vertebrate pests rats, house mice, pocket gophers, ground squirrels, tree squirrels, moles, rabbits...

Vertebrate Pests

Rats, House Mice, Pocket Gophers, Ground Squirrels, Tree Squirrels,

Moles, Rabbits and Bunnies, Deer, Pigeons, European Starlings, Etc.

Rats

There are two common rats in Southern California

The roof rat (Rattus rattus) And the Norwegian rat (Rattus

norvegicus)Rats are mostly nocturnalPoor eye sight is made up for with a keen

sense hearing, smell, taste and touch

Roof Rat

Rattus rattusSmaller than Norway ratsSometimes called black ratsTails are longer than combined head and

body lengthAgile climbers and good jumpers making

them more difficult to exclude

Roof Rat

Nests are usually above ground in shrubs and trees, and dense vegetation

In buildings they are found in enclosed, elevated spaces – cabinets, attics, false ceilings, etc

Roof rats tend to be found in the warmer more coastal regions

Norwegian Rat

Roof Rat

Roof Rat Distribution

Norway Rat

Rattus norvegicusA.K.A. brown rats or sewer ratsStocky bodiedBurrows along foundations, under debris

piles, wood piles, or other moist areasIndoors – usually found in basements or

at the ground floorFound in all 48 contiguous states

Norway Rat

Rat Comparisons

Dropping Comparison

Spotting Infestations

Droppings around dog or cat dishes or pet food storage containers

Noises coming from the attic just after dusk

Remnants of rat nests in firewood stacks


Pets bringing home dead rat carcassesEvidence rodents are feeding on fruits

and nuts that are in your yard or falling from the trees in your yard

Burrows among plants or damaged vegetables when working in the garden


Rats traveling along utility lines or on the tops of fences at dusk or soon after

Rat nests behind boxes or in drawers in the garage

Smudge marks caused by the rats rubbing their fur against beams, rafters, pipes, and walls


Burrows beneath compost piles or beneath garbage cans

Droppings in your recycling binsDrowned rats in swimming pools or

hot tubs Evidence of something digging under

garden tool sheds or doghouses

Rat Management

There three commonly used methods of controlling rat problems

SanitationBuilding construction and rodent proofingPopulation control – trapping and toxic

baits

Sanitation

Areas should be kept clear of trash and debris

Food sources should be removed Pet food should never be left out over

nightStorage containers should be tightly

sealedReduce or remove overgrown vegetation

Construction & Rodent Proofing

One of the most effective means of rodent control is exclusion – “build them out”

Seal all cracks or openings larger than 1/4”

Make certain doors, windows and screens fit securely

Rodent-Proofing Your Home

Repair or replace damaged ventilation screen around the foundation and under eaves

Provide a tight fitting cover for the crawl space

Seal all openings around pipes, cables, and wires that enter through walls or the foundation


Be sure all windows that can be opened are screened and that the screens are in good condition

Cover all chimneys with a spark arresterMake sure internal screens on roof and

attic air vents are in good repair


Cover rooftop plumbing vent pipes in excess of 2 inches in diameter with screens over their tops

Make sure all exterior doors are tight fitting and weatherproofed at the bottom

Seal gaps beneath garage doors with a gasket or weather-stripping.


Install self-closing exits or screening to clothes dryer vents to the outside

Remember that pet doors into the house or garage provide an easy entrance for rodents

Keep side doors to the garage closed, especially at night

Population Control

Limiting food sources and habitat can be an effective means of control

Periodically it becomes necessary to physically reduce the population

Bait stations are an effective means of outdoor control

Trapping is an effective means of indoor control

Snap Traps

Good for indoor use – in and under cabinets, sheds, etc.

Snap traps offer positive results

They are relatively safe and effective

Bait Stations

Some are designed for indoor useMost are for outdoor useToxic baits are put out of reach from

other animals within the bait stations

Bait Stations

The House Mouse

Mus musculus Highly troublesome pest nation wideThrives under a variety of conditions Found in and around homes and

commercial buildings, open fields and agricultural lands

The House Mouse

Mus musculus House Mouse

House Mice

Capable of causing large amounts of damage

Mice consume and contaminate human food supplies and animal and pet feed

Mice can transmit pathogensThey have not been found to transmit

hantavirus

House Mice

Mice are small rodentsWeight of about 1/2 ounceColor is light brown to gray5-1/2” to 7-1/2” long including a 3” to 4”

tailHouse mice are typically nocturnal

Mouse Signs

Mice infestations are typically recognized by:

DroppingsFresh gnaw marksTracksNests – finely shredded paper and other

fibrous materialsNests are typically found in secluded,

sheltered areas

House Mice

House mice often live in close association to humans

They are excellent climbersCapable of running up any rough vertical

surfaceThey can jump as high as 12”And can squeeze through openings

slightly larger than 1/4”

