The Use of Bat Houses in the Management = of Central=20 Florida Bats
Laura Seckbach Finn=20
In central Florida, as in other areas, bats often become a = nuisance in=20 buildings. The two species most common in central Florida = buildings are=20 evening bats (Nycticeius humeralis) and Brazilian = free-tailed bats=20 (Tadarida brasiliensis cynocephala). They are often found = roosting=20 together. Fortunately, in Florida, bats have some protection as = nongame=20 wildlife, and there are no poisons or fumigants registered for use = against=20 them. Eviction is the only permanent solution to rid a building of = bats,=20 but once they are evicted there is often nowhere for them to go. = In most=20 cases the bats will attempt to move into a nearby building that = provides a=20 similar roosting area, and the cycle begins again.=20
As part of my thesis research, I have tested the feasibility of = using=20 bat houses as a management tool in situations where bats are to be = evicted=20 from a building. If bats would use the bat houses, rather than the = buildings, the problem of nuisance bats could be solved.1 In my = attempts=20 to get bats to use bat houses, I tried three types of relocations. = I=20 "seeded" bat houses with live bats, relocated bats over a period = of=20 several days, and relocated an occupied bat house.=20
I made 13 attempts to "seed" bat houses with live bats. My hope = was=20 that bats would remain in the bat houses or at least scent the = houses with=20 guano and body oils, which might attract other bats in the future. = During=20 the early morning, I captured bats at nearby roosts and placed = them in bat=20 houses in groups of 14-115. They were not caged and were free to = leave in=20 the evening. None of the seeding experiments resulted in populated = bat=20 houses.2=20
Another relocation attempt was made when bats at a local = community=20 college were slated for eviction from the buildings in which they = were=20 living. Eight bat houses were placed on the college property, = about 1/4=20 mile from the occupied buildings. Prior to and during eviction, = bats were=20 captured at the roost site and placed in the bat houses early in = the=20 morning. As in the seeding experiments, bats remained in the bat = houses=20 during the day but were free to leave at night. On average, 58 = bats were=20 moved each morning and placed in the bat houses in groups of no = fewer than=20 six. This process was repeated for eight mornings, but after the = third=20 morning we noticed that the bats were already occupying one of the = bat=20 houses. The relocation was working! However, within six weeks of=20 occupancy, the plastic ("fiberglass") window screening that lined = the=20 roosting spaces deteriorated and began to hang out of the houses. = This=20 apparently forced the bats to abandon their new homes. After I = removed the=20 screen, we repeated the relocation and bats returned to the bat = houses on=20 their own after the second morning. Nearly two years later, six of = these=20 bat houses are still populated year-round, each with up to 400 = bats.=20
The third relocation was attempted because bats that had been = living in=20 an awning and a nearby bat house were no longer welcome after the = building=20 was sold. The tenant removed the awning, which housed a maternity = colony=20 of evening bats and free-tails. Between 50 and 75 flightless = evening bat=20 pups fell to the ground as the adults flew to the nearby bat = house. I was=20 called, and after collecting all the pups I placed them into the = bat house=20 in hopes they would be reunited with their moms. However, the = tenant now=20 insisted that the bat house be removed from the property.=20
A few days later we removed the occupied bat house from the = building.=20 After we stapled screen mesh to the bottom to prevent the bats = from=20 escaping, we moved the bat house to a site roughly five miles to = the=20 northeast. Most of the evening bats left the house prior to the = move,=20 taking their pups with them. The remaining 10-15 evening bats and = more=20 than 100 free-tailed bats with very young (hairless) pups were=20 trans-located. The evening bats were adults and pups old enough to = fly.=20 That night adult bats exited to forage, but only the evening bats=20 returned. The free tails had left their pups behind! Thirty-nine = freetail=20 pups were in the bat house with 13 evening bats, and the abandoned = pups=20 began to starve. Unfortunately, despite rehydration and feeding = attempts,=20 only six survived. The evening bats remained at the new site for = several=20 months, moving between several additional bat houses I had = provided. They=20 left in mid-August, but I anticipate seeing them this year in May. =
Bat houses have proven successful as a management tool in = central=20 Florida, though much remains to be learned. For example: Where do = the=20 evening bats go in late summer and winter, and why? I know they = are here=20 year-round, but it is common for them to change roost sites in = late=20 summer, returning in the early summer of the following year to = form=20 maternity colonies in the bat houses. The free-tailed bats, on the = other=20 hand, often stay with the same roost site throughout the year, = leaving=20 only on severely cold nights when temperatures drop below = freezing.=20
We hope that land managers and pest control/nuisance wildlife = companies=20 will provide bat houses in the future when a roost site is slated = for=20 destruction or closure. The bat houses that have proven to be = successful=20 in this project are slightly modified versions of BCI=92s small = and large=20 nursery house designs.=20
Laura Finn is an Honorary RA in Deltona, Florida. She has been = working=20 with bats and bat houses for 8 years, and 18 of her 60 bat houses = were=20 occupied in 1996. The techniques she describes pertain to = exceptional=20 circumstances, and need not be undertaken in most nuisance bat = situations.=20 Wildlife permits and a pre-exposure vaccination for rabies are = required=20 prior to capturing and handling bats.=20
![3DBV5N1F.JPG=20](3D"http://www.batcon.org/bhresearcher/IMAGES/bv5n1f.jpg")
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Evening bats are frequent users of bat houses in the =
Southeastern=20
U.S. and have been known to use bat houses in winter. =
PHOTO BY=20
MERLIN D. TUTTLE
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