Learning About the Lives of Pacific Northwest Bats

Using radio-telemetry to study base habitat use requirements

Jeffrey TaylorScience InstructorOlympus High School

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Bats: Background Information

• 1000 species of bats world-wide, second to rodents

• Only group of mammals capable of sustained flight

Bats: Background Information• Broken up into two large groups:

- Megachiroptera: fruit-eating i.e. “flying foxes” (Old

World)

- Microchiroptera: small, primarily insect-eating (our bats)

* use echolocation to detect prey * use their good night vision to

see larger objects and navigate

The Lifestyles of Northwest Bats(Everything is based on energy conservation)

• Bats have extremely high metabolisms – To maintain flight, conduct echolocation, and

maintain warmth due to their large surface area

The Lifestyles of Northwest Bats(Everything is based on energy conservation)

• To conserve energy they sleep… a lot!– They hibernate in winter using stored fat

The Lifestyles of Northwest Bats(Everything is based on energy conservation)

• To conserve energy they sleep… a lot!

– Enter torpor during the day to conserve fat reserves

– Only active about 15 min of every night hour

The Lifestyles of Northwest Bats(Everything is based on energy conservation)

• Because they sleep so much and hibernate, they live much longer than other mammals of similar size.

• A shrew weighing 5-10 grams lives about 1 year• A bat weighing 5-10 grams can live 12-30 years

Myth or Truth?• Do bats fly into people’s hair?

• Do bats have rabies?

• Do bats eat 600 mosquitoes per hour?

• Do bats drink blood?

Myth or Truth?• Do bats fly into people’s hair?

No, bats have excellent vision and sonar • Do bats have rabies?

Some do, bats carry rabies around 1-5 per 1000

Less often than raccoons, skunks, or foxes • Do bats eat 600 mosquitoes per hour?

• Do bats drink blood?

Myth or Truth?• Do bats fly into people’s hair?

No, bats have excellent vision and sonar

• Do bats have rabies? Rabies is actually rare in bats

• Do bats eat 600 mosquitoes per hour?Probably an exaggeration – especially

since they roost 45 min per hour digesting food

• Do bats drink blood? Only the Vampire bat of Central

America

Your Neighborhood Bats

• Twelve species of bats in the forested regions of the Pacific Northwest

• Some are very common, while others are rare or endangered

• There are two species likely to inhabit human dwellings in the PNW

(Big Brown Bat and Little Brown Bat).

Little Brown Myotis

(Myotis lucifugus)

Yuma Myotis(Myotis yumanensis)

These two species are difficult to distinguishMost likely bat to be found in buildingsLittle brown myotis are found across North AmericaYuma Myotis are found only west of the Rockies

Big Brown Bat(Eptesicus fuscus)

A very common bat that ranges across North America

Weighs about the same as a mouse (20-30 grams)Known to occupy buildings and will bite if handled

Silver-haired Bat(Lasionycteris noctivagans)

Hoary bat(Lasiurus cinerus)

Found across northern North AmericaLittle is known about its population status

The largest bat in North America

Largest range: All North America & Hawaii

Foliage Roosting BatsMigrate south for the winter

Townsend’s Big-eared Bat

(Plecotus townsendii)A rare cave roosting batHuge ears used to detect low-frequency moths

Probably the most endangered bat in Washington

California Myotis(Myotis californicus)

Western Small-footed Myotis(Myotis ciliolabrum)

A very small somewhat common bat More common eastside of the CascadesOften found in rock crevasses

The smallest bat of Northwest forestsMore common eastside of the CascadesFound in rock crevasses and some caves

Western Long-eared Myotis(Myotis evotis)

A common bat found in forests west of the RockiesUses peeling bark of snags as roost sites

Fringed Myotis(Myotis thysanodes)

A rare bat, uses caves and rock crevasses for roosting

Species of concern because population status is unknown

Distinguished by the fringe of hair on the tail membrane

Keen’s Myotis(Myotis keenii)

A cave roosting species found in coastal spruce forests

Endangered in Canada, status is unknown in the U.S.Smallest range of any North American bat

Long-legged Myotis(Myotis volans)

An uncommon bat of the montane forests

It is the largest of the Myotis bats in the NorthwestIt roosts under the peeling bark of snags

Control Methods for Bats in Your Homes

• Hire pest management company to close off the access points

There are ways to exclude bats without killing them:

Some bats love attics for roosting or hibernating due to the warmer temperatures.

