Answer:
Unavailability of food decrease their population.
Explanation:
The population of Galapagos Finches decreases because of unavailability of food. Galapagos Finches feeds on a specific insects whose population decreases on that Island that leads to the death of the Galapagos Finches and they decrease in number. Positive population growth occurs only if more food is available to the Finches or they adapt another food item for themselves which fulfill their need of food.
