... TROY W. GROVENBURG 1 , CHRISTOPHER N. JACQUES, CHRISTOPHER C. SWANSON, ROBERT W. KLAVER, AND ... more ... TROY W. GROVENBURG 1 , CHRISTOPHER N. JACQUES, CHRISTOPHER C. SWANSON, ROBERT W. KLAVER, AND JONATHAN A. JENKS ... Our study was conducted within the Northwestern Glaciated Plains and the Northern Glaciated Plains ecoregions (Bryce et al. ...
The human-mediated spread of exotic and invasive species often leads to unintentional and harmful... more The human-mediated spread of exotic and invasive species often leads to unintentional and harmful consequences. Invasive wild pigs (Sus scrofa) are one such species that have been repeatedly translocated throughout the United States and cause extensive damage to natural ecosystems, threatened and endangered species, agricultural resources, and private lands. In 2005, a newly established population of wild pigs was confirmed in Fulton County, Illinois, U.S. In 2011, a state-wide wild pig damage management program involving federal, state, and local government authorities directed a concerted effort to remove wild pigs from the county until the last wild pig (of 376 total) was successfully removed in 2016. We examined surveillance data from camera traps at bait sites and records of wild pig removals during this elimination program to identify environmental and anthropogenic factors that optimized removal of this population. Our results revealed that wild pigs used bait sites most duri...
Southern flying squirrels (Glaucomys volans; SFS) nest in naturally formed cavities in snags and ... more Southern flying squirrels (Glaucomys volans; SFS) nest in naturally formed cavities in snags and hardwoods found in mature, oak (Quercus spp.)-hickory (Carya spp.) forests. Intensive forest fragmentation of the Midwest United States limits the number of available nesting trees. We quantified annual nest-site selection patterns by southern flying squirrels across fragmented landscapes of west-central Illinois, USA. We used radiotelemetry to measure nest-tree use by 55 SFS (30 males, 25 females) captured during 2014-2016. Of 105 nest trees used by SFS, live trees and snags comprised 75% and 25%, respectively. Probability of diurnal nest-tree use increased 1.08/1.00-cm increase in diameter-breast-height and by 1.50/1-unit increase in the number of overstory mast trees between random and nest-tree habitat areas (i.e., 300-m 2 circular plots). Similarly, probability of diurnal nest-tree use increased 1.29/1-unit increase in the number of snags between random and nest-tree habitat areas. Our results revealed no intersexual differences in patterns of nest-site selection, which may reflect the tendency for SFS to compensate for reduced availability of key structural attributes (i.e., snags, overstory trees) across fragmented forests by exhibiting similar intersexual patterns of nest-tree use. Use of natural cavities for denning is encouraging, but also underscores the importance of unharvested oak-hickory forests in contributing essential habitat to SFS populations in fragmented Midwestern landscapes.
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Intensification of land use practices and climate change have resulted in extensive wetland loss ... more Intensification of land use practices and climate change have resulted in extensive wetland loss and declines of native submersed aquatic vegetation (SAV) species across North America. Limited by a lack of biomass and energy estimates for wetlands containing SAV, conservation planners currently are unable to accurately account for its energetic contribution in bioenergetics models for waterfowl and other waterbirds. Therefore, we estimated energetic carrying capacity of 21 semi-permanent wetlands containing SAV and identified as important stopover locations for migrating waterfowl and other waterbirds in the Midwest, USA during 2015–2017. Energy density of SAV (x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{x} $$\end{document} = 813 ± 257 EUD/ha) was generally less than managed emergent wetlands, varied by National Wetland Inventory class, and had large annual (98–4873 ΔEUD/ha) and spatial variation (8–7971 EUD/ha). We developed a visual rapid assessment index (R2m = 0.43) that may be useful to wetland managers or researchers to quickly index energy density from SAV in semi-permanent wetlands. Energetic carrying capacity of wetlands containing SAV will allow conservation planners to more precisely estimate energy supply on the landscape for waterfowl and evaluate trade-offs among alternative management strategies. Our results demonstrate negative effects of hydrologic connectivity on SAV communities in highly modified landscapes.
