In 1970 the deer population of an island forest reserve about 518 square kilometers in size was about 2000 animals. Although the island had excellent vegetation for feeding, the food supply obviously had limits. Thus the forest management personnel feared that overgrazing might lead to mass starvation. Since the area was too remote for hunters, the wildlife service decided to bring in natural predators to control the deer population. It was hoped that natural predation would keep the deer population from becoming too large and also increase the deer quality (or health), as predators often eliminate the weaker members of the herd. In 1971, ten wolves were flown into the island. The data collected during this program are shown in the following table. The Population Change is the number of deer born minus the number of deer that died during that year. Fill in the last column for each year. The first has been calculated for you. Then graph the deer and wolf populations on the graph below. Use one color to show deer populations and another color to show wolf populations What is a density-dependent limiting factor? When do density-dependent factors operate most strongly? List four density-dependent limiting factors?

Applications and Investigations in Earth Science (9th Edition)
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ISBN:9780134746241
Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
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In 1970 the deer population of an island forest reserve about 518 square kilometers in size was about 2000 animals. Although the island had excellent vegetation for feeding, the food supply obviously had limits. Thus the forest management personnel feared that overgrazing might lead to mass starvation. Since the area was too remote for hunters, the wildlife service decided to bring in natural predators to control the deer population. It was hoped that natural predation would keep the deer population from becoming too large and also increase the deer quality (or health), as predators often eliminate the weaker members of the herd. In 1971, ten wolves were flown into the island. The data collected during this program are shown in the following table. The Population Change is the number of deer born minus the number of deer that died during that year. Fill in the last column for each year. The first has been calculated for you. Then graph the deer and wolf populations on the graph below. Use one color to show deer populations and another color to show wolf populations

  1. What is a density-dependent limiting factor?
  2. When do density-dependent factors operate most strongly?
  3. List four density-dependent limiting factors?
  4. Describe what happened to the deer and wolf populations between 1971 and 1980.
  5. What happened to the deer population when the number of wolves was low?
  6. What do you think would have happened to the deer on the island had wolves NOT been introduced? Explain your answer.
  7. What is the relationship between the deer and the wolves on the island?
  8. Is the number of deer on the island a density-dependent or density-independent limiting factor for the wolf? Explain your answer.

 

 

 

LEFT Y AXIS
RIGHT Y AXIS
Number of
Deer
Deer
Wolf
Deer
Year
Predation
Starvation
Population
Change
+300
Population
Population
1971
1972
10
12
Offspring
800
920
400
480
100
240
2,000
2,300
2,500
2,360
2,224
2,094
1,968
1,916
1,952
1,000
944
996
1973
16
640
500
1974
1975
1976
1977
22
28
880
1,120
960
180
26
2
24
836
21
788
840
1978
18
766
720
1979
1980
19
780
760
19
1,972
790
760
28
12510
2488
27
2466
2444
2422
26
25
24
2378
2356
2334
23
22
2312
2290
21
WOLVES
2268
2246
20
2224
19
2202
2180
18
2158
17
2136
16
2114
2092
15
2070
2048
14
2026
2004
13
12
1982
1960
11
1938
10
1971
1973
1976
1977
1979
1980
1916
1972
1974
1975
1978
DEER
WOLVES
Transcribed Image Text:LEFT Y AXIS RIGHT Y AXIS Number of Deer Deer Wolf Deer Year Predation Starvation Population Change +300 Population Population 1971 1972 10 12 Offspring 800 920 400 480 100 240 2,000 2,300 2,500 2,360 2,224 2,094 1,968 1,916 1,952 1,000 944 996 1973 16 640 500 1974 1975 1976 1977 22 28 880 1,120 960 180 26 2 24 836 21 788 840 1978 18 766 720 1979 1980 19 780 760 19 1,972 790 760 28 12510 2488 27 2466 2444 2422 26 25 24 2378 2356 2334 23 22 2312 2290 21 WOLVES 2268 2246 20 2224 19 2202 2180 18 2158 17 2136 16 2114 2092 15 2070 2048 14 2026 2004 13 12 1982 1960 11 1938 10 1971 1973 1976 1977 1979 1980 1916 1972 1974 1975 1978 DEER WOLVES
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