Ferrets (Mustela furo) Are Aware of Their Dimensions

Abstract

Self-awareness is a complex phenomenon expressed as the ability of an individual to separate "self-entity" from "other entity". One of its earliest evolutionary components is body size awareness, namely, the ability to consider the boundaries of one's own body as factors influencing interaction with surrounding objects. For ferrets, Mustela furo, the task requiring the penetration of various holes is ecologically relevant. We designed an experimental study in which the ferrets were supposed to select one opening out of three to get the bait. The first experiment was aimed at studying whether ferrets would prefer the holes basing on the hole size. In the second experiment, we tested the ferrets' ability to select a single passable hole on the first try while the impassable ones were larger in area. Results from the first experiment show that when choosing from the three passable openings, the animals preferred the shortest path to the bait and ignored the size of the holes. In the second experiment, all tested ferrets preferred to penetrate the passable opening on the first attempt, even though the areas of the two impenetrable ones were larger. We argue that these data indicate that ferrets are aware of their own body size.

Keywords: body awareness; body size awareness; ferrets; self-awareness.

Figure 1

The experimental setup: 1—launch box; 2—finish box with bait; a, b, c—holes in the partition.

Figure 2

View of the experimental setup with ferrets: (a) a ferret enters the hole during Experiment 1; (b) a ferret enters a hole during Experiment 2. (Photo: I.A.Khvatov).

Figure 3

Location of holes during Experiment 1: 1, 2, 3—experimental trials; a—small hole (Ø 70 mm), b—medium hole (Ø 90 mm), c—large hole (Ø 110 mm).

Figure 4

Location of holes during Experiment 2: 1.1.–1.8.—successive background trials, 2.1.–2.4.—successive test trials; a1—impassable hole (Ø 40 mm), a2—impassable hole with a side of 40 mm, a3—impassable hole (horizontal rectangles 250 × 25 mm), a4—impassable hole (vertical rectangles 25 × 250 mm), b1—passable hole (Ø 70 mm), b2—passable hole (square 70 mm), b3—passable hole (horizontal rectangle 250 × 70 mm), b4—passable hole (vertical rectangle 70 × 250 mm).

Figure 5

Experiment 1 (n = 6): differences in the average number of passages through holes depending on their location in the partition; left, center, or right.

Figure 6

Experiment 2 (n = 6): (a) differences in the average number of first penetration attempts on the holes as a function of their passability/impassability; (b) differences in the average number of first approaches in relation to holes in a trial depending on their passability/impassability.