A hunting we will go

Mother's property covers five acres, much of which is wooded. Occasionally, a local hunter will ask Mother if he may hunt on her property. Mother usually allows such activity. One such hunter said to Mother that he was concerned about how Mother would know when he was lurking about.

"How will you know when I'm here?" he asserted. "I'll figure out a way to alert you!"

The next day, mother woke early and went to retrieve the paper. Upon her porch she found this: