Midwest Fish & Wildlife Conference 2019

AUTHORS: Sarah Saunders, National Audubon Society; Kristin Hall, Minnesota Department of Natural Resources; Nina Hill, University of Minnesota; Nicole Michel, National Audubon Society

ABSTRACT: Intensifying wetland stressors in the Great Lakes region of the United States have hastened the need to identify local and landscape-scale habitat characteristics important to marsh-dependent wildlife to inform conservation prioritizations. The optimal spatial scale for assessing species-habitat relationships is not always apparent, but may affect inference about wetland use and suitability. We developed occupancy and abundance models, while accounting for imperfect detection, for nine marshbird species breeding in Minnesota. We evaluated species-specific wetland cover associations at three spatial scales (12.6 ha, 50.3 ha, and 4000 ha), quantified sensitivity to anthropogenic disturbance (developed land and agriculture), and evaluated ecoregional variation in marshbird occupancy and abundance. Emergent vegetation was positively correlated with occupancy rates of 89% of species, emphasizing the conservation value of this land cover type for sustaining breeding marshbird populations in the state. Agriculture was negatively associated with occupancy for three species, and positively associated for three other species, especially at the landscape scale. Development was negatively related to occupancy for five species, but positively related for Marsh Wren. Occupancy of all species was highest in the Prairie Pothole ecoregion, and Pied-billed Grebe and Sora were most abundant at wetlands in this region. Restoration efforts targeted within the western portion of the state are most likely to boost marshbird populations and use conservation resources effectively. Future applications of our modeling framework at broader spatial extents will contribute to the conservation of marshbirds in a region where rates of wetland loss and degradation are high.

AUTHORS: Therin Bradshaw, Western Illinois University/Illinois Natural History Survey - Forbes Biological Station; Cheyenne Beach, Western Illinois University; Heath Hagy, US Fish & Wildlife Service; Christopher Jacques, Western Illinois University; Abigail Blake-Bradshaw, University of Illinois at Urbana-Champaign, Joseph Lancaster, Illinois Natural History Survey - Forbes Biological Station

ABSTRACT: Marsh birds are an understudied guild of migratory birds of conservation concern that can be valuable indicators of wetland health and may benefit from wetland management for waterfowl. I assessed marsh bird occupancy of wetlands across Illinois to better understand how natural wetland characteristics, impoundment management for waterfowl, and surrounding landscape characteristics influence marsh bird occupancy of wetlands. During late spring and early summer 2015–2017, I surveyed marsh birds three times annually at focal sites (passive or active management for waterfowl), random sites (emergent, pond, or lake polygons from the National Wetland Inventory), and Critical Trends Assessment Program (CTAP) sites (wetlands from the Illinois Natural History Survey’s CTAP). Marsh bird occupancy was greatest during my first survey period (Ψ=0.71, SE=0.11), followed by my second (Ψ=0.55, SE=0.14) and third survey periods (Ψ=0.39, SE=0.14). Focal (Ψ=0.74, SE= 0.09) sites had greater occupancy than random (Ψ=0.62, SE=0.08) or CTAP sites (Ψ=0.32, SE=0.11). Occupancy also varied by wetland complexity (greatest in the large levels of complexity [Ψ= 0.99, SE= 0.02]), waterfowl management intensity (greatest at an intermediate level of management [Ψ=0.39, SE=0.178]), percent wetland area inundated (greatest in large area of inundation [Ψ=0.74, SE=0.089]), and percent cover of persistent emergent vegetation (greatest with large percent persistent emergent vegetation cover [Ψ=0.81, SE=0.148]). Across species and marsh bird groups, detection probability decreased with ordinal date, for every week delay in marsh bird survey detection declined 7.1% (SE=2.1). Our results suggest that waterfowl habitat management positively influence marsh bird occupancy. Occupancy increased with management practices that were less intensive and focused on keeping water on the landscape with little disturbance to encourage habitat characteristics such as high habitat complexity, large area inundation and high percent cover of dense persistent emergent vegetation.

AUTHORS: Nicole Hengst, The Ohio State University; James Hansen, The Ohio State University; Brendan Shirkey, Winous Point Marsh Conservancy; John Simpson, Winous Point Marsh Conservancy; Robert Gates, The Ohio State University

