Scientific publications
Publication in Ecological Applications
Urban habitat restoration increases native bird diversity in the Midwestern United States
Urbanization is a key driver of biodiversity loss because infrastructure development replaces native habitats and remnant biodiversity becomes concentrated in fragmented, seminatural green spaces. Ecological restoration in urban areas can improve the quality of green spaces for native wildlife, but the impact of restorative management on biodiversity is often not quantified. Urban habitat management frequently involves integrating human needs such as recreational spaces with conservation aims, potentially altering the biodiversity benefits of these efforts. Furthermore, non-native species can dominate urban biodiversity, suggesting that high biodiversity in city green spaces may not be indicative of diverse native communities. Here, we use point count surveys to explore whether restoration efforts can explain variation in avian biodiversity across time and space in a large urban greenspace, Forest Park in St. Louis, Missouri, USA. First, we use surveys conducted during three distinct restoration phases spanning almost three decades to explore longitudinal effects of restoration on Shannon diversity and species richness. Second, we use data from 2023 to 2024 to explore whether variation in restoration status can explain avian biodiversity across sites. Lastly, we assess the contribution of non-native bird species to avian biodiversity. We demonstrate that restoration efforts are linked to increased diversity, but that this effect is more pronounced across a spatial rather than a temporal restoration gradient. We also show that non-native species contribute less to richness in more restored areas, but that restoration has no effect on the contribution of non-native species to Shannon diversity. We show that an urban restoration program can increase native biodiversity. We further provide insights to inform future habitat restoration efforts in cities, underscoring the importance of restoration efforts that consider landscape heterogeneity and water availability. Restoration may be most impactful in areas with limited landscape heterogeneity and water availability, and addressing these limitations may help maximize biodiversity increases. In addition, focusing on areas which already have diverse habitats and plentiful water could help reinforce existing biodiversity patterns. Our findings highlight how restoration efforts can benefit native avian biodiversity even in a multiuse urban park, with positive implications for management of biodiversity in urban greenspaces.
Publication in Journal of Mammalogy
Space use and environmental drivers of Northern Raccoon (Procyon lotor) activity in an urban park: evidence for avoidance of road crossings
Urban parks often integrate seminatural habitats with areas of intensive human use and infrastructure. Wildlife behavior in such environments is influenced by various factors including human impacts, environmental conditions, and temporal rhythms of species. In this study, we analyzed location and activity data from 10 raccoons (Procyon lotor) in Forest Park, a large urban park in St. Louis, Missouri, USA. We first present metrics on Northern Raccoon (hereafter, raccoon) movement and space use, and then explore how road crossings correlate with movement. Our findings indicate that raccoon steps cross fewer roads than simulated steps, indicating an avoidance of road crossings despite the association of roads with food resources from human activities. Additionally, we employed tri-axial accelerometers to investigate factors affecting raccoon activity patterns. Our analysis reveals distinct annual and daily activity cycles and increased activity during warmer temperatures. We also show that total nighttime activity is highest during longer nights, despite increased hourly activity during shorter nights. Our results highlight the influence of environmental factors on urban wildlife behavior and illustrate how urban settings shape space use and movement.
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Publication in Journal of Thermal Biology
Reduced thermoregulatory ability contributes to increased mortality in urban box turtles (Terrapene spp.)
