If your plants are drying out & you can’t figure out why, check your drip line for squirrel damage. They seem to love to snack on it. Maybe they’re just bored. Who knows what goes on in a squirrel’s mind?
If you fix one hole, test the line for more damage. They’ve almost certainly nibbled in a few spots. As far as preventative maintenance, consider adding a few inches of bark mulch. Out of sight, out of…..a squirrel’s teeth.