Prolific Little Rascals

House mice can have 5 to 10 litters per year

With 5 to 6 young per litterHouse mice reach reproductive maturity

in 6 to 10 weeksThe average life span is 9 to 12 months

Controls

SanitationExclusionTrapping or baiting becomes necessary

when infestations occurSnap traps or sticky trapsBait stations – toxic baits

Hantavirus Vectors

White-Footed Mouse Peromyscus maniculatus

Deer Mouse Peromyscus leucopus

Pocket Gophers

Thomomys species5 species occur in CaliforniaBurrowing rodentsNamed for fur-lined external cheek

pouchesThey are physically well equipped for

digging and burrowing

Pocket Gophers

External Cheek

Pouches

Pocket Gophers

Pocket gophers have short, fine brown furs that resists caking mud

Small eyes and large earsLarge incisor teeth6” to 10” longPowerful front-quarters with large claws

on front pawsWell suited for digging

Claws & Teeth

Gopher Habitat

Pocket gophers are typically found underground

Occasionally seen feeding aboveground or pushing soil from burrows

Activity is indicated by large, crescent-shaped mounds of fresh soil

The tunnel is plugged with soil The plug is offset from the center of the

mound

Pocket Gopher Mounds

Tunnel Systems

Tunnels appear regularly in irrigated areasNon-irrigated areas activity in fall – springBurrow systems can cover as much as 2,000

sq. ft.Tunnels 2-1/2” to 3-1/2” dia. – 6” to 12”

deepNests and storage galleries as deep as 6’Short, sloping tunnels connect tunnels to

surface – used to evacuate soil

Tunnel Systems

Pocket Gophers

Do not hibernateActive at all hours Typically solitary except when breedingReach sexual maturity in about 1 yearLife span is about 3 yearsFemales have up to 3 litter per year in

irrigated areasTypically only 1 litter in non-irrigated

areas fall - spring

Feed Holes

Feed holes are usually unplugged Vegetation is clipped around the hole

Pocket Gopher Damage

Pocket gophers feed on various landscape plants, roots and underground fleshy portions of plants

Chewing damage to plastic irrigation pipes and sprinkler heads

Tunnels can divert irrigation and cause erosion

Controls

Probing is used to find main tunnelsTrapping and baiting of main tunnelsVarious trap types are usedTraps are placed in opposing directions

in main tunnelsPlacement also occurs at the lateral

tunnels

Tunnel Probes & Probing

Tunnel Probe

Probing a Tunnel

Pocket Gopher Traps

Trap Placements

Toxic Baits

Strictly follow label directions

Requires proper placement

Exclusion

Bury hardware cloth or poultry wire 2’ deep and 1’ above ground

Use 6” to 8” of 1” gravel around irrigation pipes and utility vaults

Fumigation

Rarely effectiveRequires persistence

Moles

Scapanus speciesSmall insectivorous mammalsFound in all but the driest areas of

CaliforniaCreates a large network of shallow

interconnecting tunnelsFeeds on worms, insects, etcOccasionally feeds on bulbs, roots and

other plant materials

Moles

Stout, heavy-bodied animalShort, velvety dark colored furStrong forelimbs with large spade-like

front pawsShort, bare pointed snoutsEars are not visibleEyes are poorly developed

Mole Damage

Most damage is caused by dislodging plants

Unsightly mounds and ridges in lawns cause undermining

Mounds are circular and inline over tunnels

Mole Mounds

Mole Ridges

Controls

TrappingMole traps differ from pocket gopher

trapsScissor-jaw traps Harpoon traps

ExclusionToxic baits – not very effectiveEliminating food sources - insecticides

Mole Traps

Scissor-Jaw Trap

Harpoon Trap

California Ground Squirrels

Spermophilus beecheyiFound in nearly all regions of CaliforniaBodies are 9” to 11” long with thick,

bushy tailsBrownish-gray color with white specks

along the backCapable of climbing treesUsually retreat to burrows when

frightened

Habitat

Disturbed areas, roadsides, ditch-banks, fence rows, around buildings and edges of field crops

Large colonies of several dozen inhabitants

Tunnels can be 5’ to 30’ in length2’ to 4’ deepBurrows typically have more than one

openingFeeds within 75 yards of tunnel

openings

Burrows


Typically active through the dayMost hibernate in winter except in mild

areasIn hottest times adults can become

inactive for periods of 2 weeks or more Breed once per year7 to 8 young per litterBreeding season in Southern California

begins in December

Damage

Undermine foundationsCause slope failuresTunneling is danger to livestock,

horseback ridersDisease carriers particularly in areas

where squirrel populations are high

Bubonic Plague

Known carriers of the fleas that carry bubonic plague

Ground squirrels are susceptible to the plague

Never handle dead ground squirrelsIf ground squirrels seem to have died for

no apparent reason authorities should be notified

Controls

Various trapsToxic bait stationsFumigationHabitat modificationWhere allowed - shooting

Box Trap

Runway Traps

Conibear Trap

Bait Box

PVC Bait Station

Fumigation

Control Schedule

Red Fox Squirrel

Sciurus nigerA.K.A Eastern Fox SquirrelIntroduced species form the eastern

United StatesEstablished in most cities in CaliforniaAn established pest in commercial cropsRapid climbers escaping into treesNests in trees, attic spaces, etc.

