Phenology of Annulus Formation in Walleye and Smallmouth Bass Otoliths

Walleye Sander vitreus and smallmouth bass Micropterus dolomieu were sampled monthly (May-October) from Lake Sharpe, South Dakota during 2006 and 2007 to estimate the timing of otolith annulus formation and to evaluate the influence of fish age, sex, and sample location (walleye only) on the timing and detection of annulus formation. Timing of annulus formation was evaluated using marginal increment analysis. Walleye samples were stratified by age, sex, and sample location (i.e., upper and lower Lake Sharpe) and smallmouth bass samples were stratified by age and sex. Monthly mean marginal increment measurements for both species generally increased from May to June, declined in July, and slowly increased from August to October. Although monthly differences in marginal increment measurements across analysis strata were rarely consistent, July generally had the lowest mean marginal increment across species and strata, suggesting that annulus formation in walleye and smallmouth bass in Lake Sharpe likely occurs in July. The lack of differences in timing of annulus formation across species-specific strata was surprising given the well-known influences of age, sex, and water temperature on somatic growth. Nonetheless, results will aid managers in improving the accuracy of age estimates

An Assessment of Direct Mortality to Avifauna from Wind Energy Facilities in North Dakota and South Dakota

Renewable energy sources have the potential to provide enough energy to exceed current energy demands. In the U. S., 9% of energy consumption in 2011 was derived from renewable sources. Currently, the most technically developed and cost-effective source is land-based wind energy and the U.S. Department of Energy (DOE) has targeted 20% of electricity generated from wind by 2030. Although there are some clear advantages to using renewables, the resources are not without negative impacts to the environment. Moreover, the effects of wind energy development to wildlife are unique to each wind farm. However, these effects remain poorly understood and require additional research to elucidate and quantify. The Northern Great Plains (NGP) contains much of the remaining temperate grasslands and, within the NGP, the Prairie Pothole Region (PPR) provides important habitat for many species of waterfowl, shorebirds, waterbirds, and grassland songbirds. This region also has high wind energy potential, but the effects of wind energy developments on wildlife populations in the NGP remains understudied. Thus, our objectives were to estimate avian and bat mortality rates, document species at high risk to direct mortality, and assess the influence of habitat variables on mortality. In 2013 and 2014, we completed turbine searches for carcasses at the Tatanka Wind Farm (TAWF) and the Edgeley-Kulm Wind Farm (EKWF) in South Dakota and North Dakota. We estimated spring (Mar-Jun) mortality of 1.86 (SE = 0.22) deaths/MW at TAWF and 2.55 (SE = 0.51) deaths/MW at EKWF. Our spring mortality rates are similar to what has been estimated for yearly mortality rates in the Great Plains, suggesting that full-year mortality rates are higher at these wind farms than others in the region. Waterfowl spring mortality rates were 0.79 (SE = 0.11) and 0.91 (SE = 0.10) deaths/MW at TAWF and EKWF, respectively. We used a Generalized Estimating Equation (GEE) to estimate the influence of landscape variables around individual turbines on waterfowl mortality and documented cropland to have a negative influence on mortality rates. We suggest future wind facility siting decisions consider avoiding grassland habitats and locate turbines in fragmented and converted habitat outside of important waterfowl areas

Assessing Spring Direct Mortality to Avifauna from Wind Energy Facilities in the Dakotas

The Northern Great Plains (NGP) contains much of the remaining temperate grasslands, an ecosystem that is one of the most converted and least protected in the world. Within the NGP, the Prairie Pothole Region (PPR) provides important habitat for \u3e50% of North America\u27s breeding waterfowl and many species of shorebirds, waterbirds, and grassland songbirds. This region also has high wind energy potential, but the effects of wind energy developments on migratory and resident bird and bat populations in the NGP remains understudied. This is troubling considering \u3e2,200 wind turbines are actively generating power in the region and numerous wind energy projects have been proposed for development in the future. Our objectives were to estimate avian and bat fatality rates for wind turbines situated in cropland- and grassland-dominated landscapes, document species at high risk to direct mortality, and assess the influence of habitat variables on waterfowl mortality at 2 wind farms in the NGP. From 10 March to 7 June 2013–2014, we completed 2,398 searches around turbines for carcasses at the Tatanka Wind Farm (TAWF) and the Edgeley-Kulm Wind Farm (EKWF) in South Dakota and North Dakota. During spring, we found 92 turbine-related mortalities comprising 33 species and documented a greater diversity of species (n = 30) killed at TAWF (predominately grassland) than at EKWF (n = 9; predominately agricultural fields). After accounting for detection rates, we estimated spring mortality of 1.86 (SE = 0.22) deaths/megawatt (MW) at TAWF and 2.55 (SE = 0.51) deaths/MW at EKWF. Waterfowl spring (Mar–Jun) fatality rates were 0.79 (SE = 0.11) and 0.91 (SE = 0.10) deaths/MW at TAWF and EKWF, respectively. Our results suggest that future wind facility siting decisions consider avoiding grassland habitats and locate turbines in pre-existing fragmented and converted habitat outside of high densities of breeding waterfowl and major migration corridors