Ken Gerhard. Big Bird! Modern Sightings of Flying Monsters. CFZ Press, 2007.
In a book of old Staffordshire folklore by Charlotte Burne there is a record of a story from January 1879, of a man crossing the bridge across the Birmingham-Liverpool canal was terrified when a "strange black creature with great white eyes" sprang onto the back of his horse. He attacked it with his whip, but the whip went straight through it. A classic road ghost tale, variations of which can be found through the world, in which a ghost leaps onto the back of a horseman, an ancestor of modern tales of phantom hitchhikers. This ghost appears to have been given a name by a local policeman, the Man-Monkey.
As the story of the Man-Monkey cycled through local folklore, it appears to have modernised. Today there are 'eyewitnesses' to the Man-Monkey, now reconstructed as a typical hairy hominid. Many of these have come forward as a result of Nick Redfern's articles in the local press, and several seem to be rather strange characters, such as one used to meet on the fringes of UFO meetings. Others seem like your archetypal 'sober citizens', but their stories are equally incredible.
Redfern investigates these stories by, erm, listening to them. He seems to make no effort to find out whether such stories were print before his own articles, or to search the local newspapers for January 1879 for further details of the 1879 incident.
In some ways stories like these concentrate the mind, for of course there are no 'relict hominids' in Britain, something which Redfern realises, and therefor we are left either with 'supernatural' explanations, such as shape-shifting boggarts, which is what Redfern appears to favour, or psycho-social ones. The latter would explore these stories in terms of suggestion, road hallucinations probably associated with micro-REM, altered memories, the remembering of heard stories as personal experiences, and band wagon jumping, etc.
In some ways the same applies to the American reports of giant birds and wannbe pterodactyls reported by Ken Gerhard. Though the possibility of simple misperception and misidentification is quite a bit higher here, there is the same bizarre quality about many of these tales. The big birds are clearly not just regarded as paws-and-pelts (or feathers) animals, but as 'birds of ill omen', perhaps something in the region of harpies, or the "wicked birds of prey picking on bread crumb sins" out of Dylan's 'Gates of Eden'.