BATS

Bats are one of the most interesting and unique of all mammals.  However, they are often misunderstood.

Bats are wonderful little creatures and in fact are a beneficial component of our ecosystem.  Read all about bats and their biology and learn about building bat houses.  We encourage everyone that fears bats to read about them and by doing so you will understand their place in our environment. Build a bat house and give them an alternative to your home. One of our aims, here at The Great Gray Owl Pest Control Company, is to dispel the myths that surround them. 

While we try our best to protect them and help others to understand them, we do not discount the nuisance factor when you have bats living in your home. Herein we will give you comprehensive exclusion information.

Bat Houses •   Identification and History 
About Flight and Echolocation  •   Distribution of Bats
Biology & Behaviour  • Identifying a Problem-Does a Colony Exist?    
Bat Proofing • Exclusion, The Permanent Solution  

For the most part, bats are harmless and, in fact, are biologically useful mammals since they feed entirely upon insects, many of which are pests to agriculture. They also can consume 600 mosquitoes per hour per bat.  Wow!  A good enough reason for anyone to want to have bats around.

Easily constructed bat houses are recommended for areas with heavy bat populations because having bats in your yard is a good thing. Bats are voracious consumers of mosquitoes and other obnoxious insects.  This challenge is making sure your home or cottage is securely sealed to exclude bats from entering. Bat proofing is the only permanent way of keeping bats out!

Bat boxes, are a good idea and will aid in the preservation of beneficial bat populations while offering them an alternative to your house.

• Bat biologists have developed a variety of boxes and houses for bats, the size and shape of which are not important but the width of the entry space should not exceed 2.5 cm.
• All inner surfaces must be roughened so that bats can easily climb.
• Ideally place the house where it will catch the morning sun because the inside temperature needs to be warm, but should not exceed 100 degrees. If you must place the house in the shade insulate it by covering the top and sides with tar paper to absorb the heat of the day.
• Leave the house natural as paint and stains are toxic to bats, and only special non-toxic paints should be used if a colour is required.
• Bat houses located near water are most likely to attract bats as there are an abundance of aquatic insect prey.
• Securely fasten the house to the side of the building or tree trunk, 3 to 5 metres above the ground and protected against birds and squirrels, and other predators.
• Be patient. You may have to wait a year for bats to move in but if the house is properly located the bats will indeed come to it.
• A perfect bat house will have several partitions inside because bats like narrow spaces and this allows more surface room for roosting.
• An open bottom will facilitate cleaning and prevent birds from nesting in the bat house.
• Bat bugs are another excellent reason to exclude bats and let them live in specially built bat houses on your property. Bat bugs are parasites similar to bed bugs and bats are their primary host, however, they often do feed on humans.
• The Canadian Wildlife Federation offers instructions on how to build a bat house and other interesting information about bats.
• Purchase a beautiful pre-constructed bat home from Bill Bat Boy Bat Homes

Identification and History  
Bats belong to the order of mammals called the chiroptera which means "winged hand".  Because they possess wings, bats are the only mammals capable of true flight.

Bats have small, functional eyes but rely on echolocation (a type of sonar system) to guide themselves in flight.  Bats have prominent ears with a well developed membranous process, the tragus, which is an outgrowth from the inner base of the ear.  They emit high-pitched squeaks from their larynx in the throat which will be reflected back from objects in their path and are picked up by the ear.

There are 40 species of bats found in the United States and Canada with the two most common ones encountered being the Eptesicus fuscus, big brown bat the Myotis lucifugus, the little brown bat.  The big brown bat is relatively large measuring about 4 inches in length and having a wing span between 12 and 14 inches. It weighs only one-half ounce.  The fur and wings are usually dark brown, but the ears are blackish.  Little brown bats are about 3 inches long, a chocolate brown colour and weigh one-quarter of an ounce.  Even though there is a size difference, only a bat expert can tell the two bats apart.

