No abstract

Understanding the effects of climate change on species' persistence is a major research interest; however, most studies have focused on responses at the northern or expanding range edge. There is a pressing need to explain how species can persist at their southern range when changing biotic interactions will influence species occurrence. For predators, variation in distribution of primary prey owing to climate change will lead to mismatched distribution and local extinction, unless their diet is altered to more extensively include alternate prey. We assessed whether addition of prey information in climate projections restricted projected habitat of a specialist predator, Canada lynx (Lynx canadensis), and if switching from their primary prey (snowshoe hare; Lepus americanus) to an alternate prey (red squirrel; Tamiasciurus hudsonicus) mitigates range restriction along the southern range edge. Our models projected distributions of each species to 2050 and 2080 to then refine predictions for southern lynx on the basis of varying combinations of prey availability. We found that models that incorporated information on prey substantially reduced the total predicted southern range of lynx in both 2050 and 2080. However, models that emphasized red squirrel as the primary species had 7-24% lower southern range loss than the corresponding snowshoe hare model. These results illustrate that (i) persistence at the southern range may require species to exploit higher portions of alternate food; (ii) selection may act on marginal populations to accommodate phenotypic changes that will allow increased use of alternate resources; and (iii) climate projections based solely on abiotic data can underestimate the severity of future range restriction. In the case of Canada lynx, our results indicate that the southern range likely will be characterized by locally varying levels of mismatch with prey such that the extent of range recession or local adaptation may appear as a geographical mosaic.

There are two reasons for strategic planning in passive wildlife restoration: first, to maximize the potential for colonization of restoration sites in challenged landscapes, and second, to maximize the contribution of each restoration project to regional, management area, ecosystem, or target species goals. Landscape configuration and the demographic/dispersal characteristics of target species can govern the level of wildlife response to habitat restoration projects. This is particularly true for fragmented habitats in rapidly suburbanizing areas, where the widely held notion that wildlife can colonize any restored habitat is challenged by barriers to dispersal. Because habitat restoration is a passive means of restoring wildlife populations, equal weight needs to be given to the context (likelihood of site colonization by target species) as well as the content (habitat) of restoration projects. Defining spatial patterns of demography, dispersion, and dispersal allows restorationists to place projects where they can have the greatest impact on the threats and sensitivities of target species, and the greatest contribution to the persistence and/or recovery of populations. Further, it provides a means of evaluating the relative potential worth of different restoration sites. If passive wildlife restoration is to be successful, the constraints to colonization need to be interpreted with regional goals of ecosystem and species management in mind.

Field immobilization of native or invasive wild pigs (Sus scrofa) is challenging. Drug combinations commonly used often result in unsatisfactory immobilization, poor recovery, and adverse side effects, leading to unsafe handling conditions for both animals and humans. We compared four chemical immobilization combinations, medetomidine-midazolam-butorphanol (MMB), butorphanol-azaperone-medetomidine (BAM™), nalbuphine-medetomidine-azaperone (NalMed-A), and tiletaminezolazepam-xylazine (TZX), to determine which drug combinations might provide better chemical immobilization of wild pigs. We achieved adequate immobilization with no post-recovery morbidity with MMB. Adequate immobilization was achieved with BAM™; however, we observed post-recovery morbidity. Both MMB and BAM™ produced more optimal results relative to body temperature, recovery, and post-recovery morbidity and mortality compared to TZX. Adequate immobilization was not achieved with NalMed-A. Of the four drug combinations examined, we conclude that MMB performed most optimally for immobilization and recovery of wild pigs.