Self-recognition, the ability to understand that one’s own reflection is an image of oneself, has primarily been observed in humans and some primates. This capacity suggests a sophisticated level of self-awareness, prompting questions about its presence in other species. While birds were once thought incapable of such an ability, scientific investigations are challenging these assumptions. Research offers insights into whether birds perceive their reflection as themselves or another individual.
Assessing Self-Recognition: The Mirror Test
Scientists assess self-recognition using the mirror self-recognition (MSR) test, developed in 1970 by psychologist Gordon Gallup Jr. This technique determines if an animal identifies its own reflection. The test involves a preparatory phase where the animal becomes accustomed to the mirror, often initially reacting as if the reflection is another animal.
The MSR test involves placing a visible mark on an animal’s body in a location it cannot see directly, but which becomes visible only through the mirror. This mark is usually applied under anesthesia. After recovery, the animal is presented with the mirror. A “pass” is signified if the animal attempts to touch, inspect, or remove the mark from its own body while looking at its reflection. This behavior suggests the animal understands the image in the mirror is itself.
Birds That Demonstrate Mirror Self-Recognition
The European magpie (Pica pica) was the first non-mammalian species to show evidence of mirror self-recognition in a 2008 study. Researchers applied colored stickers to the magpies’ throats, visible only in a mirror. When confronted with their reflection, several magpies spontaneously scratched at their throats, attempting to remove the sticker. This self-directed behavior, aimed at a mark visible only in the reflection, indicated self-recognition. This suggested complex cognitive abilities like self-recognition could evolve independently in species with different brain structures.
A 2019 study reported that Indian house crows also passed the mirror test, with some individuals displaying mark-directed behaviors. However, subsequent replication attempts for both magpies and Indian house crows have yielded inconsistent results. A 2020 replication study with magpies, for example, did not confirm the original findings, showing self-directed behavior more frequently in control conditions. This indicates a need for further research to establish consistent mirror self-recognition in these species.
Understanding Birds That Don’t Pass
Many intelligent bird species, including various corvids like jackdaws, hooded crows, and carrion crows, have not passed the traditional mirror test. A “fail” does not necessarily indicate a lack of self-awareness or intelligence. The test primarily relies on visual cues, which might not be the most relevant sensory modality for all animals. For example, dogs, despite their intelligence, often fail the test as their primary sense for self-recognition might be smell rather than sight.
Birds’ natural behaviors can also influence their performance. Many species react to their reflection as if it were another bird, leading to social responses like aggression, territorial displays, or courtship behaviors, which prevent them from calmly assessing the reflection. Some birds might also not perceive the applied mark as unusual or lack the motivation to interact with it. While pigeons have been trained to pass the mirror test through conditioning, this learned behavior differs from the spontaneous self-recognition observed in other species. Recent studies, such as one involving roosters, have explored alternative methods, observing that roosters made fewer alarm calls when faced with a mirror compared to another rooster, suggesting they did not perceive their reflection as a rival.
What Mirror Self-Recognition Reveals About Bird Intelligence
The presence of mirror self-recognition in birds, even with ongoing debate, challenges assumptions about the uniqueness of certain cognitive abilities in mammals. This capacity suggests a bird’s ability to form a mental representation of its own body and understand its physical presence in space. It implies a complex level of cognitive processing beyond simply reacting to external stimuli.
The fact that magpies, with their distinct brain structures from mammals, demonstrated this ability indicates a convergent evolution of cognitive traits. Similar advanced cognitive functions can arise through different evolutionary pathways. Such findings broaden our understanding of avian intelligence, suggesting birds may possess a more sophisticated capacity for complex thought, memory, and an understanding of their own body than previously appreciated.