William J. Bleier’s research while affiliated with North Dakota State University and other places

Red-winged Blackbirds (RWBL; Agelaius phoeniceus) have a polygynous mating system and, because territorial males commonly have harems of two to five females, some second-year (SY) and after-second-year (ASY) males do not establish nesting territories, but become floaters. Previous studies have revealed high rates of extra-pair copulations in this species and that sexually mature male floaters and territory owners do not differ in size, testosterone levels, or reproductive capability, suggesting that floaters may occasionally gain paternity. During May and June 2008, we observed the behavioral responses of floater males to taxidermic mounts (models) of female RWBL placed in a precopulatory position. Floaters intruded into territories during 46% of model presentations, with 20% of intrusions by ASY floaters and 80% by SY floaters. During intrusions, ASY floaters attempted to copulate with models 93% of the time compared to 80% for SY floaters. Copulations were successful during 30% of attempts by ASY males and 25% of attempts by SY floaters. The frequency of intrusions by ASY and SY floaters, attempted copulations by SY floaters, and successful copulations by ASY floaters increased as territorial males spent more time off their territories. Responses of floater males toward models in our study suggest that floater male RWBL attempt to exploit available breeding opportunities. The lack of evidence for extrapair young (EPY) fathered by floater male RWBL in previous studies, combined with our results indicating that the presence of territorial males limits floater intrusions, copulation attempts, and successful copulations, suggests that the reproductive success of floater males is limited in part by the aggressive behavior of territorial males.

Sunflower (Helianthus annuus L.) became an economically important crop in North Dakota in the 1970s, providing a major source of food for post-breeding blackbirds (Icteridae). Reducing local blackbird populations with rice grains treated with an avicide is one proposed alternative for reducing sunflower damage. In fall 2007 and 2008, we evaluated the idea of attracting blackbirds to rice-baited trays attached to wire cages supplied with live blackbirds. During our observations (1011 h), we saw 3888 birds, consisting of 25 species and 12 families, on the bait trays. Blackbirds made up 90.4% of the bird observations, whereas sparrows (Emberizidae) made up 1.6% of the birds observed. Overall risk to non-target species appeared minimal. The bait trays, however, attracted a small number of blackbirds compared to the source population feeding in nearby crop fields. Our results strongly suggest DRC-1339-treated rice used on bait trays is unlikely to be a cost-effective method of reducing blackbird damage to ripening sunflower.

We monitored site-use and movements of 102 radio-tagged European starlings (Sturnus vulgaris) during the winter months at 2 concentrated animal feeding operations (feedlots) in central Kansas. Our research investigated the spatial ecology of wintering starlings as part of a broad epidemiological study on the possible role of starlings in pathogen transmission at feedlots. Site fidelity was 0.677 and 0.552 (days at capture-site per total days tagged) for feedlots A and B, respectively. Minimal exchange (9%) occurred between feedlots A and B and was often followed by a roost-site change. Starlings rarely abandoned the feedlot where they were captured, but we observed 41 (40%) birds that temporarily switched allegiance from their capture sites to other feedlots; the farthest bird was detected 68 km from the capture site. We speculate that the limited frequency of time spent at non-capture-site feedlots could lower the potential for risk of starlings spreading pathogens among feedlots. We suggest management strategies within the feedlot that may reduce starling populations and speculate that this would lower the risk of spreading pathogens among feedlots.

Blackbird damage to sunflower in the Prairie Pothole Region of North Dakota, South Dakota, and Minnesota is an unyielding challenge to the industry. Large populations of blackbirds and environmental concerns have driven the direction of research toward nonlethal methods that can be implemented locally. Currently, Wildlife Services field specialists lend propane cannons to growers and spray wetlands with glyphosate to fragment dense cattail stands used by roosting blackbirds. After researchers demonstrated decoy crops (wildlife conservation sunflower plots), some growers have adapted the basic principles and have started diverting blackbirds from sunflower, a high value crop, to alternative lesser-value crops, such as corn. USDA and university scientists are developing a perennial sunflower that might significantly lower the costs of planting WCSP. Growers now have access to several desiccants that hasten the crop harvest and thus avoid late-season blackbird damage. Finally, researchers are closer to developing an effective chemical bird repellent. In this paper, we outline current nonlethal blackbird management strategies.

Even though avian damage to sunflower (Helianthus annuus L.) is a worldwide economic issue, several of the current methods used to reduce sunflower damage were developed and tested in the Prairie Pothole Region of the United States. An intensive research program was conducted in that area because of the regionalized concentration of sunflower production and the severe incidences of blackbird (Icteridae) depredation. During the past 40 years, federal and university scientists tested chemical and physical frightening agents, aversive repellents, bird-resistant sunflowers, decoy crops, habitat management, population management, and cultural modifications in cropping. Some of these techniques have broad applicability and may be useful in depredation scenarios involving other bird species and crops. Population suppression is intuitively appealing, but it typically fails beyond local scales because of avian mobility, population dynamics, and public antipathy. Scare devices, repellents, habitat management, and decoy crops are more likely to meet the test of predictable efficacy and practicality.