Urban wildlife often shows pronounced differences in their ecology, behavior, and survival compared to their rural counterparts. Given the broad impacts of temperature in ecology, thermal discrepancies between cities and their rural surroundings are likely to play a major role in explaining these differences between urban and rural animals. Although experimental work has demonstrated the impacts of urban temperatures on wildlife, we lack field data on the body temperatures of free-living urban animals and the ecological impacts of these temperatures. In addition, while urban heat islands have directed research towards the impacts of warmer temperatures, relatively little focus has been given to the potential for urban organisms to experience colder temperatures, especially in reptiles. Here, we use 10 years of data to show that urban box turtles were less efficient thermoregulators at both hot and cold temperature extremes than their rural counterparts. In contrast to the heat island effect, the body temperatures of brumating urban box turtles (Terrapene mexicana triunguis) were colder and more variable in the winter compared to rural turtles, despite similar environmental temperatures. Furthermore, during the hottest months we found no evidence of an urban heat island effect, yet body temperatures of urban turtles are hotter than rural turtles. These body temperature differences suggest that urban turtles have a reduced ability for behavioral thermoregulation, likely due to lower habitat quality in the urban environment. We further showed that turtles that experience extremely cold body temperatures in the winter were less likely to survive the subsequent year, indicating that over-winter thermoregulatory ability may play an under-appreciated role in the fitness and abundance of urban ectotherms. As urbanization continues to degrade landscapes and as climate change increases the occurrence of temperature extremes, we highlight the need to understand the impacts of cold temperatures on chelonian brumation patterns/survival strategies in human-altered environments.
Publication in Urban Ecosystems
A deep dive into the waterbird community of an urban oasis: implications for park management
The rapid decline in avifauna populations across North America underscores the urgency of implementing effective conservation strategies. While waterfowl species have generally increased in abundance due to investments in habitat restoration and species management, most other waterbird species have declined. In contrast to the widespread decline of natural habitat for waterbirds, urban greenspaces have proliferated. However, the extent to which urban greenspaces provide habitat for waterbirds is largely unknown. We measured waterbird abundance in Forest Park, Saint Louis, which contains a large expanse of restored waterways. Between 2020 and 2022, we used point counts to quantify alpha and beta diversity of waterbirds across five waterbodies. We also quantified several environmental factors hypothesized to influence waterbird presence including weather, bathymetry, water quality, and prey abundance. We assessed environmental drivers of alpha and gamma diversity using generalized linear mixed models, and beta diversity with Jaccard’s similarity indices and Mantel tests. Water depth and depth heterogeneity were the strongest determinants of alpha diversity. Measured environmental variables did not predict beta diversity but improved model fit when testing gamma diversity. Forest Park is a regionally important urban habitat for waterbirds, hosting 62% (38 species) of the total regional species pool, including nine species of conservation concern and two state endangered species. Urban parks can contribute to waterbird conservation despite habitat loss elsewhere if park managers prioritize habitat restoration. In addition to the total area of waterways, water depth and water depth homogeneity are important considerations to maximize waterbird species diversity in urban greenspaces.
Publication in Frontiers in Veterinary Science
Mortality in Three-Toed Box Turtles (Terrapene mexicana triunguis) at Two Sites in Missouri
Once ubiquitous, North American box turtles are experiencing reductions in abundance and range, but the magnitude of these losses is largely unknown. In Missouri, native box turtles (Terrapene mexicana triunguis and Terrapene ornata ornata) are declining across the state due to anthropogenic disturbances such as urbanization, habitat fragmentation, and vehicle collisions. Through radio-tracking over a period of 7 years, we documented the survival of adult three-toed box turtles at two sites in Missouri: Forest Park (urban park) and Tyson Research Center (TRC) (a protected rural forest). Estimated annual survival of adult turtles in Forest Park was 79% (95% CI: 0.68–0.87) while at TRC annual survival was 93% (95% CI: 0.83–0.97). The odds of annual survival for a turtle at TRC were 3.5 times that of a turtle living in Forest Park. “Winter kill,” which refers to box turtles found dead on the surface during brumation or within 2 weeks of emergence, was the most frequently documented category of mortality in Forest Park. At TRC, winter kill was not documented; however, the reasons for most deaths were unknown. These data raise questions about the potential of large urban parks as refuges for box turtles, which we may answer by future studies that compare box turtles living in multiple urban and rural settings. Our preliminary data suggest that even the largest urban parks may not be able to sustain populations of box turtles which has severe implications as urbanization continues to degrade and eliminate box turtle habitat throughout their range.