Camera-trapping data analyzed with spatially explicit capture-recapture (SCR) models can provide ... more Camera-trapping data analyzed with spatially explicit capture-recapture (SCR) models can provide a rigorous method for estimating density of small populations of elusive carnivore species. We sought to develop and evaluate the efficacy of SCR models for estimating density of a presumed low-density bobcat (Lynx rufus) population in fragmented landscapes of west-central Illinois, USA. We analyzed camera-trapping data from 49 camera stations in a 1,458-km 2 area deployed over a 77-day period from 1 February to 18 April 2017. Mean operational time of cameras was 52 days (range = 32-67 days). We captured 23 uniquely identifiable bobcats 113 times and recaptured these same individuals 90 times; 15 of 23 (65.2%) individuals were recaptured at ≥2 camera traps. Total number of bobcat capture events was 139, of which 26 (18.7%) were discarded from analyses because of poor image quality or capture of only a part of an animal in photographs. Of 113 capture events used in analyses, 106 (93.8%) and 7 (6.2%) were classified as positive and tentative identifications, respectively; agreement on tentative identifications of bobcats was high (71.4%) among 3 observers. We photographed bobcats at 36 of 49 (73.5%) camera stations, of which 34 stations were used in analyses. We estimated bobcat density at 1.40 individuals (range = 1.00-2.02)/100 km 2. Our modeled bobcat density estimates are considerably below previously reported densities (30.5 individuals/ 100 km 2) within the state, and among the lowest yet recorded for the species. Nevertheless, use of remote cameras and SCR models was a viable technique for reliably estimating bobcat density across west-central Illinois. Our research establishes ecological benchmarks for understanding potential effects of colonization, habitat fragmentation, and exploitation on future assessments of bobcat density using standardized methodologies that can be compared directly over time. Further application of SCR models that quantify specific costs of animal movements (i.e., least-cost path models) while accounting for landscape connectivity has great utility and relevance for conservation and management of bobcat populations across fragmented Midwestern landscapes.
Sherman traps are the most commonly used live traps in studies of small mammals and have been suc... more Sherman traps are the most commonly used live traps in studies of small mammals and have been successfully used in the capture of arboreal species such as the southern flying squirrel (Glaucomys volans). However, southern flying squirrels spend proportionately less time foraging on the ground, which necessitates above-ground trapping methods and modifications of capture protocols. Further, quantitative estimates of the factors affecting capture success of flying squirrel populations have focused solely on effects of trapping methodologies. We developed and evaluated the efficacy of a portable Sherman trap design for capturing southern flying squirrels during 2015-2016 at the Alice L. Kibbe Field Station, Illinois, USA. Additionally, we used logistic regression to quantify potential effects of time-dependent (e.g., weather) and time-independent (e.g., habitat, extrinsic) factors on capture success of southern flying squirrels. We recorded 165 capture events (119 F, 44 M, 2 unknown) using our modified Sherman trap design. Probability of capture success decreased 0.10/18 C increase in daily maximum temperature and by 0.09/unit increase (km/hr) in wind speed. Conversely, probability of capture success increased by 1.2/18 C increase in daily minimum temperature. The probability of capturing flying squirrels was negatively associated with trap orientation. When tree-mounted traps are required, our modified trap design is a safe, efficient, and cost-effective method of capturing animals when moderate weather (temp and wind speed) conditions prevail. Further, we believe that strategic placement of traps (e.g., northeast side of tree) and quantitative information on site-specific (e.g., trap location) characteristics (e.g., topographical features, slope, aspect, climatologic factors) could increase southern flying squirrel capture success.
Context Distance sampling is used to estimate abundance for several taxa, including pronghorn (An... more Context Distance sampling is used to estimate abundance for several taxa, including pronghorn (Antilocapra americana). Comparisons between population estimates derived from quadrat sampling and distance sampling suggest that distance sampling underestimates pronghorn density, likely owing to violations of the critical assumption of distance sampling that all pronghorn within the innermost distance band (A band; nearest to the aircraft) are detected. Aims We sought to rigorously test the assumption that all pronghorn clusters are detected within the innermost distance band by applying a double-observer approach to an established pronghorn aerial-survey protocol. Additionally, we evaluated potential effects of cluster size, landscape composition and seat position (front seat versus rear) on the probability of detection. Methods We conducted aerial line-transect distance-sampling surveys using independent, paired observers and modelled the probability of detection with mark–recapture d...
