Changing predator communities have potential to complicate management focused on ensuring sustainable white-tailed deer (Odocoileus virginianus) populations. Recent research reported that predation on neonates by coyotes (Canis latrans) and bobcats (Lynx rufus) can limit recruitment. However, no research has been conducted in areas of the southeastern United States with 3 sympatric neonate predators such as coyote, American black bear (Ursus americanus), and bobcat. Our objectives were to estimate neonate survival rates, identify causes of neonate mortality, and determine which biological and landscape characteristics were related to neonate survival. During 2013-2015, we captured 70 neonates with the aid of vaginal implant transmitters on Tensas River National Wildlife Refuge in northeastern Louisiana, USA. We monitored neonates every 8 hours until 6 weeks of age and daily until 12 weeks of age, and assigned cause of death from field and DNA evidence. Survival of neonates to 12 weeks was 0.271 (95% CI ¼ 0.185-0.398). Of 51 mortalities, 45 (88%) were attributed to predation, 4 (8%) to starvation, 1 (2%) to other causes, and 1 (2%) to unknown causes. We used an information-theoretic approach to compare Cox proportional hazards models containing various combinations of biological and habitat covariates. Our best-supported model contained sex, mass at birth, distance to cropland, young reforestation (planted 2000-2009), and old reforestation (planted 1980-1989). Based on hazard ratios, survival was 81% higher for males than females, and survival increased 81% with every 1-kg increase in birth mass. Survival increased 8% for every 100-m increase in distance from cropland or young reforestation, and decreased 11% with every 100-m increase in distance from old reforestation, which may be a result of spatial variation in predator distribution. Our results emphasize the importance of site-specific monitoring of neonate recruitment rates in areas with burgeoning predator communities. We conclude, however, that although predation pressure was high, survival rates were similar to those observed in 2-predator systems in the region, suggesting the possibility that an upper limit to predation rates may exist for white-tailed deer neonates. Ó 2017 The Wildlife Society.
Feral swine (wild hogs) are one of the most widely distributed free-ranging mammals in the world. In the United States, feral swine serve as game animals for the sport of hunting in some areas, while they are nuisance species at other locations. Increasing feral swine populations creates negative impacts to growing crops, native plant communities, and wildlife. Feral swine can also serve as reservoirs for a number of bacterial and viral diseases that can infect wild animals, livestock, and humans. The US state governments are adopting statutes and regulations to reduce the growth and dispersal of feral swine populations. An analysis of these provisions suggests that while they seek to control feral swine populations, they are unlikely to provide any significant relief from damages to crops and native ecosystems. More localized reduction plans and a national disease control program are suggested to assuage damages being wrought by these invasive animals.
1. Degree of reproductive synchronization in prey is hypothesized as a predator defense strategy reducing prey risk via predator satiation or predator avoidance. Species with precocial young, especially those exposed to specialist predators, should be highly synchronous to satiate predators (predator satiation hypothesis), | 2537 Functional Ecology MICHEL Et aL.
BackgroundVector-borne diseases exert a global economic impact to the livestock industry. Understanding how agriculture practices and acaricide usage affect the ecology of these diseases is important for making informed management decisions. Theileria cervi is a hemoprotozoan parasite infecting white-tailed deer (Odocoileus virginianus) and is transmitted by the lone star tick, Amblyomma americanum. The purpose of this study was to determine if acaricide treatment decreased hematozoan prevalence in farmed white-tailed deer when compared to geographically-close wild deer or altered the genotypes of T. cervi present.ResultsWe compared prevalence of T. cervi in 52 farmed adult white-tailed deer which were regularly treated with permethrin and ivermectin, 53 farmed neonates that did not receive treatment for vector control, and 42 wild deer that received no form of chemical vector control. Wild deer had significantly higher prevalence of T. cervi than farmed deer. Additionally, no neonate fawns tested positive for T. cervi, and we found that age was a significant predictor of infection status. We found no difference in genotypic variation in T. cervi isolates between adjacent herds of farmed and wild white-tailed deer, although a divergent genotype X was identified. Chronic infection with T. cervi had no significant effects on mortality in the white-tailed deer.ConclusionsWe found significantly lower prevalence of T. cervi infection in farmed (40%) compared to wild white-tailed deer (98%), which may be due to the inclusion of chemical vector control strategies. More work is needed to determine the implications, if any, of mixed genotypic infections of T. cervi, although we found no significant effect of infection with Theileria on mortality in farmed deer. Theileria infection does sometimes cause disease when an animal is stressed, immunosuppressed, or translocated from non-endemic to endemic regions.
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