A spider researcher, Pia Stålhandske, knew that males of Pisaura mirabilis offer their mates a nuptial gift-a prey item, such as a cricket-whose acceptance by the female is critical for male mating success. Males wrap their generally dark-colored food gifts in white silk. Stålhandske wondered if the males wrapped their gifts to make them look like the white, silk-covered egg sacs that mated females make and protect by holding them in their jaws until the spiderlings hatch.
What theory was Stålhandske using to explore this species' courtship behavior?