Follow-up: almost nobody understands mirrors

Since several people have contacted me to defend junco intelligence after the mirror post yesterday, I thought I might talk a bit more about birds and mirrors.

Very, very few species understand mirrors, and an enormous majority of them behave as if the mirrored images are real, as the junco did. The list of birds that do not recognize themselves in the mirror is long: Budgerigar; House Sparrow; Kea; Black-capped Chickadee; Zebra Finch; Cedar Waxwing; Glaucous-winged Gull; Blue Grouse; Peach-faced Lovebird; reviewed in (1). In 1964, Edith Andrews kept an injured junco in a cage with a mirror and observed that it was quieted by the mirror, liked to perch next to it, and “appeared to be smitten with its own image” (2).

A study on pigeons (3) found that, while pigeons likely did not process the image in the mirror as an image of themselves, they could use the mirror to determine the location of objects in the real world. That is, they understood that the mirror provided information about the space around them, rather than being its own separate space.

The gold standard of understanding mirrors is self-recognition, which is tested by putting a mark on the body of the animal somewhere where it cannot see it, then giving it a mirror. If the animal uses the mirror to figure out where the mark is, it’s thought to understand that the mirror image is of itself. Evidence for this has been reported in several species of primates, elephants, dolphins, and the European Magpie (4). Only one bird! (So far. Many species haven’t yet been tested.)

So, was the junco I saw “dumb” for not understanding the mirror? Of course not. Juncos have had no reason to learn about mirrors, and have lots of company in their confusion. However, was the junco maybe a little bit foolish to continue to attack the mirror after crashing into glass three, four, five times? I think so.

1. Pepperberg, IM et al. 1995. Mirror use by African Grey Parrots (Psittacus erithacus). Journal of Comparative Psychology 109(2):182-195.

2. Andrews E. 1966. Slate-colored Junco response to mirror. Bird-Banding 37(3):206.

3. Epstein R, Lanza RP, Skinner BF. 1981. “Self-awareness” in the pigeon. Science 212(4495):695-696.

4. Prior H, Schwarz A, Güntürkün O. 2008. Mirror-induced behavior in the magpie (Pica pica): evidence of self-recognition. PLoS Biology 6(8):e202. doi:10.1371/journal. pbio.0060202

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5 thoughts on “Follow-up: almost nobody understands mirrors

  1. Thanks for the research! I knew that pigs understand mirrors, because I read somewhere that they used them to locate food (and looked behind themselves, and not behind the mirror). I was not aware that so many other species, including pigeons have some sort of understanding of how mirrors work.

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