Bird damage is a persistent challenge in food production agriculture, causing substantial economic losses worldwide. Conventional deterrent methods (e.g., scarecrows, reflective tapes, and propane cannons) are labor-intensive and prone to bird habituation. In recent years, advances in sensing, automation, robotics, and artificial intelligence have enabled the development of technology-driven bird deterrent systems that offer targeted, adaptive, and scalable alternatives. However, a well-documented and critically evaluated synthesis of the literature is lacking. Therefore, we present a systematic literature review of advanced and emerging bird deterrence technologies for crop protection. A total of 33 peer-reviewed articles were selected and analyzed. Each study was critically reviewed based on deterrent platform type, sensing modality, control strategy, target crop system, targeted bird species, reported effectiveness, and limitations. Drone-based hazing emerged as the most used approach, followed by laser deterrents and sonic net systems. The reviewed studies primarily focused on high-value agricultural systems known to suffer from bird damage, including row crops (n = 10), vineyards (n = 8), orchards/fruits (n = 6), and poultry farms (n = 2). The studies that compared technology tools to conventional deterrents were summarized, and only one study evaluated the impact of a sensor-triggered deterrent system. In general, deterrent systems integrating sensor feedback, and automated actuation can outperform conventional methods, achieving rapid flock dispersal, significant reductions in bird activity, and decreased crop damage. Despite these advances, challenges remain related to scalability, long-term effectiveness, regulatory constraints, sensor robustness, and economic feasibility. We also synthesized current trends, highlighted critical research gaps, and outlined future directions for the development of cost-effective, adaptive, and farmer-centric bird deterrent solutions that harness advanced technologies for the benefit of growers. The findings provide a well-documented knowledge base to support researchers, extension specialists, and producers in adopting next-generation deterrent technologies for sustainable food production systems.

As human populations expand and land use changes, human-wildlife conflicts are increasing, requiring costeffective management tools that balance human well-being and wildlife conservation. Hazing devices are often used to mitigate conflicts between wildlife and agriculture with drones serving as both frightening devices and monitoring systems. Artificial intelligence (AI) enables automated detection, identification, and counting of wildlife, allowing for field-based Internet of Things (IoT) systems to selectively deploy tools when target species reach a critical threshold. We acquired drone imagery of mixed-species blackbird flocks - dominated by redwinged blackbirds (RWBL) Agelaius phoeniceus - damaging sunflowers (Helianthus annuus) in North Dakota (September-October 2021-2022). We trained a ResNet-18 Convolutional Neural Network (CNN) model to A) detect flocks (accuracy = 95.0 %); and Faster Region-based Convolutional Neural Network (Faster-RCNN) models to B) detect individual blackbirds (accuracy = 65.7 %, precision = 97.6 %), C) classify individual blackbirds by species and for RWBL sex and age class, and D) count blackbirds (% difference: birds = 37.5 %; male RWBL = 39.6 %; female RWBL = 43.1 %). The model correctly classified RWBL to species (87.6 %), sex, and age class (adult males = 89.8 %; hatch-year males = 27.6 %; females = 80.0 %). The RWBL were misclassified as other blackbirds that inflict crop damage, not non-target species. Variability in background (e.g., sky, green vegetation, tan vegetation) and complexity (e.g., contrast, texture), along with bird camouflage, required background removal to enhance performance when moving drones captured still images of moving targets. Camera orientation (e.g., depth perception, target overlap) and image quality (e.g., blurred, shadowed objects) affected detection, classification, and counts. Automated deployment reduces labor and wildlife habituation, increasing longevity and efficacy of management tools.

