Alice wants to find out whether her pet gecko finds its prey based on vision. She thinks that her gecko will more easily see the colored crickets. She follows these steps: get 10 similar crickets from the pet store
tag 5 of the crickets by putting a tiny dab of bright coloring on their backs
release all 10 crickets into the terrarium with the gecko at the same time
after several hours, record the number of tagged and non-tagged crickets still alive in the terrarium
After several hours, Alice notes that only 4 non-tagged crickets were still alive in the terrarium. No tagged crickets were observed. She concludes that her gecko uses mostly its vision to capture and eat its prey.

What is another possible explanation for these results?