Environmental Threats: January 2011 Archives

Black-footed Ferrets

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blfofe.jpgBefore 1851, no one had heard of a black-footed ferret. That was the year in which John James Audubon and John Bachman wrote a book together titled The Quadrupeds of North America. This was the first work to mention the species, but it was still more than twenty-five years before their existence was proven. (Audubon, who sometimes killed fifty birds of one species to produce one painting, only got to see one ferret while working on his book, which was not enough evidence to prove that the black-footed ferret was a new species.)

Although they lived throughout the Great Plains, the ferret population has been falling ever since we first knew about them. One reason for this is that the ferrets are so dependent on prairie dogs, a species of ground squirrel. Not only are these rodents their staple food, the ferrets also cannot dig their own burrows and are squatters in prairie dog towns. When settlers moved west, many became farmers. They plowed under the prairie dog towns and hunted or poisoned many of the animals. Both the prairie dogs and the ferrets grew increasingly fewer.

Then, in 1981, a Wyoming dog named Shep found a ferret. Eventually, the animal was identified and its colony -- of about 130 animals -- found. However, this population quickly plummeted due to canine distemper and sylvatic plague. In 1986, the remaining 18 animals had to be removed from the colony. The ferret was extinct in the wild.

At this time, there were only fifty captive black-footed ferrets in the world. After years of captive breeding, the first place to reestablish a small colony was Wyoming in 1991. Now, there are fifteen established fesnyngs (or businesses: the name for a group of ferrets) in the wild, in eight US states as well as Mexico and Canada.

There are, however, still threats to their survival. Their close relationship with prairie dogs does not aid their recovery. Prairie dogs are often viewed as pests because they prevent farmers from growing crops in certain areas by rooting up the plants around their burrows. Their tunnels also make the ground less stable and more prone to collapse if animals are turned out to graze.

Because of these things, many people dislike prairie dogs. Even today they are hunted, both commercially and privately. To eradicate colonies, they are poisoned, which indirectly affects many other species. Two of the popular poisons, Rozol and the recently approved Kaput-D, contain chemicals that thin the prairie dogs' blood until they bleed to death. Not only is this horrible for the prairie dogs, any animal that eats them will encounter the same fate. Black-footed ferrets, swift foxes, American badgers, ferruginous hawks, and golden and bald eagles all prey on prairie dogs. An infected animal is easy to catch because it becomes unable to move quickly or control its motions, so many of these predators are suffering secondary poisoning. Additionally, mountain plovers and burrowing owls live and nest in prairie dog burrows and can also become infected.

Another threat to ferrets is disease, particularly sylvatic plague. Luckily, the animals can be immunized against the disease, and all ferrets born in captivity are required to be given two shots of the medicine. Although prairie dogs are also susceptible to this, it has been found more difficult to protect all of the wild colonies from the bacteria. One widespread method was to spray each burrow with flea-killing pesticides, but scientists realized that this was probably too expensive and hard to do and maintain. There had to be an easier way to accomplish this. Finally, they developed a medicine that could be mixed in with food left for the prairie dogs to eat. This also proved more efficient than the pesticides. Additionally, these studies will benefit other species susceptible to the sylvatic plague, both wild rodents and some pets.

There are now more than 1,500 ferrets throughout the established colonies, so the species has been upgraded from extinct in the wild to endangered. Although the number is low, it is still a success considering how few animals lived at one point. Black-footed ferrets are considered the most endangered mammal in North America, but the numbers are still rising to the extent that they may become relatively common over time. The current ambition is to establish ten breeding populations in the wild. When this is met, the ferret can be listed as threatened, instead of endangered. When this happens, the ferret will have returned.

Bear in Terrain

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bear.jpg"Look," Mikaela cried as we glimpsed a furry, brown leg, "A bear!"

We all ran out onto the smaller balcony and looked out. A young black bear was gazing at us, puzzled. Mom was leaning out the bedroom window taking photos with her new camera, and I was taking some pictures as well.

He was young. The year before we had discovered him, just an overgrown cub, at the fork in the unpaved road where our steep driveway met the neighbor's. Now he was bigger, we noticed, as he crossed the "animal highway." This was where deer and coyotes, but never before a black bear, made their crossing behind our house.

He loped off the other way and disappeared into a myriad of bushes and berries. He was gone.

Black bears are smaller than grizzly bears and do not have as defined a shoulder hump as their relatives. Grizzly bears' humps are shoulder muscles useful for digging up roots. Grizzly claws, partly for the same reason, are larger than black bears' claws. Signs that a bear has been somewhere are digging sites, clawed trees, and tracks which have five toes and look heavy. (The main hand is a thin egg shape with a little triangle at the end.)  A black bear is eighty-five percent vegetarian, and most of the carnivorous percentage consists of bees, ants, and yellow jackets.
 
