H. Jeffrey Homan’s research while affiliated with North Dakota State University and other places

en 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. RESUMEN es Rutas de migración y áreas de invernada de los machos del tordo Agelaius phoeniceus determinados por medio de geolocalizadores Entender cómo las aves navegan y usan paisajes a lo largo de su ciclo anual es una meta clave de la investigación sobre la migración. Se sabe que las poblaciones reproductivas del tordo Agelaius phoeniceus en el norte de los Estados Unidos y Canadá migran al sur de los Estados Unidos cada otoño y que muestran una fuerte fidelidad a las mismas áreas reproductivas cada primavera. Los estudios previos de captura-recaptura de este tordo han caracterizado sus movimientos migratorios, si bien estas estimaciones son limitadas en sus detalles porque cada individuo es capturado (y localizado) unas cuantas veces, con días o meses entre capturas subsecuentes. Usando geolocalizadores de nivel de luz, seguimos a 13 machos de este tordo a lo largo de un ciclo anual completo para investigar sus migraciones de otoño y primavera. Las aves usaron consistentemente rutas que se ceñían a las rutas Central y del Mississippi, con relativamente menores diferencias longitudinales entre sitios reproductivos y de invernada. La migración de otoño comenzó desde finales de octubre hasta finales de noviembre y la migración de primavera comenzó de mediados de febrero a finales de marzo. En promedio, estas aves viajaron mayores distancias y tuvieron periodos marginalmente más largos durante primavera que en otoño, en contraste con los patrones bien establecidos en otras aves canoras. La direccionalidad de sus rutas fue alta en la mayoría de los individuos, con poca desviación de la ruta migratoria más corta posible. Las aves que ocupaban los mismos humedales durante la estación reproductiva invernaron a lo largo de un amplio rango geográfico de localidades en el sur-centro de los Estados Unidos. En general, nuestros resultados mejoran el entendimiento de las rutas migratorias usadas por este tordo a lo largo de su ciclo anual. Nuestros resultados también tienen implicaciones para entender qué estrategias de control son las más apropiadas para el manejo de las poblaciones que causan extensos daños a los cultivos de girasoles en el norte de las Grandes Planicies.

Since their intentional introduction into the United States in the 1800s, European starlings (Sturnus vulgaris) have become the fourth most common bird species and a nuisance bird pest in both urban and rural areas. Managers require better information about starling movement and habit-use patterns to effectively manage starling populations and the damage they cause. Thus, we revisited 6 radio-telemetry studies conducted during fall or winter between 2005 and 2010 to compare starling movements (n = 63 birds) and habitat use in 3 landscapes. Switching of roosting and foraging sites in habitat-sparse rural landscapes caused daytime (0900–1500 hours) radio fixes to be on average 2.6 to 6.3 times further from capture sites than either urban or exurban landscapes (P < 0.001). Roosts in urban city centers were smaller (<30,000 birds, minor roosts) than major roosts (>100,000 birds) 6–13 km away in industrial zones. Radio-tagged birds from city-center roosts occasionally switched to the outlying major roosts. A multitrack railroad overpass and a treed buffer zone were used as major roosts in urban landscapes. Birds traveling to roosts from primary foraging sites in exurban and rural landscapes would often pass over closer-lying minor roosts to reach major roosts in stands of emergent vegetation in large wetlands. Daytime minimum convex polygons ranged from 101–229 km2 (x̄ = 154 km2). Anthropogenic food resources (e.g., concentrated animal feeding operations, shipping yards, landfills, and abattoirs) were primary foraging sites. Wildlife resource managers can use this information to predict potential roosting and foraging sites and average areas to monitor when implementing programs in different landscapes. In addition to tracking roosting flights, we recommend viewing high-resolution aerial images to identify potential roosting and foraging habitats before implementing lethal culls (e.g., toxicant baiting).

We evaluated flight feather molt of Common Grackles (Quiscalus quiscula) collected in North Dakota to determine differences by age and sex and to infer seasonal relationships with nesting and migration. On average, the HY preformative molt started and ended later than the AHY prebasic molt. Percentages of molting AHY males and females in weekly collections were !90% beginning the first and fourth weeks of July, respectively. Percentages of molting HY males and females reached !90% the first week of August. Both age classes remained .90% in molt through mid-September; thereafter percentages fell rapidly, likely caused by the passing of enough time from average onsets of molts for both resident and northern nonresident populations. By the first week of October, molting HY males and females comprised about 55% of weekly HY collections compared to 9% and 21% for AHY males and females, respectively. Extensive access to commercial sunflower fields perhaps allowed resident and nonresident AHY birds to remain in the area until molt was at or near completion. Muda de plumas de vuelo en el tordo Quiscalus quiscula RESUMEN (Spanish)-Evaluamos la muda de plumas de vuelo en el tordo Quiscalus quiscula colectados en North Dakota con el propósito de determinar diferencias por edad y sexo, y para inferir sus relaciones estacionales con anidación y migración. En promedio, la muda preformativa de las aves del primer año (HY) inició y finalizó más tarde que la muda prebásica de los individuos de después del primer año (AHY). Los porcentajes de machos y hembras AHY mudando en colectas semanales fueron !90%, comenzando en la primera y cuarta semanas de julio, respectivamente. Por su parte, los porcentajes de machos y hembras HY mudando alcanzaron !90% en la primera semana de agosto. Ambas clases de edad permanecieron con .90% en muda hasta mediados de septiembre; después dichos porcentajes declinaron con rapidez, probablemente causado por el paso de suficiente tiempo desde el inicio promedio de las mudas de poblaciones residentes y poblaciones norteñas no-residentes. Para la primera semana de octubre, los machos y hembras HY mudando comprenden cerca del 55% de las colectas semanales de HY comparados con 9 y 21% de los machos y hembras AHY, respectivamente. El acceso abundante a campos comerciales de semilla de girasol quizá les permite a las aves AHY residentes y no-residentes permanecer en el a ´rea hasta que la muda esta cerca o ha llegado a su fin. Palabras clave: daño a cultivos, fenología de la muda, Icteridae, North Dakota, tordos

