PROGRESS ON MANAGING CATTAIL MARSHES WITH RODEO® HERBICIDE TO DISPERSE ROOSTING BLACKBIRDS

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 (Icterinae). 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

Avian Use of Rice-Baited Trays Attached to Cages with Live Decoy Blackbirds in Central North Dakota

For several decades, blackbird depredation of sunflower has been a continuous problem. Sunflower growers consistently place blackbirds in the top tier of problems associated with growing sunflower in the northern Great Plains. Many non-lethal tactics have been employed in an attempt to protect ripening sunflower from foraging flocks of blackbirds. Thinning cattail-choked wetlands to reduce roosting habitat, using pyrotechniques to frighten feeding birds, planting Wildlife Conservation Sunflower Plots to lure birds away from commercial plots, applying taste repellents, and adapting cultural methods such as block planting to synchronize ripening are just a few such tactics. Even so, the numbers of blackbirds migrating through the northern Great Plains can overwhelm non-lethal techniques. That is, in some circumstances there are too many blackbirds for non-lethal techniques to be effective. One avicide, DRC-1339, is registered for use as a lethal bait in the U.S. and North Dakota. The avicide is usually mixed with brown rice at a ratio of 1:25 (treated rice kernel to untreated rice kernels). Normally, the rice mixture is broadcast on the ground in the ripening or sprouting crop. Non-blackbirds are plentiful in ripening sunflower fields, causing a potential risk to these species with the use of DRC-1339. These granivorous non-blackbirds might eat treated rice, causing an unintentional loss. A number of species of songbirds and sparrows could be at risk. Also, ring-necked pheasants (Phasianus colchicus) and mourning doves (Zenaida macroura) are species of high concern. One potential method of avoiding non-blackbirds is to put live decoys (blackbirds) in cages in areas devoid of habitat to attract free-living blackbirds to bait trays attached to the top of the decoy cages. The intent is to reduce large concentrations of blackbirds that cannot be otherwise dispersed by non-lethal means. The objective of this study is to identify and quantify the avian species visiting the bait trays. Our goal is to develop an effective and environmentally-safe method for managing locally abundant blackbird populations

INFLUENCES OF LAND USE PATTERNS ON BLACKBIRD ABUNDANCE IN THE PRAIRIE POTHOLE REGION OF NORTH DAKOTA

One issue affecting sunflower growers in the upper Great Plains of North America is crop depredation by blackbirds. In this region, blackbirds annually destroy an average of $5.4 million of sunflower. To increase the understanding of how blackbirds are influenced by large-scale land-use patterns, we developed multiple regression models to explain how various land use patterns influence blackbird abundance. We used data from the North American Breeding Bird Survey and the USGS land cover assessment to develop regression models examining associations between land use characteristics and blackbird abundance. Both red-winged blackbirds and yellow-headed blackbirds were negatively associated with the amount of developed area, while the amount of wetland area strongly influenced yellow-headed blackbird abundance. Common grackles were positively associated with the number of land-use types in the landscape. These associations can be partially explained by habitat preferences of these species; however, many variables that would seemingly be good predictors of blackbird abundance were not significant. This result suggests that either a greater number of samples are needed to identify these associations, or the relationships in question are not detectable at the landscape level

Winter Habitat Use and Survival of Female Ring-necked Pheasants (\u3ci\u3ePhasianus colchicus\u3c/i\u3e) in Southeastern North Dakota

From 1992 to 1995 we used radiotelemetry to monitor winter habitat selection and survival of female ring-necked pheasants (Phasianus colchicus) in southeastern North Dakota. We captured 100 birds at nine sites in six study blocks centered on cattail-dominated (Typha spp.) semi-permanent wetlands. Pheasants showed nonrandom habitat use at two hierarchical scales. At the second-order scale (23-km2 blocks) semi-permanent wetlands were preferred during two winters in which habitat selection could be assessed (1992–1993 and 1994–1995). An additional second-order preference for grass-covered uplands was shown during the mild 1994–1995 winter. At the third-order scale (home-range) pheasants preferred the edges of wetlands in 1992–1993 and 1994–1995. The central portions of wetlands were preferred in 1992–1993 and used proportionately in 1994–1995. Seasonal wetlands were avoided at the third order scale during 1992–1993 and 1994–1995. The average winter survival rate was 0.41, with rates ranging from 0.04–0.86 and differing significantly among winters. Survival was lower during early winter and midwinter periods for birds weighing less than 1090 g and for birds captured in semi-permanent wetlands under private ownership. A 1 C increase in the mean weekly maximum temperature decreased the probability of death by 0.06 and a 2.5 cm increase in new snow raised the probability of death by 0.08

Cattail Quantification in the Prairie Pothole Region of North Dakota Regarding Cattail Management for Reduction of Blackbird Sunflower Damage

