The scarcity of B. willow caused the Yellowstone National Park beaver population to decrease. Beavers rely heavily on willow for food and for building their dams. When willow became scarce, it impacted the beaver population adversely.
Which food source's scarcity caused the Yellowstone National Park beaver population to decrease?
A. grass
B. willow
C. otter
D. fish
1 answer
42 answers