European starlings (Sturnus vulgaris, Figure 1) are an invasive species in the United States. The first recorded release of the birds was in 1890 in New York City’s Central Park. Because starlings easily adapt to a variety of habitats, nest sites and food sources, the birds spread quickly across the country. Today, there are about 150 million starlings in North America. Conflicts between people and starlings occur mostly in agricultural settings. Conflicts can occur during winter in urban and suburban environments, especially in business districts. Starlings damage apples, blueberries, cherries, figs, grapes, peaches, and strawberries. Besides causing direct losses from eating fruits, starlings peck and slash at fruits, reducing product quality and increasing the fruits’ susceptibility to diseases and crop pests (Figure 2). Starlings gather at concentrated animal feeding operations (CAFOs) during late fall and winter. Flocks are much larger than those encountered in late summer and are harder to disperse because of a lack of alternative foods. Starlings prefer facilities with open feeder systems which provide easy access to livestock rations (Figure 5). The link between starlings and livestock health is beginning to be understood. Epidemiological evidence suggests that starlings are both biological vectors (e.g., fecal matter) and mechanical vectors (e.g., feet, beaks) of pathogens. Starlings can transmit or amplify several bacterial, fungal, parasitical and viral pathogens. Starlings carry Salmonella spp., several Escherichia coli serotypes, Campylobacter jejuni, Mycobacterium avium, Chalmydophilia psittaci, Flavivirus spp. (West Nile Virus), Avulavirus spp. (Newcastle’s disease) and transmissible gastroenteritis (a coronavirus) without showing any symptoms of illness. Pathogens survive in feed troughs, watering troughs and fecal deposits, some surviving for weeks or years. Transmission to livestock occurs through fecal–oral routes, mainly ingestion or licking among animals. Combining multiple methods that affect auditory, gustatory and visual senses is an effective approach for managing pest birds, such as starlings. Starlings quickly habituate to visual deterrents (e.g., Mylar® tape, hawk kites) and audio deterrents (e.g., recorded distress calls). You can prolong and enhance the effectiveness of deterrents by frequently changing their locations and reinforcing them with other methods, such as pyrotechnics, propane cannons, falconry, and shooting.

Some fruit-eating bird species commonly consume cultivated fruit. Species-specific variation in diet preferences could result in varying use of orchards and impacts on the fruit-producing industry by different bird species. However, species-specific studies of avian orchard use are lacking, particularly throughout the fruit-growing season. Our objectives were to quantify the frequency of daily bird visits to orchards and the amount of time birds spent visiting orchards each day over the fruit-ripening season. Birds are well-documented consumers of cultivated sweet cherries (Prunus avium), which are relatively high in sugar and low in proteins and lipids. American Robins (Turdus migratorius) and Cedar Waxwings (Bombycilla cedrorum) are common fruit-consumers in sweet cherry orchards. Robins often consume larger proportions of invertebrates and prefer lipid-rich fruits, while waxwings choose sugary fruits. Given these species-specific diet differences, we hypothesized waxwings would spend a greater proportion of days and more time each day in cherry orchards, compared to robins. We used radio telemetry to track the habitat use of 25 American Robins and 17 Cedar Waxwings in Michigan sweet cherry orchards. Over their respective radio-tracking periods, waxwings visited orchards a marginally greater percentage of days than robins (waxwings: mean = 21%, SD = 22; robins: mean = 6%, SD = 4). In addition, waxwings visited orchards for significantly more time each day. Differences in diet preferences and nutritional physiology may translate into species-specific patterns of habitat use for birds in fruit-rich environments.

