Past/Completed Research
Below are some of the projects I've already published or are otherwise completed. For a full list, see my publications page.
Urban Ecology of Free-ranging Domestic Cats
Free-ranging domestic cats (Felis catus) cats kill billions of wild animals every year, spread parasites and diseases to both wildlife and humans, and are responsible for the extinction or extirpation of at least 63 species. While the ecology and conservation implications of free-ranging cats have been well studied in some locations, relatively little is known about cats inhabiting suburban nature preserves in the United States. To address this knowledge gap, we used camera traps to study the occupancy and activity patterns of free-ranging cats in 55 suburban nature preserves in the Chicago, IL metropolitan area. From 2010 to 2018 (4440 trap days), we recorded 355 photos of free-ranging cats at 41 randomly distributed monitoring points (ψnaïve = 0.18) within 26 preserves (ψnaïve = 0.45). Cats were detected every year, but rarely at the same point or preserve, and cats were active during day and night. Cat occupancy increased with building density and detectability was highest near preserve boundaries. Based on our top-ranked model, predicted occupancy within individual preserves ranged from 0.07 to 0.42 (ψmean = 0.12) depending on the year. Overall, our results suggest that free-ranging cats are rare within suburban preserves in our study area, and that these cats are most likely owned or heavily subsidized by people (which pose different risks and management challenges than feral cats). We discuss the conservation and management implications for suburban natural areas.
2020. Vanek, J.P., G.A. Glowacki., T.S. Preuss, A.U. Rutter, & H. Jones. “Anthropogenic factors influence the occupancy of an
invasive carnivore in a suburban preserve system.” Urban Ecosystems. In Press: https://doi.org/10.1007/s11252-020-01026-x
Free-ranging domestic cats (Felis catus) cats kill billions of wild animals every year, spread parasites and diseases to both wildlife and humans, and are responsible for the extinction or extirpation of at least 63 species. While the ecology and conservation implications of free-ranging cats have been well studied in some locations, relatively little is known about cats inhabiting suburban nature preserves in the United States. To address this knowledge gap, we used camera traps to study the occupancy and activity patterns of free-ranging cats in 55 suburban nature preserves in the Chicago, IL metropolitan area. From 2010 to 2018 (4440 trap days), we recorded 355 photos of free-ranging cats at 41 randomly distributed monitoring points (ψnaïve = 0.18) within 26 preserves (ψnaïve = 0.45). Cats were detected every year, but rarely at the same point or preserve, and cats were active during day and night. Cat occupancy increased with building density and detectability was highest near preserve boundaries. Based on our top-ranked model, predicted occupancy within individual preserves ranged from 0.07 to 0.42 (ψmean = 0.12) depending on the year. Overall, our results suggest that free-ranging cats are rare within suburban preserves in our study area, and that these cats are most likely owned or heavily subsidized by people (which pose different risks and management challenges than feral cats). We discuss the conservation and management implications for suburban natural areas.
2020. Vanek, J.P., G.A. Glowacki., T.S. Preuss, A.U. Rutter, & H. Jones. “Anthropogenic factors influence the occupancy of an
invasive carnivore in a suburban preserve system.” Urban Ecosystems. In Press: https://doi.org/10.1007/s11252-020-01026-x
Responses of grassland snakes to tallgrass prairie restoration
Understanding faunal responses to habitat restoration is important in assessing restoration success. We investigated occupancy and abundance of snakes at Nachusa Grasslands, a large‐scale grassland restoration in the midwestern United States. Using artificial cover objects, we sampled within a chronosequence of 12 units converted from row‐crop agriculture 2–25 years before the start of our study. Recaptures of marked snakes revealed that movement distances differed among species in accordance with differences in body size, being least in Dekay's Brownsnakes, intermediate in the Plains Gartersnakes and Common Gartersnakes, and greatest in Eastern Foxsnakes. Consistent with this result, occupancy increased with restoration age in Dekay's Brownsnakes but was unrelated to restoration age in the three larger, more mobile species. Similarly, abundance increased with restoration age in Dekay's Brownsnake but was unrelated to restoration age in other species. The Smooth Greensnake, another small‐bodied snake with limited mobility, and an Illinois species of greatest conservation need, was not detected at Nachusa Grasslands. Given detection probabilities observed during a parallel study at a nearby large grassland‐dominated preserve, we infer that the Smooth Greensnake is truly absent from Nachusa Grasslands. Taken together, our results demonstrate that establishment of faunal components following restoration may be time‐dependent with more sedentary species colonizing only slowly (e.g. Dekay's Brownsnakes) or not at all (e.g. Smooth Greensnakes). These results emphasize the need to clearly identify faunal restoration goals and the means to achieve them.
