Publication Date

2020

Document Type

Dissertation/Thesis

First Advisor

King, Richard B.

Second Advisor

Jones, Holly P.

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Biological Sciences

Abstract

Wildlife is important to humans, offering economic, nutritional, ecological, and socio-cultural value. However, vertebrate biodiversity is being lost at rates 100 times greater than the background extinction rate, threatening human livelihood via the loss of ecosystem services. These human-induced species losses are primarily due to habitat destruction, which is increasingly tied to urban development. Conservation of wildlife resources is therefore imperative in a world where more than 50% of the human population, and 80% of people living in the United States, now live in urban areas. In this dissertation, I demonstrate how monitoring data can be applied to answer questions of ecology, management, and conservation in urban wildlife. To do so, I analyzed data collected during a long-term and ongoing wildlife monitoring program in Lake County, Illinois, a highly urbanized and fragmented county in the Chicago Metropolitan Area. For many species, the impacts of urbanization are largely unknown, particularly for cryptic species. Inventory and monitoring of urban preserves is an important step in developing effective conservation and management plans. Monitoring programs also facilitate the novel natural history observations and spur the development of novel hypotheses.

In Chapter 1, I provide an overview of a long-term wildlife monitoring program set in the suburbs of Chicago, the third largest metropolitan area in the United States. From 2009–2018, this monitoring program has recorded >200,000 occurrences of >1,000,000 individual birds, mammals, reptiles, amphibians, crayfish, and fish across 55 nature preserves in Lake County, Illinois. This overview includes the anthropogenic, ecological, and natural resources management context of the 1150 km2 study area. In the main body of the dissertation (Chapter 2–4), I analyze data collected during three different facets of the monitoring program (camera trapping, aquatic trapping, terrestrial herpetofauna surveys), with specific focus on free-ranging Domestic Cats (Felis catus), mole salamanders (Ambystoma spp.), and Painted Turtles (Chrysemys picta).

Domestic cats are one of the world’s most damaging invasive species. While the ecology and conservation implications of free-ranging cats have well studied in some locations, relatively little is known about cats inhabiting urban nature preserves in the United States. In Chapter 2, I used camera traps to study the occupancy and activity patterns of free-ranging cats in 55 preserves. From 2009–2018, the wildlife monitoring program recorded 355 photos of free-ranging cats across 26 preserves and 41 randomly distributed monitoring points. Cats were detected every year, but rarely at the same point or preserve, and cats were largely crepuscular/diurnal. Using single-season occupancy models and a "stacked" design, I found that cat occupancy increased with building density and detectability was highest near the urban/preserve boundary. Predicted occupancy within individual preserves ranged from was low and poorly correlated with preserve size or shape. Overall, these results suggest that free-ranging cats are rare within suburban preserves in the study area, and that these cats are most likely owned or heavily subsidized by people (which pose different risks and management challenges than truly feral cats). I discuss the conservation and management implications for urban natural areas.

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. In Chapter 3, I analyze artificial cover board data (a means of surveying terrestrial herpetofauna) to investigate patterns of occupancy, detectability, and population turnover for sympatric Blue-spotted Salamanders (Ambystoma laterale) and Eastern Tiger Salamanders (A. tigrinum) inhabiting 26 preserves. From 2009–2018 I detected Blue-spotted Salamanders 375 times and Tiger Salamanders 85 times. I constructed dynamic occupancy models and used an information theoretic approach to rank a priori candidate models containing landscape, survey, and management covariates. Blue-spotted Salamander occupancy was more than twice as high as Tiger Salamander occupancy. Detection probability for both species was substantially less than one 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. These results reveal that salamander populations can persist in highly fragmented urban preserve systems. I discuss management and conservation implications related to urban forests and prescribed fire.

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 Chapter 4, I investigate how urbanization impacts the sex ratios of painted turtles (Chrysemys picta), as empirical results linking male-biased turtle populations to roads and urbanization are mixed. Using eight years of aquatic trapping data, I report one of the most male-biased populations (mean = 75% male) of turtles in the USA, consistent with prevailing road mortality hypotheses. However, I 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. These results highlight the importance of replicating ecological studies across space and time and the difficulty in assessing population structure in aquatic turtles. I suggest that active conservation measures may be warranted for the continued persistence of urban turtle populations.

Lake County is a highly urbanized county with many natural areas spanning open, forested, and wetland habitats. Associated with these preserves is a high level of biodiversity, documented by a comprehensive wildlife monitoring program. The large number of preserves, randomized monitoring points, and standardized sampling protocols provides for a productive setting to explore questions and hypotheses of wildlife ecology, management, and conservation in an urban setting. In the final chapter (Chapter 5), I review the findings of the previous chapters and briefly elaborate on the efficacy of different survey techniques. I show the absence of a relationship between habitat management and wildlife diversity (and explain why that might be) and identify targets for restoration and research. Results and data presented in this dissertation will be invaluable to land managers and biologists working to conserve biodiversity in Lake County, the Midwestern United States, and urban areas worldwide.

This work was supported by the Lake County Forest Preserve District and approved by the Northern Illinois University IACUC ORC# LA14-0002. Supplementary data for Chapter 2 includes a delimited text file (.csv) containing presence-absence data, spatially and temporally explicit covariate data, and landscape predicted values. Supplementary data for Chapter 3 includes a delimited text file (.csv) containing presence-absence data, spatially and temporally explicit covariate data, a priori hypotheses, and candidate models. Supplementary data for Chapter 4 includes a delimited text file (.csv) with morphology and specimen identification data. R scripts for select analyses are also included as indicated in the text.

Extent

192 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

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