sticker to the throat of five Eurasian magpies, where they could be seen by the bird only by using a mirror. The birds were then given a mirror. The feel of the sticker on their throats did not seem to alarm the magpies. However, when the birds with colored stickers glimpsed themselves in the mirror, they scratched at their throats—a clear indication that they recognised the image in the mirror as their own. Those that received a black sticker, invisible against the black neck feathers, did not react. In 2020, researchers attempted to closely replicate the 2008 study with a larger number of magpies, and failed to confirm the results of the 2008 study. The researchers stated that while these results did not disprove the 2008 study, the failure to replicate indicated the results of the original study should be treated with caution. Some pigeons can pass the mirror test after training in the prerequisite behaviors. In 1981, American psychologist B. F. Skinner found that pigeons are capable of passing a highly modified mirror test after extensive training. In the experiment, a pigeon was trained to look in a mirror to find a response key behind it, which the pigeon then turned to peck to obtain food. Thus, the pigeon learned to use a mirror to find critical elements of its environment. Next, the pigeon was trained to peck at dots placed on its feathers; food was, again, the consequence of touching the dot. The latter training was accomplished in the absence of the mirror. The final test was placing a small bib on the pigeon—enough to cover a dot placed on its lower belly. A control period without the mirror present yielded no pecking at the dot. When the mirror was revealed, the pigeon became active, looked in the mirror and then tried to peck on the dot under the bib. However, untrained pigeons have never passed the mirror test. Fish According to a study done in 2019, cleaner wrasses were the first fish observed to pass the mirror test. The bluestreak cleaner wrasse (Labroides dimidiatus) is a tiny tropical reef cleaner fish. Cleaner fish have an adapted evolutionary behavior in which they remove parasites and dead tissue from larger fish. When put through the mirror test, using a benign brown gel injected into the skin of the fish, and resembling a parasite, the cleaner wrasse showed all the