Aim We examined the influences of regional climate and land-use variables on mallard (Anas platyrhynchos), blue-winged teal (Anas discors), ruddy duck (Oxyura jamaicensis) and pied-billed grebe (Podilymbus podiceps) abundances to inform conservation planning in the Prairie Pothole Region of the United States. Location The US portion of Bird Conservation Region 11 (US-BCR11, the Prairie Potholes), which encompasses six states within the United States: Montana, North Dakota, South Dakota, Nebraska, Minnesota and Iowa. Methods We used data from the North American Breeding Bird Survey (NABBS), the National Land Cover Data Set, and the National Climatic Data Center to model the effects of environmental variables on waterbird abundance. We evaluated land-use covariates at three logarithmically related spatial scales (1000, 10,000 and 100,000 ha), and constructed hierarchical spatial count models a priori using information from published habitat associations. Model fitting was performed using a hierarchical modelling approach within a Bayesian framework. Results Models with the same variables expressed at different scales were often in the best model subset, indicating that the influence of spatial scale was small. Both land-use and climate variables contributed strongly to predicting waterbird abundance in US-BCR11. The strongest positive influences on waterbird abundance were the percentage of wetland area across all three spatial scales, herbaceous vegetation and precipitation variables. Other variables that we included in our models did not appear to influence waterbirds in this study. Main conclusions Understanding the relationships of waterbird abundance to climate and land use may allow us to make predictions of future distribution and abundance as environmental factors change. Additionally, results from this study can suggest locations where conservation and management efforts should be focused.

Male red-winged blackbirds (Agelaius phoeniceus) exhibit a difference in nest provisioning rates along an east-west gradient, in North America. North Dakota is located in the center of North America and harbors a large population of breeding red-winged blackbirds (RWBL). This location provided an opportunity to compare provisioning rates in the central U.S. with those reported for the eastern and western populations. We placed video cameras at RWBL nests to record male and female feeding trips. Thirty-four nests were located on territories with original males and 30 were on territories where a replacement (floater) male had taken over a territory after we removed the original male by shooting or trapping. Original territory owners were more likely to feed young, and males were more likely to feed at nests with older chicks, at nests with more chicks, and later in the breeding season. Red-winged blackbird parental provisioning patterns in North Dakota appear to be similar to those observed in eastern North America.

Agricultural fields are often overlooked as post-breeding and migratory bird habitat, even though many species use row-crop fields in the northern Great Plains. We monitored bird use, crop and non-crop vegetation characteristics and abundance, and land use around (≤2.4 km) 35 8-ha Wildlife Conservation Sunflower Plots (WCSP) and one commercial sunflower and non-sunflower row-crop field, paired with each WCSP, in fall 2004 and 2005. We excluded four species of blackbirds from our analysis that commonly form large foraging flocks and ubiquitously use agricultural fields. A diverse community of migratory birds used WCSP and commercial sunflower compared to other non-sunflower crops in North Dakota. Both WCSP (mean  =  24.4 birds/ha, se  =  2.7) and commercial sunflower (mean  =  12.7 birds/ha, se  =  1.7) harbored greater densities of birds (P < 0.01) than did other non-sunflower row crops (mean  =  7.2 birds/ha, se  =  1.1). Migratory birds were more strongly associated with vegetation within fields, such as crop density (+), non-crop plant abundance (+) and crop height (+), than surrounding land uses (0–2.4 km from WCSP). We recommend management practices to maximize WCSP for fall bird habitat and discuss economic considerations for WCSP implementation as a wildlife habitat / blackbird damage management system.

North Dakota is the top sunflower producer in the United States, annually harvesting about 1 million acres (404,686 ha). Recently, corn has become a major crop within the state. Red-winged blackbirds (Agelaius phoeniceus), common grackles (Quiscalus quiscula), and yellow-headed blackbirds (Xanthocephalus xanthocephalus) often cause significant damage to these crops. The National Sunflower Association considers blackbird depredation of sunflower to be a key factor in the reduction in sunflower acreage in the Prairie Pothole Region (PPR). In 1979 and 1980, a field survey of bird damage to sunflower in North Dakota showed an estimated economic loss between $4 and 11 million (Hothem et al., 1988). This was the last comprehensive field damage survey. Peer et al. (2003) used a bioenergetic model and estimated that bird damage was valued at$5-10 million. Sunflower prices have increased 3-fold since these monetary losses were calculated. In 2008, plantings of sunflower and corn in North Dakota are projected to be 216,514 ha (535,000 acres) and 910,575 ha (2.25 million acres), respectively.

Red-winged Blackbirds (RWBL) and Common Grackles (COGR) are the two most abundant blackbird species on the continent; Brewer’s Blackbirds (BRBL) are a much less common, but closely related species, and along with European Starlings (EUST), they are two of the most common groups of birds in North America, with combined populations that reach into the several hundreds of millions; making up a significant portion of the avian population. Although one of the most common birds on the continent, certain regions have seen declines in RWBL for a number of decades. In Ohio and North Dakota, this has been attributed to certain agricultural practices. Population sizes of Rusty Blackbirds, a related species, have also been on the decline for some time due largely to habitat loss, while populations of COGR, BRBL, and EUST are either stable or increasing. Despite the decline of the RWBL in certain areas, farmers continue to endure annual monetary losses to depredation by these crop pests. In some areas, complaints of blackbird depredation have increased, giving impressions that populations in those areas are on the rise instead of decline. Damage to sunflower has been estimated at 2-4% of the value of the crops, or approximately $4-$11 million dollars. Yearly losses to corn and rice growers in the US are even higher, estimated at $25 million and$21.5 million respectively. A better understanding of blackbird population trends and how and where populations select wintering roosts would permit quicker responses and reduce the costs of identifying and managing roosts for the purposes of resource protection, and disease outbreak prevention.