl’s geographic range at two spatial scales and …

Epidemiological Modeling Of Sars-Cov-2 In White-Tailed Deer (Odocoileus Virginianus) Reveals Conditions For Introduction And Widespread Transmission, Elias Rosenblatt, Jonathan D. Cook, Graziella V. Direnzo, Evan H. Campbell Grant, Fernando Arce, Kim M. Pepin, F. Javiera Rudolph, Michael C. Runge, Susan A. Shriner, Daniel P. Walsh, Brittany A. Mosher

United States Department of Agriculture Wildlife Services: Staff Publications

Emerging infectious diseases with zoonotic potential often have complex socioecological dynamics and limited ecological data, requiring integration of epidemiological modeling with surveillance. Although our understanding of SARS-CoV-2 has advanced considerably since its detection in late 2019, the factors influencing its introduction and transmission in wildlife hosts, particularly white-tailed deer (Odocoileus virginianus), remain poorly understood. We use a Susceptible-Infected-Recovered-Susceptible epidemiological model to investigate the spillover risk and transmission dynamics of SARS-CoV-2 in wild and captive white-tailed deer populations across various simulated scenarios. We found that captive scenarios pose a higher risk of SARS-CoV-2 introduction from humans into deer herds …

Seroprevalence Of Bovine Viral Diarrhea Virus In Wild Pigs (Sus Scrofa) In 17 States In The Usa, Shari M. Kennedy, Thomas Passler, Stephen S. Ditchkoff, Vienna R. Brown, Gage W. Raithel, Manuel F. Chamorro, Paul H. Walz, Constantinos S. Kyriakis, Shollie M. Falkenberg

United States Department of Agriculture Wildlife Services: Staff Publications

Wild pigs (Sus scrofa) are among the most detrimental invasive species in the USA. They are damaging to crops and agriculture, pose a public health risk as reservoirs of zoonotic pathogens, and may also spread disease to livestock. One pathogen identified in wild pigs is bovine viral diarrhea virus (BVDV), a virus that causes an economically important disease of cattle (Bos taurus and Bos indicus). We sought to determine the BVDV seroprevalence in wild pigs in 17 states across the US and to determine whether age category, sex, or location were associated with a positive antibody …

Pathology Of Chronic Mycoplasma Ovipneumoniae Carriers In A Declining Bighorn Sheep (Ovis Canadensis) Population, Jennifer L. Malmberg, Samantha E. Allen, Jessica E. Jennings-Gaines, Marguerite Johnson, Katie L. Luukkonen, Kara M. Robbins, Todd E. Cornish, Rachel A. Smiley, Brittany L. Wagler, Zach Gregory, Daryl Lutz, Pat Hnlicka, Kevin L. Monteith, William H. Edwards

United States Department of Agriculture Wildlife Services: Staff Publications

Bighorn sheep (Ovis canadensis) across North America commonly experience populationlimiting epizootics of respiratory disease. Although many cases of bighorn sheep pneumonia are polymicrobial, Mycoplasma ovipneumoniae is most frequently associated with all-age mortality events followed by years of low recruitment. Chronic carriage of M. ovipneumoniae by adult females serves as a source of exposure of naïve juveniles; relatively few ewes may be responsible for maintenance of infection within a herd. Test-and-remove strategies focused on removal of adult females with evidence of persistent or intermittent shedding (hereafter chronic carriers) may reduce prevalence and mitigate mortality. Postmortem confirmation of pneumonia …

Molecular Characterization Of Non-H5 And Non-H7 Avian Influenza Viruses From Non-Mallard Migratory Waterbirds Of The North American Flyways, 2006–2011, Shahan Azeem, John A. Baroch, Deepanker Tewari, Kristy L. Pabilonia, Mary L. Killian, Birgit Bradel-Tretheway, Dong Sun, Sara Ghorbani-Nezami, Kyoung-Jin Yoon

