Skunk Species, Memphitis Memphitis - Research Paper Example

25 April About the Animal Mephitis mephitis is the scientific for striped skunk which is well known for its characteristic foul smelling musky odor. In fact its scientific name actually means ‘noxious gas, noxious gas’ (Kaweah Oaks) Skunks were once classified in the weasel family of Mustelidae, but more recent genetic investigations have led taxonomists to group all skunks into a subfamily of the weasel family called Mephatinae (Wood). Some of their common names are civet cat and polecat. There are five different species of North American skunk. They are: 1. Striped skunk (Mephitis mephitis) 2. Eastern spotted skunk (Spilogale putorius) 3. Western spotted skunk (Spilogale gracilis) 4. Hognose or Rooter skunk (Conepatus leucontus) and 5. Hooded Skunk (Mephitis macroura). Among these five species of skunks, the striped skunks are the largest. Striped skunks weigh up to fourteen pounds and are about the size of a house cat. They have a stout body, small head, short legs with webbed toes and a bushy tail. The thick, glossy fur is black in color with a thin white stripe down the centre of the face and a broad white stripe beginning on the back of the head which usually divides into two stripes continuing along the back. The long, bushy tail is a mixture of white and black hair. The legs have long, straight claws which they use for digging and ripping apart things as they search for food. Male striped skunks are somewhat bigger than their female counterparts. The skunk has small eyes and ears. Although it can not see well, it has a good sense of smell and hearing. Habitat and Habits The striped skunks are adaptable but prefer open areas of mixed forests and grasslands. They generally live in the abandoned dens of woodchucks, foxes or other mammals of similar or larger size and only occasionally excavate their own dens (Encyclopedia Britannica). Since they have very little fear of humans they often inhabit developed areas and nest in houses, walls, basements, culverts and beneath buildings, wood and rock piles. The striped skunks are usually not more than two miles away from water. Although striped skunks can dig their own dens, they seem to prefer moving into ones constructed by other animals. These dens may have one to five well-hidden openings that lead to a system of tunnels and chambers (University of Wisconsin-Stevens Point). They line one of the chambers with leaves and use it as a nest. The leaves are also used to plug the openings to the den during cold weather. A skunk gathers leaves by placing them under its body and then shuffling along to the den with the leaves held between its legs as it moves. Skunks are primarily nocturnal i.e., they are active at night and usually solitary animals. However, mother skunks can often be noticed with their offspring in tow. Skunks leave their den to rummage for food at any hour of the day. However, they are usually away from late afternoon or evening through the night. They usually move within a radius of about 800 m from the den looking for food but may go as far away as 2 km in a night (University of Wisconsin-Stevens Point). Males become more active during the breeding season and can travel as much as 8 km in a night. Adaptation Skunks are active throughout the year but go into a state of torpor inside their dens during the coldest spells of winter (Welcome Wildlife). They prepare for the winter by going on eating binges in the fall and developing a heavy layer of fat and a thick coat. Unlike hibernation, which involves significant drop in body temperature and considerably slow heart rate wherein the creature takes only about one or two breaths per minute, striped skunks go into sporadic groggy sleep intermittent with periods of active and awake time. Studies have shown that the heart rate, body temperature and respiration of skunks drop only a little. Skunks take long torpor naps in their dens and come out to empty their scent glands and look for food when the temperature becomes warm even slightly. Usually, the mother and the young den together, entering the den when the temperature reaches about 0° C. The males are more active than females during the winter months and den when the temperature reaches about 10° C. The male striped skunks may den with their own family or with other males but typically they choose to den alone. Range Striped skunks are found in southern Canada, the United States, and northern Mexico. They are found throughout the United States except in the deserts of Southern California and in Alaska (Encyclopedia