Charles D. Dieter

Bird mortality associated with wind turbines at the Buffalo Ridge wind resource area, Minnesota.

Abstract Recent technological advances have made wind power a viable source of alternative energy production and the number of windplant facilities has increased in the United States. Construction was completed on a 73 turbine, 25 megawatt windplant on Buffalo Ridge near Lake Benton, Minnesota in Spring 1994. The number of birds killed at existing windplants in California caused concern about the potential impacts of the Buffalo Ridge facility on the avian community. From April 1994 through Dec. 1995 we searched the Buffalo Ridge windplant site for dead birds. Additionally, we evaluated search efficiency, predator scavenging rates and rate of carcass decomposition. During 20 mo of monitoring we found 12 dead birds. Collisions with wind turbines were suspected for 8 of the 12 birds. During observer efficiency trials searchers found 78.8% of carcasses. Scavengers removed 39.5% of carcasses during scavenging trials. All carcasses remained recognizable during 7 d decomposition trials. After correction for biases we estimated that approximately 36 ± 12 birds (<1 dead bird per turbine) were killed at the Buffalo Ridge windplant in 1 y. Although windplants do not appear to be more detrimental to birds than other man-made structures, proper facility siting is an important first consideration in order to avoid unnecessary fatalities.

The Importance of Emergent Vegetation in Reducing Sediment Resuspension in Wetlands

ABSTRACT Wind-induced resuspension of bottom sediment was measured with sediment traps in Sand Lake National Wildlife Refuge, South Dakota. Resuspension was significantly greater in open water areas than in areas protected from wind by emergent vegetation. Resuspended sediment was apparently uniformly distributed through the water column.

BIRD FLIGHT CHARACTERISTICS NEAR WIND TURBINES IN MINNESOTA

Abstract During 1994–1995, we saw 70 species of birds on the Buffalo Ridge Wind Resource Area. In both years bird abundance peaked in spring. Red-winged blackbirds (Agelaius phoeniceus), mallards (Anas platyrhynchos), common grackles (Quiscalus quiscula), and barn swallows (Hirundo rustica) were the species most commonly seen. Most birds (82–84%) flew above or below the height range of wind turbine blades (22–55 m). The Buffalo Ridge Wind Resource Area poses little threat to resident or migrating birds at its current operating level.

Factors Influencing Beaver Lodge-site Selection on a Prairie River

-Physical and vegetative habitat characteristics were evaluated at 33 beaver (Castor canadensis) lodges during 1986 along the Big Sioux River in eastern South Dakota. Slope of the riverbank was the most important physical factor and horizontal vegetation cover was the most important vegetative factor influencing lodge-site selection. Beaver preferred the habitat quality of ungrazed areas for lodge sites. Although 60% of the study area was grazed, only six (18%) of 33 beaver lodges were located there.

Capture and Mortality Rates of Ducks in Selected Trap Types

Abstract We evaluated different trap styles and related mortality of trapped ducks (Anas spp.) for 3 field seasons as part of the United States–Canada Cooperative Waterfowl Banding Program. During 2002, we evaluated 4 trap designs and caught 10,966 ducks. Trap style affected capture rates (P  =  0.018, F5  =  9.02), with Benning II and oval traps catching more ducks than cloverleaf and star traps. In 2003, we tested 3 trap styles and caught 10,849 ducks. Trap style affected duck capture rates (P < 0.01, F5  =  15.16), with oval traps with 6-m lead panels catching more ducks than Benning II traps and cloverleaf traps. During 2004, we tested 3 trap styles and caught 11,737 ducks. Trap style affected capture rates (P < 0.01, F5  =  11.23), with oval traps with 6-m leads catching more ducks than either the oval trap without leads or Benning II traps. Trap style affected mortality rates of ducks, but overall mortality of trapped ducks was low with a rate of 1.16% in 2002, 0.32% in 2003, and 0.17% in 2004; mortality was not a major problem in our study. Waterfowl managers may be able to catch more ducks using oval traps with leads without increasing mortality of captured ducks.

Population Characteristics of Beavers in Eastern South Dakota

-Biological characteristics of beavers (Castor canadensis) harvested during a spring hunting season in eastern South Dakota were determined. Age ratios in the sample showed 19.5% kits, 22.6% yearlings and 57.9% adults (2.5-3 years and older). The overall male: female ratio (1.24:1.00) was not significantly different from a 1:1 ratio, but males (65%) dominated in the 4.5-5 year + age-class. Evidence of reproduction was found only in beavers 2.5-3 years of age or older. Adult females had a pregnancy rate of 62.5%. The mean number of embryos produced per breeding female was 4.0.

