Kaibab Plateau - Kaibab Deer

Kaibab Deer

At the beginning of the 20th century, the Kaibab Plateau was witness to an interesting experiment in what some might call population engineering. The plateau's pre-1905 population of deer was estimated to be around 4,000. This number was never confirmed by any kind of count or survey, and has become an accepted number mainly because no other estimate is available. The average carrying capacity of the land was unknown, in part because this concept was not widely used by naturalists at the time. Years later, Aldo Leopold famously estimated that the capacity had been about 30,000 deer. The idea in 1906 was simply to protect and expand the herd, so on November 28, President Theodore Roosevelt created the Grand Canyon National Game Preserve. Overgrazing by herds of sheep, cattle, and horses had taken place on the plateau since the 1880s. During that time, many predators were also killed by ranchers and bounty hunters. By the time Roosevelt established the game preserve, ranchers had moved most domestic livestock elsewhere. The primary change brought by the creation of the game preserve was to ban deer hunting. Government efforts, led by the United States Forest Service, began to protect the deer's numbers by killing off their natural predators once again; to this end, between 1907 and 1939, 816 mountain lions, 20 wolves, 7388 coyotes and over 500 bobcats were reportedly killed.

The deer population experienced a great increase in numbers during the early decades of the 20th century. One estimate put the population as high as 100,000 deer inhabiting the range in 1924. Again, there was no systematic survey to support this estimate, which may have been exaggerated to twice the actual number. Shortly after that time, however, the deer population did begin to decline from overbrowsing. By the mid-1920s, many deer were starving to death. After a heated legal dispute between the federal government and the state of Arizona, hunting was once more permitted, to reduce the deer's numbers. Hunters were able to kill only a small fraction of the starving deer. The range itself was damaged, and its carrying capacity was greatly reduced. Once ecologists began to study the area and reflect on the changes that had occurred there, they began to use the Kaibab deer as a simple lesson about how the removal of the deer's natural predators, which had been done in the interest of preserving the deer population, had allowed the deer to overreproduce, and quickly overwhelm the plateau's resources. Some ecologists suggested that the situation highlighted the importance of keeping a population in balance with its environment's carrying capacity. Since the actual numbers of deer and predators will never be known for certain, such a simplistic account of the changes on the Kaibab Plateau cannot be considered a reliable ecological lesson. The more meaningful lesson of the Kaibab suggests that human efforts to protect wildlife and preserve wild areas must be balanced with ecological complexity and social priorities that are difficult to predict. Changes take place, sometimes rapidly, but their effects linger for decades. Today, the Arizona Game Commission manages the area, controlling the numbers of deer as well as predators, and issues hunting permits to keep the deer in balance with the range.