Suchergebnisse

1. Introduction / Gary W. Witmer, William C. Pitt, and James C. Beasley -- 2. Biosecurity and risk management / Fred Kraus -- 3. Economics of invasive species damage and damage management / Stephanie Shwiff, Steven Shwiff, Jason Holerieath, William Haden-Chomphosy, and Aaron Anderson -- 4. Policy and regulation / Lori Williams -- 5. Ecological issues / Christopher A. Lepczyk and Daniel Rubinoff -- 6. Feeding a hungry world : threats to agriculture by invasive vertebrate species in the United States / Robert J. Lewis and Michael R. Conover -- 7. Brown tree snakes : methods and approaches for control / Larry Clark, Craig Clark, and Shane Siers -- 8. Burmese pythons / Michael E. Dorcas, Shannon E. Pittman, and John D. Willson -- 9. Frogs (coqui frogs, greenhouse frogs, Cuban tree frogs, and cane toads) / Karen H. Beard, Steve A. Johnson, and Aaron B. Shiels -- 10. Ecology, impacts, and management of invasive rodents in the United States / Gary W. Witmer and Aaron B. Shiels -- 11. Wild pigs / John J. Mayer and James C. Beasley -- 12. Ecology of the small Indian mongoose (Herpestes auropunctatus) in North America / Are R. Berentsen, William C. Pitt, and Robert T. Sugihara -- 13. Feral cats / Christopher A. Lepczyk and David C. Duffy -- 14. Feral goats and sheep / Steven C. Hess, Dirk H. Van Vuren, and Gary W. Witmer -- 15. European starlings / George Linz, Ron Johnson, and James Thiele -- 16. Monk and rose-ringed parakeets / Michael L. Avery and Aaron B. Shiels -- 17. Introduction history, impacts, and management of house sparrows in North America / Julian D. Avery and Julie L. Lockwood -- 18. Conclusions, challenges, and research needs / Gary W. Witmer, William C. Pitt, and James C. Beasley.

Context Free-roaming domestic cats are a widespread invasive species, occurring throughout the globe in urban and rural environments alike. However, robust estimates of cat occupancy and abundance, especially in rural, agricultural landscapes, are largely unknown. Aims To estimate cat occupancy and abundance within forested habitat in a fragmented agricultural region of Indiana, USA. Methods Free-roaming cats in 55 forest patches were captured from 2004 to 2010 to assess the effects of landscape attributes on cat occupancy probabilities. During 2009–10 abundance of cats in each habitat patch was estimated based on natural markings of captured individuals. Key results Across the entire study (2004–10) cats in 50 of the 55 patches were detected, but detections varied temporally and spatially. Average occupancy probability was estimated at Ψ = 0.773 (s.e. = 0.109), and detection probability was estimated as P = 0.204 (s.e. = 0.012). Distance to human structures and forest patch isolation both were found to negatively influence cat occupancy. In total, 57 individual cats were captured in 2009 and 55 in 2010, when unique individuals were distinguished. Across all forest patches, average cat abundance was n = 1.08 in 2009 and n = 0.91 in 2010, ranging from 0 to 7 among sampled patches. Conclusions Overall, the distribution of free-roaming cats across a rural agricultural landscape varied temporally and was associated with proximity to human structures and the proximity of other forest habitat. Similarly, abundance was found to vary spatially and temporally. Implications The findings suggest free-roaming cats are widespread throughout agricultural ecosystems, but their distribution is dynamic and non-random. Additionally, the potential for cats to impact native fauna inhabiting remnant forest patches is high in fragmented agricultural ecosystems due to the concentration of native species utilising these patches. Further research is needed to determine the effects free-roaming cats are having on native species in human-dominated, rural ecosystems, and what conservation measures might be implemented to best mitigate any impacts.