About Flight and Echolocation
Among living vertebrates, true flight is unique to bats and birds. Unlike most birds, however, bats are able to fly at relatively low speeds with extreme maneuverability.  The wing is a thin, fleshy membrane supported near its leading edge by the greatly elongated bones of the forelimb and second finger, and toward the tip and rear by the even more attenuated third, fourth, and fifth fingers. It is attached along the midline of the trunk and outward-directed legs, and in various species it extends between legs and tail. Only the first finger, or thumb, is free, and in most bats it alone is clawed, together with the toes.  This structure enables bats to vary the convexity of the wings dramatically and thus vary their aerodynamic lift.

All microbats navigate - and most insectivorous species, like the big brown and little brown bat, also target their prey - by echolocation.  This is the pulsed emission of high-frequency sounds that are reflected back as echoes to a bat's ears from surrounding surfaces, indicating the position, relative distance, and even the character of objects in its environment.  In this sense microbats "see" acoustically.  This is the basis for their ability to navigate in total darkness.  The physical properties of the emitted sounds vary in characteristic ways among the species.  The sound pulses are generated in the larynx, and in different species are emitted either from the mouth or nostrils.

By contrast, megabats (included here are the largest bats, the giant "flying foxes" of Africa, India, and Australo-Malaysia { the biggest bat which inhabits Java achieves a wingspan of 5.6 ft. and a body length of 16.7 inches} use vision rather than acoustics for orientation.  Only one genus has evolved an echolocation mechanism, involving the emission of audible "clicks" and it is used only when the bats fly in darkness.  The eyes of megabats are also relatively larger than those of microbats.  No bat is blind, however, and even echo locating microbats may use gross visual landmarks for homing during flight.

Distribution of Bats
Bats are divided into two suborders, larger bats or megabats and smaller bats or microbats, and their 17 families.  One of these families includes all megabats (more than 150 species) and the other 16 families are microbats.  In all, 850 to 900 species of bats exist, far more than in any other mammalian order except the order of rodents, and bats probably exceed even rodents in total abundance.

Bats occur worldwide, except in the Arctic Zone and certain remote oceanic islands.  All megabats and some families of microbats are confined to the eastern hemisphere;  other microbats are confined to the western hemisphere, and a few families are worldwide in distribution.  Bats are believed to have originated in a warm climate, probably in the early Eocene epoch (the oldest know fossil bat is about 60 million years old), and the center of their distribution and abundance remains the tropical and subtropical areas.  Members of only four families, all of them microbats, live in temperate regions, and the number of resident species diminishes pole ward.  Members of only two families reach sub arctic regions, and then only in the summer.  The differences between microbats and megabats are sufficient to suggest that they are of different evolutionary origin, with the megabats appearing much more recently than the microbats.

Bat Biology and Behaviour
Bats leave their overwintering site (winter home) and usually enter structures during the first warm days of spring (summer home).  The majority of the bats entering structures at this time of year are females preparing to give birth. The number of individuals in a colony may range between just a few to several hundred.  

When a colony contains more than 300 bats, they are likely to be little brown bats.  Big brown bats annually produce a single offspring or two, during June and July, while little brown bats have one single baby.  The newborn bat is about one-third the weight of the parent and is breast fed by the mother until able to seek its own food, usually between 3 to 7 weeks.  

Generally, colonial species raise their young in nursery colonies in caves, attics, or similar places and remain in their roost all summer.  In the fall between September and October, males increase in numbers at the roost and mating occurs.  The sperm is stored by the female during the winter and fertilization occurs in the spring upon departure from hibernation.  

As temperatures begin to drop during late fall (mid-October to mid-November) the bats leave their "summer homes" and travel to their "winter homes".  To summarize, their activity pattern is actually three phased, and involves hibernation, summer nursery colonies, and fall mating and hibernation site selection (often termed swarming).  Both species hibernate through the winter using fat, accumulated through the summer and early fall, as an energy reserve.  

Little brown bats hibernate in caves and unused mines, areas which provide the stable low temperatures (0-8 degrees C) and high humidities which appear to be essential to the species.  Little brown bats have never been found hibernating in buildings but the big brown bats are more tolerant of low and fluctuating temperatures and low humidities, and use both caves and buildings as hibernation sites.  

During milder spells in winter, big brown bats often arouse from torpor and move within or between hibernation sites and this behaviour is associated with some bat/human contacts in buildings at this time.  During the summer, when the sexes of both species are segregated, females are gregarious which allows them to form their nursery colonies with other females.  Nurseries are occupied throughout the gestation and parturition period and, in little brown bats, at least until the young are able to fly.  Big brown bats may move to less sheltered sites with their young shortly after parturition.

