If it was a regular occurrence, it should be photographed or filmed many times by now, considering the number of safari tourists.
By the way, it is not even certain what bird was actually meant by Herodotus. The lore is now associated with the Egyptian Plover, but I read also that it could be the Common Sandpiper or the Spur-winged Lapwing. Actually, I doubt a little that Herodotus differentiated similar species of waders at all.
Some Bird Forumer with interest in browsing books could actually trace the story as an interesting bird folklore/mythology/cultural meme, not as something existing in the real world. It would be an interesting publication.
Here's the relevent extract from
BIRDS IN LEGEND FABLE AND FOLKLORE
at this link
http://www.gutenberg.org/files/59598/59598-h/59598-h.htm
'Now let us look at the Trochilus legend, and trace how an African plover became changed into an American hummingbird. The story, first published by Herodotus, that some sort of bird enters the mouth of a Nile crocodile dozing on the sand with its jaws open, and picks bits of food from the palate and teeth, apparently to the reptile’s satisfaction, is not altogether untrue. The bird alluded to is the Egyptian plover, which closely resembles the common British lapwing; and there seems to be no doubt that something of the sort does really take place when crocodiles are lying with open mouth on the Nile bank, as they often do. This lapwing has a 61tall, pointed crest standing up like a spur on the top of its head, and this fact gives “point,” in more senses than one, to the extraordinary version of the Herodotus story in one of the old plays, The White Devil, by John Webster (1612), where an actor says:
“Stay, my lord! I’ll tell you a tale. The crocodile, which lives in the river Nilus, hath a worm breeds i’ the teeth of ’t, which puts it to extreme anguish: a little bird, no bigger than a wren, is barber-surgeon to this crocodile; flies into the jaws of ’t, picks out the worm, and brings present remedy. The fish, glad of ease, but ingrateful to her that did it, that the bird may not talk largely of her abroad for nonpayment, closeth her chaps, intending to swallow her, and so put her to perpetual silence. But nature, loathing such ingratitude, hath armed this bird with a quill or ***** on the head, top o’ the which wounds the crocodile i’ the mouth, forceth her open her bloody prison, and away flies the pretty tooth-picker from her cruel patient.”
A most curious series of mistakes has arisen around this matter. Linguists tell us that the common name among the ancient Greeks for a plover was trochilus (τροχίλος), and that this is the word used by Herodotus for his crocodile-bird. But in certain passages of his History of Animals Aristotle uses this word to designate a wren; it has been supposed that this was a copyist’s error, writing carelessly τροχίλος for ’ορχίλος, but it was repeated by Pliny in recounting what Herodotus had related, and this naturally led to the statement by some medieval compilers that the crocodile’s tooth-cleaner was a wren. This, however, is not the limit of the confusion, for when American hummingbirds became known in Europe, and were placed by some naturalists of the 17th century in the Linnæan genus (Trochilus) with the wrens, one writer at least, Paul Lucas, 1774 (if Brewer’s Handbook may be trusted), asserted that the hummingbird as well 62as the lapwing entered the jaws of Egyptian crocodiles—and that he had seen them do it!
This curious tissue of right and wrong was still further embroidered by somebody’s assertion that the diminutive attendant’s kindly purpose was “to pick from the teeth a little insect” that greatly annoyed the huge reptile. Even Tom Moore knew no better than to write in Lalla Rookh of
The puny bird that dares with pleasing hum
Within the crocodile’s stretched jaws to come.
The full humor of this will be perceived by those who remember that hummingbirds are exclusively American—not Oriental. Finally Linnæus confirmed all this mixture of mistakes by fastening the name Trochilidæ on the Hummingbird family.
Finally, John Josselyn, Gent., in his Rarities of New England, calls our American chimney-swift a “troculus,” and describes its nesting absurdly thus:
The troculus—a small bird, black and white, no bigger than a swallow, the points of whose feathers are sharp, which they stick into the sides of the chymney (to rest themselves, their legs being exceedingly short) where they breed in nests made like a swallow’s nest, but of a glewy substance; and which is not fastened to the chymney as a swallow’s nest, but hangs down the chymney by a clew-like string a yard long. They commonly have four or five young ones; and when they go away, which is much about the time that swallows used to depart, they never fail to throw down one of their young birds into the room by way of gratitude. I have more than once observed, that, against the ruin of the family, these birds will suddenly forsake the house, and come no more.