When human-wildlife conflict exists, estimates are important for quantifying animal abundance and assessing tool efficacy to disperse wildlife and reduce damage. We used drones to capture images of mixed-species blackbird (Icteridae) flocks damaging sunflower (Helianthus annuus) in North Dakota (Aug-Oct). We evaluated the ability of 20 biologists to make estimates close to an automated count (i.e. ImageJ). While estimates were highly correlated (Spearman: R = 0.94, P < 0.001), biologist estimates (range = 25-50,000 birds) were on average 16% lower and 69% different (absolute value of difference) than automated counts (range = 57-6,272 birds). Biologists were closer to automated counts when observing smaller flocks and images later in the photo set. We found no effect of self-reported experience. Although drone imagery provides a standardized method for counting flocks at far distances, in-field estimates are needed given that entire flocks are not easily captured in a single frame. Drone imagery can be used to train biologists and reduce estimation errors among observers and by an observer making multiple estimates when flock sizes vary and reach large aggregations. Additionally, autonomous drone systems could use real-time imagery during hazing to target nuisance species of certain flock sizes for efficient resolution of human-wildlife conflict.

Context Drones can be used as frightening devices to resolve avian-agriculture conflicts. Blackbird (Icteridae) flocks respond to drones making them a suitable scare device to protect sunflower (Helianthus annuus), but with limited efficacy on large flocks. Integrating a non-lethal avian repellent on the same drone as used for hazing may increase efficacy, but responses of flocks towards drones with spraying capabilities need to be evaluated to inform application protocols. Aim We evaluated flock responses to a drone capable of spraying when first approached and with 10 min of hazing, to inform protocols for delivering repellents on agricultural landscapes. Methods We used eye-in-the-sky drones to video the drone with spraying capabilities and observed whether flocks took flight within 80 m (i.e. range of potential spray drift). We measured flight initiation distance (FID) when close approach occurred (i.e. drone <= 80 m from flock). While hazing, we piloted the drone to (1) repeatedly cut through a flock and create chaos or (2) move along the flock edge to herd birds out of target habitat (i.e. sunflower or cattail). We recorded abandonment, flock reduction, and return rate of birds in response to drone hazing. Key results The probability of a close approach was greater with birds in cattail than in sunflower, but habitat did not influence mean FID when the drone was within 80 m (FID = 40 m +/- 14.3 s.d.), abandonment (31 of 60 flocks), or mean percentage flock reduction (50% +/- 37 s.d.). FID was shorter with smaller flocks, later in the day, but abandonment increased with smaller flocks as the day progressed. Although 52% of flocks abandoned, 81% returned after the end of hazing. Flight path of the drone (i.e. chaotic or herding) did not affect abandonment or flock reduction. Conclusions Although blackbirds perceived the drone approach as riskier (>FID) while foraging in sunflower earlier in the day, increased abandonment that occurred later in the day was likely to be due to satiation and movement to night-time roosts, instead of hazing impacts. Birds in sunflower interspersed with cattail used local refugia until the threat passed, then resumed foraging. Implications If applying an avian repellent with a spraying drone, protocols should consider time of day, flock size, and habitat. When selecting a flight path, pilots need to be concerned only with optimizing spray drift to reach areas with foraging blackbirds.

