Pathogen surveillance and epidemiology in endangered Peninsular bighorn sheep (Ovis canadensis nelsoni).

Peninsular bighorn sheep (Ovis canadensis nelsoni) are found exclusively in Southern California and Baja Mexico. They are federally endangered due to multiple threats, including introduced infectious disease. From 1981 - 2017, we conducted surveillance for 16 pathogens and estimated population sizes, adult survival, and lamb survival. We used mixed effects regression models to assess disease patterns at the individual and population levels. Pathogen infection/exposure prevalence varied both spatially and temporally. Our findings indicate that the primary predictor of individual pathogen infection/exposure was the region in which an animal was captured, implying that transmission is driven by local ecological or behavioral factors. Higher Mycoplasma ovipneumoniae seropositivity was associated with lower lamb survival, consistent with lambs having high rates of pneumonia-associated mortality, which may be slowing population recovery. There was no association between M. ovipneumoniae and adult survival. Adult survival was positively associated with population size and parainfluenza-3 virus seroprevalence in the same year, and orf virus seroprevalence in the previous year. Peninsular bighorn sheep are recovering from small population sizes in a habitat of environmental extremes, compounded by infectious disease. Our research can help inform future pathogen surveillance and population monitoring for the long-term conservation of this population.

Landscape Seroprevalence of Three Hemorrhagic Disease-Causing Viruses in a Wild Cervid.

Disease plays a major role in shaping wildlife populations worldwide, and changes in landscape conditions can significantly influence risk of pathogen exposure, a threat to vulnerable wild species. Three viruses that cause hemorrhagic disease affect cervid populations in the USA (Odocoileus hemionus adenovirus, bluetongue virus, and epizootic hemorrhagic disease virus), but little is known of their distribution and prevalence in wild populations. We explored the distribution and co-occurrence of seroprevalence of these three pathogens in southern mule deer (Odocoileus hemionus fuliginatus), a subspecies of conservation concern and a harvested species native to southern California, to evaluate the distribution of exposure to these pathogens relative to landscape attributes. We found that habitat type, level of development, and proximity to livestock may affect hemorrhagic disease seroprevalence in southern mule deer. Continued monitoring of hemorrhagic disease-causing viruses in areas where deer are in proximity to cattle and human development is needed to better understand the implications of future outbreaks in wild populations and to identify opportunities to mitigate disease impacts in southern mule deer and other cervid species.

Survival and Mortality of Pumas (Puma concolor) in a Fragmented, Urbanizing Landscape.

Wide-ranging large carnivores pose myriad challenges for conservation, especially in highly fragmented landscapes. Over a 13-year period, we combined monitoring of radio collared pumas (Puma concolor) with complementary multi-generational genetic analyses to inform puma conservation in southern California, USA. Our goals were to generate survivorship estimates, determine causes of mortality, identify barriers to movement, and determine the genetic and demographic challenges to puma persistence among >20,000,000 people and extensive urban, suburban, and exurban development. Despite protection from hunting, annual survival for radio collared pumas was surprisingly low (55.8%), and humans caused the majority of puma deaths. The most common sources of mortality were vehicle collisions (28% of deaths), and mortalities resulting from depredation permits issued after pumas killed domestic animals (17% of deaths). Other human-caused mortalities included illegal shootings, public safety removals, and human-caused wildfire. An interstate highway (I-15) bisecting this study area, and associated development, have created a nearly impermeable barrier to puma movements, resulting in severe genetic restriction and demographic isolation of the small puma population (n ~ 17-27 adults) in the Santa Ana Mountains west of I-15. Highways that bisect habitat or divide remaining "conserved" habitat, and associated ongoing development, threaten to further subdivide this already fragmented puma population and increase threats to survival. This study highlights the importance of combining demographic and genetic analyses, and illustrates that in the absence of effective measures to reduce mortality and enhance safe movement across highways, translocation of pumas, such as was done with the endangered Florida panther (P. c. coryi), may ultimately be necessary to prevent further genetic decline and ensure persistence of the Santa Ana Mountains population.