ABSTRACT: Secretive marsh bird populations are threatened by habitat loss throughout their ranges. In Ohio, Virginia rails (Rallus limicola) and soras (Porzana carolina) are species of concern and legally harvested. Very little work has been conducted to understand movements and habitat selection by Virginia rails and soras in coastal wetlands of the western Lake Erie basin. Managed wetlands are an important source of rail habitat in Ohio, yet little is known about how manipulation of water levels to produce food and cover for waterfowl affects migrating and breeding rails. Virginia rails and soras were captured and fitted with VHF radio-transmitters and tracked daily during March-September, 2016-2018. Twenty-seven percent of radio-marked rails migrated or dispersed from the study site within 1-2 days of capture in May-August. Mean home range sizes were 6.51 and 3.67 ha (SE = 1.40, n = 57 and SE = 0.95, n = 7) for Virginia rails and soras, respectively. Of the 166 radio-marked rails that remained at the study site at least one day after capture, 138 used only one impoundment unit at the study site. This allowed us to examine movement patterns of Virginia rails and soras in response to water level changes during 2016-2018. Vegetation surveys were conducted in 2018 to compare differences in habitat characteristics between locations of radio-marked rails and random points and to identify wetland habitat characteristics that rails select for as water levels change. Vegetation surveys were conducted weekly at individual radio-locations and at the end of the growing season within home ranges of radio-marked rails. Twenty-two percent of the weekly surveys indicated rails using areas dominated by cattail (Typha spp.) with water cover <40% and medium interspersion. This work will provide additional understanding of rail ecology and aid in better informed wetland management for rail species in northern Ohio.

AUTHORS: Ross P. McLean, University of Wisconsin-Stevens Point

ABSTRACT: Whooping Cranes (WHCR) are federally endangered and in 2001, a reintroduction effort was initiated at Necedah National Wildlife Refuge (NNWR) in Wisconsin to establish an Eastern Migratory Population (EMP). However, despite seventeen years of management, recruitment remains low. Greater Sandhill Cranes (SACR, Antigone canadensis tabida) are biologically similar to WHCRs and have similar breeding ecology. We studied colt survival for both crane species at NNWR to determine if low recruitment is unique to the Eastern Migratory Population (EMP) of WHCRs, or an issue for both North American crane species in the initial introductory breeding grounds of the EMP. Additionally, we lowered water levels in some wetland impoundments to better mimic the natural annual water cycle. This management action was part of an effort to increase wetland and forage access for wading birds during summer months. Our objectives were to determine (1) if summer drawdowns and reduced wetland water levels increase survival of WHCR and SACR colts compared to cranes reared in or near impoundments with full water levels, and (2) differences in overall colt survival rates between species. We hypothesized that (1) WHCR would use the drawdown areas more than available wetlands with higher water levels, and (2) that colt survival would be higher in lower water wetlands due to increased mobility and access to prey. We placed VHF transmitters on adults and colts of both species to collect colt survival status and family group locations every day during the 2017-2018 field seasons. Analyses are ongoing, but many of the fledged colts were raised in areas with lower water. We will discuss implications for crane management in the Midwest. <a href="applewebdata://63650BC7-DDE7-47CB-BF71-58A32F69113E#_msoanchor_1"></a>

AUTHORS: Kyle Kuechle, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources; Elisabeth B. Webb, U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources; Doreen Mengel, Missouri Department of Conservation, Resource Science Division; Anson Main, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources.

ABSTRACT: Neonicotinoid insecticides (NI) are commonly used as seed-treatments on major agricultural row crops (e.g., corn). Indeed, neonicotinoid treated agricultural crops are often planted directly in floodplain wetlands managed for wildlife, specifically waterfowl. Numerous studies have documented impacts of neonicotinoids to aquatic invertebrates in laboratory and mesocosm settings; however, there is limited information on impacts to aquatic invertebrate in field settings. We investigated invertebrate community response to planting of neonicotinoid-treated seed in managed wetland ecosystems in Missouri. In 2016, we sampled water, sediment, and aquatic invertebrates from 22 paired wetlands during spring (pre-wetland drawdown) and fall (post-wetland flood-up) followed by a third sampling period (spring 2017). During summer, portions of study wetlands were planted with either neonicotinoid-treated corn or untreated corn (control). Water and sediment concentrations of the three most common neonicotinoids were used to calculate overall NI toxicity equivalents (NI-EQs) based on an additive model of NI toxic equivalency factors. Mean total NI-EQs for sediment (0.60 μg/kg) were an order of magnitude greater than water (0.02 μg/L). Water quality parameters and pesticide concentrations were used to evaluate effects of neonicotinoid concentrations on aquatic macroinvertebrates using a series of generalized linear mixed effects models. Preliminary results indicate an overall decrease in aquatic invertebrate diversity and abundance with increasing NI-EQs in both wetland water and sediments. Post-treatment, treated wetlands had lower benthic invertebrate diversity and abundance compared to untreated wetlands, but a recovery in abundance and diversity followed in spring 2017. Our results have implications for aquatic invertebrates and wetland-dependant species (e.g., migrating birds) as neonicotinoid concentrations, although below regulatory limits, are impacting wetland ecosystems. Research results will be useful to wetland managers in making decisions regarding use of neonicotinoid seed-treatments, specifically, and potentially, provide broader considerations of the role agriculture may play in future wetland management and conservation plans.