Pelicans and flamingos

 One of the animals that shows up in bestiaries is called the pelican. The most intriguing feature of the pelican in these accounts is that it feeds its young with its own blood. Eventually this became a Catholic symbol of Christ.

The weird thing is that pelicans don't do this, and pelicans are a common animal throughout Europe. So why does it say this? One clue is that Isidore of Seville writes:

 Isidore of Seville [7th century CE] (Etymologies, Book 12, 7:26): The pelican [pelicanus] is an Egyptian bird inhabiting the solitary places of the river Nile, whence it takes its name, for Egypt is called canopos. It is reported, if it may be true, that this bird kills its offspring, mourns them for three days, and finally wounds itself and revives its children by sprinkling them with its own blood.

There is a bird that annually migrates to Egypt, but it isn't the pelican-- it's the flamingo. And flamingos produce red crop milk in their digestive tract and feed it to their young:

 So I think what happened is that the name pelicanus is used for one bird in Isidore's time but another bird in later times. This sort of thing happened all the time. The Old Testament is full of names of animals that are mistranslated.

The early illustrators of bestiaries didn't know what a pelicanus looked like, so they just drew it as a generic bird. Later illustrators did know what a pelican was, so they drew it (Louisiana state flag):

 but by that time the knowledge of what bird was intended was lost.

I found one other note that has made the same connection, from 1869:

https://penelope.uchicago.edu/oddnotes/pelicans2.html 

A bunch of the mythological animals from the bestiaries I think started the same way. Like the unicorn of Pliny the Elder is pretty clearly describing a rhinoceros. Or the catoblepas, which is describing some kind of buffalo.