For sunflower producers in North Dakota, blackbird (Icterinae) damage is a chronic problem costing millions of dollars annually. Sunflower damage surveys were last completed in the state in 1979-1980. Since the last surveys, corn plantings have increased 6-fold to 1500 x 10(3) ha, whereas sunflower hectarage has declined by >75% to 310 x 10(3) ha. Blackbirds forage on both crops, and this rapid change in North Dakota's agricultural landscape was a sound inducement for reassessing crop damage. Field surveys are an important step in damage methods development because they are used for measuring efficacy, as well as assessing historical changes in the quality and quantity of damage. During 2009-2010, we conducted damage surveys on corn and sunflower. We surveyed 120 randomly selected 3.2 x 3.2-km plots in North Dakota's Prairie Pothole Region. This region of numerous wetlands has historically produced the majority of the state's sunflower crop, in addition to harboring a blackbird population of 25 million birds. Over the 2-year study, we measured damage in 68 cornfields and 27 sunflower fields. Annual damage averaged 5.0 x 10(3) t (12 kg/ha, US $1.3 million) for corn and 7.2 x 10(3) t (45 kg/ha, US$3.5 million) for sunflower. Percentage damage was significantly greater in sunflower ((x) over bar = 2.7%) than corn ((x) over bar = 0.2%). The lower per-unit cost of producing corn makes it a potential lure crop for managing blackbird damage to sunflower. However, the two crops should be phenologically synchronized because corn matures earlier than sunflower and becomes less attractive to blackbirds. Published by Elsevier Ltd.

Knowledge of the behavior and movement patterns of European starlings (Sturnus vulgaris L.) is important to wildlife managers that seek to resolve conflicts at livestock facilities. We captured and radio tagged 10 starlings at each of 5 dairies in northeastern Ohio. From September 19 to October 31, 2007, we obtained sufficient data from 40 birds to study their behavior and movements. The birds visited the dairies where they were initially captured (home sites) on 85% of the days, spending 58% of each day at the dairies. Onsite arrival and departure times were 2.5 h after sunrise and 3.1 h before sunset. Daily visits by radio-tagged cohorts from the other dairies were greatest for the 2 most proximate dairies (1.3 km apart), with number of visits between this pairing >7× that of the 9 other pairings combined (4.1-6.5 km apart). Two birds used their home sites intermittently as roosts, arriving 3.8 h before sunset and departing 0.2 h after sunrise. In addition to using home-site roosts, these birds also used a distant roost (22 km) that was used by 36 of the 40 birds. The efficacy of starling management programs, especially lethal management, depends on degree of site fidelity, use of other facilities, and roosting behavior. For example, starlings that use dairies as roosting sites may require a different management strategy than required at dairies used as daytime sites because of differences in arrival and departure behavior. Our research will help resource managers evaluate current management strategies already in place and change them, if needed, to fit the behavior profile of starlings using dairies and other types of livestock facilities.

In the U.S., DRC-1339 baitings for blackbirds (Icteridae) are generally done under the pesticide label, Compound DRC-1339 Concentrate – Staging Areas. DRC-1339 is a slow-acting avicide and gives the birds enough time to leave the baiting sites. Carcass searches and other forms of onsite counts are ineffective. Instead, linear models (LM) are used. The LM are based on esophageal analyses of several blackbird species collected while feeding at staging area bait sites. Biases and large variances can occur with this type of sampling. As an alternative to the LM, we developed a semi-mechanistic model (SM) that combined mechanistic modeling of environmental and biophysical processes with statistical modeling of DRC-1339 toxicities, avian physical and physiological traits, and foraging behavior. We used simulated baiting scenarios in Missouri and Louisiana to quantify and compare mortality between the LM and SM. The SM accounted for meteorological and regional effects on feeding rates, and we ran the SM scenarios for both mild and inclement weather conditions during January, a month when DRC-1339 baitings frequently occur. Mortality was calculated for males and females of three blackbird species. We used brown rice as the delivery substrate in a mix consisting of 11.34 kg untreated and 0.45 kg 2% DRC-1339 treated rice (1:25 dilution ratio). Compared to the LM, estimates by the SM ranged from 5% higher for male common grackles [Quiscalus quiscula L] to 59% lower for male brown-headed cowbirds [Molothrus ater Boddaert]. On average, the SM was 29% lower (x¯ = 8635, SE = 274.6) than the LM (x¯ = 12,131, SE = 1530.8, P < 0.001). Mortality estimates by the SM were 21% lower (x¯ = 7630, SE = 235.2, n = 12) under inclement than mild conditions (x¯ = 9641, SE = 276.3, P < 0.001). Latitudinal difference between the states did not affect mortality estimates produced by the SM (P > 0.65). Unlike the LM, the SM used avian physiological and behavioral responses to environmental and meteorological conditions based on individual characteristics of the modeled blackbird species. It represents a scientifically rigorous and broad-scale approach that can be applied at all staging area baitings regardless of region or time-of-year. The SM will produce much lower mortality estimates compared to the LM when brown-headed cowbirds are the major species using staging area sites.

After the reproductive period, blackbirds in the northern Great Plains aggregate in large flocks that feed on ripening crops, especially sunflower. At today’s prices, blackbirds eat about $8–12 million of sunflower annually in northern Great Plains, with most of this damage occurring in North Dakota and South Dakota (Peer et al. 2003). Additional expenditures are incurred by producers trying to protect their crop, including the costs in time, travel, and materials for hazing blackbirds. A chemical feeding repellent would be ideal for protecting sunflower from blackbirds because it would not only cut the amount of losses from foraging but also reduce hazing costs.