BATS ON MAIN STREET

Main Street Matters - February 2014

 

Article written by Howard Langner, architect with Texas Main Street Program 

It would be accurate to state that every Texas Main Street City has at least one building where bats are roosting. The simple fact is that old buildings offer a wonderful roosting opportunity for bats with their open windows, loose eave/soffit boards, and other areas of disrepair.

First of all, what should we in the Main Street community know about bats? Well, unfortunately, bats have been given a bum rap over the years—think vampires and Count Dracula. The truth is that bats are vital to controlling insect pests, pollinating plants, and dispersing seeds. Have a look at these Bat Facts from Bat Conservation International (www.batcon.org):

  • In Texas and around the world, bats are natural enemies of night-flying insects.
  • The millions of Mexican free-tailed bats at Bracken Bat Cave (west of New Braunfels) alone eat up to 200 tons of insects nightly. 
  • If we lose our bat species we increase the demand for chemical pesticides, jeopardizing whole ecosystems of other animal and plant species and harming human economies. 

The other thing we tend to associate bats with is rabies. Here are some more facts from Bat Conservation International:

  • Like most mammals, bats can contract rabies. However, the vast majority of bats are not infected, and even those that are, normally bite only in self defense and pose little threat to people who do not handle them.
  • The fear of rabies is far disproportionate to the actual risk. To put the risk into perspective: about 386,000 Americans are treated for dog bites each year and about 16 people die from the attacks. Bat bites, on the other hand, have led to an average of two human deaths per year from rabies.

You now recognize the value of bats. You may even love the little critters, but you also realize that they don’t belong in your Main Street buildings. Now its time to know something about excluding bats from entering buildings in the first place and if they are already roosting, how to permanently and humanely evict them. 

How do I know if bats are in my Main Street buildings?
The existence of bats in buildings is sometimes indicated by the presence of black or brown stains from body oils or droppings (guano) around cracks or crevices. Bat droppings may also appear on walls or beneath dilapidated ceilings. Bat guano may resemble small, hard rodent pellets, but it is actually soft and easily crushed revealing shiny insect parts (their diet) in the process.

How do I evict bats from my Main Street buildings? 
All potential entry points must be sealed. This is the only effective and permanent solution. Trapping and relocating have proven to be ineffective methods because bats have powerful homing instincts and will simply return even when released at great distances. Pesticide use against bats is illegal. 


How do I prevent bats from entering my Main Street buildings in the first place?
The first step involves inspecting the interior of the building. While the bats are likely roosting in the attic or roof cavities, start with the other interior spaces to be sure the roosting doesn’t extend further. All openings connecting the attic space to their potential roosting areas should be sealed while entry points on the outside of the building are left open. Caulking, flashing, screening, or insulation can be used to seal most openings on the inside.

The next step requires setting up a method whereby bats can leave but are unable to reenter. It is not proper procedure to wait for bats to fly out at night and then seal openings. This is because not all of the bats leave at the same time and some may remain in the building throughout the night especially during inclement weather. 

When should bat exclusion occur?
Don’t embark upon the bat exclusion process until young bats are able to fly otherwise they will be trapped inside the building away from their mothers (who do go out nightly to feed) and die of starvation. In Texas the maternity season for bats begins as early as mid April and the young won’t learn to fly until late August. This means that bat exclusions should not occur between April and late August. 

How are bats excluded?
Chances are whoever is reading this article will not be performing the actual physical work involved in excluding bats, but like so many aspects of the Main Street Program, it’s nice to have a working knowledge. 

The two primary methods of excluding bats are: tubes and netting. The idea behind both is very simple yet very clever. Both methods create a safe and humane means of egress but prohibit re-entry.

  • The Tube Method - The tube method involves placing small plastic tubes in strategic locations in a downward orientation from roof overhangs. The bats recognize the opening as an exit and they pretty much “slide” out of the tube. When they want to get back in, the tube, because of its vertical orientation and smooth inner surface, prevents them from “climbing” back up. 
  • The Netting Method- The netting method works on a vertical surface or when placing a tube is impractical. The netting acts as a flap over an existing hole or louver in the surface of the building. The trick is to attach the netting on the top and sides over the entire hole or louver but leave it unattached at the bottom. What happens in this setup is the bats will crawl down from the hole and exit under the bottom edge of the netting. When they return, the netting is laying flat against the vertical building surface and they can not “lift” it and climb back up to the exit hole.

