Squirrels keep ruining my efforts to grow a lush lawn by digging spiral-like shallow holes in the grass.
Recently I raked thatch and dry patches of grass in a thin burnt part of the lawn that I intend to re-seed but before I could get to it, squirrels dug up the whole patch.
The lawn is mostly shady ( narrow garden with many shrubs and trees ) but a few spots get full sun. The squirrels dig up lawn all over. I flip the chunks of grass back and press them in but it spoils the grass which already grows rather thin because of the shade. The soil is excellent , black and loamy, Ontario lakebed, in Toronto.
Thank you for contacting Toronto master gardeners.
From your note I am unsure if you have seen the squirrels digging or if it is at night in which case it could be skunks and raccoons. If it is at night then it may be the skunks and racoons letting you know you have a grub problem. If so you probably have noticed the grubs while digging and preparing the areas of lawn you are trying to fix. here is a link that describes the Grub problem and various solutions.
If it is Squirrels then they are either burying food or looking for seeds. Getting rid of squirrels in Toronto is not a reasonable expectation. Take one away and it will quickly be replaced. There are repellents available but the reviews of these products online are mixed. The only true deterrent I have seen is a dog.
To protect an area you are working on you can always lay down chicken wire which stops the squirrels from digging in an area while allowing seeds to germinate and plants to grow.
Another solution is to use alternate ground covers rather than grass. This can include things from various mulches and stonework to plants that grow well and can tolerate some traffic. Here is a site that lists some of the more popular ground cover choices in Ontario.
Good luck and I hope this helps.