Scientific publications
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 corticosteroneconcentrations 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.