BURROWING RODENTS GROUND SQUIRRELS SANTA CLARA COUNTY AGRICULTURAL OFFICE

BURROWING RODENTS GROUND SQUIRRELS SANTA CLARA COUNTY AGRICULTURAL OFFICE

GOPHERS & SQUIRRELS different life styles so different methods of controls (Traps & baits differ) Squirrels- white eye liners, upright ears More subtle: squirrels have more grey fur, less whiskers

SQUIRREL - DAMAGE Plant consumption Destruction of cables, irrigation pipe, fence, & building foundation Disturbed ground for invasive plants & mowing Plants and trees damaged Root girdling Erosion (channeling water run off) Disease vector : plague, rabies, salmonella, Lyme disease, leptospirosis & tularemia Undermine foundations Disease & pest vectors

SQUIRREL BIOLOGY ACTIVITY Hibernate in winter and summer Omnivorous Active during daylight Surface feeders Chart from Univ. of California Trapping for squirrels in the middle of summer may not be effective

ENDANGERED ANIMALS THAT USE SQUIRREL BURROWS BEING AWARE OF ENVIRONMENTAL HAZARDS Burrowing Owl Calif Tiger Salamander Calif Red Legged Frog San Joaquin Kit Fox we have the habitat, no known inhabitants

CONTROL HABITAT MODIFICATION - SQUIRRELS Remove brush and debris piles Fencing 2-3 feet deep in soil Good climbers seasonal shock wire along fence or sheet metal caps Putting up fence shade cloth 3 feet up the fence Removing food sources

CONTROL - REPELLENTS Castor Oil Repellent: limited effectiveness, in addition poisonous to humans and pets Sonic vibrations, moth balls, and Juicy Fruit Bubble gum: no evidence these work (& unregistered) Plaster of Paris - illegal Remember trapping/repelling are pest control & commercial pest control needs to be licensed CONTROL FLOODING Flooding can control rodent activity

CONTROL - DEEP TILLING/BURROW RIPPING 20 inches deep recommended 12 inch shanks had no effect Unsuitable for rocky areas

CONTROL TRAPS Gophers: Macabee, Cinch, Gophinator, Death-Klutch Squirrels Macabee, Box & tunnel traps, Conibear, Live traps Pro: Effective Environmental Impact is small Cons: Trap shyness Time Consuming digging & checking traps

CONTROL SETTING TRAPS Monitor & Identify main burrow Dig & set trap Check in 2 days move traps Wear leather gloves to wind/ set traps

CONTROL EXPLOSIVE DEVICE Propane & oxygen mixture ignited Destroys burrows (preventing reinfestation) Potential turf destruction Potential fire risk Loud Bystander risk Studies are not favorable 30-50% success rate

CONTROL FUMIGANTS INCENDIARY DEVICES Recent study: 62-86% control Risk of fire in dry conditions Risk to other species using burrows Tunnels can be quickly sealed During hibernation/aestivation Requires persistence Road flares are not legal

CONTROL FUMIGANTS CARBON MONOXIDE Study of 3 devices at 5 sites: -7% to 100% control Tunnels can be quickly sealed Road flares & car exhaust are not legal in California must use registered device No use reporting

CONTROL TUNNEL FUMIGANTS- CARBON DIOXIDE Current legal product Rat Ice labeled for burrowing rats Dry Ice, 10 foot buffer to habitable areas As long as other label instructions are followed other pests can be treated Ground squirrel & gopher control ARE LEGAL uses Other Bait labels are specific to species and bait cannot be used on unlabeled pests Other Carbon Dioxide devices may not be legal For example CO2 canisters used for soda machines are NOT legal

CONTROL FUMIGANTS ALUMINUM PHOSPHIDE Labeling requirements FMP Signs Buffer zones SCBA or monitor device Cannot be used on residential property Restricted Material requirements Recent study 97-100% control

CONTROL SHOOTING Lead bullets - 2019 no longer allowed Limited in urban areas Labor intensive

CONTROL - BAITS Not as labor intensive as traps Bait Shyness Secondary poisoning Bait Placement and timing crucial for effectiveness

ACUTE TOXICANTS ONE TIME FEEDING CONTROL - BAITS Strychnine.5%, used below ground, natural substance in seeds, affects nerve cells Zinc Phosphide, turns to phosphide gas with the presence of water & acid, prevents cells from producing energy

CONTROL - BAITS Pesticide permits are required if product is only labeled for agricultural areas. No permit is required if product label has residential instructions. Restricted material bait, Aluminum phosphide, always requires a permit Baits can only be used on labeled species

1 ST GENERATION ANTICOAGULANTS Diphacinone and chlorophacinone are first generation anticoagulant. Breakdown of the compound occurs naturally with sunlight and soil microbial action. It requires multiple feedings for effective control and breaks down relatively rapidly in animal tissues when compared to second generation anticoagulants.

2 ND GENERATION ANTICOAGULANTS Second generation anticoagulants are intended for a single feeding. Brodifacoum, Bromadialone or Difethialone Found in rat baits, not labeled for squirrels or gophers. Stored in the body and has a high secondary killing risk.

BAIT STATIONS SQUIRRELS Commercial or homemade Must be affixed

BAIT ZINC PHOSPHIDE ACUTE TOXICANTS SINGLE FEEDING (4-6 GRAINS) Less expensive ZP has minimal no secondary risks (turns to gas) Potential bait shyness Some labels allow broadcast treatment Cannot be used around buildings No antidote Pre baiting necessary, low acceptance Another acute toxicant, Strychnine, currently not labeled for squirrels Gophers only

BROADCAST BAIT ZINC PHOSPHIDE Read the label for distribution amounts Pre-bait highly recommended!! Limited situations

TUNNEL BAIT ZINC PHOSPHIDE Hand bait through mound Or Use a probe to find tunnels Spoon or funnel to place bait Ensure no bait is outside the tunnel Plug hole Check for new mounds & bodies

TREATMENT PLAN Ground Squirrels Monitor Large population No endangered species Chemical Treatment Plan Zinc phosphide in autumn Aluminum phosphide in spring Anticoagulant bait stations or trapping in late spring thru early summer Sensitive Site PCB posted a habitat restoration area sign and fences

QUESTIONS? SANTA CLARA COUNTY AGRICULTURAL OFFICE 408.918.4600