Rutkiewicz J.,University of Michigan |
Nam D.-H.,University of Michigan |
Cooley T.,Wildlife Disease Laboratory |
Neumann K.,Saving Our Avian Resources |
And 4 more authors.
Ecotoxicology | Year: 2011
In this study, we assessed mercury (Hg) exposure in several tissues (brain, liver, and breast and primary feathers) in bald eagles (Haliaeetus leucocephalus) collected from across five Great Lakes states (Iowa, Michigan, Minnesota, Ohio, and Wisconsin) between 2002-2010, and assessed relationships between brain Hg and neurochemical receptors (NMDA and GABA A) and enzymes (glutamine synthetase (GS) and glutamic acid decarboxylase (GAD)). Brain total Hg (THg) levels (dry weight basis) averaged 2.80 μg/g (range: 0.2-34.01), and levels were highest in Michigan birds. THg levels in liver (r p = 0.805) and breast feathers (r p = 0.611) significantly correlated with those in brain. Brain Hg was not associated with binding to the GABA A receptor. Brain THg and inorganic Hg (IHg) were significantly positively correlated with GS activity (THg r p = 0.190; IHg r p = 0.188) and negatively correlated with NMDA receptor levels (THg r p = -0245; IHg r p = -0.282), and IHg was negatively correlated with GAD activity (r s = -0.196). We also report upon Hg demethylation and relationships between Hg and Se in brain and liver. These results suggest that bald eagles in the Great Lakes region are exposed to Hg at levels capable of causing subclinical neurological damage, and that when tissue burdens are related to proposed avian thresholds approximately 14-27% of eagles studied here may be at risk. © 2011 Springer Science+Business Media, LLC.
Dornbos P.,University of Michigan |
Strom S.,Bureau of Wildlife Management |
Basu N.,University of Michigan
Ecotoxicology | Year: 2013
River otters are fish-eating wildlife that bioaccumulate high levels of mercury (Hg). Mercury is a proven neurotoxicant to mammalian wildlife, but little is known about the underlying, sub-clinical effects. Here, the overall goal was to increase understanding of Hg's neurological risk to otters. First, Hg values across several brain regions and tissues were characterized. Second, in three brain regions with known sensitivity to Hg (brainstem, cerebellum, and occipital cortex), potential associations among Hg levels and neurochemical biomarkers [N-methyl-d-aspartic acid (NMDA) and gamma-aminobutyric acid (GABAA) receptor] were explored. There were no significant differences in Hg levels across eight brain regions (rank order, highest to lowest: frontal cortex, cerebellum, temporal cortex, occipital cortex, parietal cortex, basal ganglia, brainstem, and thalamus), with mean values ranging from 0.7 to 1.3 ug/g dry weight. These brain levels were significantly lower than mean values in the muscle (2.1 ± 1.4 ug/g), liver (4.7 ± 4.3 ug/g), and fur (8.8 ± 4.8 ug/g). While a significant association was found between Hg and NMDA receptor levels in the brain stem (P = 0.028, r p = -0.293), no relationships were found in the cerebellum and occipital cortex. For the GABA receptor, no relationships were found. The lack of consistent Hg-associated neurochemical changes is likely due to low brain Hg levels in these river otters, which are amongst the lowest reported. © 2013 Springer Science+Business Media New York.
Bolenbaugh J.R.,University of Arkansas |
Cooper T.,U.S. Fish and Wildlife Service |
Brady R.S.,Bureau of Wildlife Management |
Willard K.L.,University of Arkansas |
Krementz D.G.,University of Arkansas
Waterbirds | Year: 2012
The migratory population of the King Rail (Rallus elegans) has declined dramatically during the past 50 years, emphasizing the need to document the distribution and status of this species to help guide conservation efforts. In an effort to guide King Rail breeding habitat protection and restoration, a landscape suitability index (LSI) model was developed for the Upper Mississippi River and Great Lakes Region Joint Venture (JV). To validate this model, 264 sites were surveyed across the JV region in 2008 and 2009 using the National Marshbird Monitoring protocol. Two other similarly collected data sets from Wisconsin (250 sites) and Ohio (259 sites) as well as data from the Cornell Laboratory of Ornithology's eBird database were added to our data set. Sampling effort was not uniform across the study area. King Rails were detected at 29 sites with the greatest concentration in southeastern Wisconsin and northeastern Illinois. Too few detections were made to validate the LSI model. King Rail detection sites tended to have microtopographic heterogeneity, more emergent herbaceous wetland vegetation and less woody vegetation. The migrant population of the King Rail is rare and warrants additional conservation efforts to achieve stated conservation population targets.
