great Londonist video describing them and tube map style graphic.
But even these resources don't show all of them - such as the less well known Beverly Brook Walk. This follows the river - or rather the brook - of that name from New Malden (*) to the Thames by Putney.
While on the map the brook pops out of the ground around Worcester Park this initial part is not included in the walk. And to be honest the route is a bit DIY in that it appears more of an idea to connect together various other walks rather than an integrated and signed path.
There was a noticeable absence of signs apart from when the walk crossed main roads, and even then the signs pointed directly across busy roads not where there was a pedestrian crossing, as if their numbers had been limited by budget.
So I'd suggest that if you walk you take a few key points and then make your own way alongside the river as you're as likely as not do ok. I wasn't entirely sure if this was right route though it matches this GPS track:
Beverley Brook Restoration Project.
Then there's the distinctly unglamorous South Circular to cross (and walk along for a bit), a confusion of commons (Barnes, Putney etc.) before the path sort of comes back together for the final push to the Thames and where I found that gun a few years ago.
In terms of wildlife, it is said that there are Kingfishers somewhere but I just saw the usual, such as geese and dogs being taken for walks:
So a nice walk though more a collection of existing tracks than (say) the clearly defined and connected Thames Path.
(*) I actually started from Raynes Park as the walk was slightly closer and there was only a tiny look at Beverley Brook before the Coombe Lane Flyover