Black-footed Ferret Conservation

Black-footed Ferret Conservation

Abstract:

Introduction:

The Black-footed ferret, Mustela nigripes, is one of few ferrets living in the wild, native to the continent of North America and one of the most endangered mammals in the continent. They are roughly the size of a mink and differs from the European polecat by the contrast between its dark limbs and pale body and short tail length. However, differences between the black-footed ferret and the steppe polecat of Asia are very slight, to the point where it was believed the two were conspecific. The only differences between the two are the formers much shorter and coarser fur, larger ears and longer postmolar extension of the palate.

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It is a solitary and nocturnal species, with exceptions for breeding and raising kits. Up to 90% of their diet is composed of prairie dogs. Its most active above ground from dusk to midnight and 4am to mid-morning. Activity above ground is at its peak during late summer and autumn when juveniles become independent. Climate does not limit the ferret’s activity; however, it may remain inactive in burrows during winter for up to 6 days at a time.

The black-footed ferret has a long and slender body with outlines on body sections such as the feet, ears, parts of the face and its tail. The forehead is arched and broad and the muzzle is short. They have triangular ears which are short, erect and broad. The neck is long and legs stout, they have very few whiskers and toes with concealed arched claws covered in fur, even on the sole of the foot. Males measure 500-533 millimetres in body length and 114-127 millimetres in tail length, constituting 22-25% of its body length. Females are generally 10% smaller than males. They weigh around 650-1,400 grams. Captive-bred ferrets used for reintroduction projects were found to be smaller than wild counterparts, though these animals rapidly attained historical body sizes once released.

Non-native disease and habitat loss are the two leading threats to the recovery of the species. Black-footed ferrets are entirely dependent on their food source of prairie dogs, which make up 90% of their diet. These mammals and their colonies provide the ferrets with food, shelter and a location to raise kits.  The species was once thought to be extinct in the wild in 1996, but over the last 30 years due to tremendous conservation efforts from many organisations the species is making its comeback, with approximately 370 living in the wild. Through captive breeding efforts and releases, the species was moved to endangered.

The captive breeding programme for black-footed ferrets was first initiated in October 1985 by the Wyoming Game and Fish Department in cooperation with the US Fish and Wildlife Service. Eighteen black-footed ferrets were believed to be captured between 1985 and 1987 from the last-known population in attempt to start a captive breeding population with the end goal of reintroduction (Miller et al. 1996).

Discussion:

Current efforts to conserve the species are producing encouraging results, with there being approximately 370 individuals alive in the wild. To protect these animals during their population recovery, scientists and volunteers conduct night time spotlight surveys. In late summer, these scientists and volunteers make efforts to locate the litters born in the wild, for protection and population monitoring. Biologists have been known to use traps and transponder chips to identify individual ferrets which are kept on a database. And finally, during winter, snow tracking may be carried out to locate ferrets in the wild.

The dedication and constant monitoring of those in captivity and the wild shows the drive conservationists have for reviving this once-extinct species. Currently, there are few welfare concerns for those kept in captivity. As these animals are fed an appropriate diet, housed in colonies like that of prairie dogs and kept at the right climate. They are kept away from the public to prevent disease being contracted such as sylvatic plague, which is a leading threat to the recovery of the species. Those who are too old for breeding and cannot be reintroduced into the wild are kept in facilities for educational purposes and cared for the same as those in breeding programmes. To prevent sylvatic plague, the BFFSSP created a partnership with the US Geological Survey and formed an experimental sylvatic plague vaccine for the black-footed ferrets to eliminate the threat on the species recovery.

Over the years, the BFFSSP has compiled a lot of research to aid in the recovery of the species, with a large list of ongoing and completed research. For example, the BFFSSP have completed research on F1-V (plague vaccine), Canine Distemper Virus, Preconditioning, Reproduction/Captive Breeding/Husbandry and Telemetry. Many advancements have been made through research and adaptive management and research into the husbandry of ferrets. Studies on reproduction, caging, diet, enrichment and behaviour have made captive breeding a major success. With the constant flow of encouraging results, it proves not only is the species recovering, but it will make a full recovery in years to come.

To save the species, ferrets were taken from prairie dog colonies in Wyoming. It is believed by conservationists that the recovery of the species is solely down to conservation and captive breeding. In early attempts at conservation, not much was known about the reproductive biology of the black-footed ferret. While early attempts to breed were successful in the 1970s, none of the offspring survived. Over the last 30 years, as conservationists have attained more knowledge on the species, we have managed to revitalise the population of ferrets greatly. Since 1986, over 8,500 kits have been produced at captive breeding facilities, and in recent years, 150-220 kits have been released yearly which is a major success for the wild population of black-footed ferrets.

‘Biologists within the Wyoming Game and Fish Department and the US Fish and Wildlife Service convened domestic ferret breeders and reproductive experts from the Association of Zoos and Aquariums.’ -Black-footed ferret species survival plan. (BFFSSP)

All kits produced on the survival plan are entered into a studbook, which contains individual animal information, as well as a pedigree of each animal. Information that is recorded is monitored by programme leaders and breeders, and the data collected on each animal, as well as genetic data, is used to select pairings of these animals. A proposal is needed for DNA analysis to establish heterozygosity and mean kinship. The facilities begin checking both the males and females for reproductive readiness in January since these animals are seasonal breeders. Since the SSP (Black-footed ferret species survival plan) is genetically a closed population, with no new unrelated black-footed ferrets found since 1987, all pairings are done to minimise the loss of genetic diversity. The primary task of the SSP is to produce as many kits as possible to support ongoing efforts for reintroduction.

Due to relatedness among the majority of the eighteen ferrets captured, genetic contributions equate to no more than seven founder equivalents. From 1985, more than 8,000 Black-footed ferrets have been born in captivity, with 323 kits weaned in 2014. In 1991, Ferrets were being reintroduced at sites in eight Western U.S states, one site in Mexico and one in Canada. In 2014, 202 kits were released in nine separate reintroduction sites. One of the leading conservation organisations for black-footed ferrets is the National Black-footed Ferret Conservation Centre, who have contributed to the 150-220 kits released every year. There are currently 29 sites for reintroduction and release, however organisations believe that many more sites are needed to fully revive the species.