2020. R.B. King and J.P. Vanek. “Responses of grassland snakes to tallgrass prairie restoration.” Restoration Ecology. 28(3): 573-582.
Blog Post: https://www.nachusagrasslands.org/nachusa-blog/snakes-and-prairie-restoration
Understanding faunal responses to habitat restoration is important in assessing restoration success. We investigated occupancy and abundance of snakes at Nachusa Grasslands, a large‐scale grassland restoration in the midwestern United States. Using artificial cover objects, we sampled within a chronosequence of 12 units converted from row‐crop agriculture 2–25 years before the start of our study. Recaptures of marked snakes revealed that movement distances differed among species in accordance with differences in body size, being least in Dekay's Brownsnakes, intermediate in the Plains Gartersnakes and Common Gartersnakes, and greatest in Eastern Foxsnakes. Consistent with this result, occupancy increased with restoration age in Dekay's Brownsnakes but was unrelated to restoration age in the three larger, more mobile species. Similarly, abundance increased with restoration age in Dekay's Brownsnake but was unrelated to restoration age in other species. The Smooth Greensnake, another small‐bodied snake with limited mobility, and an Illinois species of greatest conservation need, was not detected at Nachusa Grasslands. Given detection probabilities observed during a parallel study at a nearby large grassland‐dominated preserve, we infer that the Smooth Greensnake is truly absent from Nachusa Grasslands. Taken together, our results demonstrate that establishment of faunal components following restoration may be time‐dependent with more sedentary species colonizing only slowly (e.g. Dekay's Brownsnakes) or not at all (e.g. Smooth Greensnakes). These results emphasize the need to clearly identify faunal restoration goals and the means to achieve them.
2020. R.B. King and J.P. Vanek. “Responses of grassland snakes to tallgrass prairie restoration.” Restoration Ecology. 28(3): 573-582.
Blog Post: https://www.nachusagrasslands.org/nachusa-blog/snakes-and-prairie-restoration
Dynamic Occupancy of Sympatric Urban Salamanders
Conserving amphibian populations living in urban areas is challenging due to a lack of information about urban amphibian natural history, ecology, and responses to habitat management. To address these knowledge gaps, we used 10 years of monitoring data to investigate patterns of occupancy, detectability, and population turnover for sympatric Ambystoma laterale (Blue-spotted Salamanders) and A. tigrinum (Eastern Tiger Salamanders; hereafter Tiger Salamanders) inhabiting 26 suburban preserves in the third largest metropolitan area in the United States, Chicago. From 2009 to 2018 we conducted 2181 artificial cover object surveys at 158 randomly distributed monitoring points and detected Blue-spotted Salamanders 375 times and Tiger Salamanders 85 times. Blue-spotted Salamander occupancy was more than twice as high as Tiger Salamander occupancy and was influenced by forested ephemeral wetlands. Detection probability for both species was substantially <1 and was influenced by both survey and landscape covariates. Prescribed fire was an important predictor of colonization for Blue-spotted Salamanders and both species exhibited higher rates of colonization at sites near breeding wetlands. Overall rates of turnover were low for both species. Our results reveal that salamander populations can persist in highly fragmented urban preserve systems. We recommend that urban land managers maintain a mosaic of forests and wetlands and consider the impacts of habitat management on non-target species (such as salamanders).
