Why are squirrels eagerly digging up a Berkeley lawn?
DEAT JOAN >> I just returned from throwing a baseball at a squirrel voraciously digging deep into my once beautiful lawn.
I presumed at first they were digging for nuts they buried for the winter. The problem with that theory is that, if they were buried earlier, I would have then noticed digging during the burial process.
This is the very first time in 20-plus years squirrels have ever dug up our lawn, so I wonder why they are digging now and what they are looking for. Is this a seasonal phenomenon?
They’ve been at it for two weeks. I’ve tried cayenne pepper spray, rat poison and my urine, to no avail. Please, help if you can.
— Dennis Smith, Berkeley
DEAT DENNIU >> Assuming your squirrels are of the tree variety and not the ground type, they are digging holes in the lawn for nut storage or caching, which occurs mostly in the autumn when food is plentiful.
That’s really the only reason tree squirrels dig, to store or recover food.
They aren’t interested in grubs or other insects that might be in your lawn. The holes are relatively shallow — 1 to 2 inches deep — and are covered with the excavated soil. Researchers at UC Berkeley have learned that squirrels use something called spatial chunking to remember, generally, where they have buried their nuts. The squirrels also group the nuts by type, size and even nutritional value.
That doesn’t really help you with your problem, but I thought you might have more appreciation for the squirrels if you knew how truly clever they are.
Squirrels also are — how should I say this? — a bunch of thieves. If one sees a squirrel stashing a nut, it will go dig it up and put it with its own collection. As a deterrent, squirrels will sometimes pretend to bury a nut, going through the bother of digging the hole and then covering it up. When a thief tries to steal the nut, it finds the cupboard bare.
It could be that the squirrels are playing this game in your yard. The thieves are looking for nuts and not bothering to disguise the scene of the crime, leaving empty holes in your yard.
It is possible for the squirrels to hide nuts in your lawn without you noticing. Usually the damage is minor and not worth the effort of trying to keep the squirrels off the lawn, which is near impossible anyway.
Not much works against them, but you could try leaving some unplanted pots around and hope they’ll use those instead. Lawns usually are too large to adequately protect by using barriers or things like hot peppers or rags soaked in ammonia. And predator pee is more effective than human urine. Chucking baseballs at them might be your best bet, as long as they don’t start batting them back at you.
If you’re finding large holes with tunnels, then you likely have ground squirrels, and keeping them out will require fencing and shock wires.
Please don’t use poisons on any squirrels. Poisons kill very painfully, and the poison gets passed on to any creature that might eat them.