Red Fox Squirrel

10” to 12” longBrownish orange-red furLong bushy tailsActive during the dayForages on ground and in treesFeeds on insects, fungi, pine nuts, acorns

and other seeds, whatever handouts they receive, eggs and young birds

Red Fox Squirrel

Damage

Damage to buildings and gardensDamage to fruits, nuts, various crop and

ornamental plantsDig in turf areas to hide nutsGnaw through phone cablesGnaw into irrigation pipes and sprinkler

headsCarries diseases transmissible to humans

Controls

Difficult to controlTunnel trapsExclusion Only the red fox squirrel

may be killed without permits – other tree squirrels are protected by the California Fish & Game Code

Natural Squirrel Control

Meadow Voles

Microtus speciesA.K.A. Meadow MiceMouse-like 5” to 8” including the tailCompact, heavy-bodied with short-furred

tailShort blackish-brown to grayish-brown

long coarse furSmall eyes and partially hidden ears

Meadow Voles

Meadow Vole Habitat

Often seen in aboveground runwaysRunways partially hidden under tall grass

and other ground coversActive 24 hours a day, year-roundLive in small colonies of adults and

youngHerbivorous – feeding on bulbs and

tubers, grasses, herbaceous plants, bark and roots

Vole Runs

Vole Damage

Meadow Voles

Voles breed throughout the yearPopulations can explode into the

thousands per acreFemale become sexually mature in 35 to

40 daysVoles have 5 to 10 litters per year3 to 6 young per litterLifespan is 10 to 12 months

Controls

Habitat modification Removal or reduction of vegetative coverWeed-free strips around perimeters acts as

buffersCleared circles 4’ dia. around trees help

reduce damage

TrapsSticky mouse trapsSnap traps – without bait

Toxic baits Repellants

Controls

ExclusionWire fences with mesh less than 1/4”Wire mesh cylinders around trees

Meadow Vole Exclusion

Rabbits

Of eight species in California 3 cause the most damage

Jackrabbits – Lepus californicusDesert cottontail – Sylvilagus auduboniiBrush rabbit – S. bachmani

Jackrabbits

Large, fast rabbitsWeighs from 3 lbs to 7 lbs17” to 21” in lengthGrayish-brown furLong, black-tipped earsTop of tail is blackLong front legsLonger back legs

Jackrabbits

Jackalope

Cottontails

Small rabbit1-1/2 lbs to 2-3/4 lbs12” to 15” longPale gray fur with yellowish tints

Cottontail Rabbits

Brush Rabbits

Very small rabbitOften referred to as “bunnies”1-1/4 lbs to 1-3/4 lbs11” to 13” in length Brown fur

Brush Rabbits

Rabbits

Most rabbits are active day or nightRabbits do most damage close to the

groundGnaw bark on young trees girdling

stemsClip herbaceous plants and grasses

close to the groundDamage irrigation pipes and sprinkler

headsRabbits can carry disease – Tularemia

(rabbit fever)

Controls

Rabbits are difficult to controlClassified as a game mammal by the

California Fish and Game CodeSpecial restrictions apply to their control

Exclusion

One of the more effective meansUse of fences at least 48” highThey should be buried at least 10” below

groundMesh should be less than 1”Gates should fit tightlyNothing should be around the fence for

the rabbits to use as a perchRequires constant monitoring

Other Means of Control

Trapping Live traps are not recommendedIllegal to relocate mammals without permits

RepellantsVarious chemical repellants availableLimited success

Habitat managementShooting

Requires licenses Restrictions apply

Raccoons

Procyon lotorUp to 25 lbs.Over 36”Carries rabiesHunts fish in fish

pondsGoes through

garbageCan become

aggressive

Rock Dove

A.K.A. PigeonColumba liviaTo 13”Droppings damage

buildings, statues, cars, walks, etc.

Nests in attics, old buildings

Carries disease

Opossums

Didelphis virginianaThe only North

American native marsupial

24” to 36” long Up to 15 lbs

Opossums

Feeds out of pet bowlsAlso feeds on garden snailsEats fruits, berries and vegetables from

the gardenNo real threatOther than that – just plain adorable

European Starlings

Sturnus vulgaris7-1/2” to 8-1/2”Carries diseaseDamages fruit cropsCompetes with hole-

nesting birds

European Starlings

House Finches

Carpodacus mexicanus5” to 5-3/4” Damages buds and

flowersEats fruits and berriesDamages seed crops

and seedlings

House Finches

Female House Finch Male House Finch

House Sparrow

Passer domesticus5-3/4” to 6-1/4”Damages seedlingsEats fruits, buds and flowersHighly destructive to newly seeded lawnsDroppings damage buildingsDestroys nestlings of other species

House Sparrow

vertebrate pests rats, house mice, pocket gophers, ground squirrels, tree squirrels, moles, rabbits...

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