Use of Experimental Translocations of Allegheny Woodrat to Decipher Causal Agents of Decline

Abstract

Translocations are an important tool for wildlife conservation, although progress in the field of reintroduction biology has been hindered by the ad hoc and opportunistic nature of many translocations. We used an experimental translocation to elucidate the role of raccoon roundworm (Baylisascaris procyonis) and inbreeding depression in the decline of the Allegheny woodrat (Neotoma magister), an endangered species. We translocated woodrats from genetically diverse populations in the core of the species range to 4 previously occupied sites (reintroductions) and 2 sites supporting genetically depauperate populations (reinforcements) in Indiana (U.S.A.). In 2 reintroduction sites and 1 reinforcement site, we distributed anthelmintic baits to passively deworm raccoons and reduce the risk of woodrat exposure to roundworms. The remaining sites served as controls. We used raccoon latrine surveys and fecal flotation to monitor temporal variability in roundworm prevalence and effect of treatment. We used live trapping and microsatellite genotyping to monitor the demographic and genetic response of translocated populations over the following 54 months. At the conclusion of the study, 4 of 6 translocations were successfully maintaining abundance through local recruitment. The distribution of anthelmintic baits reduced levels of roundworm contamination, but levels of contamination were also low in 2 of 3 control sites. Reintroductions failed at control sites, one of which was due to high roundworm exposure. The other failed control reintroduction was likely attributable to demographic stochasticity and limited reproductive potential following initial mortality within the first 4 months. In both control and treatment reinforcements, increases in both allelic richness and heterozygosity were accompanied by increases in abundance, which is suggestive of genetic rescue. Our results demonstrate that mitigation of roundworm exposure through the distribution of anthelmintic baits can facilitate woodrat recovery and that diversity within genetically depauperate populations can be restored through the introduction of a limited number of individuals.

Parasite zoonoses and wildlife: One health, spillover and human activity

“…Endangered Allegheny woodrats became infected with Baylisascaris when translocated into contaminated environments (LoGiudice, 2003). A recent intervention using anthelmintic baits was shown to facilitate woodrat recovery (Smyser et al, 2013). Other wildlife species are also thought to be at risk and not just in the USA, but also in Europe and Japan where raccoons have been introduced (Bauer, 2013;Page, 2013).…”

Natural and anthropogenic factors affecting Allegheny woodrat occupancy

“…It has been extirpated from the northern periphery of the historical range and is designated as a species of special conservation concern in most states in the central and southern extents of the Appalachian Mountains (Wright , Castleberry et al ). A myriad of factors—including reduced hard‐mast production, prevalence of raccoon roundworm ( Baylisascaris procyonis ), and increased predation—have likely contributed to declines (Balcom and Yahner , LoGiudice , Smyser et al ). However, habitat loss and fragmentation, which can lead to reduced connectivity among habitat patches and subsequently loss of genetic diversity, may be the ultimate driver of declines (Balcom and Yahner , Ford et al , Smyser et al ).…”

Pursuing packrats: An evaluation of noninvasive detection methods for Neotoma

“…Additionally, daily visits to each site for rebaiting is not ideal for noninvasive wildlife detection because it increases site disturbance, financial costs, and personnel time. Though apple slices are commonly used as bait for trapping woodrats (e.g., Mengak , Knowles and Burger , Smyser et al ), they may not have been as attractive to woodrats as other baits commonly used for live‐trapping woodrats (e.g., sunflower seeds, birdseed, peanut butter, dog food). However, such baits would have attracted mice or larger nontarget species that could have rendered track plates nonfunctional.…”