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 to 32 m from laser units (Stick Trials), and in two trials birds foraged on ripe corn grown from seed in the flight pen (Natural Trials). We aimed to determine if laser-treated plots had significantly less damage overall and closer to the laser unit, and whether birds became more or less likely to forage in laser-treated plots over time. RESULTS: Lasers reduced damage overall, marginally in Stick Trials and dramatically in Natural Trials. Damage increased during each week in both trial types. Damage increased significantly with distance from lasers, and significant treatment effects occurred up to similar to 20 m from lasers. CONCLUSION: Our results concur with recent field trials demonstrating strong reductions in sweet corn damage when lasers are deployed. This study provides a first look at how birds respond to repeated laser exposure and whether damage increases with distance from lasers. Key differences between pen and field trials are discussed. (c) 2023 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Abstract A variety of acoustic strategies have been implemented to disperse wildlife from areas of human‐wildlife conflict. Propane cannons are a popular tool; however, their efficacy based on avian behavior has yet to be fully explored. We collected sound attenuation data for a propane cannon, compared to a rifle and shotgun, with reference to hearing capabilities in birds. We evaluated the behavioral responses of red‐winged blackbirds (Agelaius phoeniceus, RWBL) and brown‐headed cowbirds (Molothrus ater, BHCO) to detonations of a cannon. We placed birds in individual enclosures, void of visual stimuli, at 15–495 m from a cannon and evaluated responses (i.e., relaxed, vigilant, startled) to cannon blasts using 2 approaches: 1) incremental, where individual birds were exposed to a series of detonations at decreasing distances and 2) random assignment, where individual birds were randomly assigned distances and exposed to 2 series of 4 cannon blasts. We found behavioral responses of birds significantly decreased at greater distances (χ2(1) = 127, P < 0.001), regardless of species (χ2(1) = 0.74, P = 0.389), when incrementally approached. The probability of startling (i.e., flinch, wing flap, feather compression, or flight) was greater than vigilance (i.e., increased head turning, sudden head‐up, or neck extension) within 64 m for BHCO and 136 m for RWBL. We found a significant effect of distance (χ2(1) = 97.8, P < 0.001), between species (χ2(1) = 19.6, P < 0.001), and blast number (χ2(3) = 17.6, P < 0.001) when birds were randomly assigned a distance from the cannon. With the first cannon blast, the probability of startling was greater than vigilance or relaxed within 334 m for BHCO and 153 m for RWBL. With subsequent blasts the probability of startling was greater than vigilance and relaxed within 204–221 m of the cannon for BHCO, but startling was never greater than vigilance for RWBL. We note that the estimated range of the cannon is conservative given birds are contained with limited flight ability. Nevertheless, information on effective range and avian responses to repeated blasts informs managers on the potential interstimulus timing and distribution of propane cannons to protect resources from birds.

Multiple management strategies exist to combat bird damage to agriculture. We explored combining two tools, drones as frightening devices and an avian repellent, to assess effectiveness of an integrated method to deter large flocks on complex landscapes. We evaluated the ability of a spraying drone (DJI Agras MG-1P) deploying Avian Control (i.e. active ingredient: methyl anthranilate; hereafter MA) or water to elicit abandonment, flock reductions, latency to return, and behavioral changes of blackbirds (Icteridae) foraging in sunflower Helianthus annuus. Following hazing and spraying (MA = 32; water = 32 trials), the percent of flocks abandoning, partially abandoning, or remaining was 56%, 31%, and 13% for MA and 50%, 25%, and 25% for water, respectively. Following full abandonment, 14% more flocks returned following MA (83%) than water (69%), averaging 3.96 min +/- 3.51 (SD) to return (MA = 4.12 min +/- 4.03; water = 3.73 min +/- 2.68). When reduction occurred, average decline was 47% +/- 35 (SD) with MA and 44% +/- 39 (SD) with water. Site conditions impacted the ability to maneuver the drone and observe flock behaviors, potentially resulting in variables other than treatment explaining the probability of abandonment and flock reduction. When controlling for flock size, number of lift-offs following water treatments (0.23 min-1 +/- 0.17 SD) was statistically less than the pre-hazing period (0.43 min-1 +/- 0.28 SD), however no relationship existed for MA treatments (post: 0.29 min-1 +/- 0.32 SD; pre: 0.31 min-1 +/- 0.20 SD). This difference may be due to a longer latency to return, decreasing the post-hazing time period, or flightier birds after MA exposure. We found eight mins of hazing, and a 9-l tank of repellent, was insufficient to elicit differences between water and repellent applications. We suggest extended hazing or additional negative stimuli (e.g. multiple drones, increased repellent) to increase efficacy.

