One of the most popular myths is that of "trochilus" as Herodotus, and later Aristotle and Pliny, call it. This is supposed to be an Egyptian bird that flies into the mouth of a basking crocodile and feeds on scraps of food and leeches attached to the jawline and tongue. Herodotus describes it as follows: "...for the crocodile, when he leaves the water and comes out upon the land, is in the habit of lying with his mouth wide open, facing the western breeze: at such times the trochilus goes into his mouth and devours the leeches. This benefits the crocodile, who is pleased, and takes care not to hurt the trochilus." Many have attributed this behaviour to the Egyptian plover (Pluvianus aegyptius) which is a very common bird often seen around basking Nile crocodiles, although there's no proof that this is what Herodotus was referring to.
This description of a bird that cleans the teeth of crocodiles has undoubtedly entered popular culture, so much so that crocodiles are often used by advertising agencies to promote dental hygiene. But is it true? Do plovers or indeed any other birds actually clean the teeth of crocodiles?
(c) Warren Photographic, Used with Permission
So what's going on? Am I just a born skeptic? Perhaps I am, but that doesn't mean there isn't something in this compelling relationship. Birds of various species are often found feeding in close proximity to crocodiles, and immobile crocodiles basking on the bank in the sun are rarely if ever concerned about birds wandering between them, standing on their back, or straying close to their jaws. Birds are opportunists too, and they will feed on flies and other insects on and around crocodiles. It may even appear that they are removing flies from the crocodile's jaws on occasion. But extrapolating this into a mutual relationship between crocodile and bird is going a bit far. Crocodiles hardly benefit from the presence of the birds, and yet they tolerate their presence because it's just not worth chasing them. Crocodiles aren't always in the mood for feeding, and they're smart enough to let difficult to catch prey like alert birds pass them by.
So if you ask me, the crocodile bird exists in name only. There is no mutual relationship between them, as none has ever been seriously documented, no advantage would be gained by the crocodile, and the hypothesis just doesn't add up. Of course, I like to think that I'll reconsider anything based on actual evidence. I wait in hope.