Bats feeding cycle begins at twilight.  Usually, all members of a colony leave the roost at about the same time.  After obtaining their water at a nearby stream or pond, they feed for an hour or two and then return to roost.  Some feeding may occur throughout the night and by sunrise all bats have returned to their daytime roosts.  

Identifying the Problem.  Does a Colony Exist?
Aside from the direct observation of bats, other signs indicating the presence of bats include accumulated droppings below roosting sites.  Bat droppings may be mistaken at first for mouse droppings, but the bat droppings are more irregular in shape, crumble readily and glisten.  The odour and stain caused by urine and droppings may be clues, and though bats are rather quiet creatures, their high-pitched squeaks, a clicking sound and rustling sounds coming from walls and attics are also telltale signs of infestation.  Some discolouration from body secretions is commonly found around the edges of small openings where bats exit from a building.  If droppings and insect parts are found in the absence of any other evidence of bats, this may indicate temporary roosting sites between nighttime foraging periods.  These sites (porches, decks etc.) are likely to be less confined than are daytime or regular roosts.

The discovery of one or two bats in the house is probably the most frequent problem associated with bats. As pest management specialists, we receive our most desperate calls for help with bats in the middle of the night.  Bats can come in through open windows and doors or uncapped fireplaces.  If unused chimneys are utilized by bats as summer roosts, the young may fall or crawl through the damper and into the house when they are learning to fly, and their parents may follow.  

Bats may suddenly appear in mid-winter during a warm weather spell and fly about the house.  Migratory bats occasionally enter buildings overnight during their spring and fall migrations.  A bat will usually find the way out by detecting fresh air movement; therefore, a possible solution to rid the building of the bat is to open all windows and doors leading to the outside.  If it came in during the day and is still present at nightfall, the light should be turned off to help the bat find open windows or doors.

If the lights are turned on, the bat may seek refuge behind drapes and wall hangings and generally disrupt the whole household. In our experience, we find people will in many cases try to capture the frightened bat, all the while screaming, and flailing brooms and the like at the helpless creature. This is not only stressful for the bat but people too! Bats will not usually attack a person, even when chased. So, the best approach in dealing with a bat found inside the house during the night, that will not exit opened windows or doors, is to close off the room from the rest of the house, if possible, and wait until morning.  

In the morning the bat will most likely be found sleeping, hanging upside down from a window sill or other ledge-like roost. Using heavy gloves you can very gently pluck the sleeping bat and place into a container or bag to be released outside.

Openings attractive to bats may be found in all frame structures when boards shrink, warp, or become loosened.  They commonly enter buildings through the overhang of the roof made by overlapping sheeting or drop siding.  They are most often found in attics, between roofs and ceilings or roof spaces, in cornices, fascias and other crevices around the roof, in walls, in chimneys, around drain pipes, behind rafters and sheeting in open barns, between a window and screen, and occasionally in crawl spaces.

Outside, bats will fly around swimming pools from which they may drink and catch insects that are attracted to the water.  Street and porch lights attract flying insects which in turn attract the bats.  Mercury vapour lights attract the most insects, while high pressure sodium vapour lights attract insects the least, give good quality lighting, and are more energy efficient.

Bat Proofing - The Only Permanent Solution
The first step in bat management is to determine the extent of the bat problem with an outdoor inspection of the structure's roof area at dusk. This inspection will reveal the entry and exit points of the bats, structural deficiencies of the building, and size of the colony.  Sources of air leakage may also provide access to bats.  Simple homemade devices will locate the general direction of air leak in the structure.  One consists of a piece of very thin bathroom tissue or thin plastic film attached to a clothes hanger by tow clothes pins or tape.  The tissue and film are very sensitive to slight air movements, so when the gadget is placed in front of a wall outlet or window frame, a flutter in the materials indicates that air is causing the movement.  Another method to test windows and doors for air tightness is to move a lighted candle around the frames and sashes (using extreme caution not to ignite curtains etc.);  the air movement will cause the flames to dance indicating that caulking and/or weather stripping is needed.  Air leaks can be easily found by the use of an inexpensive air-flow indicator, air tester, smoke generator, or smoke stick.  Remember, bats can crawl through narrow slits and openings as small as 1 cm.