Invasive birds cause damage to economies, natural resources, and human safety across the globe.In the United States, rock doves (Columba livia), Eurasian collared doves (Streptopelia decaocto), rose-ringed parakeets (Psittacula krameri), monk parakeets (Myiopsitta monachus), common mynas (Acridotheres tristis), European starlings (Sturnus vulgaris), and house sparrows (Passer domesticus) are among the invasive and often harmful small-bodied birds inhabiting periurban habitats.The destructive nature of these species warrants a review of methods to reduce or eradicate populations along with methods to reduce damage when population eradication cannot be achieved.We reviewed damage management literature from these species' native and introduced ranges.Additionally, we used the behavior and ecology of these species to inform tool recommendations and potential efficacy under various damage scenarios, while being sensitive to cultural preferences and location of implementation (residential, commercial, and agricultural).Although this review focuses on invasive birds in the United States, it is applicable to other pest species across the globe.Our review highlights areas where research is needed to validate promising damage management methods (lethal control, fertility control, habitat modification, exclusionary methods, frightening devices, and chemical repellents).Where birds are invasive, integrated pest management techniques should focus on eradication or population reduction (toxicants, shooting, and trapping) to keep populations at levels where nonlethal tools can reduce damage.We acknowledge the efficacy of an eradication campaign depends on biological, environmental, and economic factors, along with social license for lethal removal.We recommend integrated pest management strategies including lethal and nonlethal tools specific to the damage problem.Sustained efforts to reduce invasive populations should be used along with integrated deterrent strategies for short-term damage relief.

Crop depredation by blackbirds (Icteridae) results in substantial economic losses to the United States sunflower industry, and a solution to effectively reduce damage remains elusive. We evaluated the utility of uncrewed aircraft systems (UAS), or drones, as hazing tools to deter foraging blackbirds from commercial sunflower (Helianthus annuus) fields in North Dakota, USA, between September and October 2017. We compared the efficacy of 3 drones: a fixed-wing predator model mimicking the form of an aerial raptor, a fixed-wing airplane of similar size, and a multirotor drone. Multirotor drones are relatively easy to fly and are a multifunctional tool for agricultural use; however, they may not be an effective avian deterrent due to a lack of similarity in appearance with natural predators. Free-ranging blackbird flocks (n = 58) reacted to every drone approach by initiating flight and took flight 1.6 times sooner for the fixed-wing predator model (flight initiation distance [FID] = 90 m) and 1.8 times sooner for the fixed-wing airplane (FID = 98 m) compared to the multirotor drone (FID = 55 m). However, the probability of a blackbird flock (n = 53) abandoning a field was greater with smaller field and flock sizes, rather than the specific drone deployed. In an applied setting, the performance of drones as avian hazing devices will likely depend on a combination of factors including platform selection, drone trajectory, duration of use, season, landscape context, and natural history of the pest species.

Over 40 species of parrots, members of order Psittaciformes, have established nonnative populations globally. Monk parakeets (Myiopsitta monachus) are among the most invasive bird species worldwide. In their introduced range, populations of monk parakeets have caused negative impacts on native species, habitats, economies, and human safety. Lethal population management has been complicated by the intelligence of monk parakeets, as they quickly alter behavior to avoid risks. Further, lethal control programs have been halted due to public controversy, as parakeets are highly charismatic. The contraceptive DiazaCon has been demonstrated to effectively reduce fertility in monk parakeets and other psittacines. In field applications, chemical control agents (e.g., toxicants and contraceptives) must be delivered in a manner that prohibits access by nontarget species. We developed and tested a parakeet-selective feeder. The feeder allows access by parakeets and limits access by nontarget bird species by lowering a wire exclusion curtain around the feeder, requiring a zygodactyl toe arrangement to access food. We tested the parakeet-selective feeder in trials with captive and free-ranging monk parakeets and nontarget species in Florida, USA. Monk parakeets successfully accessed food from the parakeet-selective feeder throughout the study. The mean number of daily feeder uses by nontarget species decreased from a high of nearly 16 uses per day when the exclusion curtain was not implemented to <1 use per day when implemented. Our findings suggest the parakeet-selective feeder is a promising tool for delivery of bait treated with chemical control agents to manage monk parakeets and other nonnative parakeet populations, but implementation success will likely vary by target species, location, local faunal diversity, and availability of alternative forage.