The spread of cattail across the Northern Great Plains has increased the amount of breeding and roosting habitat available to marsh-nesting blackbirds. In the fall, dense cattail stands attract large numbers of roosting blackbirds, that damage crops like sunflower. In an effort to disperse roosting blackbirds and reduce the resulting crop damage, scientists from the USDA’s National Wildlife Research Center and North Dakota State University have developed wetland habitat management techniques using a glyphosate-based aquatic herbicide. These techniques have been used by USDA Wildlife Services as a nonlethal method for reducing blackbird damage. Previous research on individual wetlands has demonstrated that wetland habitat management can disperse congregations of roosting blackbirds, reduce the number of breeding blackbirds, and increase attractiveness of the wetlands to other wildlife, like waterfowl. The prospect of an expanded cattail control program has raised concerns about the scale of management efforts and the effects of habitat alterations on other wetland species. A precise estimate of the amount of cattail habitat presently available will form a basis to address concerns about the overall scope of the cattail management program

HABITAT CHARACTERISTICS AROUND FALL BLACKBIRD ROOSTS

In the fall, blackbirds form large flocks and roost overnight in cattail marshes. These blackbirds cause millions of dollars in damage to ripening sunflower fields in North Dakota, South Dakota, and Minnesota. By knowing the habitat characteristics around fall blackbird roosts sites, management officials may be able to predict future roost locations and then implement control techniques to help reduce blackbird damage to sunflower fields. We present data on the available habitat around blackbird roosts to determine if there is a relationship between the habitat and fall roost sites

QUANTIFICATION OF CATTAIL (\u3ci\u3eTYPHA\u3c/i\u3e SPP.) IN THE PRAIRIE POTHOLE REGION OF NORTH DAKOTA IN RELATION TO BLACKBIRD DAMAGE TO SUNFLOWER

Sunflower is an important crop for many farmers in the upper Midwest, especially in North Dakota and South Dakota. Blackbirds have been a major problem for the sunflower grower community. Bud depredation to a field can be devastating. The USDA-APHISWS is charged with reducing the conflict between the birds and the farmers. Many methods have been employed by Wildlife Services and other agencies to lessen the damage. One method is the reduction of the cattail (Typha spp.) habitat used by blackbirds in and around wetlands; however, cattails are used by other animals. Consequently, there is a need to insure habitat manipulation is not significantly affecting non-target species, hence knowing what portion of the total cattail habitat is being manipulated is critical. The purpose of this study was to quantify cattail habitat in the Prairie Pothole Region (PPR) of North Dakota. Remote sensing using aerial infrared photographs was used to sample 120, 10.36 km sq. plots, randomly distributed throughout each of four strata dividing the PPR in ND. ArcInfo 8x Geographic Information System (GIs) software was used to run a supervised classification to delineate cattail from other vegetation. Results found 2,245 =t 257 (S.E.) km sq. of cattail in the PPR. These findings show that less than one percent of the total cattail stand in the PPR is being affected by the USDA cattail management efforts

AVIAN USE OF ROADSIDE HABITAT IN THE SOUTHERN DRIFT PLAINS OF NORTH DAKOTA AND IMPLICATIONS FOR CATTAIL (\u3ci\u3eTYPHA\u3c/i\u3e SPP.) MANAGEMENT

We determined avian use of roadside rights-of-way to develop proper management strategies for the manipulation of roadside cattail. Cattail management is a technique used to reduce nesting and roosting habitat for problematic blackbird species, which might feed on sunflower crops in the vicinity of cattail-dominated wetlands. Thirty quarter sections (1 quarter section ≈ 64.75 ha) located in the Southern Drift Plains of North Dakota served as our study units. Roadside habitat along two 0.5 mile (-0.8 km) transects bordering these quarter sections was surveyed to assess avian use. Additionally, nest surveys were , conducted to provide an index of breeding bird use of this roadside habitat. Finally, roadside habitat was surveyed for a number of different habitat variables. We found 49 different species during the surveys. Of the 2,529 birds found in this habitat, 1,479 (41.5%) were blackbirds. Blackbirds were also the primary nesting birds, contributing to 89% of the active nests found in roadside habitat. In terms of avian use and nesting, blackbirds, especially redwings, were the dominant bird species using roadside cattail. With proper management of roadside habitat, potential effects on non-blackbirds can be minimized, and nesting habitat for blackbirds can be reduced. Our data Indicate that a loss in nesting habitat will likely result in fewer blackbirds and a subsequent reduction in sunflower damage

Food Preferences of Common Grackles, Red-Winged Blackbirds, and Yellow-Headed Blackbirds Presented with Cracked Corn, Sunflower Meats, and Brown Rice

Blackbirds migrating through North Dakota in late summer damage sunflower crops shortly after the yellow ray petals begin to wither and fall (Besser 1985). DeHaven (1982) reported bird damage losses of $7.4 million on 2.2 million acres in 1980. Various behavioral, chemical, and mechanical strategies have been employed over the past decade to reduce the damage. Although some of these methods have effectively dispersed or reduced blackbird populations, many have proven to be ineffective over time, economically infeasible, or culturally unacceptable (Guarino 1984)