We studied home range use, spatial activity patterns, and annual survival of southern flying squi... more We studied home range use, spatial activity patterns, and annual survival of southern flying squirrels (SFS; Glaucomys volans) across fragmented landscapes of west-central Illinois. We calculated seasonal home range sizes and annual survival from 67 animals (36 males, 31 females) captured during 2014-2016. Home range and core area sizes were similar (P ≥ 0.46) among males and females across summer (April-September) and winter (October-March) seasons. Average distance between consecutive animal locations did not vary by sex, season, or year. Similarly, cumulative distance between consecutive locations did not vary by sex, season, or year and ranged from 1,189 to 1,661 m between summer and winter seasons. Mean annual composite home range and core area sizes were 10.39 and 1.25 ha, respectively; estimated home ranges (10.3 ha) of females are the largest documented for this species. We documented 8 deaths, all attributed to predation, the majority (63%) of which occurred during winter; annual survival was 71%. Our results underscore effects of habitat productivity on seasonal home range dynamics and space use patterns of SFS in fragmented landscapes. SFS may compensate for reduced availability of overstory mast-producing trees that characterize unproductive habitats and low-density populations by exhibiting similar movement patterns and use of available habitat by both sexes throughout the year. Winter communal nesting appears to be influenced by availability of cavity trees, thereby confirming the importance of standing snags in contributing essential habitat to flying squirrel populations in fragmented forests.
Few studies have evaluated how wetland and forest characteristics influence the prevalence of men... more Few studies have evaluated how wetland and forest characteristics influence the prevalence of meningeal worm (Parelaphostrongylus tenuis) infection of deer throughout the grassland biome of central North America. We used previously collected, county-level prevalence data to evaluate associations between habitat characteristics and probability of meningeal worm infection in white-tailed deer (Odocoileus virginianus) across eastern South Dakota, US. The highest-ranked binomial regression model for detecting probability of meningeal worm infection was spring temperature + summer precipitation + percent wetland; weight of evidence (wi=0.71) favored this model over alternative models, though predictive capability was low (Receiver operating characteristic=0.62). Probability of meningeal worm infection increased by 1.3-and 1.6-fold for each 1-cm and 1-C increase in summer precipitation and spring temperature, respectively. Similarly, probability of infection increased 1.2-fold for each 1% increase in wetland habitat. Our findings highlight the importance of wetland habitat in predicting meningeal worm infection across eastern South Dakota. Future research is warranted to evaluate the relationships between climatic conditions (e.g., drought, wet cycles) and deer habitat selection in maintaining P. tenuis along the western boundary of the parasite.
Winter habitat and resource use of white-tailed deer (Odocoileus virginianus) have been studied e... more Winter habitat and resource use of white-tailed deer (Odocoileus virginianus) have been studied extensively throughout their northern range. However, limited information exists on deer use of late season standing corn. We evaluated standing corn use by female white-tailed deer on winter range in north-central South Dakota during winter 2005–2006. Results indicate that cover type selection occurred at the population (P < 0.001) and home range (P < 0.001) levels. Population level analysis indicated selection for standing corn (ŵ = 4.31) and CRP (ŵ = 2.81). Similarly, at the home range level, deer selected for standing corn (ŵ = 1.35) and CRP (ŵ = 1.44). Deer disproportionately increased use of standing corn and CRP as habitat availability increased. Moreover, deer used wetlands and forested habitat in proportion to availability. In this region of the Northern Great Plains, availability and distribution of traditional cover habitats (i.e., forested and wetland habitats) is limited. We speculate that deer substituted late season standing corn to optimize thermoregulatory and forage requirements, and visual protection against potential predators.