Rose-ringed parakeets (Psittacula krameri; parakeets) are among the most invasive bird species worldwide. In their introduced range, populations of this species have caused negative effects on native species, natural environments, economies, and human safety. Lethal population management has been complicated by the intelligence of the birds, as they quickly alter behavior to avoid risks. Further, lethal control programs have been halted due to public opposition, as parakeets are considered to be charismatic by animal welfare advocates. The contraceptive DiazaCon has been demonstrated to effectively reduce fertility in captive parakeets. In field applications, any chemical control agents (e.g., toxicants or contraceptives) must be delivered in a manner that prohibits access by non-target species. Parakeets are known to feed from bird feeders throughout their native and introduced range, suggesting contraceptive-treated bait may be a useful management strategy. However, our 24-week trials with free-ranging parakeets using platform, hopper, and tube feeders on the island of Kaua'i did not result in any parakeet visitation and thus precluded further testing of using feeders to selectively deliver fertility control products. Nonetheless, multiple citizen science reports and other documentation indicate parakeets using feeders on the island of O'ahu over a period of >10 years, and recently on the island of Maui. Our findings suggest the chemical control of nonnative parakeet populations is a promising technique, but implementation success will likely vary by target population acceptance, location, local faunal diversity, and availability of alternative forage.

Rose-ringed parakeets ( Psittacula krameri ) are one of the most widespread invasive avian species worldwide. This species was introduced to the island of Kaua‘i, Hawai‘i, USA, in the 1960s. Depredation of crops by this species causes extensive economic losses. Large congregations in evening roosts damage trees and lead to excessive noise and droppings in public areas. We evaluated the efficacy of a roost culling program conducted by an independent contractor from March 2020 – March 2021. We estimated island-wide minimum abundance was 10,512 parakeets in January 2020 and 7,372 in April 2021. Over 30 nights of culling, approximately 6,030 parakeets were removed via air rifles with 4,415 (73%) confirmed via carcasses retrieval. An estimated average of 45 parakeets were removed per hour of shooter effort. The ratio of culled juveniles to adults was approximately 1.6:1.0. Age and sex structure of animals removed varied seasonally; the proportion of adult females removed in 2020 was 1.9× greater when culled outside of the estimated nesting season. Of the four roosts where culling occurred, the parakeets fully abandoned three and partially abandoned one site; of the three fully abandoned roosts, an estimated average of 29.6% of birds were culled prior to roost abandonment. This study was conducted during the COVID-19 pandemic, when tourist numbers and foot traffic were greatly reduced; it is unknown how public perception of roost culling in public areas may impact future efforts. Findings can be used to inform implementation of roost culling for management of nonnative rose-ringed parakeet populations.

Many bird species migrate to southern overwintering locations to avoid harsh conditions at their breeding grounds, but at the cost of an energetically demanding migration that may delay their spring reproductive development. Previous work on the relationship between migration distance and reproductive readiness has primarily focused on early season baseline testosterone in both males and females. However, for females, testosterone alone may not be the appropriate measurement of reproductive development. Estradiol, a metabolite of testosterone that is essential for breeding behaviors and reproduction, should also be measured. Furthermore, baseline testosterone varies throughout the day and may change due to social interactions that occurred prior to sampling. Injection of gonadotropin-releasing hormone (GnRH) elicits an individual’s maximum potential testosterone production, minimizing daily and social variation. We explored relationships between migration distance and reproductive status after arrival to the breeding ground in Red-winged Blackbirds (Agelaius phoeniceus). We predicted that individuals that travel a shorter distance will have higher levels of reproductive hormones upon arrival given they are able to invest less in migration and more in reproduction. This is important because individuals that breed earlier often have higher reproductive success. In females, we measured baseline estradiol and testosterone. In males, we assessed baseline and GnRH-induced testosterone. Hormone values were related to migration distance, estimated by stable isotope analysis of claw samples collected before breeding began in eastern North Dakota. We found that males with shorter inferred migration distances have higher baseline testosterone upon arrival. However, inferred migration distance was not correlated with GnRH-induced testosterone. Female inferred migration distance was not correlated with baseline testosterone, but it was correlated with baseline estradiol. Females with higher testosterone had lower estradiol, suggesting that testosterone in females is not a reliable indicator of estradiol levels, thus readiness to breed. Our observations suggest that baseline hormone levels were related to migration distance, but baseline testosterone alone may not provide a complete assessment of a male or female’s preparedness to breed following spring migration.

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.]).

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 biomassderived 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.

