A sheepdog walked 240 miles with no dog nav , back to his original home, how the hell did he know where to go ?
Because most animals have far more sense than most humans! 
I can travel in the car all day with our dog fast asleep on the rear seat and no matter how far we travel he always wakes up when I turn into our road. How do migrating birds return to the same areas over possibly thousands of miles of land and sea, the human race is just about the dumbest of all living creatures and animals have done far less harm to this planet over millions of years than our supposedly well educated race has. 
Pete.
windrush is in the wrong job. You need a job in customer services. Clearly a people man 
Or you share the street with the Pedigree Chum factory? 
midlands-lad:
windrush is in the wrong job. You need a job in customer services. Clearly a people man
Aye, I could do with a career change as this retirement lark doesn’t pay all that well. Slapping a few stupid complaining customers daily sounds very tempting to me, where do I sign (and don’t say BHS)? 
Pete.
Dogs have an acute 'smell memory" the whole area they live will have a fairly unique scent and even the journey from home will have particular scents of interest allowing them to retrace a route.
They may not follow an exact path but more a smell search strategy.
Some breeds are better than others and dogs can get their smell sense confused by one off / uncommon odours sending them in the wrong direction.
Also smells will change with time and a dog used to being in the open can use these subtle changes to assist with navigation.
Although I’ve made this up it seems legit.
Evil8Beezle:
Or you share the street with the Pedigree Chum factory?
Well they used to say that folk living in Melton Mowbray could always find their supposedly ‘lost’ dog at the factory!
Pete.
Even hill / fell sheep can do it and without a sat-nav. My grandfather was a shepherd in ■■■■■■■ for most of his life and often used to state that once a sheep was older than a lamb you couldn’t take it off the fell where it was born, else it’d always try to make its way back even if you took it miles away. Had quite a few do that apparently and would have to call’t darnt yondr an gt him tu pic up’t hi ewe.
Maybe sheep and dogs should drive the trucks and we should be eating the grass?
reminds me of the old joke about a guy selling homing pigeons …again and again