If you’re really keen, you might like to try identifying hogs by their natural markings. Now might be an ideal opportunity. It can be quite rewarding and sometimes makes a bit more sense of some of the behaviour. These are some tips which I put together a while back.
If you want a book to read about hogs, I recommend ‘Hedgehogs’ by Pat Morris. Try to get an up-to-date version. I think it has been revised at various times – originally written in 1983 so knowledge has moved on a bit since then. There are still one or two out of date things in my copy (2014) such as re. milk where the text seems slightly ambivalent, whereas nowadays it is generally accepted that hogs are lactose intolerant so shouldn’t be given milk at all. All they need to drink is water – so much easier, anyway!