Hi Joanna, the only thing that works for me is chicken wire and it has to go into ground on the edge for about 2-3 inches to have any effect. They are digging around though! I just do not want to bother with extra efforts and will not buy any tulips if I can help it ( tendency to forget good intentions , anyone ?
). Chicken poop fertilizer was useless after a week. Trying to cover soil with some limestone screening and see how it works... Chipmunks nest? Maybe watering it on regular basis ? I am sure that they won't like it ... it just depends how long are those tunnels and how waterproof is your foundation ...