How to Manage Pests
UC Pest Management Guidelines
Two introduced and one native tree squirrel species are occasional pests in tree fruit and nut orchards.
Eastern fox squirrels are reddish brown in color and are the primary tree squirrel pest. They reproduce once or twice per year with litters occurring between January and April and between July and September.
Eastern gray squirrels are somewhat smaller than fox squirrels and lack their reddish-brown coloration. Eastern gray squirrels can also bear two litters per year, one in late winter, and one in late summer.
Western gray squirrels are large silver-gray squirrels with a peppered back and white stomach. As with the other tree squirrel species, they can have two litters per year.
Tree squirrels typically live in woody areas along creeks and river banks from where they can invade orchards. The western gray squirrel is found up to elevations greater than 5,000 feet except in desert areas. This species is fairly common where found, but is often out-competed by the eastern fox squirrel. The eastern fox squirrel is more numerous than the eastern gray squirrel. Regions with large numbers of eastern fox squirrels include agricultural and natural areas around Fresno and Sacramento, as well as coastal areas south of San Francisco as far as Los Angeles County. The eastern gray squirrel is found in localized pockets in the San Francisco Bay Area, the San Joaquin Valley, and Calaveras and San Joaquin counties.
Tree squirrels can cause substantial nut loss due to their feeding and hoarding activities. They also occasionally damage fruit crops and are known to strip bark from trees sometimes causing severe damage. As with all rodents, they can gnaw on irrigation pipe, potentially causing water and monetary losses to growers.
Relatively few options exist for controlling tree squirrels.
When possible, shooting can be effective at removing tree squirrels from orchards as well. A .22 caliber rifle or high-powered air rifle is the best option, although shotguns can be effective as well. Keep in mind that lead ammunition is no longer allowed in California condor range, and will be completely banned starting 2019. Non-lead ammunition is typically more expensive and may not be available depending on the caliber of gun used. Additional information on this lead ban can be found the California Department of Fish and Game website.
You must have a depredation permit from California Department of Fish and Wildlife to trap or shoot eastern and western gray squirrels; this permit is not required for the eastern fox squirrel. However, if shooting during the tree squirrel hunting season, no depredation permit is usually required as long as all hunting regulations are adhered to, although various regional laws may prohibit this as well. It is best to check with local authorities before shooting tree squirrels to ensure that all local regulations and ordnances are followed.
UC IPM Pest Management Guidelines:
UC ANR Publication 3471
R. A. Baldwin, Department of Wildlife, Fish, and Conservation Biology, UC Davis