Reproductive Success and Brood Movements of Giant Canada Geese in Eastern South Dakota

Abstract The population of resident giant Canada geese (Branta canadensis maxima) has increased dramatically in eastern South Dakota since reintroduction efforts were initiated in the 1960s. In order to effectively manage this population of Canada geese, it is important to determine their reproductive success. We collected information on goose nesting success and related brood movements using Very High Frequency (VHF) telemetry. We captured Canada geese in seven counties in eastern South Dakota during summers, 2000–2003. The reproductive success of 88 females was monitored during spring 2001–2004. Half of the geese had successful nests, 20.5% were unsuccessful, and 29.5% did not attempt to nest. Apparent and Mayfield nesting success estimates averaged 71% and 63%, respectively. Overall egg success was 62.6% and overall hatching success was 88.8%. Mean total clutch size averaged 5.73 ± 0.17 while the number of goslings leaving the nest averaged 5.02 ± 0.25. Forty-nine percent of marked females nested on or around the shoreline of their previous summers capture wetland. The remaining 51% nested on peripheral wetlands ranging from seasonal wetlands to permanent lakes. Mean distance from the capture wetlands to nest sites across years was 1.5 km ± 0.18. Biologists need to consider long distance movement of giant Canada goose broods when making management decisions.

Home Range and Habitat Use of Northern Flying Squirrels in the Black Hills, South Dakota

Abstract Northern flying squirrels (Glaucomys sabrinus) of the Black Hills National Forest (BHNF) of South Dakota represent a unique and isolated population, but little is known about the home range size and habitat use of this population. Fifty-nine northern flying squirrels (34 males and 25 females) were radio-collared and tracked during their active period, from dusk until dawn, by point sampling. Minimum convex polygons (MCPs) were determined from observation locations of squirrels with ≥15 radio-tracking locations (n  =  49). Males occupied larger home ranges (n  =  30; 11.23 ± 1.48 ha) than females (n  =  19; 6.91 ± 0.94 ha; P  =  0.02). Using the radiotelemetry data and GIS vegetation layers, habitat use (grass-shrub, aspen-birch, bur oak and pine) and structural stage class (1, 3A, 3B, 3C, 4A, 4B and 4C) selection were determined for all squirrels with ≥10 radio-tracking locations (n  =  54). Habitat selection was determined by comparing the proportion of radio-tracking locations (observed) within each habitat to the proportion of habitat within the MCPs (available) using techniques developed by Neu et al. (1974). Ponderosa pine (Pinus ponderosa), which dominates 83% of BHNF, was the only habitat used proportionally more than available. Within their home ranges northern flying squirrels also selected larger trees and more canopy cover, as well as more live trees >12.7 cm dbh, higher basal area of live trees and fewer snags. This study aids managers in understanding habitat use by northern flying squirrels in pine dominated habitat of BHNF and an isolated population at the southern edge of their range.

Evaluation of the Microtox Test to Detect Phorate Contamination in Wetlands

ABSTRACT The Microtox test was evaluated as a tool to measure the presence of phorate, an organophosphate insecticide, in northern prairie wetlands. Microtox test results were inconsistent with results of other in situ toxicity tests with aquatic invertebrates and ducklings. The Microtox test often indicated no toxicity, even though both invertebrates and ducklings died. Caution should be used when interpreting the results of the Microtox test to evaluate wetlands for pesticide contamination.

Effects of phorate on ducklings in Northern Prairie wetlands

Phorate is a toxic organophosphorus insecticide that has been associated with accidental wildlife poisonings. Because of concern for effects on waterfowl, we studied the effects of phorate on mallard (Anas platyrhynchos) ducklings in littoral mesocosms in South Dakota wetlands. In each of 3 wetlands, we constructed 4 mesocosms. One mesocosm was a control, and to the others we applied phorate at rates of 1.2, 2.4, and 4.8 kg/ha, respectively. Phorate caused mortality to ducklings at all concentrations. Ducklings in control mesocosms (0.0 kg/ha) survived longer (P < 0.05) than those in treated mesocosms. Ten-day-old ducklings were more sensitive (P < 0.05) to phorate than were 21-day-old ducklings. Brain and blood cholinesterase (ChE) activity of treated ducklings was reduced (P < 0.01) compared with that of reference ducklings. Phorate concentrations in prairie wetlands can reduce duckling survival; therefore, alternatives to phorate should be considered.