So, you may want to seal off the vents

Control Methods for Bats in Your Homes

• Between November and March is the best time

There are ways to exclude bats without killing them:

If the bats are hibernating elsewhere, then when they return in spring, they can not get into your house.

Control Methods for Bats in Your Homes

• If you do exclude them in the summer, wait until at least August after the young have fledged

Otherwise the mothers will not be able to get back to them to feed them.

There are ways to exclude bats without killing them:

Control Methods for Bats in Your Homes

• NEVER exclude them in the day! Wait until they have emerged for the night.

• Otherwise you will have an attic full of desperate bats that will starve to death.

There are ways to exclude bats without killing them:

How do we Conserve Bat Populations?• Bats are very important to the ecology and economy of

many ecosystems.• They feed on many insects that cause great damage to

forests, agricultural crops, and people.

Understanding the Ecology of Bats in Pacific Northwest Forests

Habitat Fragmentation is Considered the Biggest Threat to Bat Populations

My Job

• Learn about the ecology of bats in the forests of the Cascade range.

• Find out what habitat types and ecological features are important to bats.

• Determine and make recommendations for timber management practices with bats in mind.

The Long-legged Myotis

• The long-legged myotis is generally considered to be associated with late-successional forests

• Listed by the Northwest Forest Plan as a species of concern and in need of further study

• Concerns that populations of this and other Myotis species were declining in the Northwest

Information Needs for Myotis volans

• What are the specific roost-site structures preferred by the long-legged myotis?

• What is habitat use compared to availability? I.e. what successional stages do they prefer?

• Will the long-legged myotis use retention implemented under the Northwest Forest Plan?

#1- Capture long-legged myotis with mist-nets at water sources (caves and water troughs)

Mist Nets

Your on your way to get a drinkThen boom, you caught in a giant net, bright lights

shine upon you, giant hands handle you. Then…

Alien Abduction!

Take Measurements and Place Radio-transmitters on Their Backs

Alien Abduction!

My hypothesis was that they were roosting in the cave in the day and would head out at dusk

Instead, I captured them going INTO the caves at dusk!

But why?

Unexpected Results and More Questions

#2- Release them and track them to their day-roost locations the next morning.

As it turns out, they were using the caves to get a drink after they woke up and before they’d head out to hunt for moths.

They were roosting in trees in the day!

Roost height, diameter, canopy cover, canopy height, snag class and snag species

#3- Take roost measurements including:

Analysis

• GPS each roost-site location• Create a circle with a radius from the

water source to the furthest roost-site • Use a GIS and aerial photos to map

roost-sites and available habitat• Place habitat polygons into circles • Use a computer program to determine

habitat use versus availability

Eight habitat types were delineated

Douglas fir/grand fir forests

Stem initiationEarliest Succession Stage

Retention Types in Managed Forests

Early Successional Retention Types

Aggregate Retention Patch Shelterwood

Mid-successional Stages

Stem Exclusion Stem Initiation Small

Young trees are so densely packed that no new sprouts can grow

Some of the young trees die, allowing more light to hit the ground and more new seedlings

can survive

Late-Successional Stages

Stem Reinitiation Medium Stem Reinitiation Large

Where the Bats Roosted

West Site Habitat Selection

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70

80

90

SI SH AR SE SRS SRM SRL

% Used % Available

Snag Species Selection

West Used West Random East Used East Random0

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90

grand fir Douglas fir ponderosa pine w. hemlock other

Conclusions• Long-legged myotis use snags as day-roosts

• Prefers late-successional forests

• Strongly prefers large grand fir snags

Conclusions

• Avoid early successional stages, but occasionally use aggregate retention patches and shelterwoods.

• Unknown what effect lack of late-successional stands has on population size or reproductive success

What can you do to protect bat populations?

• Leave dead or dying trees on your property

• Place a bat box on any large trees about 20 feet high

• Avoid using insecticides, bats can be poisoned

• If you find bats in buildings other than your homes, such as barns and sheds, let them stay!

• If you have bats in your attic, leave them if they are not causing problems

Management Implications

• Leave snags for bat species

• Leave at least small patches of late-successional forests in managed forests

• Grand fir should be maintained in management prescriptions for wildlife

http://upload.wikimedia.org/wikipedia/commons/7/72/SnagTree.jpg