Fish out of water: Insights from a case study of a highly social animal that failed the mirror self-recognition test

Abstract

Mirror self-recognition (MSR) tests have been conducted with a variety of species with the aim of examining whether subject animals have the capacity for self-awareness. To date, the majority of animals that have convincingly passed are highly social mammals whose wild counterparts live in complex societies, though there is much debate concerning what constitutes passing and what passing means in terms of self-awareness. Amid recent reports that a fish (cleaner wrasse, Labroides dimidiatus ) passed, it is intriguing that a mammal as highly social, tolerant, attentive, and cooperative as the grey wolf ( Canis lupus ) reportedly failed the test. Given the many possible reasons for failure, we aimed to elucidate the wolves’ responses at various stages of the MSR test to pinpoint potential problem areas where species-appropriate modifications to the test may be needed. Thus, we evaluated 6 socialized, captive grey wolves as a case study of failed MSR in socially complex canids. At a minimum, wolves did not respond to their reflection as an unfamiliar conspecific. Unfortunately, the wolves rapidly lost interest in the mirror and were uninterested in the applied marks. We note limitations of the MSR test for this species, recommend changes for future MSR tests of wolves, discuss other emerging self-cognizance methods for socially complex canids, and highlight the need for a suite of ecologically relevant, potentially scalable self-cognizance methods. Our findings and recommendations may aid in understanding self-cognizance in other untested highly social, cooperatively-hunting, coursing, terrestrial carnivores such as African wild dogs ( Lycaon pictus ), spotted hyenas ( Crocuta crocuta ), and African lions ( Panthera leo ).