Britannica). Self Defense The repulsive odor that is characteristic of the skunk is used to mark the skunk’s territory and as a defense mechanism. This defensive secretion is frequently referred to as ‘skunk spray’ or ‘skunk musk’ (Encyclopedia Britannica). When threatened, the striped skunk gives a warning by growling, hissing and stamping its front feet rapidly. The odorous musk is used as a last desperate measure after repeated warning signals. The odor is produced by a thick, yellow, oily fluid or musk called mercaptan – a name derived from the fact that the compounds of the musk form compounds with mercury (Wood). The musk is secreted by two glands (anal sacs) located on either side of the anus at the base of the tail. The glands are about the size of a grape and are connected to two nipples that are situated just outside the anal opening. The glands are surrounded by muscle tissue that can contract to disperse a fine spray. The spray can reach as far as 6 m and can be aimed with considerable accuracy for up to 3 m. The musk is produced rather slowly, at a rate of about one-third of an ounce a week. To spray the musk, the striped skunk usually humps its back and turns in a U-shaped position so that both the head and tail face the enemy. The odor is strong enough to be carried almost 1 km on the wind. At close range the spray of a skunk causes severe burning of the eyes, temporary blindness and even nausea, but these symptoms soon disappear as the nasal passages quickly become desensitized to the odor. Diet Skunks are omnivorous mammals and feed actively during the night. The striped skunk’s diet is primarily made up of insects like bees, grubs and various larvae. They also eat earthworms, snails, grains, nuts, fruits, frogs, vegetation, birds, eggs and nestlings, reptiles, small mammals, fish, dead animals and garbage (Encyclopedia Britannica). However, seasonal changes can impact availability and feeding patterns of skunks. Generally, skunks are opportunistic foragers that will eat nearly anything that they can find or catch. Since they are not fast enough to pursue their prey, they usually stalk or hunt by lying in wait. Skunks do not accumulate food, instead they raid the food accumulated by other mammals, especially that of weasels. Reproduction Striped skunks mate from mid-February to mid-March. After mating, the male wanders off in search of other mates and leave the work of raising the babies to their female counterpart. Striped skunks exhibit delayed implantation which means that after mating, the fertilized egg can be held dormant for many weeks before they are implanted in the uterine wall (EHow). Once the fertilized egg gets implanted on the uterine wall, the development of the fetus continues. The babies are born about two months after implantation. Mother skunks give birth to litters of two to ten young each year, usually in the month of May. Skunk babies (kits) are blind, skinny, hairless, deaf and without teeth when they are born. In three weeks, their eyes open and in six weeks their fur is fully grown. The kits are nursed by their mother in the den for about six weeks after which they begin to follow their mother on nighttime food hunts. They stay with their mother for up to a year and leave for good during the next mating season. Locomotion Unlike the western and eastern spotted skunks, the striped skunk rarely moves in a hurry (Encyclopedia Britannica). They cannot climb and have no ground speed. They walk in a slow and winding fashion taking their time to go from one place to another. It moves at a speed of about 1 mph. however, when necessary, they can move in a speed of about 3 to 4 mph. The fastest they can move is at a speed of 6 mph. Predators Even with their powerful defense mechanism, striped skunks find it challenging to ward of predators like the great horned owls, hawks, coyotes, badger, bobcat, fox and domestic dogs that can act swiftly before the skunk can spray (Encyclopedia Britannica). The great horned owl in particular seems relatively unaffected by the scent and has made the skunk its principal prey. Humans are also a threat to the skunks because they kill the skunks casually or out of fear. Like porcupines, skunks are overly confident of their defense mechanisms. Therefore, large numbers of skunks get run over by automobiles when they cross highways. Striped skunks are also hunted and trapped by humans for their fine and silky fur. In Canada, trappers take 6 000 to 7 000 skunks a year (Canadian National Trappers Association). However, this represents only a small fraction of the total skunk population