United States Department of Agriculture Wildlife Services: Staff Publications

The surveillance of migratory waterbirds (MWs) for avian influenza virus (AIV) is indispensable for the early detection of a potential AIV incursion into poultry. Surveying AIV infections and virus subtypes in understudied MW species could elucidate their role in AIV ecology. Oropharyngeal–cloacal (OPC) swabs were collected from non-mallard MWs between 2006 and 2011. OPC swabs (n = 1,158) that molecularly tested positive for AIV (Cts ≤ 32) but tested negative for H5 and H7 subtypes were selected for virus isolation (VI). The selected samples evenly represented birds from all four North American flyways (Pacific, Central, Mississippi, and Atlantic). Eighty-seven …

Home Range And Resource Selection Of Virginia Opossums In The Rural Southeastern United States, Jacob E. Hill, David A. Bernasconi, Richard B. Chipman, Amy T. Gilbert, James C. Beasley, Olin E. Rhodes Jr., Guha Dharmarajan

United States Department of Agriculture Wildlife Services: Staff Publications

The Virginia opossum (Didelphis virginiana) has a rapidly expanding distribution in North America, but many aspects of its ecology remain relatively understudied, particularly in rural areas of its core range. We collected GPS telemetry data from 93 opossums in a rural, non-agricultural landscape in South Carolina, USA (2018–2019) to examine factors influencing space use and resource selection. Estimated male home ranges (99% utilization distributions) were on average 50% larger than those of females (mean home range 115.9 ± 103.7 ha vs 76.7 ± 75.0 ha). The home range size decreased on average by 20% with each 20% increase …

Expanding Cwd Disease Surveillance Options Using Environmental Contamination At Deer Signposts, Miranda Hsiang-Ning Jacobson Huang

United States Department of Agriculture Wildlife Services: Staff Publications

1. Environmental surveillance can allow early detection of diseases, which increases management options and can improve disease trajectories. Chronic wasting disease (CWD) in cervids is a significant prion disease that has been spreading across North America since the 1960s, leading to cervid population declines and concern from hunters and state wildlife agencies. White-tailed deer have a unique breeding season behavior called scraping, where they deposit urine and saliva at shared sites. Since both these fluids can contain CWD prions, scrape sites have the potential to serve as sentinel sites for environmental surveillance of CWD.

2. To examine this potential, we …

Taphonomic Signatures Of Early Scavenging By Black And Turkey Vultures, Marian L. Wahl, Grant N. Burcham, Amanda M. Herbert, Lee A. Humberg, Patrick A. Zollner, Landon R. Jones, Brandon M. Quinby, Bryan M. Kluever

United States Department of Agriculture Wildlife Services: Staff Publications

Scavenging is critical for nutrient cycling and maintenance of healthy ecosystems. While there is substantial research into the identification of taphonomic signatures from facultative mammalian scavengers, early stage scavenging signatures by vultures remain unknown. Further, some vulture species are opportunistic predators, highlighting the need to define signatures observed in the course of normal scavenging behavior. We placed stillborn neonatal calves in an unoccupied pasture and used motion-trigger camera traps to quantify scavenging effort, then conducted necropsies to evaluate the effect of black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) scavenging effort on carcass consumption. We …

Relief Displacement Of Airborne Objects, Esteban Fernández-Juricic, Joe Crumpton, Morgan B. Pfeiffer, Sathishkummar Saiappan, Jared A. Elmore, Landon R. Jones, B. Santhana Krishnan, Raymond B. Iglay, Bradley F. Blackwell

United States Department of Agriculture Wildlife Services: Staff Publications

The increasing availability of unoccupied aircraft systems (UAS, also referred to as drones) has led to their use in taking vertical aerial photographs at relatively small spatial scales. These photographs can be used to measure the distances between objects appearing in the photographs. However, relief displacement can cause an object above or below ground level to appear at a point in a vertical aerial photograph that is not directly in-line with the object’s actual location, causing a measurement error. A UAS was used in this study as a photographed airborne object because its location and altitude could be controlled. We …