Front Range Colorado Naturalist: March 2015

Mustela nigripes

Here is another blog where I will not be able to use my own photos, for alas I have only a few bad pictures of a pair in a museum in Fort Collins but nothing very usable.

I will hopefully give everyone the correct credit for the photos I use!

HISTORY:

The Black-footed ferret is one of the most endangered mammals in North America. Once numbering in the tens of thousands, its numbers have been decimated to less than two percent of its original range. It is North America’s only ferret (the domesticated ferret is a kind of European ferret).

When I went to Fort Collins Museum of Discovery I learned that the Black-footed ferret had been thought to be extinct, and they nearly had been.

The last time it was thought they had gone extinct, the black-footed ferret was rediscovered by none-other-than someone’s pet dog. The dog had dutifully brought the dead black-footed ferret home to its owner, and the curious owner brought it to a local taxidermist to figure out what the animal was that his dog had brought home.

When it was discovered that it was the thought-to-be-extinct black-footed ferret, it made big news! Scientists found the last patch of these ferrets and watched the 120 animals, the last of their kind. They studied them, learned everything they could from just observing these resilient animals.

But then something terrible happened. They started dying. All of a sudden their numbers started plummeting, as a disease was killing off the last of these ferrets. Scientist argued whether or not this was a sign, they were thought to have been extinct before, should they let nature take its course?

Happily, it was decided that they intervene and they rounded up what was remaining of the black-footed ferret. Of the 120 that originally made up this last pocket of black-footed ferret, only 18 were left at this point, and not all of these were breedable.

For those of you who understand genetics, this means there was a HUGE genetic bottleneck...the best way to explain this is to imagine if all of a sudden there were only 30 people left in the world. They all happen to be white, but have some hair color variation like blonde hair, brown hair, and black hair. By only having 30 people to repopulate the planet, there would be a huge loss in diversity. Only one kind of skin color, three colors of hair, so on and so forth. Over time, there will be more variation, but at first, there is very little.

A genetic bottleneck of this size means that the next generation is almost clones of the first, with little variation between them. This makes it harder for them to adapt and thrive.

Nature.com describes the definition of a genetic bottleneck as: A population bottleneck is an event that drastically reduces the size of a population. The bottleneck may be caused by various events, such as an environmental disaster, the hunting of a species to the point of extinction, or habitat destruction that results in the deaths of organisms.

Because of this genetic bottleneck, current black-footed ferrets have lost immunity to diseases that their ancestors would have been immune to. They can even get diseases from humans, so scientists have to be very careful around them during the black-footed ferrets repopulation process.

Lately black-footed ferrets have been released back into their ancestral habitats, most recently in Soapstone Prairie Natural Area in Fort Collins, Colorado. http://www.fcgov.com/naturalareas/finder/soapstone

The Fort Collins Museum of Discovery is the only museum in the world to have black-footed ferrets, and they have two. They are Mr. Brightside and June, two retired breeders who now spend the rest of their lives relaxing in the museum. They are too old and not healthy enough to be released back into the wild.

In the wild, black-footed ferrets can live from 1-3 years, and in captivity they can live up to nine years. Mr. Brightside is 6 years old and has chipped teeth, and June is 5 years old.

Today, there are 500 living in the wild and 300 in the captive breeding program.

HABITAT AND DIET

Sometimes called the prairie bandit, the black-footed ferret lives in the short grass prairie in prairie dog villages. You might think it’s nice of the prairie dogs to share, but they don’t share willingly. The black-footed ferret’s main prey is the prairie dog. In fact, prairie dogs make up over 90% of the black-footed ferrets diet.

The black-footed ferret might look cute and cuddly, but it is a voracious and fierce little predator. A single ferret could eat more than 100 prairie dogs in one year, and will sometimes eat the occasional ground squirrel, rabbit, small rodent, or even bird.

Because the black-footed ferret is so reliant on the prairie dog, prairie dog colonies must be large and healthy to support a black-footed ferret.

Their range used to extend from Southern Canada to Northern Mexico all across the great plains.

A black-footed ferret is dragging a prairie dog into its burrow.

BEHAVIOR

Black-footed ferrets are nocturnal, and spend most of their time underground. This means it is a rare treat to see one, and you should appreciate the rareness of such a sighting!

They live in abandoned prairie dog holes (no prairie dog would keep them as a roomie!)

They hunt prairie dogs at night, and strangle the bulkier prairie dogs with their teeth while the prairie dogs are sleeping. Not so cute and cuddly now, right?

REPRODUCTION

The young are called kits, and are born blind and covered in thin white fur. They remain underground until they are two months old. The females raise the kits alone, and by October the young are mature enough to be independent and they go off on their own. They are solitary animals and only come together to breed.