Clare J.D.J.,University of Wisconsin - Stevens Point |
Clare J.D.J.,University of Maine, United States |
Anderson E.M.,University of Wisconsin - Stevens Point |
MacFarland D.M.,Bureau of Wildlife Management |
Sloss B.L.,University of Wisconsin - Stevens Point
Wildlife Society Bulletin | Year: 2015
Determining cost-effective field methods for detecting carnivores is critical for effective survey and monitoring studies. As the bobcat (Lynx rufus) undergoes range expansion in the northern and eastern United States, field methods may be useful for informing revisions in population management. We paired 2 scat detection-dog teams and 16 remote cameras at 4 survey sites within central Wisconsin, during summer 2011, and compared detection totals, detection probabilities, and costs between methods. Laboratory expenditures are an additional cost for scat collection, and we modeled the probability that a collected scat was genetically confirmed as bobcat as a function of dog, handler, site, and the strength of the dog's behavior. We estimated that detection-dog surveys required only 2 days to achieve a 90% probability of detecting a bobcat in a 4-km2 area, while a single camera station would require 7-8 weeks. But a month of detection-dog surveys cost 33% more than a 4-month camera survey, with projected cost differences increasing annually. There were dog-specific differences in collection rate, and the probability that a collected scat was genetically confirmed as bobcat was best predicted by the individual dog associated with collection and the survey area, rather than the handler or the dog's observed response. We recommend cameras as a generally more cost-efficient bobcat survey method, and we advise against relying on the strength of an individual dog's response as a means of screening samples for genetic analysis. However, the most appropriate survey method is likely to be goal-dependent, and we recommend that detection-dog contractors both advertise and match the strengths and weaknesses of specific dogs with the needs of clientele. © The Wildlife Society, 2014.
Glisson W.J.,Plant Science and Conservation |
Glisson W.J.,University of Idaho |
Brady R.S.,Bureau of Wildlife Management |
Paulios A.T.,Bureau of Wildlife Management |
And 2 more authors.
Journal of Wildlife Management | Year: 2015
Wetland loss, biological invasions, and ecological restoration are major factors altering wetland resources in the Midwestern United States. Large-scale plant-community change associated with these factors is an under-investigated, potentially strong driver of habitat suitability for wetland-dependent wildlife, such as secretive marsh birds (SMBs), which are of widespread conservation concern. We employed multi-year, hierarchical Bayesian occupancy modeling to investigate sensitivity of 3 SMB species (American bittern, sora, and Virginia rail) to habitat and vegetation characteristics in Wisconsin, USA. We contrasted habitat characteristics and SMB occupancy in natural wetlands with those restored under the federally funded Wetlands Reserve Program (WRP). We also examined the extent to which SMB occupancy was explained by 3 levels of habitat assessment that encompassed different spatial scales and levels of sampling effort (landscape, rapid, and intensive). All species were significantly associated with variables derived from intensive assessment, and showed high sensitivity to differences in plant-community composition and vegetation quality. Both American bittern and Virginia rail were negatively associated with abundance of the invasive wetland grass, Phalaris arundinacea (reed canarygrass), and were positively associated with an indicator of plant-community quality (mean coefficient of conservatism, or C-value). Sora occupancy was positively associated with Typha (cattail) abundance. For all 3 species, occupancy was greater in natural sites than in restored sites, which were characterized by greater Phalaris abundance and lower mean C-values. Our results show broad agreement between botanical and avian indicators of wetland quality, suggesting that enhancing the condition of wetland vegetation can yield ancillary benefits for SMBs. In this region, efforts to control Phalaris and restore diverse, native-dominated plant communities are likely to increase wetlands' capacity to support SMBs. © 2015 The Wildlife Society.