Excerpt from the book Animals Evolution Avoided. This book describes 40 animals that ought to exist but don’t, because I made them up.
The Green Fox lived in the lowlands of Scotland before the last ice age where its green coat allowed it to hunt freely in the fields and grasslands of the region. This natural camouflage meant the fox was able to pick off its prey with ease and the numbers of green foxes proliferated to such an extent that many foxes had to move further and further away to catch prey.
The longer journey time spent on hunts meant an increase in pressure on the leg joints of the foxes and soon the species began to suffer from arthritic hips and ankle joints. Scientists have found evidence of this condition in skeletons of green foxes discovered in the Melrose and Selkirk areas of the Scottish Borders.
With their ability to walk and sprint after prey severely depleted the number of green foxes began to fall. As a result, the numbers of the prey typically caught by foxes, such as rabbits, songbirds, and rats began to rebound. The increase in prey would have led to the green fox’s regeneration, if the last Ice Age hadn’t come along and spoiled everything.
With the increased amounts of ice and snow and with glaciers cutting through the countryside, the Scottish lowlands became predominately white. The green foxes natural colouring now worked against them. Prey could see them coming for miles and kept out of their way. The foxes tried to move south towards greener pastures, but their arthritic joints counted against them and it’s believed the Green Fox species died out about 12,000 years ago.
However, it is entirely possible that a strain of the Green Fox species did make it through to the southern part of England, where the glaciers didn’t reach, and where prey was plentiful. Over time their coats may have changed to fit in with their surroundings and some of the foxes seen today in most of the UK could be descended from Green Foxes who made that epic migration 12,000 years ago.