Kermode Bear Planet Green.jpgThere is such a thing as a Kermode or Spirit Bear. These are rare, white subspecies. Only one in ten are completely white, and some are tan with patches. It is very special to see a Kermode bear. They are not albino, however, and are white because of a recessive gene. Other subspecies include the Eastern black bear, the Florida black bear and the Newfoundland black bear. The Florida black bear deserves special attention because it is threatened. At first, the Fish and Wildlife Department declared it threatened except in areas where it was a game animal. This was a rather hypocritical statement, as a bear could be passing a hunting area, though it was born in a refuge. Probably the Fish and Wildlife Department realized that after the criticism that they got. The Florida black bear is listed as threatened wherever it occurs.

In the case that you meet a black bear on a trail, rangers advise you to put up your hands and raise a backpack (if you have one) above your head to frighten it off. Do not do this unnecessarily, like if you hear rustling in the bushes a ways off the trail. However, do talk or clap your hands in such cases. Finally, if a black bear attacks you, fight back.

Harboring Harbor Seals

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harborseal.jpgThere's a good reason why the harbor seal is also called the "common seal." They're found all over the northern hemisphere's coastlines, in the Pacific and Atlantic oceans and throughout the North and Baltic seas. They are also the most widespread pinniped, a term which refers to true seals, eared seals (sea lions and fur seals), and walruses. (Neither true seals nor walruses have ear flaps, known as pinnas.)

Harbor seals are true seals. They have small flippers that do not rotate and consequently have a hard time moving around on land. They rely on layers of blubber for warmth, buoyancy, and extra energy. The blubber also allows the seal's skin to be the temperature of the water surrounding it, while their core temperature, or how warm they are inside, is 100° F. They have large eyes, but most scientists think that their color vision is very bad, if existent. Harbor seals have better eyesight than humans underwater, but worse on land. Since blind seals have been found with pups in the ocean, scientists believe that sight is unimportant to harbor seals. Although they usually stay closer to the surface and come up for air once in ever three to seven minutes, they can dive 1,500 feet underwater and stay submerged for 40 minutes! Mostly, these seals catch fish, but sometimes when they've gone that deep they'll eat shrimp, crabs, mollusks, octopods, and squids.

Harbor seals spend approximately half of their time in the ocean, and the other half on land. Although they typically stay in the water only when feeding, they have been known to sleep in the water, too. Places where they regularly rest on land are called "haulouts," and the process of a seal climbing up onto the land is called "hauling out." Unfortunately, if people repeatedly disturb them they will abandon their haulouts or even their babies. Sometimes, seals dart into the sea as soon as they see or hear people. That's why beaches often post signs warning people to stay at least 100 feet away from the seals and use binoculars or cameras. Goat Rock Beach suggests 150. The Point Reyes National Seashore website advises visitors to come no closer than 300 feet.

To attract a mate, male seals will form a group, put their heads together and call the females. It is thought that the females select the strongest males. Although they can be seen at any time of the year, the best time to view harbor seals in California is probably from February to April, when they are having their babies. In the Arctic, they may wait until July! Young seals are called pups and usually born with a spotted coat. If you see a pup with a white coat, called a lanugo, it was born prematurely. (In the Arctic, the pups are born with the white fur but molt soon afterwards.)

sealsgoatrock2.jpgHarbor seals haul out on many beaches. We saw them in February on California's Goat Rock beach. (The origin of Goat Rock's name is disputed. There is a very large rock connected to the beach by a thin strip of land, and the most popular theory states that goats used to be permitted to graze on the rock because they were the only species surefooted enough to climb it.)

The Californian or Pacific harbor seal is a subspecies of harbor seal found along the entire coastline of California. In the San Francisco bay, some seals appear reddish. This unusual coloration is thought to result from tiny quantities of elements, such as iron or selenium, in the water.

Some field guides make it sound like it is very difficult to tell a harbor seal from a sea lion, but it is actually very simple. Harbor seals are usually light gray, and sea lions are dark brown. The sea lion is able to flip its flippers forward so that it can walk on land. For the most part, the seals lie on the beach, while the sea lions sit up on their front flippers and grunt. Additionally, studying a photo of any animal beforehand will help you identify it in the field.

The worldwide population of harbor seals is five or six million. Hunting seals is illegal throughout most of their range, but certain subspecies are threatened. Besides people disturbing them on beaches, the seals are caught in fishing nets and hit by boats. They are endangered by chemicals dumped in the water or released by power plants. Diseases such as the phocine distemper also threatened them. And while it is illegal in the United States to hunt harbor seals, if a seal is thought to endanger a fishery it can legally be killed. Happily, however, the numbers of harbor seals have been rising on the east coast of the US, and some have even been spotted in Florida. With care, these seals will continue to haul out throughout their widespread range.

About this Archive

This page is a archive of entries in the Environmental Threats category from January 2011.

Environmental Threats: July 2010 is the previous archive.

Environmental Threats: February 2011 is the next archive.

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