Stepping Stone Biotopes.
A biotope (habitat) is a place where life exists, it can be as small as a window box or rotten log or can involve many hectares of land.
The illustration Matt has provided demonstrates stepping stone biotopes, the text is in German but it is self explanitory, for examples he has used four species, the Hermit Beetle with a radius or range of only 400 metres, the Stag Beetle with a radius of 2 km and the Woodpecker with a radius of 50 km and the Lions Mane Mushroom which can spread spores over hundreds of kms.
We can see at once from the illustration that the Hermit Beetle can never escape the biotope it is in if that biotope is cut off from the surrounding countryside. The Stag Beetle can escape provided that the next biotope is near enough. The Woodpecker with a 50 km radius is able to escape to another area.The Lions Mane Mushroom may have a large radius but would depend on wind direction and strength and has no control over it's destination.
If there are species on Middlewick with a radius simular to the Hermit Beetle they could cease to exist in the event of any development.
This brings us to the importance of biotope net working, they need to be connected by hedges and swathes of untouched land beetween them, this way species with a small radius can work their way along such corridors to the next area where they can exist, albeit at 400 metres at a time. This is especially important for rare creatures such as Dormice as they will not cross open ground. It is with some sense of irony I say the M25 is an excellent example of networking corridors with wide untouched verges for miles connecting one biotope to the next.