Post-translocation dynamics of black-tailed prairie dogs (Cynomys ludovicianus): A successful conservation and human-wildlife conflict mitigation tool.

Prairie dogs have declined by 98% throughout their range in the grasslands of North America. Translocations have been used as a conservation tool to reestablish colonies of this keystone species and to mitigate human-wildlife conflict. Understanding the behavioral responses of prairie dogs to translocation is of utmost importance to enhance the persistence of the species and for species that depend on them, including the critically endangered black-footed ferret. In 2017 and 2018, we translocated 658 black-tailed prairie dogs on the Lower Brule Indian Reservation in central South Dakota, USA, a black-footed ferret recovery site. Here, we describe and evaluate the effectiveness of translocating prairie dogs into augered burrows and soft-released within presumed coteries to reestablish colonies in previously occupied habitat. We released prairie dogs implanted with passive integrated transponders (PIT tags) and conducted recapture events approximately 1-month and 1-year post-release. We hypothesized that these methods would result in a successful translocation and that prairie dogs released as coteries would remain close to where they were released because of their highly social structure. In support of these methods leading to a successful translocation, 69% of marked individuals was captured 1-month post-release, and 39% was captured 1-year post-release. Furthermore, considerable recruitment was observed with 495 unmarked juveniles captured during the 1-year post-release trapping event, and the reestablished colony had more than doubled in the area by 2021. Contrary to our hypothesis, yet to our knowledge a novel finding, there was greater initial movement within the colony 1-month post-release than expected based on recapture locations compared with the published average territory size; however, 1 year after release, most recaptured individuals were captured within the expected territory size when compared to capture locations 1-month post-release. This research demonstrates that while translocating prairie dogs may be socially disruptive initially, it is an important conservation tool.

Assembling a safe and effective toolbox for integrated flea control and plague mitigation: Fipronil experiments with prairie dogs.

BACKGROUND: Plague, a widely distributed zoonotic disease of mammalian hosts and flea vectors, poses a significant risk to ecosystems throughout much of Earth. Conservation biologists use insecticides for flea control and plague mitigation. Here, we evaluate the use of an insecticide grain bait, laced with 0.005% fipronil (FIP) by weight, with black-tailed prairie dogs (BTPDs, Cynomys ludovicianus). We consider safety measures, flea control, BTPD body condition, BTPD survival, efficacy of plague mitigation, and the speed of FIP grain application vs. infusing BTPD burrows with insecticide dusts. We also explore conservation implications for endangered black-footed ferrets (Mustela nigripes), which are specialized predators of Cynomys. PRINCIPAL FINDINGS: During 5- and 10-day laboratory trials in Colorado, USA, 2016-2017, FIP grain had no detectable acute toxic effect on 20 BTPDs that readily consumed the grain. During field experiments in South Dakota, USA, 2016-2020, FIP grain suppressed fleas on BTPDs for at least 12 months and up to 24 months in many cases; short-term flea control on a few sites was poor for unknown reasons. In an area of South Dakota where plague circulation appeared low or absent, FIP grain had no detectable effect, positive or negative, on BTPD survival. Experimental results suggest FIP grain may have improved BTPD body condition (mass:foot) and reproduction (juveniles:adults). During a 2019 plague epizootic in Colorado, BTPDs on 238 ha habitat were protected by FIP grain, whereas BTPDs were nearly eliminated on non-treated habitat. Applications of FIP grain were 2-4 times faster than dusting BTPD burrows. SIGNIFICANCE: Deltamethrin dust is the most commonly used insecticide for plague mitigation on Cynomys colonies. Fleas on BTPD colonies exhibit the ability to evolve resistance to deltamethrin after repeated annual treatments. Thus, more tools are needed. Accumulating data show orally-delivered FIP is safe and usually effective for flea control with BTPDs, though potential acute toxic effects cannot be ruled out. With continued study and refinement, FIP might be used in rotation with, or even replace deltamethrin, and serve an important role in Cynomys and black-footed ferret conservation. More broadly, our stepwise approach to research on FIP may function as a template or guide for evaluations of insecticides in the context of wildlife conservation.

Sylvatic Plague Vaccine Partially Protects Prairie Dogs (Cynomys spp.) in Field Trials.

Sylvatic plague, caused by Yersinia pestis, frequently afflicts prairie dogs (Cynomys spp.), causing population declines and local extirpations. We tested the effectiveness of bait-delivered sylvatic plague vaccine (SPV) in prairie dog colonies on 29 paired placebo and treatment plots (1-59 ha in size; average 16.9 ha) in 7 western states from 2013 to 2015. We compared relative abundance (using catch per unit effort (CPUE) as an index) and apparent survival of prairie dogs on 26 of the 29 paired plots, 12 with confirmed or suspected plague (Y. pestis positive carcasses or fleas). Even though plague mortality occurred in prairie dogs on vaccine plots, SPV treatment had an overall positive effect on CPUE in all three years, regardless of plague status. Odds of capturing a unique animal were 1.10 (95% confidence interval [C.I.] 1.02-1.19) times higher per trap day on vaccine-treated plots than placebo plots in 2013, 1.47 (95% C.I. 1.41-1.52) times higher in 2014 and 1.19 (95% C.I. 1.13-1.25) times higher in 2015. On pairs where plague occurred, odds of apparent survival were 1.76 (95% Bayesian credible interval [B.C.I.] 1.28-2.43) times higher on vaccine plots than placebo plots for adults and 2.41 (95% B.C.I. 1.72-3.38) times higher for juveniles. Our results provide evidence that consumption of vaccine-laden baits can protect prairie dogs against plague; however, further evaluation and refinement are needed to optimize SPV use as a management tool.

