Q: Is there any way that I can prevent the squirrels from raiding my avocado tree? What’s the sense in trying to grow anything if the squirrels take all?
A: Ground squirrels are the bane of every gardener’s existence. If you have a fruit tree, they will strip it bare in an afternoon, taking a single bite out of every single fruit and tossing it on the ground. They can destroy a vegetable garden just as quickly. One of my neighbors saw a squirrel actually rolling a cantaloupe out of his garden. These are not the cute, fluffy-tailed tree squirrels of the northeast. They are bushy-tailed rats.
The California ground squirrel thrives in residential areas that are surrounded by open fields. Grassy areas with good visibility enable them to monitor for the presence of predators. Unlike tree squirrels, ground squirrels will retreat to their burrows when threatened. These burrow systems can be quite extensive and can reach as deep as six feet. Their digging is as destructive as their eating habits. If they burrow near trees, they can damage roots and weaken or kill the tree. They will gnaw on irrigation boxes, sprinkler heads, and drip lines. They will also gnaw the bark off trees, often killing them by girdling.
As if all this wasn’t bad enough, they also carry fleas that harbor bubonic plague. They are susceptible to plague as well, and entire colonies have been wiped out by the disease.
Ground squirrels are classified as a non-game animal in California, which means they can be controlled by any legal, humane means. (Tree squirrels, on the other hand, are considered game animals and can only be hunted with a permit.) No permit is needed for a landowner or tenant who wishes to control ground squirrels.
Fumigation is one of the most effective means of controlling ground squirrels, followed by toxic bait. When considering fumigation, you should be certain that the target burrow is occupied by ground squirrels. Many other (nice) animals live in abandoned squirrel burrows, including kangaroo rats, kit foxes, toads, lizards, and burrowing owls.
Fumigation is most effective in the spring, after rainy season. Gas is less likely to escape when the ground is still a bit moist. Early spring fumigation also kills the squirrels before they have a chance to reproduce.
Later in the season, toxic bait is more effective. Use bait with diphacinone, which is a first-generation rodenticide. This type of poison requires multiple feedings in order to work, so they are less harmful to non-target wildlife. This bait is applied using a bait station, which prevents access by non-target animals. Do not use old bait that might be the outdated second-generation rodenticide. These toxins work quickly, but they have had a devastating effect on non-target wildlife and have recently been banned.
An energetic dog can keep ground squirrels out of a small area but are no match if there’s a huge population in an adjacent field.
Electronic repellent devices are not effective in keeping squirrels away.
Burrow exploding devices, although highly gratifying and entertaining, are not recommended for residential use.
Source: www.mercurynews.com