It depends what you include as ‘rewilded’.
There are enormous areas of North America that were clear felled and even cultivated between 1700 and 1900, which are now dense, largely wild forest.
There are also extensive areas of southern, Mediterranean Europe that were quite intensively cultivated up until the late 20th century, and which are now reverting to oak scrub and maquis.
Or there are absolutely vast areas of ex-Eastern bloc countries that are reverting quite rapidly to woodland. The most extreme is Bulgaria, which is a case study in post-industrial woodland expansion.
Nearer to home, the Central Belt of Scotland is covered in patches of woodland, grassland and rough pasture in areas that were very heavily industrialised. In the Edinburgh area alone, I can think of 10-15 areas of quite biodiversity rich woodland that were industrial areas within the last 80 years.
However, these are seldom included when people talk about rewilding. Instead, people tend to mean a very narrow subset of post-agricultural land use changes involving aggressive management to deliberately recreate some sort of Pleistocene-lite environment. Even here, there are examples that have worked, have worked well, and appear to be sustaining that success over at least 20-30 year time scales. The Biesbosch in the Netherlands is a good example. Carrifran woodland in Scotland is arguably another.
It’s worth bearing in mind that the term ‘rewilding’ has only been in common use for maybe 10 years. That’s really too short a time to make any judgements about ecological success.
Well done
@Mungo, you fared better than my wildlife group associates
One of the most interesting places is around the site of the Chernobyl incident, wildlife has apparently thrived since humans were forced to vacate the area - but that wasn't the intention of that incident and it's a fortunately rare (unique?) case given that it was such a carastrophic failure of humans which kicked the whole thing off
Most of the more successful rewilding examples, of which I have any depth of knowledge, required support (usually long-term) from central funding, the areas weren't entirely abandoned & left to go their own way
The regrown clear-fell or brwonfield sites weren't usually consciously rewilded either, any "return to nature" was typically an after effect of their abandonment by humans
And
Where areas are abandoned by humans and left to nature it can be argued that they are unlikely to fully return to their original primeval state anyway and probably not without a lot of human effort in the early years at least
I'm involved in a couple of projects here in West London, one of which which has appeared on local & national news as a "success story" - which it is in a way - but it only got going and can only be sustained via a combination of grants, charitable donations & volunteer support. Remove any of those and the whole project will fold, plus it's not an entirely self-sustaining or self-managing ecosystem anyway. Non-native species were removed and must be kept at bay plus the target species has to be managed - ie excess population is trapped and taken to other sites. Thus the area, valuable though it is, will never be truly rewilded in my opinion
Maybe I'm nit-picking though, my cynical disposition showing itself again I suppose
But
I like to think that by my, admittedly limited, participation in such work I'm not a total knee-jerk critic of rewilding (maybe I kid myself)
I just think that too many of those who are self-declared rewilders are deluded/misguided/ill-informed and that the projects they desire are too-often doomed to failure from the start - those who recently abandoned those unfortunate Lynx for example