Genetic signature of disease epizootic and reintroduction history in an endangered carnivore

Emerging infectious diseases have recently increased in wildlife and can result in population declines and the loss of genetic diversity in susceptible populations. As populations of impacted species decline, genetic diversity can be lost, with ramifications including reduced effective population size and increased population structuring. For species of conservation concern, which may already have low genetic diversity, the loss of genetic diversity can be especially important. To investigate the impacts of a novel pathogen on genetic diversity in a genetically depauperate endangered species, we assessed the ramifications of a sylvatic plague-induced bottleneck in black-footed ferrets (Mustela nigripes). Following a plague epizootic, we genotyped 184 ferrets from Conata Basin and Badlands National Park, South Dakota, at seven microsatellite loci. We compared our results to pre-plague studies in the same population. We observed population substructuring into three genetic clusters. These clusters reflect founder effects from ferret reintroduction events followed by genetic drift. Compared to the pre-plague population, we observed losses of allelic diversity in all clusters, as well as significantly reduced heterozygosity in one cluster. These results indicate that disease epizootics may reduce population size and also genetic diversity. Our results suggest the importance of early and sustained management in mitigating disease epizootics in naïve populations for the maintenance of genetic diversity.

Urethral catheterization as an alternative method for collecting sperm in the black-footed ferret (Mustela nigripes)

The endangered black-footed ferret (BFF; Mustela nigripes) is an important example of the benefits of assisted reproduction in species conservation with both semen evaluation and artificial insemination using fresh and frozen sperm being successfully incorporated into the breeding program. Currently, electroejaculation (EE) is routinely utilized for semen collection in BFFs, a technique that requires custom equipment and experienced operators, and does not consistently yield viable samples in this species. In this case study, we evaluated the feasibility of urethral catheterization (UC) for semen collection, a method predominately tested in domestic and non-domestic felids, on four occasions (three BFF males). After general anesthesia with a combination of ketamine, midazolam and α2-agonist dexmedetomidine (thought to promote semen release into the urethra), a lightly lubricated, flexible feeding tube was passed into the urethral opening and advanced ~7–8 cm into the urethra. A syringe attached to the feeding tube was used to apply mild negative pressure to collect sperm. Semen samples were successfully collected on all four attempts. Sperm characteristics ranged as follows: 10.5–26.0 × 106 sperm/ml concentration, 50–90% motility and 36–61% normal sperm morphology. This is the first report of the use of UC as a potential alternative to EE in the BFF, a more field-friendly technique that is less invasive and more consistent for obtaining samples free of urine contamination.

Rarely Observed Behaviors and Occurrences of Black-footed Ferrets Preconditioning for Wild Release 2014–2017

Black-footed ferrets Mustela nigripes became extinct in the wild in 1987 when the last known wild animals were removed from a remnant population in an attempt to save the species by beginning a captive breeding program. Breeding efforts were successful, and since 1991 wildlife managers have annually released ferrets back into the wild at sites within the ferrets' historic range. Before their release into the wild, ferrets undergo a preconditioning stage in a quasi-natural habitat which better prepares them for life in the wild after a captive upbringing. Due to their nocturnal, fossorial, and largely solitary lifestyle, combined with their expansive habitat and endangered status, there are undoubtedly a multitude of behaviors ferrets exhibit that are not commonly observed. Here I detail multiple aspects of rarely described black-footed ferret ecology including black-tailed prairie dog Cynomys ludovicianus hunting stratagems, interactions with prairie rattlesnakes Crotalus viridis viridis, predation on birds, and sudden unexplained deaths of entire ferret family groups. The preconditioning setting that serves as an intermediate step between a captive and wild life for captive-reared ferrets allows for wildlife managers to witness ferret behaviors, though similar situations conceivably occur somewhat regularly in the wild.

Managing Populations, Diseases, and Landowner Perceptions of Prairie Dogs for Black-Footed Ferret Reintroduction

The black-footed ferret (Mustela nigripes) is one of the rarest mammal species in North America. Captive breeding has prevented extinction of this species, but successful reintroduction of ferrets into their native grassland habitat is a complex endeavor. As specialist predators, ferrets depend almost exclusively on prairie dogs (Cynomys spp.) for both food and shelter, so successful black-footed ferret reintroduction hinges on maintaining large colonies of prairie dogs. However, prairie dogs are also considered agricultural pests and are often subjected to eradication programs. These eradication programs hamper efforts to reintroduce ferrets and disrupt the valuable ecosystem services prairie dogs provide in their role as both keystone and foundation species. Even when agreements are reached to maintain prairie dog colonies, plague (Yersinia pestis), which infects both prairie dogs and ferrets, can threaten the success of a ferret reintroduction program. We describe the research on the complex ecological relationships and socio-environmental challenges of reintroducing endangered black-footed ferrets, with a focus on the most abundant prairie dog species, the black-tailed prairie dog (Cynomys ludovicianus).