... TROY W. GROVENBURG 1 , CHRISTOPHER N. JACQUES, CHRISTOPHER C. SWANSON, ROBERT W. KLAVER, AND ... more ... TROY W. GROVENBURG 1 , CHRISTOPHER N. JACQUES, CHRISTOPHER C. SWANSON, ROBERT W. KLAVER, AND JONATHAN A. JENKS ... Our study was conducted within the Northwestern Glaciated Plains and the Northern Glaciated Plains ecoregions (Bryce et al. ...
The human-mediated spread of exotic and invasive species often leads to unintentional and harmful... more The human-mediated spread of exotic and invasive species often leads to unintentional and harmful consequences. Invasive wild pigs (Sus scrofa) are one such species that have been repeatedly translocated throughout the United States and cause extensive damage to natural ecosystems, threatened and endangered species, agricultural resources, and private lands. In 2005, a newly established population of wild pigs was confirmed in Fulton County, Illinois, U.S. In 2011, a state-wide wild pig damage management program involving federal, state, and local government authorities directed a concerted effort to remove wild pigs from the county until the last wild pig (of 376 total) was successfully removed in 2016. We examined surveillance data from camera traps at bait sites and records of wild pig removals during this elimination program to identify environmental and anthropogenic factors that optimized removal of this population. Our results revealed that wild pigs used bait sites most duri...
Southern flying squirrels (Glaucomys volans; SFS) nest in naturally formed cavities in snags and ... more Southern flying squirrels (Glaucomys volans; SFS) nest in naturally formed cavities in snags and hardwoods found in mature, oak (Quercus spp.)-hickory (Carya spp.) forests. Intensive forest fragmentation of the Midwest United States limits the number of available nesting trees. We quantified annual nest-site selection patterns by southern flying squirrels across fragmented landscapes of west-central Illinois, USA. We used radiotelemetry to measure nest-tree use by 55 SFS (30 males, 25 females) captured during 2014-2016. Of 105 nest trees used by SFS, live trees and snags comprised 75% and 25%, respectively. Probability of diurnal nest-tree use increased 1.08/1.00-cm increase in diameter-breast-height and by 1.50/1-unit increase in the number of overstory mast trees between random and nest-tree habitat areas (i.e., 300-m 2 circular plots). Similarly, probability of diurnal nest-tree use increased 1.29/1-unit increase in the number of snags between random and nest-tree habitat areas. Our results revealed no intersexual differences in patterns of nest-site selection, which may reflect the tendency for SFS to compensate for reduced availability of key structural attributes (i.e., snags, overstory trees) across fragmented forests by exhibiting similar intersexual patterns of nest-tree use. Use of natural cavities for denning is encouraging, but also underscores the importance of unharvested oak-hickory forests in contributing essential habitat to SFS populations in fragmented Midwestern landscapes.
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Intensification of land use practices and climate change have resulted in extensive wetland loss ... more Intensification of land use practices and climate change have resulted in extensive wetland loss and declines of native submersed aquatic vegetation (SAV) species across North America. Limited by a lack of biomass and energy estimates for wetlands containing SAV, conservation planners currently are unable to accurately account for its energetic contribution in bioenergetics models for waterfowl and other waterbirds. Therefore, we estimated energetic carrying capacity of 21 semi-permanent wetlands containing SAV and identified as important stopover locations for migrating waterfowl and other waterbirds in the Midwest, USA during 2015–2017. Energy density of SAV (x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{x} $$\end{document} = 813 ± 257 EUD/ha) was generally less than managed emergent wetlands, varied by National Wetland Inventory class, and had large annual (98–4873 ΔEUD/ha) and spatial variation (8–7971 EUD/ha). We developed a visual rapid assessment index (R2m = 0.43) that may be useful to wetland managers or researchers to quickly index energy density from SAV in semi-permanent wetlands. Energetic carrying capacity of wetlands containing SAV will allow conservation planners to more precisely estimate energy supply on the landscape for waterfowl and evaluate trade-offs among alternative management strategies. Our results demonstrate negative effects of hydrologic connectivity on SAV communities in highly modified landscapes.