If bats are present they will emerge every evening unless the weather is extremely inclement.  To perform the inspection situate two people at opposite corners of the structure so that each can view two roof areas at the same time - more wings to a structure require more observers.  Begin your inspection approximately one half hour before dusk and continue for about an hour after the first bat emerges.  Pay close attention to the most common exit points i.e. attic louvers, rooflines (between the roof sheathing and fascia boards), and any openings resulting from building deterioration.  Openings of only 3/8 of an inch are sufficient for bat entry.  In some cases, such as barns, exit and entry points may be the actual doorways.  Exit/entry locations can often be determined by pre-emergence noise, droppings below the exit points, odour, or smudge marks in the area of entry.

Exclusion of Bats
Going...going...gone! At last!  Yes, it is possible to make a structure "bat-proof".  In fact, it is the most logical and biologically acceptable way to control bats.  The goal is to rid a building of the colony permanently and exclusion is the only method that can guarantee results. The best time of the year to bat-proof a building is either in late fall after the bats depart for hibernation or in late winter-early spring before the bats arrive.  If it must be done in the summer, do not do it mid-May through mid-August because the young will be trapped within the structure and die.  This is not only inhumane but it most certainly will create odour problems.  

Exclusion programs must be carefully planned and done in two phases.  First, all but one or two of the principle openings should be sealed.  Wait a few days to allow the bats to adjust to the remaining openings and then seal those openings some evening just after the bats have left for their nightly feeding.

To seal openings, materials such as one quarter inch hardware cloth, sheet metal, plywood, or aluminum flashing can be used.  Seal all openings 3/8 of an inch and larger.  Unlike rodents, bats will not gnaw their way through softer building materials.  These materials can be conveniently attached to the building with a heavy duty staple gun.  Fiberglass or urethane foam insulation can be used to fill wall voids once occupied by bats.  If foam or other loose type insulation is used, be certain that any substantial amount of droppings are removed and not just covered over, otherwise objectionable odours may continue and may also attract new bats.

Small openings and cracks or gaps can be sealed with quick-setting hard putty, weather-stripping, caulking that expands, urethane foam, or steel/brass wool.  When sealing, pay particular attention to chimneys, louvers, vents, cornices, warped sidings, and locations where the roof joins the walls in the area of the eaves.  For any temporary sealing needs use rags of cheese cloth.  

Provide bat houses on your property for the bats that do not disperse to other areas and flounder around the plugged holes.  Also close observation over the next several evenings will determine whether the bats have found an entry hole you may have missed.  The disadvantage of bat control by exclusion is that it may not be economically feasible, practical, or even possible in large buildings or old homes that have unlimited cracks and crevices large enough for bats to enter.  There are, however, some repellents, other new products, and simple techniques that provide practical, economical, and permanent exclusion, even for buildings like barns.

One of these products is polypropylene bird netting which was originally developed to protect high value agricultural crops from birds.  The netting has been around for many years and can be used as a simple barrier to exclude all passage or as a check valve which allows bats exit only.  Bats can easily find their way out of one inch mesh flexible netting, but cannot find their way back in.  Ultimately, they go elsewhere to roost.  This type of netting has proved to be effective in excluding bats from a structure, is durable against climatic conditions and bats, is practical and economical to apply, and aesthetically tolerable.  

The following simple techniques have also proved effective in some cases:

• Use bright lights in attics and underneath eaves, using four or more 150 watt bulbs - direct the lights so all darkened areas are illuminated. Flood lights can also be mounted on the outside of structures pointing directly at the bat's entry area to the building.
• Carefully directed drafts produced by electric fans and air conditioners installed in bat roosts and turned on in April may discourage bats from roosting since they prefer high temperatures for rearing their young.
• Bat houses should be constructed before any exclusion program has begun, to provide the bats with alternate shelter during the gradual exclusion process. Check out The Canadian Wildlife Federation bat home building instructions, and if you would like to purchase a beautiful pre-constructed bat house check out Bill Bat Boy Bat Homes