Red Squirrel caching preferences By Miklos Eger

Questions: Do squirrels preferentially select the pine cones they cache for the winter? If so, do they form a search image for the most common or closest trees, or do they “go out of their way” for a specific species of pine seeds? Also, if so, how strong is their affinity for the type of seed they prefer?

Relevance Seed predation can take a toll on plant reproduction (Janzen). If squirrels select certain seeds exclusively, this could make a significant impact in the composition of the forest. Insight into what foods squirrels prefer could lay the groundwork for new nutrition research on squirrels.

Foraging Patterns Don’t minimize predation risk (Lima et al.) Maximize foraging efficiency (Lima et al.) Don’t maximize energy intake (Smallwood et al.) What are they looking for when they forage?

Hypotheses Squirrels preferentially cache cones If they preferentially cache cones, they will form a search image for the most common tree in the immediate vicinity. (10m) Subalpine Fir will be absent or underrepresented in the results because their cones fall apart when mature.

Methods Collect and dry five Chickory kitchens in different forest types: Mixed forest, predominantly Subalpine Fir and Limber Pine forest far from the road, Lodgepole pine forest near the road. Quantify the types of tree in the 10m surrounding each Chickory kitchen using the point-quarter method and avoid sampling bias by randomizing the angle (0-360) and distance (0-10) from each chickory kitchen. Mix each sample well and take a half-cup sample from each. Count the number of scales of each type in the sample Run 2-factor Anova test with replication

Comparison of Contents of Chickory Kitchens to Expected Values Tree types: 1. Engelmann spruce 2. Subalpine Fir 3. Lodgepole Pine 4. Limber Pine.

Results Summary Red squirrels have a strong preference for Engelmann Spruce Subalpine Fir cones were underrepresented as expected, but Limber Pine scales were completely absent from all the piles. The hard, spiky scales of the pines were far less common, and the softest scale, that of the Engelmann Spruce, was the most common by far.

Discussion Do the squirrels prefer Engelmann Spruce so much to fulfill a dietary need? What nutrients are more abundant in the Engelmann Spruce seeds, if any? The hard, spiky scales of the pines were far less common, and the softest scale, that of the Engelmann Spruce, was the most common by far. One explanation for this could simply be that the pine cones are more inconvenient to handle and eat than Spruce Cones