Black Vulture Conflict and Management in the United States: Damage Trends, Management Overview, and Research Needs

Contrary to rapid declines of many vulture (Accipitridae, Cathartidea) species worldwide, black vulture (Coragyps atratus) populations are increasing and expanding their range in North America. Vultures exhibit complex behaviors and can adapt to any human-dominated landscape or land use. These traits, combined with population growth and range expansion, have contributed to increased human–vulture conflicts. Our goal was to summarize the current status and trends in human–black vulture conflicts (hereafter human–vulture conflicts), review available management strategies, identify knowledge gaps, and provide recommendations to enhance management and understanding of this species and the associated conflicts. We found human–vulture conflicts are increasing in agriculture (livestock), private and public property (both personal and infrastructure-based), and threats to human health and safety. The greatest increases in conflicts were reported in agriculture and private and public property damage. Regarding livestock depredation, good progress has been made toward assessing producer perceptions of the conflicts, including estimates of economic damage and mitigation strategies, but a basic understanding of the underlying mechanism driving the conflict and advancing strategies to mitigate damage is lacking. For damaged property, little information is available regarding economic losses and perceptions of stakeholders who are experiencing the damage, and most of the tools recommended for mitigating this damage have not been rigorously evaluated. Regarding human health and safety, recent research quantifying flight behavior of black vultures has direct implications for reducing aircraft collision risks. However, it is unclear what factors influence roost site selection and the most effective means to leverage the sensory ecology of the species to mitigate risks. We identify additional knowledge gaps and research needs that if addressed could increase managers’ understanding of black vulture ecology and facilitate enhanced management of this species while simultaneously allowing for the species to provide valuable ecosystem services

Cultivation of Industrial Hemp on and Near Airports: Implications for Wildlife Use and Risk to Aviation Safety

Land-use planning on and near airports should consider possible revenue from land covers, associated maintenance costs, and potential for land covers to attract vertebrate species recognized as hazardous to aviation safety. The U.S. Federal Aviation Administration has expressed interest in recent attention given to industrial hemp (Cannabis sativa L.; hemp) as a revenue-producing land cover that might be cultivated on or near airports. Our purpose was to better understand the potential production value of hemp as well as its possible role in affecting aviation safety if cultivated on or near airports. Our objectives were to: (1) review the literature relative to a historical perspective of hemp cultivation in the United States, projected cultivation practices, and anticipated economic viability, (2) use our review to gather information on vertebrate use of hemp cultivars, and (3) revisit U.S. and international regulations on land covers near airports relative to attraction of species recognized as hazardous to aviation safety. We found, via review of peer-reviewed and gray literature, that hemp holds potential as an emerging crop in the United States, contributing to food, medicine, and biomass-derived products as well as evidence that birds will use, if not depredate, the crop. However, future markets promoting cultivation of hemp remain tentative. Further, there has been no objective quantification of bird and other wildlife use of hemp alone or as a component of a land cover matrix on or near airports and relative to implications for aviation safety. We make recommendations for future research on wildlife use of hemp and metrics necessary to inform aviation safety

Industrial Hemp as a Resource for Birds in Agroecosystems: Human–Wildlife Conflict or Conservation Opportunity?

Industrial hemp (Cannabis sativa L.; hemp) is an emerging crop in the United States with little known about bird use or the potential for birds to become an agricultural pest. We identified birds associated with hemp fields, using repeated visits to oilseed plots in North Dakota, USA (n = 6) and cannabinoid (CBD) plots in Florida, USA (n = 4) from August to November 2020. We did not control for plot area or density; our observations were descriptive only. We observed 10 species in hemp, 12 species flying over hemp, and 11 species both foraging in and flying over hemp fields in North Dakota. In Florida, we observed 4 species in hemp, 5 species flying over hemp, and 4 species exhibiting both behaviors. When we observed birds in hemp, we found them perched in the canopy or foraging on the ground. Counts were highest in oilseed and lowest in CBD varieties. The Florida sites were mainly CBD varieties, which explains lower species diversity and raw counts of birds given the lack of seeds produced. Maximum raw counts of the most common birds (mourning doves [Zenaida macroura] = 116; house finches [Haemorhous mexicanus] = 53; and American goldfinches [Spinus tristis] = 40) using very small fields (116–324 m2) in North Dakota suggest oilseed hemp could suffer yield losses but potentially benefit farmland bird conservation and act as a decoy crop to protect other commodities (e.g., sunflower [Helianthus annuus L.])