Each of these methods should be left in place a minimum of 5 to 7 days to ensure all bats have left. The openings are then permanently sealed. The method of sealing depends upon the location and material composition around the opening.

Permanent roosts versus perching
Bats will take breaks from their “feeding frenzies” during the night while they are out and about. They will find a porch, canopy, or roof overhang and use their break time to digest the insects they have eaten. They usually perch for a short while although they might return to the same perching spot night after night (this was the case at my residence when I was living in the Big Bend of Texas many years ago). The experts at Bat Conservation International suggest that you just leave the perching bats alone; they don’t stay in those spots for long periods, don’t tend to make noticeable waste, and tend to remain solitary while perching. If the perching activity proves to be a nuisance there are simple, humane methods that can be used to discourage the bats from perching. See  www.batcon.org for more information.

How does a Main Street program start the bat conversation about bat conservation?
A Texas building owner in Mineral Wells received some nation-wide attention through the National Trust for Historic Preservation for her bat infested building. Her story is fascinating because she took the unlikely approach of leaving the bats in place and allowing them to continue their habitation. You can read about her situation here: www.preservationnation.org/magazine/story-of-the-week/2009/bat-woman-mineral-wells.html. 

Her story was written back in 2009 so it is likely that things are different now, but the point of the article is twofold: the fate of a bat colony that occupies an old commercial building should be carefully considered and plans for the future use of the historic building itself should also be carefully considered. In the case of the Mineral Wells building, the bats were the impetus for actually saving the building. 

Cuero, which happens to be one of our south Texas Main Street communities, has had bats on its radar screen since 2006 when there were a series of public meetings and presentations from bat specialists with the Texas Department of Parks and Wildlife: http://news.google.com/newspapers?nid=861&dat=20061013&id=7UJTAAAAIBAJ&sjid=i4UDAAAAIBAJ&pg=5161,2827756

Since then, there has been renewed interest with a new round of presentations organized by Bridgette Bise, Cuero Main Street Manager, and site visits from bat experts. You can read about her situation here: www.victoriaadvocate.com/news/2013/oct/22/cuero_bats_sl_102313_222641/?print

One thing to come out of the discussions and educational presentations was the potential benefit of constructing bat houses near the downtown.

What is a bat house?
The majority of the discussion thus far has been about removing bats safely and humanely from our Main Street buildings. The point that is missing here is where do the bats go once they are excluded? Remember, they are enormously beneficial to our ecosystem and they eat tons of moths and mosquitoes! One way to have bats stay in your community without having them seek lodging in your Main Street buildings is to build bat houses. A well designed, well built bat house stands a good chance of attracting bats. Bat Conservation International research has shown that bats will inhabit an average of 61percent of all reported bat houses in rural areas and 50 percent in urban and suburban areas. Furthermore, 90 percent of all occupied bat houses were used within two years with 50 percent occupancy in the first year. The remaining bat houses needed three to five years for bat occupancy.

The only catch, if it can be called such, is that bats have to find these new roosts on their own. You cannot simply place one in a bat house and expect it and the colony to relocate. First of all it is illegal to handle the bat and second, it has to choose the location on its own. Successful placement of bat houses has been influenced by such factors as temperature, compass orientation, construction materials, mounting location, mounting height, and over time, how well you maintain their house. That’s right, bats require a clean and safe house if you want them to stay. That means wasp and mud dauber nests need to be cleaned out each winter after bats and wasps have departed. Bat houses also need to be monitored at least monthly to detect problems with predators, temperature, deterioration of the bat house components, and so on.

Summary
Now you know why bats are important creatures. They help control pests and are vital pollinators and seed dispersers for countless plants. Years of misinformation and myths have given bats a bad name and it is good for us to learn everything we can about bats, educate others, and support ongoing research. Granted, bats don’t belong in our historic buildings but now we have shared something about how to deal with the situation in a safe and humane manner. Hopefully you will be inspired to organize bat house projects in your Main Street communities.