The mating season is from March to April, with a gestation period of 41-43 days. This means the kits are born around May or June. They will have 3 to 4 kits on average.

FUN FACTS

A group of black-footed ferrets is called a business
Thought to be extinct in the 1970’s, was rediscovered in 1981
The last wild population was in Meeteetse, Wyoming. It was plague that nearly brought this last business of ferrets to become extinct.
The vocalizations of the black-footed ferret are chattering and hissing.
Sometimes called the Prairie bandit because of its black mask
The domesticated ferret is of European origin and has been domesticated for hundreds of years. A black-footed ferret is a wild animal and will not make a good pet.

Have a few minutes? Watch this great video!

Remember, these guys are predators. and there is a short scene where they kill a prairie dog as a part of their reintroduction process.

This video is of the reintroduction process for the black-footed ferrets in Colorado.

Photograph courtesy Jeff Vanuga/Corbis

SOURCES:

ARKive

http://www.arkive.org/black-footed-ferret/mustela-nigripes/

Defenders of Wildlife

http://www.defenders.org/black-footed-ferret/basic-facts

Fort Collins Museum of Discovery

http://www.fcmod.org/

http://www.fcmod.org/?s=black-footed+ferret

National Geographic

http://animals.nationalgeographic.com/animals/mammals/black-footed-ferret/

U.S. Fish and Wildlife

http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A004

Zoo America

http://www.zooamerica.com/animals/details.php?id=63

PHOTO SOURCES:

ARKive

http://www.arkive.org/black-footed-ferret/mustela-nigripes/

This entry will not have my own photos (I like to use only my own pictures of animals to avoid accidentally stealing someone's work or not giving the right credit where it's due) I will make sure I credit every photo that I use here!

Although I have been living in Colorado for almost two years now, I still have yet to see a fox! I know they are out there however, as there are four species of fox in Colorado. The Swift fox, the Kit fox, the Red fox and the Gray fox.

KIT FOX

Vulpes macrotis

Found in Western Colorado, the kit fox is the smallest of North American foxes and is commonly known as the desert fox. It has large ears that help it dissipate heat, a great adaptation for its life in the desert!

It has dense fur on its paws that help protect it from the hot sand, and will also help give the fox traction. The coat of the kit fox varies from season to season, with a rusty-tan in the summer and a gray color in the winter. This helps the fox blend in while it hunts.

Kit foxes are monogamous and often mate for life. Kit foxes will begin denning in October if they already have a mate. Mating occurs from December to January, with litter sizes varying from one pup up to seven. They are usually born mid-February to mid-March with a gestation period of 49-55 days. It takes about four weeks for the pups to start emerging from the dens, and they are independent in five to six months from birth.

Their food of choice consists of rodents, rabbits, invertebrates, birds, lizards, snakes, carrion and a small amount of fruit.

Living in the desert, kit foxes have adapted not to need to drink water, but they will drink it whenever it is possible. They get most of their hydration from their prey.

Coyotes are the top threat for kit fox and coyote predation accounts for 75% of kit fox mortality. Red fox, bobcat and large raptors often compete with kit fox for food or predate on the kit fox.

Humans are a large problem for kit foxes, as most of their habitat is being taken for agricultural land.

Federally, kit foxes are listed as species of least concern, even though populations are continually declining due to habitat loss. The kit foxes status could change if the habitat loss trends continue at the rate they are now. In Colorado, kit foxes are classified as Endangered.

A paper written by Carron A. Meaney, Melissa Reed-Eckert, and Gary P. Beauvais entitled Kit Fox (Vulpes macrotis) A Technical Conservation Assessment is a great read on the relatively current status of the kit fox. It was written in 2006 , and the link is below.

http://www.fs.fed.us/r2/projects/scp/assessments/kitfox.pdf

SWIFT FOX

Vulpes velox

It was only until recently that the swift fox and kit fox were recognized as separate species, though both foxes are “swift” and can run in short bursts up to 25 miles per hour.

Swift fox looks very similar to the kit fox but it has ears that are set slightly further apart on its head.

Swift fox live in shortgrass and mixed-grass prairies, and are found in Eastern Colorado. Like most foxes they tend to be nocturnal and occasionally crepuscular, which means they are active during dawn and dusk.

Prairie dog towns are a preferred habitat for the swift fox (and the kit fox too! Lots of animals depend on prairie dog colonies, which is one more reason why protecting prairie dogs are so important!).

Swift foxes breeding starts when they are 1 to 2 years old, in February and March. They have a gestation period of 52-53 days with an average litter size of 4 to 5 pups. The young won’t emerge from their dens until they are 3 to 4 weeks old, and the pups are independent when they are 4 or 5 months old.

