Over the past decade, abnormalities have been documented in white-tailed deer (Odocoileus virginianus) in west-central Montana. Hypotheses proposed to explain these anomalies included contact with endocrine disrupting pesticides, such as imidacloprid. We evaluated the effects of imidacloprid experimentally at the South Dakota State University Wildlife and Fisheries Captive Facility where adult white-tailed deer females and their fawns were administered aqueous imidacloprid (an untreated control, 1,500 ng/L, 3,000 ng/L, and 15,000 ng/L). Water consumption, thyroid hormone function, behavioral responses, and skull and jawbone measurements were compared among treatments. Additionally, liver, spleen, genital, and brain imidacloprid concentrations were determined by an enzyme-linked immunosorbent assay (ELISA). Results indicated that 1) control deer consumed more water than treatment groups, 2) imidacloprid was present in the organs of our control group, indicating environmental contamination, 3) as imidacloprid increased in the spleen, fawn survival, thyroxine levels, jawbone lengths, body weight, and organ weights decreased, 4) adult female imidacloprid levels in the genitals were negatively correlated with genital organ weight and, 5) behavioral observations indicated that imidacloprid levels in spleens were negatively correlated with activity levels in adult females and fawns. Results demonstrate that imidacloprid has direct effects on white-tailed deer when administered at field–relevant doses.

No abstract

Offspring survival is generally more variable than adult survival and may limit population growth. Although white-tailed deer neonate survival has been intensively investigated, recent work has emphasized how specific cover types influence neonate survival at local scales (single study area). These localized investigations have often led to inconsistences within the literature. Developing specific hypotheses describing the relationships among environmental, habitat, and landscape factors influencing white-tailed deer neonate survival at regional scales may allow for detection of generalized patterns. Therefore, we developed 11 hypotheses representing the various effects of environmental (e.g., winter and spring weather), habitat (e.g., hiding and escape cover types), and landscape factors (e.g., landscape configuration regardless of specific cover type available) on white-tailed deer neonate survival up to one-month and from one- to three-months of age. At one-month, surviving fawns experienced a warmer lowest recorded June temperature and more June precipitation than those that perished. At three-months, patch connectance (percent of patches of the corresponding patch type that are connected within a predefined distance) positively influenced survival. Our results are consistent with white-tailed deer neonate ecology: increased spring temperature and precipitation are likely associated with a flush of nutritional resources available to the mother, promoting increased lactation efficiency and neonate growth early in life. In contrast, reduced spring temperature with increased precipitation place neonates at risk to hypothermia. Increased patch connectance likely reflects increased escape cover available within a neonate’s home range after they are able to flee from predators. If suitable escape cover is available on the landscape, then managers could focus efforts towards manipulating landscape configuration (patch connectance) to promote increased neonate survival while monitoring spring weather to assess potential influences on current year survival.

Pronghorn (Antilocapra americana) in North Dakota have experienced habitat fragmentation due to agricultural practices, roads, and oil development. We analyzed patterns of female pronghorn habitat selection in 2006 and 2014, years with contrasting pronghorn density and oil production in western North Dakota. We quantified resource selection and fawn:female ratios relative to proximity to active wells, road density, land cover, development, normalized difference vegetation index (NDVI), and agricultural practices. We also assessed patterns of well placement relative to the same environmental variables. Pronghorn selected sagebrush and areas with low NDVI but avoided developed areas, roads, forests, and wetlands. Pronghorn selected areas close to oil and gas wells because wells were located in high‐value habitats (e.g., native sagebrush‐steppe ecosystems selected by pronghorn). For the majority of variables tested, selection was stronger when pronghorn density was low, consistent with current resource selection theory. Although females selected relatively open habitats, fawn:female ratios within areas selected by females were positively correlated with NDVI. Our results demonstrate that pronghorn avoid human development and roads but not oil and gas wells. Although wells are not actively avoided by pronghorn, their placement in high‐value habitat for this species leads to significant habitat fragmentation. In light of these results, we recommend efforts to conserve pronghorn habitat such as constructing wells away from sagebrush, using existing roads to service newly constructed wells, and re‐vegetating well pads with sagebrush plantings once they are no longer in use. © 2016 The Wildlife Society.

We analyzed a unique 51-year time series for a population of mule deer in the North Dakota badlands, USA to examine the effects of seasonal weather on autumn recruitment. Winter weather recorded prior to birth of fawns and weather conditions recorded during spring the previous year (lagged effect), but not during spring or summer after birth, were related to observed patterns in autumn recruitment. When deer density was low (approx. 1 deer/km 2 ) during the 1960s, fawn/female ratios were high ranging from 1.1 to 1.4 when minimum temperatures during the prior winter averaged À168 C and À88 C, respectively. Likewise, during the 2000s, when deer density was high (approx. 3 deer/km 2 ), fawn/female ratios ranged from 0.6 to 0.9 when minimum daily temperatures during the previous winter were À168 C and À88 C, respectively. Large-scale Pacific-based climatic indices (>2,000 km to the Pacific coast) were correlated with local weather and helped explain variability in autumn recruitment. Higher values of the multivariate el niño southern oscillation and Pacific decadal oscillation were correlated with warmer and drier winters in the North Dakota badlands, whereas the North Pacific Index was correlated with colder and snowy winters. The ability to predict recruitment from local weather or from broad-scale climate indices (oscillations) provides greater opportunities for conservation and management, such as adjusting harvest quotas prior to autumn harvest.