The Sunflower magazine, the voice of the National Sunflower Organization, featured articles in January 1978 and December 1996 that began with these words, "If Old King Cole was a merry old soul, it was probably because he had only four and twenty blackbirds to contend with, and they were all out of commission!" This quotation captures the sentiments of sunflower growers, who have identified blackbirds as a major production problem since the 1960s. The National (formerly Denver) Wildlife Research Center, a unit within the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service Wildlife Services, is charged with both improving and developing new methods for managing blackbird damage to sunflower. The Sunflower has chronicled these research efforts championing studies with clear objectives and opposing studies, sometimes vehemently, that use resources for seemingly esoteric research. In this paper, the history of blackbird research in the northern Great Plains is traced through The Sunflower

Anthraquinone is an effective chemical seed repellent that protects newly planted crops from depredation by granivorous birds. We are experimenting with foliar applications of 9,10-anthraquinone (AQ) to reduce blackbird (Icteridae) damage to ripening sunflower. Sunflower heads generally turn downward as the achenes mature. With the methods currently available for spraying crops, application of AQ directly onto sunflower achenes is nearly impossible. Blackbirds sometimes remove sunflower bracts prior to eating achenes. Thus, getting AQ droplets directly on the achenes may not be necessary, and spraying the heads should expose blackbirds to AQ as they remove bracts. Studies using caged red-winged blackbirds showed that AQ sprayed onto the backs of sunflower heads reduced damage. However, field trials using fixed-wing aerial sprayers and ground sprayers produced inconclusive results. We are currently experimenting with methods to increase spray coverage of AQ while simultaneously attempting to reduce AQ contamination of achenes, thus reducing the likelihood of having to establish food tolerance limits for this comparatively long-lived compound. In this paper, we summarize results from several AQ studies and speculate on when a repellent might be available for sunflower producers.

Blackbirds are reported to cause between 1-2% crop damage per year, but the distribution of damage is not uniform, with some fields this number can be as high as 20%. With many consumers in today’s market concerned with animal welfare, nonlethal management techniques have become more important. Many of these techniques exploit natural predator-prey systems. One area of research that has not been previously addressed is the physiological response of birds to visual and auditory scare devices designed to imitate predators. The current project is part of a series of studies that aim to develop knowledge of both physiological and behavioral trade-offs of female red-winged blackbirds when exposed to predation risk as a chronic stressor. Breeding colonies were exposed to an avian predator, avian nest parasite, or a non-threatening avian effigy with corresponding bird call at the beginning of the breeding season. Behavioral responses were monitored across the season, including general response to the predators and reproductive trade-offs. We predicted that female response to perceived predation risk would be greater than response to parasites or control treatments, and that females would make a greater reproductive trade-off in favor of future breeding seasons when presented with the perceived risk and stress of predation. Results suggest that red-winged blackbirds do have a greater response to the perceived risk of predation than to the parasites or control treatments. In terms of nest success and lay date, females do not seem to have different reproductive behavioral trade-offs under different treatments. However, there is a trend for larger clutches in nests found within the predator treatment, suggesting that females may actually be making a trade-off for the current rather than future seasons. Future work will focus on analyzing the physiological trade-offs that females make during the breeding season, especially while under chronic stress of predation risk. Results will help provide a basis for applied research aimed at improving bird damage management.

Routes that cattle become exposed to and contaminated with Escherichia coli O157 remain enigmatic. To ascertain the potential role of wild birds, particularly European starlings, in the transmission of Escherichia coli O157:H7 among dairy farms, the ecology of this pathogen in these birds was studied. Bird movement from roost sites to farms was monitored using radio-telemetry (n = 49). Concurrently, frequency of livestock feed contamination and E. coli O157:H7 carriage in birds and in cattle was ascertained. Most of the birds tagged from farms in the limited geographic region roosted communally at a location within 20 km of the farms where they were tagged. Individual birds returned frequently to the same farm on a daily basis for feeding. E. coli O157:H7 was cultured from approximately 3% of starlings and 4% of cattle in the study population. We have previously reported the isolation of indistinguishable molecular subtypes of E. coli O157 from starlings from different farms. Clearly, European starlings can serve as a vehicle to disseminate this pathogen from farm to farm. What remains to be determined is the magnitude of the contribution that birds have in the overall ecology of E. coli O157 in livestock populations, and how this might be mitigated.

When using DRC-1339 Concentrate, applicators have sometimes found that blackbirds will not feed on standard grain baits. While the search for more attractive baits has generally focused on alternate grains, fruits, and occasionally processed foods, a first-rate candidate may be insects. To our knowledge, no feeding tests using red-winged blackbirds have been conducted to measure consumption rates among various commercially available insects. Our results indicated that large-sized mealworms were the best bait for red-winged blackbirds during fall, whereas crickets were favored over small-sized meal¬worms and waxworms in summer. We speculate that choice was based to some extent on the quantity of fat available among the different foods. We plan to conduct similar feeding trials with European starlings.

