Answer:
Genetic drift
Step-by-step explanation:
In the given question, out of ten dark-colored birds, 2 dies and out of five light-colored birds 3 dies. This produces only the dark-colored birds in the next generation but no light colored birds.
From this, we can observe that the gene pool of the small population has changed due to chance event or random event.
Since in the given situation, the small population of birds is taken into account in which the gene pool has changed due to a random event is known as the Genetic drift.
The genetic drift is the phenomenon which is associated with the shift or drift in the gene pool therefore is the answer.