and has no appreciable effect on its numbers. Relationship with humans Skunks can be both useful and harmful to humans. They are useful to humans because they eat insects and small rodents such as mice and therefore help control pests that are harmful to crops. In fact, skunks have proved to be an efficient enemy of the hop grub in New York State due to which a legislation was passed to protect the skunk (Southwest Wildlife). Striped skunks have proved to be the most important predator of insect pests in many of the areas within their range. In the period following the First World War, the thick and lustrous fur of the skunk was in great demand in the U.S. to make coats and jackets. Today, that market is no more there since the cost of raising the skunk for its fur is much more than the cost of the fur. However, in Canada, there is still a demand for jackets and coats made of skunk fur, with most of the skunk fur coming from eastern Canada. Skunks can also be harmful to the humans when they become pests themselves and start feeding on crops, poultry, and eggs meant for human consumption. Although skunks may become a nuisance to poultry and bee keepers, the damage they inflict is not economically important. Skunks can also be tamed to become pets. However, people should take special care in handling them. Skunks are common carriers of the rabies virus. Rabies is an acute and fatal encephalitis caused by a bullet shaped virus (genus Lyssavirus). An infected skunk can transmit the disease to other wildlife, livestock and humans through bites or direct contact. In many parts of Canada, the occurrence of skunk related rabies is a continuing problem. Although skunks would normally shy away from humans, a rabid skunk will often show no fear. Children in particular should be careful and stay away from over-friendly skunks. Medical authorities recommend that when a person comes into contact with a potentially rabid skunk, they should immediately wash the wound or exposed surfaces with soap and water. Any clothing that could have been contaminated should be removed and the person should consult a doctor immediately. Since rabies is a reportable disease, the doctor who treats the person will be required to notify the local medical officer of health about the case. The disease can be prevented if the person who has come into contact with a rabid animal seeks treatment promptly. Interesting Facts about Striped Skunks There are numerous interesting facts about the striped skunks: 1. The skunk can produce enough of the odorous liquid in its body so that it can spray five times in a week. 2. The skunk helps the farmers by eating insects and rodents that destroy their crops. 3. The odor of the skunk musk is so strong that gentle breezes can carry the scent to a distance of almost 1 km. 4. The most active ingredient in the foul smelling discharge is 1-butanethiol. 5. The foul smelling musky odor is so strong that the skunk itself can not stand it. Therefore, they do not use their spray to fight with each other or as a defense mechanism in a confined space. 6. Skunks are resistant to snake venom and can survive 10 times the venom needed to kill an animal of the same size. 7. Of all the animals that have coloration, the striped skunk is easily recognized and is successful at deterring its predators. 8. Skunks have poor vision but their ability to smell and hear is good. 9. A skunk can spray its musk accurately up to a distance of 10 feet and less accurately to a distance of about 16 feet. 10. A common myth is that tomato juice can neutralize the odor of skunk spray. However, the apparent disappearance of the odor can be explained by human olfactory fatigue. Scientifically, it has been proved that the repulsive scent of skunk spray can be easily neutralized by oxidation to sulfonic acids. 11. The striped skunks are the chief carrier of rabies in the United States, especially in the Midwest. 12. The average lifespan of the striped skunks in the wild is 6 years. Reasons the striped skunk has been studied Striped skunks (Mephitis mephitis) are among the most recognizable and ubiquitous animals in North America and has been the focus of research interest for a variety of reasons: 1. One of the main reasons the species has been studied is to understand its role as a rabies reservoir. The striped skunk has been identified as one of the main vectors of the rabies virus. They are known to carry 3 known rabies variants: one in the south central United States, one in the north central United States, and one in California. Numerous studies have been conducted to investigate the occurrence and role of rabies virus in striped skunks because striped skunks are one of the most common mammals reported with rabies each year (Krebs et al., 825, Hass and Dragoo, 1912). Therefore, a focus on rabies research is an extremely important topic within the urban/suburban environment. 