Spatial risk modeling of cattle depredation by black vultures in the midwestern United States

ock operations through depredation of stock are a cause of human‐wildlife conflict. Management of such conflict requires identifying environmental and non‐environmental factors specific to a wildlife species\u27 biology and ecology that influence the potential for livestock depredation to occur. Identification of such factors can improve understanding of the conditions placing livestock at risk. Black vultures (Coragyps atratus) have expanded their historical range northward into the midwestern United States. Concomitantly, an increase in concern among agricultural producers regarding potential black vulture attacks on livestock has occurred. We estimated area with greater or lesser potential for depredation of domestic cattle by black vultures across a 6‐state region in the midwestern United States using an ensemble of small models (ESM). Specifically, we identified landscape‐scale spatial factors, at a zip code resolution, associated with reported black vulture depredation on cattle in midwestern landscapes to predict future potential livestock depredation. We hypothesized that livestock depredation would be greatest in areas with intensive beef cattle production close to preferred black vulture habitat (e.g., areas with fewer old fields and early successional vegetation paired with more direct edge between older forest and agricultural lands). We predicted that the density of cattle within the county, habitat structure, and proximity to anthropogenic landscape features would be the strongest predictors of black vulture livestock‐depredation risk. Our ESM estimated the relative risk of black vulture‐cattle depredation to be between 0.154–0.631 across our entire study area. Consistent with our hypothesis, areas of greatest predicted risk of depredation correspond with locations that are favorable to vulture life‐history requirements and increased potential to encounter livestock. Our results allow wildlife managers the ability to predict where black vulture depredation of cattle is more likely to occur in the future. It is in these areas where extension and outreach efforts aimed at mitigating this conflict should be focused. Researchers and wildlife managers interested in developing or employing tools aimed at mitigating livestock‐vulture conflicts can also leverage our results to select areas where depredation is most likely to occur

Modeling Wildlife Damage to Crops in Northern Indiana

Comprehensive information on crop damage by wildlife species is critical if effective strategies for controlling wildlife damage are to be formulated. Discriminating how landscape composition and configuration attributes influence crop damage is important for implementing landscape management techniques to resolve human–wildlife conflicts. We analyzed crop damage data from 100 corn fields and 60 soybean fields located in the Upper Wabash River Basin of northern Indiana during 2003 and 2004. We used negative binomial regression to model the rate of damage to corn and soybean crops in response to local and landscape variables. Rate of crop damage was best predicted by a combination of local and landscape variables for both corn and soybeans. Models with landscape configuration variables were better able to explain patterns of corn damage, and models with landscape composition variables (specifically, amount of wooded areas) were better able to explain patterns of soybean damage. In general, rate of crop damage was negatively related to size of the crop field and positively related to proportion of a field’s perimeter that was adjacent to wooded areas, amount of wooded areas, amount of forest edge, and mean size of forest patches. Specific associations between local and landscape variables and rates of crop damage may serve as a guide to planting strategies and landscape management to minimize wildlife damage to crops

Wildlife collisions with aircraft: A missing component of land-use planning for airports

Projecting risks posed to aviation safety by wildlife populations is often overlooked in airport land-use planning. However, the growing dependency on civil aviation for global commerce can require increases in capacity at airports which affect land use, wildlife populations, and perspectives on aviation safety. Our objectives were to (1) review legislation that affects airports and surrounding communities relative to managing and reducing wildlife hazards to aviation; (2) identify information gaps and future research needs relative to regulated land uses on and near airports, and the effects on wildlife populations; and (3) demonstrate how information regarding wildlife responses to land-use practices can be incorporated into wildlife-strike risk assessments.We show that guidelines for land-use practices on and near airports with regard to wildlife hazards to aviation can be vague, conflicting, and scientifically ill-supported. We discuss research needs with regard to management of storm water runoff; wildlife use of agricultural crops and tillage regimens relative to revenue and safety; the role of an airport in the landscape matrix with regard to its effects on wildlife species richness and abundance; and spatial and temporal requirements of wildlife species that use airports, relative to implementing current and novel management techniques. We also encourage the development and maintenance of data sets that will allow realistic assessment of wildlife-strike risk relative to current airport conditions and anticipated changes to capacity. Land uses at airports influence wildlife populations, and understanding and incorporating these effects into planning will reduce risks posed to both aviation safety and wildlife species