Camera-trapping data analyzed with spatially explicit capture-recapture (SCR) models can provide ... more Camera-trapping data analyzed with spatially explicit capture-recapture (SCR) models can provide a rigorous method for estimating density of small populations of elusive carnivore species. We sought to develop and evaluate the efficacy of SCR models for estimating density of a presumed low-density bobcat (Lynx rufus) population in fragmented landscapes of west-central Illinois, USA. We analyzed camera-trapping data from 49 camera stations in a 1,458-km 2 area deployed over a 77-day period from 1 February to 18 April 2017. Mean operational time of cameras was 52 days (range = 32-67 days). We captured 23 uniquely identifiable bobcats 113 times and recaptured these same individuals 90 times; 15 of 23 (65.2%) individuals were recaptured at ≥2 camera traps. Total number of bobcat capture events was 139, of which 26 (18.7%) were discarded from analyses because of poor image quality or capture of only a part of an animal in photographs. Of 113 capture events used in analyses, 106 (93.8%) and 7 (6.2%) were classified as positive and tentative identifications, respectively; agreement on tentative identifications of bobcats was high (71.4%) among 3 observers. We photographed bobcats at 36 of 49 (73.5%) camera stations, of which 34 stations were used in analyses. We estimated bobcat density at 1.40 individuals (range = 1.00-2.02)/100 km 2. Our modeled bobcat density estimates are considerably below previously reported densities (30.5 individuals/ 100 km 2) within the state, and among the lowest yet recorded for the species. Nevertheless, use of remote cameras and SCR models was a viable technique for reliably estimating bobcat density across west-central Illinois. Our research establishes ecological benchmarks for understanding potential effects of colonization, habitat fragmentation, and exploitation on future assessments of bobcat density using standardized methodologies that can be compared directly over time. Further application of SCR models that quantify specific costs of animal movements (i.e., least-cost path models) while accounting for landscape connectivity has great utility and relevance for conservation and management of bobcat populations across fragmented Midwestern landscapes.
Sherman traps are the most commonly used live traps in studies of small mammals and have been suc... more Sherman traps are the most commonly used live traps in studies of small mammals and have been successfully used in the capture of arboreal species such as the southern flying squirrel (Glaucomys volans). However, southern flying squirrels spend proportionately less time foraging on the ground, which necessitates above-ground trapping methods and modifications of capture protocols. Further, quantitative estimates of the factors affecting capture success of flying squirrel populations have focused solely on effects of trapping methodologies. We developed and evaluated the efficacy of a portable Sherman trap design for capturing southern flying squirrels during 2015-2016 at the Alice L. Kibbe Field Station, Illinois, USA. Additionally, we used logistic regression to quantify potential effects of time-dependent (e.g., weather) and time-independent (e.g., habitat, extrinsic) factors on capture success of southern flying squirrels. We recorded 165 capture events (119 F, 44 M, 2 unknown) using our modified Sherman trap design. Probability of capture success decreased 0.10/18 C increase in daily maximum temperature and by 0.09/unit increase (km/hr) in wind speed. Conversely, probability of capture success increased by 1.2/18 C increase in daily minimum temperature. The probability of capturing flying squirrels was negatively associated with trap orientation. When tree-mounted traps are required, our modified trap design is a safe, efficient, and cost-effective method of capturing animals when moderate weather (temp and wind speed) conditions prevail. Further, we believe that strategic placement of traps (e.g., northeast side of tree) and quantitative information on site-specific (e.g., trap location) characteristics (e.g., topographical features, slope, aspect, climatologic factors) could increase southern flying squirrel capture success.
Context Distance sampling is used to estimate abundance for several taxa, including pronghorn (An... more Context Distance sampling is used to estimate abundance for several taxa, including pronghorn (Antilocapra americana). Comparisons between population estimates derived from quadrat sampling and distance sampling suggest that distance sampling underestimates pronghorn density, likely owing to violations of the critical assumption of distance sampling that all pronghorn within the innermost distance band (A band; nearest to the aircraft) are detected. Aims We sought to rigorously test the assumption that all pronghorn clusters are detected within the innermost distance band by applying a double-observer approach to an established pronghorn aerial-survey protocol. Additionally, we evaluated potential effects of cluster size, landscape composition and seat position (front seat versus rear) on the probability of detection. Methods We conducted aerial line-transect distance-sampling surveys using independent, paired observers and modelled the probability of detection with mark–recapture d...
