1. Bats

2. 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

3. 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

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

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

6. Identification
Little brown myotis

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

8. Identification
Big Brown Bat

9. Identification
Hoary Bat

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

11. 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

12. Roosting

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

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

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

16. 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

17. 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

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

19. Nursery

20. 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)

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

22. Guano

23. 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

24. Bats for insect management

25. 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

26. Bat houses - outrageous

27. Bat houses - moderate

28. Bat house design

29. 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

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

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

32. Bat house design

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