Arming yourself against a ground squirrel invasion

DEAR JOAN >> Since the water district has turned over maintenance of the portion of the Santa Teresa hills behind my house to the city of San Jose, we have been invaded by hordes of ground squirrels.

Has San Jose ceased exterminating ground squirrels, and do the stakes that emit highpitched sounds really keep the squirrels away? — Tom Watts, San Jose DEAR TOM >> You have my deepest sympathy on your invasion.

Ground squirrels, which are native to California, are, I believe, the most destructive of creatures that we try to coexist with. Of course, I do have a bias.

When I founded a demonstration garden with the Contra Costa County Master Gardeners in 2009, the ground squirrels thought I had opened up a free buffet. They ate newly planted crops to the ground and refused to share.

We finally gained the upper hand by building an underground fence 2 feet down, and topping it with a 6-foothigh above-ground fence, which was then fitted with a shock wire. That is the only proven method for keeping ground squirrels out of an area they desperately want to get into.

Those sonic devices that claim to ward off gophers and moles with an electronic buzzing sound have not proven helpful, especially when you’re dealing with large numbers of ground squirrels.

We have had luck with a device that looks a lot like the buzzing stakes, but these telegraph danger, emitting a noise that sounds like an animal in distress. We’ve used them to keep ground squirrels from burrowing under our storage sheds at the garden. These stakes are marketed under a few different names, including Molemax. They come two to a package and sell for about $25.

San Jose, like most cities, has a pest-abatement program for city parks, but not in undeveloped areas or on private property. It is used when public safety or infrastructure are threatened. Ground squirrel tunneling can cause uneven surfaces and open holes, which can be a safety issue for people walking there, and those tunnels have been known to damage sidewalks, buildings and water, sewage and utility lines.

DEAR JOAN >> A pigeon laid two eggs on my metal plant shelf, but then abandoned them.

Do you know why? — Rose Marcus, Bay Area DEAR ROSE >> There are several reasons a bird — any bird — will abandon her nest. The first one is perhaps the most obvious: Something happened to the bird.

Life can be hard for birds. They have a lot of predators after them, as well as human-contrived obstacles. With some birds, it doesn’t even have to be the mother that gets killed. Pigeons and mourning doves, to name two, co-parent, taking turns sitting on the eggs and providing food for the hatchlings. They just can’t make it alone.

You didn’t say how long the bird stayed with the eggs. Very young or very old birds can lay infertile eggs that won’t hatch. The mom will stick with them for a while, but when it becomes obvious the eggs aren’t hatching, she moves on.

Another reason for nest abandonment is a predator or nosy neighbor that frightens the mother away.