Bats

Bat Myths Bats will suck your blood They'll fly into your hair They're flying rats Most of them have rabies Bats are blind

Bat Facts Only three species worldwide feed on blood Bats freak out when they get trapped inside your house and you’re screaming and waving your arms And they can see fairly well

Rabies 1 in 1,000 bats have rabies in CA Exaggerated problem

Taxonomy 22 species in California, most common: Little brown myotis Mexican free-tailed Big brown Hoary bat

Identification Little brown myotis

Identification Mexican free tailed weight 0.5 ounce wingspan 12-14 in. Webbed tail

Identification Big Brown Bat

Identification Hoary Bat

Biology Roost in caves and trees Foraging areas near water Migrate or hibernate during winter Nocturnal feeders

Roosts In summer, bats most active, raising young One roost during the day where they sleep and another roost at night for resting and digesting food Day roosts tend to be cryptic and concealed; night roosts more open and exposed Both roosts can be used by multiple species

Roosting

Biology Most insectivores Use sonar (echolocation) Consumes half their weight in insects per night

Biology Bats have up to 23 audible calls for various activities – territory, mating, feeding, birthing, physical contact, etc.

Echolocation “talk” at 30 sounds/sec “locate” at 60 sounds/sec

Bat Feeding In summer up to 7 billion corn earworm moths emerge from cornfields of the Rio Grande Valley After dusk they ascend up to 1,000’s of feet and ride the prevailing winds north They can make the 250-mile flight in one night Each female then lays as many as a thousand eggs

Bats and Bugs in Texas 100 million Mexican Free-tailed bats live in caves and under bridges Each must eat 50% of body weight each night = 2 million lbs. of insects per night Doppler radar used to track flights

Biology Mate in the fall and winter Female may retain sperm in uterus until spring when they ovulate Pregnant females congregate

Nursery

Biology Birth occurs April thru July Usually one pup per female Ready to fly within 3 weeks Can live up to 10 years (two tagged recorded at 29 and 30 years)

Damage Some bats use structures to roost Noise Urine Guano Body secretions/ectoparasites

Guano

Damage One or two in a house is most frequent problem – usually big brown bat They don’t attack – fly to seek shelter Open a window or use a net

Bats for insect management

Potential colony diet - 1 summer (150 big brown bats) 50,000 leafhoppers 38,000 cucumber beetles 16,000 June bugs 19,000 stinkbugs + other insects not counted

Bat houses - outrageous

Bat houses - moderate

Bat house design

Bat house design At least 2’ tall x 14” wide 3 to 6” landing area Roost partitions 3/4-1” apart 1-4 roosting chambers Vents if above 85° July (avg.) Sun exposure (hours) Water + food sources Weather protection - roof, caulking

Bat house design 10-20’ high On building/pole 20-25’ from trees Orientation S-SE

Bat House paint color dark blue <85° (black) light blue 85-95° (dark) pink 95-100° (medium) green >100° (light)

Bat house design

Bat colony sizes Single chamber = 50 bats Multi. chamber = 200-20K! Control = balance of bat vs. insect numbers