FLEAS OF BLACK-FOOTED FERRETS (MUSTELA NIGRIPES) AND THEIR POTENTIAL ROLE IN THE MOVEMENT OF PLAGUE.

Sylvatic plague is one of the major impediments to the recovery of the black-footed ferret ( Mustela nigripes ) because it decimates their primary prey species, prairie dogs ( Cynomys spp.), and directly causes mortality in ferrets. Fleas are the primary vector of Yersinia pestis , the causative agent of sylvatic plague. The goal of this research was to better understand the flea fauna of ferrets and the factors that might influence flea abundance on ferrets. Fleas from ferrets were tested for Y. pestis in a post hoc assessment to investigate the plausibility that some ferrets could act as incidental transporter hosts of fleas infected with Y. pestis . Fleas were collected from ferrets captured on the Lower Brule Indian Reservation in central South Dakota, US from 2009 to 2012. A total of 528 fleas collected from 67 individual ferrets were identified and tested for the presence of Y. pestis with a nested PCR assay. The predominant flea recovered from ferrets was Oropsylla hirsuta , a species that comprises 70-100% of the fleas recovered from prairie dogs and their burrows in the study area. Yersinia pestis was detected at low levels in fleas collected from ferrets with prevalence ranging from 0% to 2.9%; male ferrets harbored significantly more fleas than female ferrets. Six of 67 ferrets vaccinated against plague carried fleas that tested positive for Y. pestis , which suggests ferrets vaccinated against plague could inadvertently act as incidental transporter hosts of Y. pestis -positive fleas.

Spatial interactions between sympatric carnivores: asymmetric avoidance of an intraguild predator.

Interactions between intraguild species that act as both competitors and predator-prey can be especially complex. We studied patterns of space use by the black-footed ferret (Mustela nigripes), a prairie dog (Cynomys spp.) specialist, and the American badger (Taxidea taxus), a larger generalist carnivore that competes for prairie dogs and is known to kill ferrets. We expected that ferrets would spatially avoid badgers because of the risk of predation, that these patterns of avoidance might differ between sexes and age classes, and that the availability of food and space might influence these relationships. We used location data from 60 ferrets and 15 badgers to model the influence of extrinsic factors (prairie dog density and colony size) and intrinsic factors (sex, age) on patterns of space use by ferrets in relation to space use by different sex and age categories of badgers. We documented asymmetric patterns of avoidance of badgers by ferrets based on the sex of both species. Female ferrets avoided adult female badgers, but not male badgers, and male ferrets exhibited less avoidance than female ferrets. Additionally, avoidance decreased with increasing densities of prairie dogs. We suggest that intersexual differences in space use by badgers create varying distributions of predation risk that are perceived by the smaller carnivore (ferrets) and that females respond more sensitively than males to that risk. This work advances understanding about how competing species coexist and suggests that including information on both intrinsic and extrinsic factors might improve our understanding of behavioral interactions between sympatric species.

The ecological future of the North American bison: conceiving long-term, large-scale conservation of wildlife.

Many wide-ranging mammal species have experienced significant declines over the last 200 years; restoring these species will require long-term, large-scale recovery efforts. We highlight 5 attributes of a recent range-wide vision-setting exercise for ecological recovery of the North American bison (Bison bison) that are broadly applicable to other species and restoration targets. The result of the exercise, the "Vermejo Statement" on bison restoration, is explicitly (1) large scale, (2) long term, (3) inclusive, (4) fulfilling of different values, and (5) ambitious. It reads, in part, "Over the next century, the ecological recovery of the North American bison will occur when multiple large herds move freely across extensive landscapes within all major habitats of their historic range, interacting in ecologically significant ways with the fullest possible set of other native species, and inspiring, sustaining and connecting human cultures." We refined the vision into a scorecard that illustrates how individual bison herds can contribute to the vision. We also developed a set of maps and analyzed the current and potential future distributions of bison on the basis of expert assessment. Although more than 500,000 bison exist in North America today, we estimated they occupy <1% of their historical range and in no place express the full range of ecological and social values of previous times. By formulating an inclusive, affirmative, and specific vision through consultation with a wide range of stakeholders, we hope to provide a foundation for conservation of bison, and other wide-ranging species, over the next 100 years.