Publication in Urban Ecosystems
Home ranges of box turtles in a rural woodland and an urban park in Saint Louis, MO; implications for turtle conservation
The negative consequences of fragmentation, infrastructure development, and urbanization on biodiversity are well known. However, careful urban planning can provide viable habitat for some species and communities. Generally, r-selected species are more likely to persist in urbanizing landscapes, while long lived, mobile species, such as turtles, are likely to decline toward extinction. Understanding species responses across urban gradients is important for developing mitigation planning. We used VHF telemetry to quantify ranging behavior of three-toed box turtles in fragmented urban forest patches and a semi-contiguous large rural forest in Saint Louis, Missouri. We then simulated movement trajectories based on empirical data from the two turtles with the largest and smallest home ranges, overlaid on forest cover and road network maps of Missouri, to quantify the state-wide probability of turtles encountering roads. Home range (HR) size varied from 1–250Ha. The mean home range estimate of rural turtles was > 9 times larger than that of urban turtles. Simulations indicated that the least mobile turtle (HR 1Ha) would have a 22% likelihood of encountering a road if placed randomly in suitable habitat anywhere in the state. The likelihood increased to 90% for the most mobile turtle (HR 250Ha), with 10 road crossings per year. High turtle mortality, range restriction and population fragmentation are likely even in rural areas. In urban cityscapes, large, roadless forest patches offer the highest conservation potential for this species.
Publication in Human-Wildlife Interactions
No difference in corticosterone concentrations between Missouri three-toed box turtles living in an urban and a rural site
Baseline health data for species of conservation concern are important for understanding threats to the long-term viability of populations. One indication of health is physiological stress among individuals. Corticosterone (CORT) is frequently used to quantify stress in free-living reptile populations, as high values may be associated with reduced fitness. Herein, we describe and validate methods for quantifying blood CORT levels in three-toed box turtles (Terrapene mexicana triunguis). We subsequently use this information to evaluate stress levels in 2 populations of free-living three-toed box turtles in Missouri, USA. To our knowledge, this is the first quantification of CORT levels in the three-toed box turtle. In 2012 we collected blood samples from 11 three-toed box turtles in human care at the Saint Louis Zoological Park (zoo), St. Louis, Missouri for assay validation, and from 2012 to 2016 we collected 220 samples from 144 free-living three-toed box turtles at 2 sites, 1 urban and 1 rural. In the zoo turtles, mean CORT concentration was 0.71 ± 0.10 ng/mL. Following a handling experiment, CORT concentration increased to 3.14 ± 0.72 ng/mL (P = 0.011). Mean CORT levels between free-living turtles at the urban and rural sites did not differ (urban = 0.54 ± 0.08 ng/mL, rural = 0.37 ± 0.02 ng/mL, F pr = 0.12). Sex did not influence CORT levels (F pr = 0.29). These results suggest that the turtles living in the urban environment did not experience chronic elevated glucocorticoid production and supports urban parks as potential habitat for box turtles.
Publication in Journal of Wildlife Diseases
Clinical Mycoplasma sp. Infections in Free-living Three-toed Box Turtles (Terrapene carolina triunguis) in Missouri, USA
Mycoplasma species, which can cause upper respiratory tract disease (URTD), are significant pathogens of birds, mammals, fish, and reptiles. Mycoplasmosis is of high concern for chelonian conservation, with the most well- documented cases in gopher and desert tortoises. Mycoplasma sp. infections have been reported in captive and free-living box turtles (Terrapene spp.). We documented URTD associated with Mycoplasma sp. in two free-living, three-toed box turtles (Terrapene carolina triunguis) in Missouri, US. Both turtles were Mycoplasma sp. positive by PCR and had URTD-like clinical signs, including nasal and ocular discharge, palpebral edema, lethargy, and weight loss, during a 6–8-wk period between June and September 2014.