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

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.

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.

In late summer, red-winged blackbirds forage heavily on ripening sunflower crops in the Dakotas. Sunflower achenes have a distinct fatty acid profile that should influence the fatty acid composition in tissues of these birds. To determine if fatty acid composition in tissue could be used as a biomarker indicating dietary history, we fed 18 red-winged blackbirds a sunflower diet for 2 weeks and compared fatty acid profiles in their muscle and liver tissues to a control group of red-winged blackbirds (n = 15) fed a birdseed mix supplemented with safflower seed. Three subjects from each treatment group were sacrificed at Day 0, 7, 14, and 21, with Day 0 the day the treated group was switched to sunflower. The remaining birds were sacrificed on Day 35. Breast muscle and liver tissue were collected, extracted, and analyzed for levels of linoleic, oleic, palmitic, and stearic acids. Differences existed in levels of all 4 fatty acids between treatment groups pooled across time (P ≤ 0.05, ANOVA). When comparing fatty acid profiles between treated and controls by day sacrificed, we observed differences in levels of ≥1 of the fatty acids at Day 7, 14, and 21 in breast muscle, and Day 7 and 14 in liver tissue (P ≤ 0.05, t-test). Within-bird comparisons of fatty acid levels in liver and breast indicated temporal lags in metabolism between tissue types (P ≤ 0.05, paired t-test). Our results demonstrated that fatty acids profiles in body tissues can be used as biomarkers to verify recent foraging in sunflower by red-winged blackbirds.

Kansas is a major producer of livestock and has an abundance of over-wintering European starlings. Roost sizes for over-wintering starlings can be as large as 5 million individuals. Starlings cause a substantial amount of economic damage to farmers. Escherichia coli O157:H7 and Salmonella can cause illness in both livestock and humans, and cattle with Johne’s disease must be culled. Crohn’s disease in humans is suspected to be caused from Mycobacterium avium subsp. paratuberculosis (Johne’s disease). We banded, leg-flagged, and radio-tagged starlings using feedlots near Great Bend, Kansas. Our objectives were to track daily movements of starlings visiting feedlots in this area and screen starlings for E. coli O157:H7, Salmonella spp., and M. a. subsp. paratuberculosis. Preliminary data show that starlings in Kansas are moving among feedlots rather than remaining at one feedlot. Pathogens were detected at a low prevalence. Our results can be used to develop plans for the management of transmissible diseases carried by starlings.

The Compound DRC-1339 Concentrate – Staging-Areas label is approved in North Dakota for use in non-crop staging areas near blackbird roosts. Potential blackbird damage affects sunflower planting patterns and reduces profits. One option to manage damage is to reduce the local blackbird population using DRC-1339 bait. The challenges are to limit nontarget bird hazards while attracting large numbers of blackbirds. During fall 2007, we assessed the nontarget bird risks of using rice baits on elevated bait trays attached to the top of decoy traps. During random visits to bait sites, we recorded 968 individual birds and 12 avian species. Blackbirds accounted for 95% of all tray visits. Sparrow species were the most prevalent of the non-blackbirds. Strategic placement of the bait trays near large roosts will be necessary for this technique to be successful. Ultimately, Wildlife Services might use DRC-1339-treated rice baits on bait trays for managing local blackbird damage.

Bait preference studies with red-winged blackbirds (Agelaius phoeniceus) in North Dakota sunflower fields indicated that sunflower seeds and a combination of sunflower seeds and chopped corn (MIX) were more successful in producing affected blackbirds, primarily red-winged blackbirds, than pearl barley or chopped corn used separately. A subsequent study compared the effectiveness of commercial Avitrol FC corn Chops-99S to 4-aminopyridine-trealed MIX-99S baits for reducing blackbird damage to ripening sunflower. Both baits significantly reduced damage in fields nearest a blackbird roost (within two miles), but were largely ineffective in fields farther than two miles from a roost. The ramifications of these results are discussed.

Managing European starlings with DRC-1339 near urban and suburban areas can lead to adverse publicity resulting from encounters by the public with dead and dying birds. Collectors could retrieve the birds, if the likely sites of mass mortalities were known. In December 2009, we radio tagged 50 starlings at 3 sites in central New Jersey and studied their movements and behavior. Two of the sites were ensconced in a mosaic of suburban and urban habitats, whereas the other was in a rural setting. The sites were selected from a list of agricultural producers that had requested assistance from the Wildlife Services program in New Jersey. Starlings using the rural study site showed strong site fidelity (x-bar = 78% of days tracked), stayed closer during daytime wanderings (x-bar = 2 km), and roosted onsite. In contrast, starlings in the urban-suburban mosaic showed less fidelity (x-bar’s = 10% and 36%), wandered farther (x-bar’s = 6 km and 4 km), and seldom roosted onsite. No study sites were visited by members from the other radio-tagged cohorts. Major roosts in the urban-suburban mosaic averaged 10 km (n = 4, SE = 1.4) from the study sites. We predict that most starlings will remain within 6 km of the site during daytime. Poisoned starlings may become lethargic and seek refuge in dense vegetation (e.g., evergreens) near the baited site. Birds >6 km from a bait site are probably on a direct bearing between the bait site and roosting site.