Context. Lethal control of predators is often undertaken to protect species of conservation concern. Traps are frequently baited to increase capture efficacy, but baited traps can potentially increase predation risk by attracting predators to protected areas. This is especially important if targeted predators can escape capture due to low trap success. Snake traps using live mouse lures may be beneficial if traps effectively remove snakes in the presence of birds and do not attract additional snakes to the area. Aims. The present study evaluated whether mouse-lure traps in areas occupied by birds (simulated by deploying bird-lure traps) could influence predation risk from an invasive snake on Guam. Methods. Snake traps were used, with Japanese quail (Coturnix japonica) as a proxy for predation risk, to assess if an adjacent trap with a mouse (Mus musculus) would attract brown treesnakes (Boiga irregularis) to a focal area and increase contact between an invasive snake and avian prey. Catch per unit effort (CPUE) at stations containing either a bird-lure trap, mouse-lure trap or pair of traps (i.e. one bird-lure and one mouse-lure trap) was evaluated. Key results. Bird-lure traps paired with mouse-lure traps did not differ in CPUE from isolated bird-lure traps. At paired stations, CPUE of snakes in mouse-lure traps was 2.3 x higher than bird-lure traps, suggesting mouse lures were capable of drawing snakes away from avian prey. Bird-lure traps at paired stations experienced a decay in captures over time, whereas CPUE for isolated bird-lure traps increased after 9 weeks and exceeded mouse-lure traps after 7 weeks. Conclusions. Mouse lures did not increase the risk of snakes being captured in bird-lure traps. Instead, mouse-lure traps may have locally suppressed snakes, whereas stations without mouse-lure traps still had snakes in the focal area, putting avian prey at greater risk. However, snakes caught with bird lures tended to be larger and in better body condition, suggesting preference for avian prey over mammalian prey in larger snakes.

Understanding how birds move through and use landscapes across their annual cycle is a key goal of migration research. Breeding populations of Red-winged Blackbirds (Agelaius phoeniceus) in the northern United States and Canada are known to migrate to the southern United States each fall and exhibit strong fidelity to the same breeding areas each spring. Previous mark-recapture studies of Red-winged Blackbirds have characterized migratory movements, but these estimates are limited in detail because each bird is only captured (and located) a few times, with days to months between subsequent captures. Using light-level geolocators, we tracked 13 male Red-winged Blackbirds across one complete annual cycle to investigate both their fall and spring migrations. Birds consistently used routes straddling the Central and Mississippi flyways, with relatively small longitudinal differences between breeding and wintering sites. Fall migration began in late October to late November, and spring migration began in mid-February to late March. On average, birds traveled longer distances and had marginally longer migration periods during the spring than the fall, in contrast to well-established patterns in other songbirds. Route directness was high for most individuals, with little deviation from the shortest possible migratory routes. Birds occupying the same wetlands during the breeding season wintered across a relatively wide geographic range of locations in the south-central United States. Overall, our results improve our understanding of the migratory pathways used by Red-winged Blackbirds across their annual life cycle. Our results also have implications for understanding which control strategies are most appropriate for managing populations of Red-winged Blackbirds that cause extensive damage to sunflower crops in the Northern Great Plains.

Bird damage, from sowing to crop establishment, is an important issue for farmers in many parts of the world. However, reliable and cost-effective solutions remain elusive because management tools and research on the subject are limited. The spatial variability of damage across landscapes and the adaptative behaviour of birds create further challenges. Additionally, the issue must be tackled at the landscape scale and involve a variety of stakeholders with conflicting interests and objectives. We summarize some of the challenges and opportunities identified to face these difficulties and address four major research directions for operational solutions including 1) crop damage assessment, 2) methods and tools development at the landscape scale, 3) coordination of stakeholders, and 4) pest bird ecology in agroecosystems. More fundamentally, we address the question of large-scale ecological dynamics that can explain changing damage patterns such as the recent observations of increased damage in Europe. Despite the impact to the agricultural sector, research effort to understand vertebrate pest damage is still modest. We advocate for the creation of networks to share knowledge and feedback and engages multiple stakeholders, including ecological and agricultural researchers, farmers, and policy makers.