What is easiest to see from an airplane a black cow or a white cow?

There are several factors involved here: is this in winter or summer? Is the animal viewed at night or at day? If it were winter, a black cow is easier to spot than a white one. If it was summer, then a white bovine is easier to spot than a black one. At night, a white cow is easier to see than a black one, and vice versa in the day time.