2. Researchers have also studied the role of striped skunks as nest predators especially that of duck and waterfowl. Scientists studied the spatial organization of the skunk during the bird’s nesting season (Lariviere & Messier, 199). Since the skunk feeds on eggs of these birds, their population growth can be significantly affected by the predator behavior of striped skunks. This can cause imbalance in the ecosystem. Detailed studies have revealed the positive influence of removing the striped skunk from the nesting sites of these birds (Greenwood, 6). 3. Scientists have also been interested and have conducted numerous studies to identify the chemicals that are present in skunk musk. Thomas Aldrich did a considerable amount of work in identifying the ingredients of the skunk musk and based on his research, it is believed that the musk has anesthetic and antispasmodic properties (Aldrich, 323). 4. Scientists have also been studying the striped skunk as an urban pest. The animal has been found to be very adaptive and is one of the species that has increased in population as more forest land has been cleared (Loudoun Wildlife Conservancy). 5. There are very few genetic studies have been performed on the striped skunks. Researchers are now beginning to look into the potential for genetic subspecies of the animal. Scientists are trying to determine the levels of genetic variation within striped skunk populations found in the geographic distribution of the south central strain of rabies in the United States. Preliminary data indicates two distinct haplotype groups among samples from Oklahoma, Kansas, New Mexico, and Texas (Smith, K.A. & Haynie, M.L.). 6. The Striped skunks have also been identified as an intermediate host for Sarcocystis neurona. According to a recent study, striped skunks that were initially negative for antibodies to Sarcocystis neurona, formed sarcocysts in skeletal muscles after inoculation with S. neurona sporocysts collected from a naturally infected Virginia opossum (Cheadle, M.A. 843). Based on this finding, the striped skunk has been identified as an intermediate host of Sarcocystis neurona. In conclusion, the striped skunk is a very interesting animal with a characteristic odor and an adaptable lifestyle. The animal has a dual influence on humans in that they can be beneficial as well as harmful to us. Although numerous studies have been conducted on the animal, we are still exploring more about the animal’s behavior and influence in the environment that it shares with the humans. Works Cited Aldrich, T. B. A Chemical Study of the Secretion of the Anal Glands of Mephitis mephitica (Common Skunk), with Remarks on the Physiological Properties of this Secretion. Journal of Experimental Medicine. 1896, 1, 323. Canadian National Trappers Association. Striped Skunk. Accessed on April 25, 2011 < http://www.trapper.ca/skunk.html> EHow. How to Mate a Skunk. Accessed on April 23, 2011 http://www.ehow.com/ how_2307884_mate-skunk.html> Encyclopedia Britannica. Skunk. Britannica Elementary Library. Chicago: Encyclopedia Britannica, 2011. Greenwood, R. J. Influence of striped skunk removal on upland duck nest success in North Dakota. Wildlife Society Bulletin 14:6–11. Hass, C. C., and J. W. Dragoo. Rabies in hooded and striped skunks in Arizona. Journal of Wildlife Diseases. 42:825–829. Kaweah Oaks. Striped Skunk. Accessed on April 20, 2011 Krebs, J. W., E. J. Mandel, D. L. Swerdlow, and C. E. Rupprecht. Rabies surveillance in the United States during 2004. Journal of the American Veterinary Medical Association. 227:1912–1925. Lariviere, S., and F. Messier. Spatial organization of a prairie striped skunk population during the waterfowl nesting season. Journal of Wildlife Management. 62:199–204. Loudoun Wildlife Conservancy. Striped Skunk. Accessed April 23, 2011 < http://www.loudounwildlife.org/HHStripedSkunk.htm Southwest Wildlife. Striped Skunk. Accessed on April 24, 2011 < http://www.southwestwildlife.org/ pdf/skunkglance.pdf> Smith, K.A. & Haynie, M.L.Wilderness Trapping and Living. Accessed on April 23, 2011 < http://www.trapperman.com/forum/ubbthreads.php/topics/1518622/1/Striped_Skunk_Research_Out_to_.html> University of Wisconsin-Stevens Point. Mephitis mephitis: The Striped Skunk. Accessed on April 25, 2011 Read More