Field Grid for Testing Winter Feeding by Rabbits or Cottontails

Abstract

This field experiment requires 4–6 days. Setup on day 1 requires about 2 h, and daily checking of the results on the following days requires about 30–60 min.

Food choice experiments with free-ranging animals in the field have many advantages over tests in the laboratory or with fenced-in subjects, because they happen in the “real world.” Any practical applications of repellents or attractants will eventually occur in this real world, regardless how they have been tested before. However, the field presents a significant disadvantage to the experimenter: During the growing season free-ranging animals enjoy a vast food base against which any bait placed by the experimenter is infinitesimal. In winter, by comparison, the food supply of herbivores has shrunk to a few survival foods. Therefore, in winter mammals accept the bait much more readily, and experiments can yield very good results in terms of food discrimination, provided the animals are not extremely starved. In a typical experiment, twigs of palatable plants such as apple trees are coated with a repellent or feeding inhibitor. This renders the food less attractive. We can address different questions:

How do different compounds, mixtures of compounds, or complex plant extracts compare in their repellent effects?

How does concentration affect the repellent effect of one particular compound?

Do extracts from different plant parts (leaves, flowers, stem, and roots) differ in their repellent effects?

Do herbivores become less selective, i.e., accept more repellent, over the course of the winter?