2019. Vanek, J.P., King, R.B, Glowacki, G.A. “Landscape and management factors influence the occupancy dynamics of sympatric salamanders in an urban system.” Global Ecology and Conservation. 20:e00742. Open Access Link
Conserving amphibian populations living in urban areas is challenging due to a lack of information about urban amphibian natural history, ecology, and responses to habitat management. To address these knowledge gaps, we used 10 years of monitoring data to investigate patterns of occupancy, detectability, and population turnover for sympatric Ambystoma laterale (Blue-spotted Salamanders) and A. tigrinum (Eastern Tiger Salamanders; hereafter Tiger Salamanders) inhabiting 26 suburban preserves in the third largest metropolitan area in the United States, Chicago. From 2009 to 2018 we conducted 2181 artificial cover object surveys at 158 randomly distributed monitoring points and detected Blue-spotted Salamanders 375 times and Tiger Salamanders 85 times. Blue-spotted Salamander occupancy was more than twice as high as Tiger Salamander occupancy and was influenced by forested ephemeral wetlands. Detection probability for both species was substantially <1 and was influenced by both survey and landscape covariates. Prescribed fire was an important predictor of colonization for Blue-spotted Salamanders and both species exhibited higher rates of colonization at sites near breeding wetlands. Overall rates of turnover were low for both species. Our results reveal that salamander populations can persist in highly fragmented urban preserve systems. We recommend that urban land managers maintain a mosaic of forests and wetlands and consider the impacts of habitat management on non-target species (such as salamanders).
2019. Vanek, J.P., King, R.B, Glowacki, G.A. “Landscape and management factors influence the occupancy dynamics of sympatric salamanders in an urban system.” Global Ecology and Conservation. 20:e00742. Open Access Link
Assessing the Impacts of Urbanization on Sex Ratios of Painted Turtles (Chrysemys picta)
Turtles are particularly susceptible to the negative impacts of urbanization due to low mobility and a life history strategy emphasizing long generation times and high adult survival. In addition to declines directly through habitat loss, urbanization has been hypothesized to limit populations of aquatic turtles through changes in population structure, as adult females are disproportionately killed on and near roads, leading to male-biased populations, which can lead to population declines or local extirpations. The purpose of this study was to better understand how urbanization impacts the sex ratios of painted turtles (Chrysemys picta) in an urban ecosystem, as empirical results linking male-biased turtle populations to roads and urbanization are mixed. Using eight years of trapping data from a long-term monitoring program in a suburb of Chicago, IL, USA, we report one of the most male-biased populations (x¯ = 75% male) of turtles in the USA, consistent with prevailing road mortality hypotheses. However, we found no evidence that male-biased populations were related to road density or the amount of protected area around a sampling location and found that impervious surface (a metric of urbanization) was weakly related to less male-biased populations. Our results highlight the importance of replicating ecological studies across space and time and the difficulty in assessing population structure in aquatic turtles. We suggest that active conservation measures may be warranted for the continued persistence of urban turtle populations.
2019. Vanek, J.P. and Glowacki, G.A. “Assessing the impacts of urbanization on sex ratios of painted turtles (Chrysemys picta).” Diversity. 11(5), 72. Open Access Link
Turtles are particularly susceptible to the negative impacts of urbanization due to low mobility and a life history strategy emphasizing long generation times and high adult survival. In addition to declines directly through habitat loss, urbanization has been hypothesized to limit populations of aquatic turtles through changes in population structure, as adult females are disproportionately killed on and near roads, leading to male-biased populations, which can lead to population declines or local extirpations. The purpose of this study was to better understand how urbanization impacts the sex ratios of painted turtles (Chrysemys picta) in an urban ecosystem, as empirical results linking male-biased turtle populations to roads and urbanization are mixed. Using eight years of trapping data from a long-term monitoring program in a suburb of Chicago, IL, USA, we report one of the most male-biased populations (x¯ = 75% male) of turtles in the USA, consistent with prevailing road mortality hypotheses. However, we found no evidence that male-biased populations were related to road density or the amount of protected area around a sampling location and found that impervious surface (a metric of urbanization) was weakly related to less male-biased populations. Our results highlight the importance of replicating ecological studies across space and time and the difficulty in assessing population structure in aquatic turtles. We suggest that active conservation measures may be warranted for the continued persistence of urban turtle populations.
2019. Vanek, J.P. and Glowacki, G.A. “Assessing the impacts of urbanization on sex ratios of painted turtles (Chrysemys picta).” Diversity. 11(5), 72. Open Access Link
Island dwarfism in barrier island Hog-nosed Snakes
The island rule postulates that the special ecological conditions on islands, such as limited resource availability, can cause populations of large-bodied animals to evolve smaller sizes and small-bodied populations to evolve larger sizes. Although support for the island rule is well documented (with notable exceptions and debate) in mammals and birds, similar trends are poorly explored in ectothermic vertebrates. As part of a larger study investigating the ecology of Eastern hog-nosed snakes (Heterodon platirhinos Latreille 1801), we compared the mean and maximum sizes of a population from a barrier island (~4,000 ha) to snakes on an adjacent larger island (~363,000 ha) and two mainland sites (450 total snakes across all study sites). We did not observe a difference between the small and large islands but did find differences between the smallest island and the mainland. Female snakes on the barrier island were 8% smaller than those on the mainland, and the largest barrier island female was 35% smaller than the largest documented H. platirhinos. In addition, we found that males did not exhibit dwarfism. We hypothesize the observed dwarfism is a result of limited availability of large prey items and recommend that future studies distinguish between sexes in their analyses.
*This project was a serendipitous result of my masters research, which focused on the spatial ecology and natural history of Eastern Hog-nosed Snakes. We noticed that the snakes we were finding were oddly small, and wound up doing a formal analysis to confirm it! This is the part of natural history I love, the "sixth sense" that something is different than you might expect!
2019. Vanek, J.P. and Burke, R.L. “Insular dwarfism in female Eastern hog-nosed snakes (Dipsadidae; Heterodon platirhinos) on a barrier island.” Canadian Journal of Zoology. In press.
The island rule postulates that the special ecological conditions on islands, such as limited resource availability, can cause populations of large-bodied animals to evolve smaller sizes and small-bodied populations to evolve larger sizes. Although support for the island rule is well documented (with notable exceptions and debate) in mammals and birds, similar trends are poorly explored in ectothermic vertebrates. As part of a larger study investigating the ecology of Eastern hog-nosed snakes (Heterodon platirhinos Latreille 1801), we compared the mean and maximum sizes of a population from a barrier island (~4,000 ha) to snakes on an adjacent larger island (~363,000 ha) and two mainland sites (450 total snakes across all study sites). We did not observe a difference between the small and large islands but did find differences between the smallest island and the mainland. Female snakes on the barrier island were 8% smaller than those on the mainland, and the largest barrier island female was 35% smaller than the largest documented H. platirhinos. In addition, we found that males did not exhibit dwarfism. We hypothesize the observed dwarfism is a result of limited availability of large prey items and recommend that future studies distinguish between sexes in their analyses.
*This project was a serendipitous result of my masters research, which focused on the spatial ecology and natural history of Eastern Hog-nosed Snakes. We noticed that the snakes we were finding were oddly small, and wound up doing a formal analysis to confirm it! This is the part of natural history I love, the "sixth sense" that something is different than you might expect!
2019. Vanek, J.P. and Burke, R.L. “Insular dwarfism in female Eastern hog-nosed snakes (Dipsadidae; Heterodon platirhinos) on a barrier island.” Canadian Journal of Zoology. In press.
Spatial Ecology of the Eastern Hog-nosed Snake at the Northeastern Limit of its Range
Populations at the edge of the natural range of a species may deal with ecological challenges that differ from those at the core of the range. These differences can result in different patterns of resource use, which may confound resource managers and conservation biologists who must develop management strategies based upon the best available information. One such species is the Eastern Hog-nosed Snake (Heterodon platirhinos), a species of conservation concern in the northeastern part of its geographic range due to habitat loss, declines in amphibian prey species, and wanton killing. To address these knowledge gaps, we used radio-telemetry to study the spatial ecology and natural history of six H. platirhinos at the northern-most portion of the range of the species in New York. Snakes that we tracked had mean home-range sizes (100% minimum convex polygon = 23.7 ± 21.2 ha) smaller than populations reported in New Hampshire, Massachusetts, Arkansas, and Ontario. Snakes also used forests extensively, although compositional analysis revealed that they selected open and edge habitats in greater proportion to their availability, consistent with other studies. Snakes were more likely to be found in close proximity to coarse woody debris than was randomly available, and they selected microhabitats with denser vegetation than average, but we found no evidence of selection for ground cover, canopy cover, or proximity to trees.