We studied home range use, spatial activity patterns, and annual survival of southern flying squi... more We studied home range use, spatial activity patterns, and annual survival of southern flying squirrels (SFS; Glaucomys volans) across fragmented landscapes of west-central Illinois. We calculated seasonal home range sizes and annual survival from 67 animals (36 males, 31 females) captured during 2014-2016. Home range and core area sizes were similar (P ≥ 0.46) among males and females across summer (April-September) and winter (October-March) seasons. Average distance between consecutive animal locations did not vary by sex, season, or year. Similarly, cumulative distance between consecutive locations did not vary by sex, season, or year and ranged from 1,189 to 1,661 m between summer and winter seasons. Mean annual composite home range and core area sizes were 10.39 and 1.25 ha, respectively; estimated home ranges (10.3 ha) of females are the largest documented for this species. We documented 8 deaths, all attributed to predation, the majority (63%) of which occurred during winter; annual survival was 71%. Our results underscore effects of habitat productivity on seasonal home range dynamics and space use patterns of SFS in fragmented landscapes. SFS may compensate for reduced availability of overstory mast-producing trees that characterize unproductive habitats and low-density populations by exhibiting similar movement patterns and use of available habitat by both sexes throughout the year. Winter communal nesting appears to be influenced by availability of cavity trees, thereby confirming the importance of standing snags in contributing essential habitat to flying squirrel populations in fragmented forests.
Few studies have evaluated how wetland and forest characteristics influence the prevalence of men... more Few studies have evaluated how wetland and forest characteristics influence the prevalence of meningeal worm (Parelaphostrongylus tenuis) infection of deer throughout the grassland biome of central North America. We used previously collected, county-level prevalence data to evaluate associations between habitat characteristics and probability of meningeal worm infection in white-tailed deer (Odocoileus virginianus) across eastern South Dakota, US. The highest-ranked binomial regression model for detecting probability of meningeal worm infection was spring temperature + summer precipitation + percent wetland; weight of evidence (wi=0.71) favored this model over alternative models, though predictive capability was low (Receiver operating characteristic=0.62). Probability of meningeal worm infection increased by 1.3-and 1.6-fold for each 1-cm and 1-C increase in summer precipitation and spring temperature, respectively. Similarly, probability of infection increased 1.2-fold for each 1% increase in wetland habitat. Our findings highlight the importance of wetland habitat in predicting meningeal worm infection across eastern South Dakota. Future research is warranted to evaluate the relationships between climatic conditions (e.g., drought, wet cycles) and deer habitat selection in maintaining P. tenuis along the western boundary of the parasite.
Winter habitat and resource use of white-tailed deer (Odocoileus virginianus) have been studied e... more Winter habitat and resource use of white-tailed deer (Odocoileus virginianus) have been studied extensively throughout their northern range. However, limited information exists on deer use of late season standing corn. We evaluated standing corn use by female white-tailed deer on winter range in north-central South Dakota during winter 2005–2006. Results indicate that cover type selection occurred at the population (P < 0.001) and home range (P < 0.001) levels. Population level analysis indicated selection for standing corn (ŵ = 4.31) and CRP (ŵ = 2.81). Similarly, at the home range level, deer selected for standing corn (ŵ = 1.35) and CRP (ŵ = 1.44). Deer disproportionately increased use of standing corn and CRP as habitat availability increased. Moreover, deer used wetlands and forested habitat in proportion to availability. In this region of the Northern Great Plains, availability and distribution of traditional cover habitats (i.e., forested and wetland habitats) is limited. We speculate that deer substituted late season standing corn to optimize thermoregulatory and forage requirements, and visual protection against potential predators.
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