The objective of this study is to model the effects of urbanization and resultant habitat fragmentation on disease dynamics in large carnivore species--ecologically pivotal organisms that are sensitive to human disturbances. Bobcats, puma, and domestic cats will be evaluated simultaneously in three divergent ecosystems: high mountain desert (Colorado), everglades (Florida), and Mediterranean scrub habitat (California). The research will: (1) assess the relationship between habitat fragmentation and prevalence of viral, bacterial, and parasitic pathogens across a gradient of urbanization, (2) use transmission dynamics of selected disease agents as markers of connectivity of fragmented populations, and (3) evaluate the effect of urbanization on the incidence of cross-species disease transmission.
The combination of a uniquely qualified research team with an extensive dataset on large carnivores presents an unprecedented opportunity to investigate the disease dynamics in these rare and difficult to study species. Training of graduate students in ecology, infectious disease, and epidemiology will be emphasized, as will training for pre- and post-doctoral veterinarians. Results will be made widely available to other scientists, conservation practitioners, and the general public. This research has a tremendous capacity to broadly impact areas of public and post-graduate education, career development for new investigators and persons from under-represented groups, and to enhance understanding of complex infectious disease ecological problems using extensive multi-disciplinary collaborations.
The rapid progression of urban development has significant implications for disease spread between humans, their pets, and wildlife living in these areas. The project, "The effects of urban fragmentation and landscape connectivity on disease prevalence and transmission in North American felids" was designed to understand how urbanization, and consequent fragmentation of wildlife habitat, impacts movement, interaction, and disease spread among domestic cats, puma, and bobcats. These species were targeted because of the close association between humans and pet cats, the high likelihood of interactions between felid species in our targeted study sites, and the different home range requirements for puma (large), bobcat (moderate), and domestic cats (small). We sampled over 1800 domestic cats, puma and bobcats from 6 locations in California, Colorado, and Florida and tested these samples for evidence of infection with a number of pathogens. These included Yersinia pestis (the agent that causes plague), intestinal parasites and bacteria that can infect humans, and viruses that infect cats, including feline immunodeficiency virus (FIV), the feline equivalent to HIV. We also closely evaluated movement and interactions of cats, puma, and bobcats in California and Colorado through GPS telemetry collars and motion-activated cameras. We then evaluated whether disease transmission increased when animals lived in close proximity to human development. Some of our specific and surprising conclusions were that bobcats, pumas, and domestic cats closely interact in and around urban areas. We documented contact between these species that can lead to transfer of disease from wild felids to domestic cats to humans. We generally found that local climactic or ecological factors are more important in determining which diseases are present in each study region than the degree of human development. However, we found individual instances where the urban environment perturbed infectious disease patterns in wildlife. For example, bobcats in California were more likely to be infected with an intestinal parasite that infects humans (Giardia duodenalis) if they lived closer to human development. These animals were also more likely to be infected with a bacteria (Bartonella henselae) that infects domestic cats if they lived closer to the urban edge. One striking discovery made during this project is that puma appear to be infected with two viruses that typically infect bobcats--FIV, and a newly discovered Herpesvirus (similar to the virus that causes Mononucleosis in people)--in California and Florida, but not in Colorado. It does not appear that the ‘bobcat’ strains of these viruses replicate well in pumas, but our evidence suggests interactions between bobcats and puma in these areas that can result in disease spread. We also documented that wild felids are exposed to the plague bacteria, and a parasitic disease that can cause illness in humans (Toxoplasmosis) at high rates, implicating these animals as important reservoirs for these diseases. We were able to show that bobcats in southern California are constrained by urban development and major roadways, resulting in subpopulations in these areas that are distinguishable by their genetic characteristics. Surprisingly, we noted that FIV was still spread from one subpopulation to the other across the Interstate 5, one of the busiest roadways in the United States. This finding indicates that bobcats can cross freeways and consequently spread disease, but have difficulty establishing territories and successfully reproducing. We were able to develop a computer model simulating animal movement through fragmented landscapes that also predicted this outcome. Our project also included a social science component to better understand how human perceptions impact disease dynamics in domestic cats. We administered questionnaire surveys investigating attitudes and beliefs of urban residents about conflicts between pet cats and wildlife, and associated disease threats. This work provided important new information about the extent to which cats roam into natural areas, their degree of spatial and temporal overlap with wild felids, and hence the potential for contact and disease transmission. This research will be used to develop public education campaigns to encourage pet owners to minimize risks to their pets and the wildlife around their residences. Our highly interdisciplinary team included undergraduate and graduate students, postdoctoral fellows, and faculty, and involved collaborators from over 20 different institutions and governmental agencies. Accomplishments include 30 successful grant proposals, 16 published scientific papers, over 70 talks at scientific venues, and local to international media coverage. We collaborated with scientists, resource managers, and conservation practitioners across the United States, and in Germany, Poland, and Australia. We trained 3 postdoctoral fellows and 4 graduate students, with an additional 8 graduate, 7 veterinary, and 9 undergraduate students mentored in ecology and infectious disease research projects. This included 21 women and several minority students, typically underrepresented in the disease ecology field. We also conducted K-12 education and outreach via use of motion-activated cameras to excite and educate young scientists about wildlife in urban areas.