2017. Vanek, J.P. and Wasko, D.K. “Spatial ecology of the eastern hog-nosed snake (Heterodon platirhinos) at the northeastern limit of its range.” Herpetological Conservation and Biology. 12(1): 109-118. Open Access Link
Populations at the edge of the natural range of a species may deal with ecological challenges that differ from those at the core of the range. These differences can result in different patterns of resource use, which may confound resource managers and conservation biologists who must develop management strategies based upon the best available information. One such species is the Eastern Hog-nosed Snake (Heterodon platirhinos), a species of conservation concern in the northeastern part of its geographic range due to habitat loss, declines in amphibian prey species, and wanton killing. To address these knowledge gaps, we used radio-telemetry to study the spatial ecology and natural history of six H. platirhinos at the northern-most portion of the range of the species in New York. Snakes that we tracked had mean home-range sizes (100% minimum convex polygon = 23.7 ± 21.2 ha) smaller than populations reported in New Hampshire, Massachusetts, Arkansas, and Ontario. Snakes also used forests extensively, although compositional analysis revealed that they selected open and edge habitats in greater proportion to their availability, consistent with other studies. Snakes were more likely to be found in close proximity to coarse woody debris than was randomly available, and they selected microhabitats with denser vegetation than average, but we found no evidence of selection for ground cover, canopy cover, or proximity to trees.
2017. Vanek, J.P. and Wasko, D.K. “Spatial ecology of the eastern hog-nosed snake (Heterodon platirhinos) at the northeastern limit of its range.” Herpetological Conservation and Biology. 12(1): 109-118. Open Access Link
Quantifying New York’s Diamondback Terrapin Habitat
Spartina marshes (S. patens [Salt Meadow Cordgrass] and S. alterniflora [Saltmarsh Cordgrass]) are critical foraging, nursery, and overwintering habitats for Malaclemys terrapin (Diamondback Terrapin). However, the relationships between Spartina marsh quality, quantity, and distribution and resulting Diamondback Terrapin distribution, abundance, and movements are poorly understood. To develop a model for predicting these relationships, we needed a way to prioritize the locations where data are collected for model building. As an initial effort, we used available data on New York Spartina salt marsh distribution and estimates of Diamondback Terrapin home range to identify marshes for initial surveys and pilot work for studies of habitat quality. We present GIS-model results showing New York locations with 50-, 100-, and 260-ha hypo-thetical home ranges (consisting of 50%, 75%, and 100% Spartina marsh), and use this information to identify New York locations most likely to harbor Diamondback Terrapins. Our models indicated there should be relatively large populations of terrapins in western Hempstead Bay and eastern Jamaica Bay, but failed to identify a known terrapin popula-tion at Piermont Marsh on the Hudson River.
2015. Brown, J.P., Kanonik, A., Vanek, J.P., Crown, CA, and Burke, RL. “Quantifying New York’s diamondback terrapin habitat.” Northeastern Naturalist. 22(3): 630-642
Spartina marshes (S. patens [Salt Meadow Cordgrass] and S. alterniflora [Saltmarsh Cordgrass]) are critical foraging, nursery, and overwintering habitats for Malaclemys terrapin (Diamondback Terrapin). However, the relationships between Spartina marsh quality, quantity, and distribution and resulting Diamondback Terrapin distribution, abundance, and movements are poorly understood. To develop a model for predicting these relationships, we needed a way to prioritize the locations where data are collected for model building. As an initial effort, we used available data on New York Spartina salt marsh distribution and estimates of Diamondback Terrapin home range to identify marshes for initial surveys and pilot work for studies of habitat quality. We present GIS-model results showing New York locations with 50-, 100-, and 260-ha hypo-thetical home ranges (consisting of 50%, 75%, and 100% Spartina marsh), and use this information to identify New York locations most likely to harbor Diamondback Terrapins. Our models indicated there should be relatively large populations of terrapins in western Hempstead Bay and eastern Jamaica Bay, but failed to identify a known terrapin popula-tion at Piermont Marsh on the Hudson River.
2015. Brown, J.P., Kanonik, A., Vanek, J.P., Crown, CA, and Burke, RL. “Quantifying New York’s diamondback terrapin habitat.” Northeastern Naturalist. 22(3): 630-642