They can live up to ten years in the wild, and use their dens year round for cover and protection. These dens may be made by other animals, like badgers or prairie dogs, or the fox may make its own burrow.

The swift fox and the kit fox eat the same things, mostly rodents, rabbits, birds, invertebrates, lizards, and sometimes even prairie dogs.

The swift fox faces the same predators as the kit fox, these being coyote, red fox, bobcat, and large birds of prey. As with the kit fox, the coyote is the main predator of the swift fox, and both foxes have suffered from the extirpation of the prairie wolf, which controlled coyote populations in the past.

Swift fox abundance has been reduced roughly 40 percent from its original habitat, and has been extirpated (extinct or removed from an area it used to live in, but is not extinct as a species) from Canada. It has been recently been reintroduced into some parts of Canada.

The swift fox is listed as a species of least concern. They were historically abundant in prairies, but numbers decreased in the late 1880’s to early 1900’s. They last Canadian swift fox was collected in 1928 with a single sighting in 1938.

RED FOX

Vulpes vulpes

The red fox is the largest of the true foxes, and had the widest distribution of any carnivore. Easily recognized by their gorgeous red coat and white tipped tail, the red fox can also have many different colored coats from the well-known red to a black or gray.

A silver furred red fox

Red fox eat whatever they can find, from small mammals and reptiles to birds, fruits, insects and will even rummage though human trash for food.

The red fox is able to live anywhere from Arctic to desert habitats, but prefer forests and grasslands.

The breeding season is typically in late December to March, and they have a gestation period of 51-53 days. The average litter size is 5, and the pups remain in the den for the first month of their life. It is unknown if the red fox is monogamous or polygamous.

The young will begin to leave their dens to find their own territory by mid-September to early October. Sometimes the female pups will stay another year to help raise the next litter with their parents.

Red foxes tend to live up to 3 or 4 years in the wild. Predators of the red fox may include gray wolves, bobcat, lynx, mountain lions and coyotes. Humans are also a predator of fox, either for fur, sport, or as pest removal.

Red foxes are the most common carrier or rabies, and rabies can cause a 60 to 80 percent mortality within a population.

A successful predator that is adaptable and cunning, the fox is listed as a species of Least Concern. They are still hunted by hounds for sport in England, and their population has exploded in Australia after they were introduced in 1850.

Their range in North America has expanded since colonial times as their main competitor the wolf, was extirpated. The only fox on this list to have benefited from the removal of wolves in North America.

GRAY FOX

Urocyon cinereoargenteus

Not to be confused with a red fox with a silver coloring, the gray fox is colored gray with a reddish-brown coloring on its sides, chest, legs, and back of head. It’s busy tail has a stripe on top. Unlike red foxes, they have oval shaped pupils, whereas a red fox has slip shaped pupils, like a cat.

Some unique traits of the gray fox, like its retractable claws and short legs, have lead some researchers to believe that the gray fox is a more primitive carnivore.

The gray fox eats a wide variety of foods, from small mammals, birds, insects, and fruit. Grasshoppers and crickets make up an important part of its diet in summer and fall.

Gray foxes tend to live in deciduous or pine forests that have some old fields within or nearby. They can also be found in agricultural lands or riparian habitats.

The breeding season is from January to April (it can vary depending on the region) with a gestation period of 50-53 days. They will have 1 to 7 pups, which at 4 months old will be able to hunt for themselves. The same males and females tend to mate together each year. Both parents help feed and take care of the offspring, while the father is usually the one to teach the pups how to hunt and stalk.

Gray foxes tend to be solitary and only get together during mating season, and gray foxes live from 6 to 8 years in the wild.

Unlike other foxes, gray foxes tend to only use dens when mating and rearing young. They are also the only fox that can climb a tree.

Predators of the gray fox include bobcats, eagles, great horned owls, and coyotes. They are sometimes killed by humans for their fur, and in some places are sold illegally as pets. Coyote remain their top predators however, and their population size depends greatly on coyote presence.

The gray fox is listed as a species of Least Concern, and there currently is not enough information on whether their populations are rising or declining.

SOURCES:

KIT FOX

ARKive

http://www.arkive.org/kit-fox/vulpes-macrotis/

IUCN Red List of Threatened Species

http://www.iucnredlist.org/details/41587/0

Meaney, Carron A, Ph. D., Reed-Eckert, Melissa, and Beauvais, Gary P. Ph.D.

A Technical Conservation Assessment

http://www.fs.fed.us/r2/projects/scp/assessments/kitfox.pdf

SWIFT FOX

ARKive

http://www.arkive.org/swift-fox/vulpes-velox/