Density-habitat relationships of white-tailed deer (Odocoileus virginianus) in Finland

In heterogeneous landscapes, resource selection constitutes a crucial link between landscape and population-level processes such as density. We conducted a non-invasive genetic study of white-tailed deer in southern Finland in 2016 and 2017 using fecal DNA samples to understand factors influencing white-tailed deer density and space use in late summer prior to the hunting season. We estimated deer density as a function of landcover types using a spatial capture-recapture (SCR) model with individual identities established using microsatellite markers. The study revealed second-order habitat selection with highest deer densities in fields and mixed forest, and third-order habitat selection (detection probability) for transitional woodlands (clear-cuts) and closeness to fields. Including landscape heterogeneity improved model fit and increased inferred total density compared with models assuming a homogenous landscape. Our findings underline the importance of including habitat covariates when estimating density and exemplifies that resource selection can be studied using non-invasive methods.

A Comparative Spatial and Climate Analysis of Human Granulocytic Anaplasmosis and Human Babesiosis in New York State (2013-2018)

Human granulocytic anaplasmosis (HGA) and human babesiosis are tick-borne diseases spread by the blacklegged tick (Ixodes scapularis Say, Acari: Ixodidae) and are the result of infection with Anaplasma phagocytophilum and Babesia microti, respectively. In New York State (NYS), incidence rates of these diseases increased concordantly until around 2013, when rates of HGA began to increase more rapidly than human babesiosis, and the spatial extent of the diseases diverged. Surveillance data of tick-borne pathogens (2007 to 2018) and reported human cases of HGA (n = 4,297) and human babesiosis (n = 2,986) (2013-2018) from the New York State Department of Health (NYSDOH) showed a positive association between the presence/temporal emergence of each pathogen and rates of disease in surrounding areas. Incidence rates of HGA were higher than human babesiosis among White and non-Hispanic/non-Latino individuals, as well as all age and sex groups. Human babesiosis exhibited higher rates among non-White individuals. Climate, weather, and landscape data were used to build a spatially weighted zero-inflated negative binomial (ZINB) model to examine and compare associations between the environment and rates of HGA and human babesiosis. HGA and human babesiosis ZINB models indicated similar associations with forest cover, forest land cover change, and winter minimum temperature; and differing associations with elevation, urban land cover change, and winter precipitation. These results indicate that tick-borne disease ecology varies between pathogens spread by I. scapularis.

Small-mammal abundance differs between pipelines, edges, and interior boreal forest habitat

Oil and gas development alters boreal forests by creating early-successional habitat and an increased amount of edge. We evaluated which small-mammal species used pipeline rights of way, the influence of vegetation recovery on pipelines, and edge effects in the adjacent forest. Meadow voles (Microtus pennsylvanicus (Ord, 1815)) were the most common species on pipelines, whereas adjacent forest was dominated by southern red-backed voles (Myodes gapperi (Vigors, 1830)), northern red-backed voles (Myodes rutilus (Pallas, 1779)), and North American deer mice (Peromyscus maniculatus (Wagner, 1845)). Deer mouse abundance was greater along pipeline transects with greater vegetation recovery. Within the forest, irrespective of vegetation recovery on pipelines, meadow voles and deer mice increased near edges. Red-backed voles showed a mixed (i.e., neutral or positive) response to edge. Vegetation variables (i.e., canopy type and cover, ground cover, stem counts, and volume of downed woody material) were important predictors of small-mammal abundance in the forest, but they could not fully account for observed edge effects. Altered small-mammal communities on and adjacent to pipelines may have implications for boreal forest management and conservation through potential changes in predator–prey dynamics and boreal food webs; these implications require further study.

Rodent species as possible reservoirs of Borrelia burgdorferi in a prairie ecosystem

Lyme borreliosis is the most commonly reported vector-borne disease in the United States and Europe. It is caused by a group of spirochete bacteria belonging to the Borrelia burgdorferi sensu lato complex. These pathogens are transmitted among vertebrate reservoir hosts through the bite of hard-bodied ticks. While the enzootic cycle of Borrelia transmission is well understood in its primary reservoir, the white-footed mouse, Peromyscus leucopus, far less is known about other reservoir hosts, particularly in grassland ecosystems. This study assessed the prevalence of B. burgdorferi s. l. among four non-Peromyscus rodents in a prairie ecosystem in the Midwestern United States over a four-year period. We found high prevalences of the bacteria in all four species studied. Our results help to support the roles of Microtus species as reservoirs of B. burgdorferi and add to the literature that suggests Zapus hudsonius may also be a reservoir. Additionally, we identified a previously unknown possible reservoir, Ictidomys tridecemlineatus. Our study also identifies the need to study the dynamics of Lyme borreliosis in habitats and areas outside of the typical range of P. leucopus.