Survival and Cause-Specific Mortality of Wild Turkeys in Northern Indiana

Information regarding survival and cause-specific mortality of eastern wild turkeys (Meleagris gallopavo silvestris) is vital to their management, especially in small or isolated populations. Between January 2003 and August 2005, we used radio telemetry to investigate survival and cause-specific mortality of 87 [44 male (24 adult and 20 juvenile) and 43 female (34 adult and 9 juvenile)] wild turkeys in northern Indiana. We estimated annual and seasonal survival using the Kaplan-Meier product-limit method. Mean male and female annual survival estimates were 0.257 and 0.777, respectively. Annual survival estimates were different between sexes within years, but were homogenous within sexes between years. Survival estimates did not differ among seasons for either sex. However, differences in survival estimates between sexes were detected in the spring, fall and winter seasons. Hunter harvest (46.2% male mortality) and predation (33.3% female mortality) were the leading known causes of mortality for male and female wild turkeys, respectively. Predators (canids, birds and unknown mammals) were responsible for 28.6% of mortality for both sexes combined. Although predation on adult birds was not severe, high mortality of male turkeys in the form of legal spring harvest, in addition to other causes of mortality, warrants concern for small, exploited populations in highly fragmented landscapes like those of northern Indiana

Intrafield patterns of wildlife damage to corn and soybeans in northern Indiana

Management programs aimed at reducing wildlife damage to row crops rely on information concerning the spatial nature of wildlife damage at local and landscape scales. In this study we explored spatial patterns of wildlife damage within individual corn and soybean fields by describing relationships between specific locations where wildlife damage was recorded and distances from such locations to various habitat types that presumably influenced animal abundance and movements in our study area. Using stratified random sampling, we conducted depredation surveys of 100 corn fi elds and 60 soybean fields from May through October both in 2003 and 2004 and recorded the specific global positioning satellite (GPS) coordinates of wildlife damage to individual corn and soybean plants. We then generated random point locations in the same fields using a geographic information system (GIS) and evaluated whether damage point locations and random point locations differed with respect to distances to the nearest patches of forest, developed area, or grassland and shrubland habitats. For both crop types, damage point locations were significantly closer to forest patches than were random point locations, but farther from developed areas than random point locations. Logistic regression analyses further indicated that distance to forest influenced the probability of wildlife damage within fields, although pseudo r2 values of the best models were low (0.15). Our results clearly indicated that field portions that were nearest to forested habitats were more likely to suffer wildlife damage than field portions farther from forested habitats. We suggest that targeted removals of depredating species, concentrated along crop-forest interfaces, may be an effective, cost-effective means of reducing corn and soybean damage in areas where wildlife damage is especially problematic

Industrial Hemp as a Resource for Birds in Agroecosystems: Human-Wildlife Conflict or Conservation Opportunity?

Industrial hemp (Cannabis sativa L.; hemp) is an emerging crop in the United States with little known about bird use or the potential for birds to become an agricultural pest. We identified birds associated with hemp fields, using repeated visits to oilseed plots in North Dakota, USA (n = 6) and cannabinoid (CBD) plots in Florida, USA (n = 4) from August to November 2020. We did not control for plot area or density; our observations were descriptive only. We observed 10 species in hemp, 12 species flying over hemp, and 11 species both foraging in and flying over hemp fields in North Dakota. In Florida, we observed 4 species in hemp, 5 species flying over hemp, and 4 species exhibiting both behaviors. When we observed birds in hemp, we found them perched in the canopy or foraging on the ground. Counts were highest in oilseed and lowest in CBD varieties. The Florida sites were mainly CBD varieties, which explains lower species diversity and raw counts of birds given the lack of seeds produced. Maximum raw counts of the most common birds (mourning doves [Zenaida macroura] = 116; house finches [Haemorhous mexicanus] = 53; and American goldfinches [Spinus tristis] = 40) using very small fields (116–324 m2) in North Dakota suggest oilseed hemp could suffer yield losses but potentially benefit farmland bird conservation and act as a decoy crop to protect other commodities (for example, sunflower [Helianthus annuus L.])