The following graph shows the number of Kaibab deer on the isolated Kaibab Plate
ID: 113142 • Letter: T
Question
The following graph shows the number of Kaibab deer on the isolated Kaibab Plateau in northern Arizona. It was declared a National Game Preserve in 1906, and predator removal was encouraged to protect the deer. Between 1907 and 1937, more than 800 mountain lions were removed. Wolves were exterminated by 1926, and more than 7,000 coyotes and bobcats were also removed. The deer population increasde, and by 1915, there was a significant damage to the grasses, shrubs and trees that were being eaten by deer.
Interpretation
1. With the initial level of predators, what was the probably carrying capacity (K) of the Kaibab Plateau for deer at the start of this story?
2. Once the population had passed its probable K, would it be able to sustain itself at the higher numbers? Explain your answer.
3. In what 2- to 3-year period did the deer population have the highest reproductive growth rate?
Advance your thinking (besides your thinking, please use the book, or the internet for your answers)
4. Explain the factors - growth, resistance, and density-dependent and density independent factors - that accounted for the changes in population number for the 1905, 1915, and 1930.
5. Did Kaibab deer behave like an r-selected species or K-selected species? Justify your answer.
6. Before the predators were exterminated, the habitat if the Kaibab Plateau consisted of meadows and forests with a wide diversity of grasses, shrubs, and trees. How do you think it probably looked in 1935, after 30 years of damage?
Kaibab Deer Population 100,000 100 1 Seven successive warnings 60% of herd starved in two winters 75 First fawn starved Damage seen; first 501 warning given Probable capacity if herd reduced in 1918 40,000 25 30,000 10,000 25,000 20,000 1905 1910 19151920 1925 1930 1935 1940 YearExplanation / Answer
1. The initial level of predator was around 8500 and the carrying capacity of the Kaibab Plateau for the deer was around 50,000.
2. No the population was not able to sustain itself at the higher numbers because any increase in the population would damage the resource of the forest significantly. The lack of food for the deer will decrease the population significantly.
3. During the time period from 1921-1923 the population increased significantly and it has the highest reproductive rate as can be seen from the graph.
4. In 1905 most of the predators was removed from the reserve in order to protect the deer. This result in increase in population of the deer significantly. In 1915 the deer population was increasing because the more and more predators were being removed. In 1930 the population decreased signifantly because there was significant damage in the grasses, shrubs, trees that were being eaten by the deer. So due to overgrazing and starvation the population decreased significantly abd becomes 25,000 after the peak of 1,00,000 around a period of 1920-1925.
5. The Kaibab deer acted more like K selected species because they have traits like less offspring and long term parenting.
6. In 1905 the habitat of the Kaibab plateau was covered with meadows and forests with a great diversity of trees, shrubs and grasses and there was plenty of food for the deer. But after the removal of predators the deer population increased significantly and due to overgrazing and starvation the land looked like barren with little bushes and little trees left in 1935 after 30 years of damage.
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