Regarding the colouration of feral cats I have a theory.

When one looks at feral cats in an urban environment they look much like the cats what we would find in our homes, often being tortoiseshell or otherwise having large portions of white or spots.

Now, when they are seen in more wilder environments they seem to be tabby, ginger and black but mostly tabby and black. This makes sense, in the wilderness environmental stresses would dictate that the best suited to this new environment would survive and pass on their genes. A tabby cat is particularly suitable to hunting in the Australian environment whereas a white one would stick out quite a lot. Black is quite noticeable too but it would be less so in the dark, cats are specialists so within a population some will predominately hunt certain kinds of prey while others will hunt different prey again, the time they hunt also varies.

But why then are these large cats all black in the wild and not tabby? I would conjecture that either the Black cat hunting at night enables it to hunt larger prey making the cat bigger, or that the cat is able to hunt more prey at night and this makes it bigger though I don't fully support this theory as predators tend to adapt size to what they prey on and factors like that, not how much of it they can get. Animals adapt to environmental pressure, an animal might develop the ability to eat large game so that they can target a niche that others cannot but evolving to eat more of the same game makes little sense, they would be more likely to remain small but have larger populations or smaller ranges.