2018, Biology - High School
Download PDF Document Question 21: Multiple-Choice
Reporting Category: Ecology
Standard: 6.2 - Analyze changes in population size and biodiversity (speciation and extinction) that result from the following: natural causes, changes in climate, human activity, and the introduction of invasive, non-native species.
 

In 1937, two male and six female ring-necked pheasants were introduced to an island off the coast of Washington state. The pheasants mainly ate wheat. The only known predators on the island were house cats, hawks, and owls. After five years, the pheasant population on the island had increased to 1,325 individuals. The population size then remained stable.

Which of the following most likely explains why the pheasant population size remained stable after five years?

 
 A.The hawks learned to hunt only owls.
B.A limited amount of wheat grew on the island.
 C.All the house cats that lived on the island died.
 D.The original male and female ring-necked pheasants died.