Growth of ungulate populations is typically most sensitive to survival of neonates, which in turn is influenced by maternal nutritional condition and trade-offs in resource selection and avoidance of predators. We assessed whether resource use, multi-predator risk, maternal nutritional effects, hiding cover, or interactions among these variables best explained variation in daily survival of free-ranging neonatal white-tailed deer (Odocoileus virginianus) during their post-partum period (14 May–31 Aug) in Michigan, USA. We used Cox proportional hazards mixed-effects models to assess survival related to covariates of resource use, composite predation risk of 4 mammalian predators, fawn body mass at birth, winter weather, and vegetation growth phenology. Predation, particularly from coyotes (Canis latrans), was the leading cause of mortality; however, an additive model of non-ideal resource use and maternal nutritional effects explained 71% of the variation in survival. This relationship suggested that dams selected areas where fawns had poor resources, while greater predation in these areas led to additive mortalities beyond those related to resource use alone. Also, maternal nutritional effects suggested that severe winters resulted in dams producing smaller fawns, which decreased their likelihood of survival. Fawn resource use appeared to reflect dam avoidance of lowland forests with poor forage and greater use by wolves (C. lupus), their primary predator. While this strategy led to greater fawn mortality, particularly by coyotes, it likely promoted the life-long reproductive success of dams because many reached late-age (>10 years old) and could have produced multiple generations of fawns. Studies often link resource selection and survival of ungulates, but our results suggested that multiple factors can mediate that relationship, including multi-predator risk. We emphasize the importance of identifying interactions among biological and environmental factors when assessing survival of ungulates.
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The spatial scales at which animals make behavioral trade-offs is assumed to relate to the scales at which factors most limiting resources and increasing mortality risk occur. We used global positioning system collar locations of 29 reproductive-age female black bears (Ursus americanus Pallas, 1780) in three states to assess resource selection relative to bear population-specific density, an index of vegetation productivity, riparian corridors, or two road classes of and within home ranges during spring–summer of 2009–2013. Female resource selection was best explained by functional responses to vegetation productivity across nearly all populations and spatial scales, which appeared to be influenced by variation in bear density (i.e., intraspecific competition). Behavioral trade-offs were greatest at the landscape scale, but except for vegetation productivity, were consistent for populations across spatial scales. Females across populations selected locations nearer to tertiary roads, but females in Michigan and Mississippi selected main roads and avoided riparian corridors, whereas females in Missouri did the opposite, suggesting population-level trade-offs between resource (e.g., food) acquisition and mortality risks (e.g., vehicle collisions). Our study emphasizes that female bear population-level resource selection can be influenced by multiple spatially dependent factors, and that scale-dependent functional behavior should be identified for management of bears across their range.
Emerging foodborne pathogens present a threat to public health. It is now recognized that several foodborne pathogens originate from wildlife as demonstrated by recent global disease outbreaks. Zoonotic spillover events are closely related to the ubiquity of parasitic, bacterial, and viral pathogens present within human and animal populations and their surrounding environment. Foodborne diseases have economic and international trade impacts, incentivizing effective wildlife disease management. In North America, there are no food safety standards for handling and consumption of free-ranging game meat. Game meat consumption continues to rise in North America; however, this growing practice could place recreational hunters and game meat consumers at increased risk of foodborne diseases. Recreational hunters should follow effective game meat food hygiene practices from harvest to storage and consumption. Here, we provide a synthesis review that evaluates the ecological and epidemiological drivers of foodborne disease risk in North American hunter populations that are associated with the harvest and consumption of terrestrial mammal game meat. We anticipate this work could serve as a foundation of preventive measures that mitigate foodborne disease transmission between free-ranging mammalian and human populations.
Assessing ungulate reproduction is important to biologists for managing populations and predicting trends. We compared efficacy of trans‐abdominal ultrasound and pregnancy‐specific protein B (PSPB) white‐tailed deer (Odocoileus virginianus) pregnancy estimates, respectively, from January to mid‐April 2009–2011 in the south‐central Upper Peninsula of Michigan, USA. We observed a strong agreement (K = 0.68, SE = 0.13, 95% CI = 0.42–0.94) of PSPB and ultrasound in categorizing pregnant and nonpregnant deer. Five deer were determined to be pregnant by ultrasound but not by PSPB and 6 females were judged to be nonpregnant using either method. Total cost for PSPB testing of 101 deer was US$2,220, whereas ultrasound equipment cost US$14,150. Trans‐abdominal ultrasound and PSPB provided accurate detection of pregnancy in live white‐tailed deer. We recommend PSPB for studies testing comparatively small numbers (up to several hundred) of deer. However, we recommend ultrasonography if real‐time pregnancy determination is needed (e.g., vaginal implant transmitter use), particularly for large numbers (i.e., several hundred to thousands) of deer. © 2012 The Wildlife Society.
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