Mirror stimulation in Eurasian jays (Garrulus glandarius)

Abstract

Mirror exposure elicits a wide range of behavioral responses, some of which have been considered as part of possible evidence of mirror self-recognition (MSR). These responses can range from social behaviors, indicating that an animal considers its own reflection as a conspecific, to mirror-guided and self-directed actions. Evidence of MSR has been found categorically in only a few species, such as in magpies, chimpanzees, horses, and elephants. Evidence in corvids is currently debated due to inconsistent findings. In this study, we investigated the reaction of Eurasian jays when presenting them with three mirror-stimulation tasks. Based on the overall behavioral patterns across these three tasks, conclusions about birds' understanding of a reflective surface, and their perception of the reflection as either themselves or as a conspecific, appear premature. We highlight how the high neophobia of corvids and other methodological constraints might have hindered the likelihood to approach and explore a mirror, preventing the emergence of behaviors typically associated with MSR. Furthermore, we discuss how motivational factors, methodological constraints and species differences should be considered when interpreting behavioral responses to mirrors.

Keywords: Avian cognition; Corvids; Neophobia; Self-awareness.

Figure 1. (A) Mean of food taken in front of the mirror and the wooden panel during Mirror Preference Task (Task 1); (B) Mean of food taken in front of the mirror and the wooden panel during Mirror Preference Task with Varying Food Quality (Task 2); (C) Total duration of looking time towards the mirror and the wooden panel during the Mirror Preference Task with Varying Food Quality (Task 2); (D) Latency time to approach and retrieve a waxworm across the four combinations presented to the jays in Vertical vs. Horizontal Mirror Habituation Task (Task 3); Mirror, horizontal (MH) and vertical (MV); Wood, horizonal (WH) and vertical (WV).

Box plot: the horizontal line shows the median, the box extends from the lower to the upper quartile and the whiskers to the interquartile range above the upper quartile (max) or below the lower quartile (min); solid circles indicate each individual jay.