Toads are crossing roads, full of spawn waiting to be born.
They're slowly plodding back to the ponds where they developed from egg to toadlet. The best time to see them is at night. Take a torch with you to the edge of a pond and you might see a bunch of males, all clambering over each other as they try to mate with a single female.
Also keep an eye out on the roads for a sign showing a toad inside a red triangle. When surveyed by the AA, many motorists said they thought it meant they were approaching a French restaurant. In fact it's a warning that you're nearing a 'toad crossing point'.
People often help out at these locations to ensure the toads get safely from one side of the road to their breeding pond on the other. The toads will have been making this journey for many years, possibly before the road was built.