Did you notice the foxes and hares decreased during a specific period, or has it been gradual?
Your neighbors are right - logging and development are really the main causes. When forests are cut down, animals simply have nowhere to live and find food, so they either move to other places or their population declines. The situation with foxes is especially sad because they need large territories for hunting.
You can actually make some changes, but it works slowly. If there are still forest patches left in your region, it makes sense to protect them - plant new trees, prevent existing ones from being cut down. Many regions create special protected areas specifically for this. Even a small forest, if left alone, will recover over time and animals will come back. I saw this happen at Lake Olkhon - when people stopped actively hunting there and started taking care of the forest, wild animals began appearing more often.
The forest won't disappear completely if you take care of it, but without effort it will definitely only get worse. It's worth thinking about whether there are any public organizations in your area working on forest restoration - they often look for volunteers.