JoAnne Skelly: Overrun with ground squirrels

Those pesky ground squirrels are out in force these days. I think they are on their second or third series of babies. I can tolerate them out in our field. However, when they dig under the house, it’s time to get serious about control, before they undermine the foundation. While there are 23 species and 119 subspecies of ground squirrels in the United States, the Belding ground squirrel is the most common problem in Nevada.

Ground squirrels eat plants, seeds, fruits, some insects, bark off bushes and trees, roots, birdseed and occasionally birds’ eggs and road kill. Tulip bulbs seem particularly delectable. They need little to no water, getting moisture from dew or the vegetation they eat.

These pests dig burrows that they occupy year after year. Each year they lengthen the tunnels and make their burrows more complex. There are numerous entrances to each tunnel and burrow. They hibernate in winter. The males emerge about 10 to 14 days ahead of the females. Breeding occurs shortly after they come out of hibernation within a three-week period. Gestation is 28 to 32 days and the young venture above ground at about seven weeks old. Five to eight young are born that live four to five years. In favorable years, there can be more than 100 squirrels per acre. Not only do they cause significant damage to home landscapes and gardens, they also transmit plague.

Squirrels can dig under fences even when the fencing material is buried several feet deep. Or they can climb over them. They are sometimes discouraged by wide areas kept free of vegetation. You can’t frighten them and repellents don’t work. Toxic baits are the best management method. Some baits kill quickly and others are slower-acting anti-coagulants. The latter require more bait and multiple feedings. Death is delayed with the anti-coagulants. Baiting for squirrels needs to be done very carefully. Application of poisons must follow label directions exactly to avoid killing non-target animals such as pets, livestock or predators of the squirrels directly or secondarily when an animal or bird finds and eats a corpse. Bait stations properly constructed are some of the safer ways of applying baits. Too little bait leads to bait shyness and ineffective control. Timing is critical to good control.

If you need specific control methods and diagrams on how to make a bait station, go to the Internet Center for Wildlife Damage Management website at http://icwdm.org/handbook/rodents/ro_b151.pdf.

JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension and may be reached at skellyj@unce.unr.edu or 887-2252.