Sunflower producers in the northern Great Plains are annually plagued by feeding flocks of blackbirds, especially red-winged blackbirds (RWBL). Past techniques aimed at reducing blackbird damage have had varying degrees of success, but the estimated annual loss of sunflower remains at ≥$10 million. Thus, there is a need for new innovative approaches to managing blackbird damage. One approach is to find non-lethal species-specific methods of lowering reproduction by discovering vulnerable behavioral tendencies in the reproductive cycle of RWBL. Male RWBL are a good candidate for reproductive control because of their territorial and polygynous reproductive behavior. We have designed a study to assess the male RWBL response to a model placed in pre-copulatory position under different treatment scenarios. Our objective is to discover the conditions under which we can attract the largest numbers of males to the model, keeping in mind that these models could potentially be used as a delivery system for a reproductive inhibitor. While we had nearly no response from territorial males, we found that floater males (those that do not hold territories) readily copulate with conspecific models. Floater intrusion and copulation occurs more often in the early part of the breeding season and while females were most fertile. Of the floater males that attempted to copulate with a model, 96% were SY (second-year) males; SY males are considered “non-breeding”. Preliminary results show that reproductive management would be most successful in the floater male population. Since the majority of floaters are SY males, it is likely that they will attain territories in future breeding seasons. This would require the use of a long-term sterilant. This method has the potential to target specific breeding populations, but more research is needed on movement patterns of floater males.

In August and September 1989 and 1990, we aerially sprayed 8 cattail (Typha spp.) marshes with Rodeo® herbicide to begin evaluating its use for fragmenting dense cattail stands used by roosting blackbirds (lcterinae). Treated marshes were effectively eliminated as roost sites for blackbirds. After 2 years, cattail densities in 4 marshes treated with Rodeo® at 5.8 - 7.0 L/ha were 87 % lower than pretreatment densities (P = 0.0001 ). In 1990, we treated 4 marshes with Rodeo® at 4.7 L/ha. One year later, 6% of the cattails survived in the sprayed areas. Of 7 groups of "indicator birds," only marsh wren (Cistothorus palustris) and rail (sora, Porzana carolina; and Virginia rail, Rallus limicola) populations were adversely affected by cattail fragmentation. These preliminary results led to an increased research effort to develop marsh management techniques aimed at eliminating blackbird roosts.

Wildlife damage to crops has a significant impact on crop productivity, and mitigating the impacts of damage requires managers to employ multiple and creative solutions. The development of Unmanned Aerial Systems (UAS, drones) provides a new tool that may be effective in managing bird damage to crops. We used multisensory video/audio playback to assess the behavioral responses of red-winged blackbirds (RWBL) to videos of UAS. Captive birds were individually exposed to movies comprised of five video clips that varied in stimulus content on two occasions. Video stimuli included a known predator, UAS, and avian controls (birds that are not predators of RWBL). Although all test birds interacted with the movies, not all displayed the behaviors that were measured. Of those that did display the behaviors measured, responses to most video stimuli were reduced during the second trial compared to the first. These findings suggest that blackbirds are responding to videos; however, they habituate to video stimuli perceived as a non-threat and adjust their behavioral responses accordingly.

The National Sunflower Association has identified blackbird damage as a key reason for growers to abandon sunflower. In the 1980s, National Wildlife Research Center scientists showed that “decoy” plantings of sunflower can significantly reduce bird damage to nearby commercial sunflower fields. For a variety of reasons, largely logistical and economic in nature, decoy sunflower fields did not become wide-spread. Over the last decade, new federal farm programs have placed more emphasis on wildlife conservation. Thus, decoy sunflower fields planted to ameliorate blackbird damage and establish habitat for wildlife might garner broad support from both agricultural and conservation groups. We present preliminary data on avian use of ripening sunflower fields that support the notion of “Wildlife Conservation Sunflower Plots” (WCSP) as a broad-based dual-purpose wildlife management strategy. We also outline research plans designed to refine the concept of WCSP.

Wildlife Conservation Sunflower Plots (WCSP) have shown potential to reduce blackbird (Icteridae) damage in commercial sunflower. Also known as lure, decoy, or trap crops, WCSP are strategically placed food plots that provide an easily available and proximate food source that entices blackbirds away from valuable commercial crops. By providing an alternative food source, WCSP reduce direct damage to commercial fields, while also lowering indirect costs that producers incur attempting to prevent blackbird damage. However, cost inefficiencies have deterred widespread use of WCSP. Cost-benefit ratios of using WCSP would be greatly improved if a perennial sunflower were used instead of the annual types currently available. Perennial sunflower would reduce seed cost and planting cost, and perhaps lower opportunity costs, if able to thrive on poorer quality soils. In the near-term, scientists are focused on producing a perennial sunflower sufficiently productive to replace annual WCSP plantings. In 2013, scientists from the University of Minnesota, USDA-Agricultural Research Service, and USDA Wildlife Services National Wildlife Research Center evaluated a test plot of an open-pollinated variety of perennial sunflower resulting from genetic crossing of a domesticated annual species (Helianthus annuus) and a perennial wild species (H. tuberosus). Here, we report on results from the 2013 field test and discuss the outlook for development of perennial sunflower, which would help lessen damage to commercial sunflower when used in WCSP; provide a pesticide-free food source for beneficial insects, such as honey bees; help stabilize highly erodible lands near wetlands; and provide year-round habitat for wildlife. Lastly, we provide an initial strategy for using perennial sunflower to reduce blackbird damage in commercial sunflower.