Context Over the past few decades, the frequency of wild pig–vehicle collisions (WPVCs) and number of human fatalities associated with these accidents have increased with expanding populations of this species, particularly in regions outside its native distribution. Aims To better understand this widespread and growing human safety threat, we quantified habitat attributes associated with 311 WPVC locations occurring between 1983 and 2012 at the Savannah River Site (SRS) in South Carolina, USA, to test the hypothesis that WPVCs occur more frequently in areas proximal to preferred habitats (i.e. riparian and bottomland hardwood habitats). Methods At each collision site, we measured the distance to the nearest wetland and stream, as well as the composition of habitats within 100-m and 1699-m buffers. We then contrasted habitat attributes associated with collision sites with those from randomly selected locations along the same roads, to identify habitat characteristics contributing to a higher incidence of these accidents. Key results WPVCs were non-randomly distributed across both spatial scales measured, with collisions occurring more frequently in areas of preferred habitat for this species. Specifically, collisions occurred in areas closer to streams and containing less pine forest than at random locations at both spatial scales evaluated. Conclusions Similar to vehicle accidents with other ungulate species, our study suggested that vehicle collisions involving wild pigs are spatially clustered around preferred habitat types. Management efforts to reduce vehicle collisions with wild pigs should be focussed in areas where roadways bisect preferred habitats such as stream crossings and bottomland hardwood or other riparian habitats. Implications These data will aid in the development of mitigation strategies to reduce the frequency and impacts of WPVCs in areas of high wild-pig densities. However, given the paucity of data on WPVC mitigation, additional research is needed to quantify the efficacy of various methods (e.g. signage, fencing, underpasses) at reducing the frequency and severity of collisions with this species.

Context Wild pigs are an invasive species linked to numerous negative impacts on natural and anthropogenic ecosystems in many regions of the world. Robust estimates of juvenile wild pig survival are needed to improve population dynamics models to facilitate management of this economically and ecologically important invasive species. Despite this critical knowledge gap, to date no successful known-fate study of wild piglet survival (<5 months of age) has been conducted, due to a lack of appropriate method for this species. Aims To aid in locating and tagging neonates, we piloted the use of vaginal implant transmitters (VITs) in adult wild pigs and evaluated average retention times of stud ear-tag transmitters, clip ear-tag transmitters, sutured and epoxied transmitters, harness transmitters, and surgically implanted transmitters to monitor known-fate survival of piglets. Methods We captured pregnant female pigs and implanted them with VITs. We tagged subsequently located neonates and piglets captured in traps with the aforementioned transmitters and monitored them to determine retention times and feasibility of each method. Key results VITs were effectively used to determine the location and time of wild pig parturition, allowing counting and tagging of neonate wild pigs. Stud ear-tag and abdominal implant transmitters were well retained by piglets weighing ≥3kg, in contrast to the other tested transmitters. Conclusions Stud ear-tag and abdominal implant transmitters allowed known-fate monitoring of juvenile wild pigs, although, of these, stud ear-tag transmitters may be more practical as they do not require field surgery on piglets. Due to their relatively large size, the stud ear tag transmitters were infeasible for monitoring of true neonates (~1kg); however, this application method may be suitable for neonates upon development of lighter-weight transmitters. The other transmitter attachment methods we tested were ineffective for monitoring of piglet survival, due to poor retention of transmitters. Implications The techniques piloted in this study will facilitate research into the reproductive ecology of wild pigs and known-fate studies of piglet mortality to aid in population modelling and evaluation of cause-specific mortality and factors affecting survival of these often-invasive animals.

Food webs developed under classical theoretical models often depict simplistic interactions among trophic levels linked by predation (Hairston et al. 1960). As a result, extensive research efforts have been devoted to studying predator-prey interactions, often ignoring the contribution of scavenging in food-web dynamics. However, recent advancements in food-web theory have recognized the widespread and critical role that scavenging plays in stabilizing food webs in ecosystems throughout the world, thus suggesting that previous models may have greatly underestimated the importance of scavenging in food web research ( Wilson and Wolkovich 2011; Barton et al. 2013). Such disregard for the importance of scavenging likely stems from a number of factors, such as human aversion to decomposing matter, difficulties in identifying scavenged versus depredated materials, and the fact that most species utilize carrion opportunistically (DeVault et al. 2003). Nonetheless, recent population declines of a number of obligate scavengers (e.g., vultures) have drawn international attention to this important group of species, and have sparked a renaissance in research on scavenging (Koenig 2006; Sekercioglu 2006; Ogada et al. 2012a; Moleón and Sanchez-Zapata 2015; Buechley and Şekercioğlu 2016a, 2016b; Ogada et al. 2016). ; This work was partially funded by project CGL2012-40013-C02-02 Spanish Government. The input of James C. Beasley was supported through funding provided by the US Department of Energy under Award Number DE-FC09-07SR22506 to the University of Georgia Research Foundation. This work has partially been funded by the Spanish Ministry of Economy and Competitiveness through grant no. CGL2012-40013-C02-01/02 MIMECO and FEDER funds. ; Peer reviewed