Land Management - The Lesson of the Kaibab Deer

Land Management: The Lesson of the Kaibab Deer Objectives: • Graph data on the Kaibab deer population of Arizona from 1905 to 1939 • Determine factors responsible for the changing populations • Determine the carrying capacity of the Kaibab Plateau The environment may be altered by forces within the biotic community, as well as by relationships between organisms and the physical environment. The carrying capacity of an ecosystem is the maximum number of organisms that an area can support on a sustained basis. The density of a population may produce such profound changes in the environment that the environment become sun suitable for the survival of that species. For instance, overgrazing of land may make the land unable to support the grazing of animals that lived there. Background Before 1905, the deer on the Kaibab Plateau were estimated to number about 4000. The average carrying capacity of the range was then estimated to be about 30,000 deer. On November 28th,1906, President Theodore Roosevelt created the Grand Canyon National Game Preserve to protect the "finest deer herd in America. "Unfortunately, by this time the Kaibab forest area had already been overgrazed by sheep, cattle, and horses. Most of the tall grasses had been eliminated. The first step to protect the deer was to ban all hunting. In addition, in 1907, The Forest Service tried to exterminate the predators of the deer. Between 1907 and 1939, 816 mountain lions, 20 wolves, 7388 coyotes and more than 500bobcats were killed. Signs that the deer population was out of control began to appear as early as 1920 - the range was beginning to deteriorate rapidly. The Forest Service reduced the number of live stock grazing permits. By 1923, the deer were reported to be on the verge of starvation and the range conditions were described as "deplorable. "The Kaibab Deer Investigating Committee recommended that all livestock not owned by local residents be removed immediately from the range and that the number of deer be cut in half as quickly as possible. Hunting was reopened, and during the fall of 1924, 675 deer were killed by hunters. However, these deer represented only one-tenth of the number of deer that had been born that spring. Over the next two winters, it is estimated that 60,000 deer starved to death. Today, the Arizona Game Commission carefully manages the Kaibab area with regulations geared to specific local needs. Hunting permits are issued to keep the deer in balance with the irrange. Predators are protected to help keep herds in balance with food supplies. Tragic winter losses can be checked by keeping the number of deer near the carrying capacity of the range.DATA1. Graph the deer population data. Determine the independent variable (X axis) and dependent variable (Y axis) 2. Were these methods successful? Use the data from your graph to support your answer. Exterminating predators of the deer was successful because around 1910 began a huge spike in the deer population shown by a steeper line. No animal was hunting and killing the deer so their survival rate increased.3. Why do you suppose the population of deer declined in 1925, although the elimination of predators occurred? In 1925, the population declined because the deer ate all the food and began to starve due to over population. The overpopulation resulted in overgrazing. There wasn’t enough food to sustain the population of the deer.4. Why do you think the deer population size in 1900 was 4,000 when it is estimated that the plateau has a carrying capacity of 30,000? The deer population was not reaching its biotic potential due to predation and hunting.5. Suggest what YOU would have done in the following years to manage deer herds.1915: I think that the decision to exterminate predators was awful and negatively impacting the environment. Therefore, I would reintroduce those animals to that ecosystem. But keep hunting illegal.1926: Fix the issue of overgrazing by relocating the animals safely to a new ecosystem to allow for regrowth to occur.6. It is a criticism of many population ecologists that the pattern of population increase and subsequent crash of the deer population would have occurred even if the bounty had not been placed on the predators. Do you agree or disagree with this statement. Explain your reasoning. I agree because the forest was already overgrazed so the food source was decreasing to begin with. Therefore, the population was fated to decline. The bounty on predators resulting in over population speeded up the overgrazing.7. What future management plans would you suggest for the Kaibab deer herd? Leave animals to live alone, do not exterminate any species. Not interfering with their ecosystem is the best solution. If a human-caused issue occurs then fix the issue itself. For example, if pollution is a cause for the decline in a certain species then mitigate the pollution. But if a predator (whose existence is natural to the ecosystem) is the cause of the decline, leave it alone. But absolutely eliminate hunting and limit interference of humans.