Thursday, August 12, 2010
In most years, mid- to late-summer is the peak of when calls about conflicts with bats come in from clients. This rise in calls typically coincides with the stage in the bat’s life history where young of the year are testing their wings, but have not quite mastered flight yet. As a result, these wayward juveniles end up in someone’s living room or elsewhere in the living space and cause a panic for the occupants.
This year seems to be especially conflict-ridden for some reason. Calls are running about 15-20% above normal, based on my logs from previous years. Based on the number of calls I have been receiving from agents, I suspect many of you may be noticing a similar trend.
In an effort to facilitate dealing with these calls, I wanted to highlight some available and/or recommended resources and discussion points for when you encounter clients who are experiencing such problems. First, the materials we used to have in our own Extension publication library were outdated and currently are being completely revised. As a result, though, there are no resources internally to turn to right now. Instead, I would recommend that you “bookmark” the web site of Bat Conservation International (http://www.batcon.org) and refer clients to the resources available there. Among the “hot links” provided on the opening page of their web site, you will find a heading entitled Bats & People. Under this heading you will find a number of sub-links that provide a wealth of very good and useful (and science-based) information on dealing with bats in the home, how to conduct exclusion work, how to safely remove a bat from the home, etc. They even provide a short video demonstration on how to catch and remove a bat. Pretty much all a homeowner would need to begin coping with a bat situation can be found at this site.
Another useful resource is the list of nuisance wildlife operators provided on the Department of Game and Inland Fisheries (VDGIF) web site (http://www.dgif.virginia.gov/wildlife/nuisance/trappers/). At this opening page, simply locate your county or city of interest from the pull-down menu attached to the “location” box. The site will provide a list of all nuisance wildlife operators who provide service in that area and the species they agree to work on. Unfortunately, bats do not appear among the species at the top of the list. However, a fair number of the operators do work on bats, so you will have to ask to determine those who do. Because this is a statewide listing, be sure to utilize those on the list who reside in your immediate area first as a means to potentially reduce costs associated with travel.
Several tips about dealing with bat colonies in residential structures and exclusion techniques . . . exclusion is far and away the most effective and preferred approach to dealing with these complaints. However, timing of any exclusion work is crucial and must be given special consideration. There should be no exclusion efforts during the period from about mid-May until about the first or second week of September. The “softness” of these dates is due to the wide disparity across the state in when young of the year reach maturity —northern and western populations tend to mature a little earlier than those in the piedmont and coastal plain. Thus, people should not be performing exclusion work yet as there still is a very high likelihood of trapping immature and not fully mobile young behind in the roost. As a result, you may be creating a worse problem with foul decay odors and eruptions of carcass-feeding insects as these trapped young bats die and fall to the floor of the roost site. Between now and September, this is a great opportunity to spend time outdoors at dusk watching the perimeter of a residence for bats exiting the structure. This is a sure-fire way to locate the openings and access spots bats actually use and that will need attention later when exclusion work can begin in earnest. Remember, bats need only an opening of about ½ to ¾ inch to gain access — these are relatively small openings that many people tend to overlook. Preferred points of entry typically occur around the following: gable, ridge, or other attic vents, especially those that do not have a net backing; soffits and eaves; old chimneys that lack meshed chimney caps; roof flashing that has come loose or detached, especially around chimneys; places where the trim woodwork and edges of the siding meet; places where utility service enter the building near the roof.
Although we do have several active registrations for bat repellents, all are based on use of one active ingredient: naphthalene, the base constituent of moth balls. However, moth balls are not registered for use and should not be recommended — only the formulations that have received EPA registration can be used. Despite the fact that these registrations are available, caution is advised. The vapors produced from the distribution of naphthalene products tend to be “heavy” and sink. This poses several issues: 1) it is difficult to dispense the repellent effectively and in a manner that makes it a useful treatment against bats (they roost in elevated spots near the peaks or high spots of the roost site) — it is near impossible to get the stuff in any reasonable concentration up where the bats are located to have the desired repellent effect (assuming it actually has a repellent effect); and 2) because the vapors tend to sink, they will find their way through gaps down into the living space and become a nuisance (and, in some cases, a potential health hazard) to the occupants of the dwelling. As a general rule of thumb, repellents are not a viable option.
Finally, because bats are protected by state regulation, under most situations it would illegal to kill a bat (see §29.1-100 of the Code of Virginia; provisions of the “nuisance species” clause specify conditions under which wildlife may be taken [see inclusion below]). Homeowners who encounter a bat in the living space at night are encouraged to remove the bat to the outdoors, using all due precautions (see the Bat Conservation web site). Because bats are known to be one of our rabies-vector species, we do not want people needlessly handling bats or doing so without proper equipment/protection (e.g., thick leather gloves, long-sleeved shirts, etc.). Sometimes a butterfly net or a landing net used for fishing (one that has small mesh size) can be used to capture and relocate a bat in the living space; again, precautions to protect the individual doing the capture are needed. Alternatively, if the room in which the bat is known to be located can be shut off from the rest of the house, simply opening wide all windows and doors that lead outside and turning off all interior lights often will allow the bats to find their own way out without need for any “assistance.” Given the growing concerns about very high mortality among bats due to white-nose syndrome (http://www.nwhc.usgs.gov/disease_information/white-nose_syndrome/index.jsp) , we do not want to be seeing any other needless mortality occurring with these species.
Hopefully this information will help as these calls continue to come in to our offices. There are other concerns related to bat problems that may need to be addressed (e.g., potential disease issues related to guano accumulations), but I can provide help on those situations on a case-by case basis if necessary. If you have questions beyond what is covered here, by all means give me a call.
Jim
James A. Parkhurst, Ph.D.
Associate Professor of Wildlife Science and
Extension Wildlife Specialist
Department of Fisheries and Wildlife Sciences
144 Cheatham Hall (0321)
Virginia Tech
Blacksburg, VA 24061
tel. 540.231.9283
fax 540.231.7580
e-mail: jparkhur@vt.edu
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§29.1-100 Code of Virginia: "Nuisance species" means blackbirds, crows, cowbirds, grackles, English sparrows, starlings, or those species designated as such by regulations of the Board, and those species found committing or about to commit depredation upon ornamental or shade trees, agricultural crops, wildlife, livestock or other property or when concentrated in numbers and manners as to constitute a health hazard or other nuisance. However, the term nuisance does not include (i) animals designated as endangered or threatened pursuant to §§ 29.1-563, 29.1-564, and 29.1-566, (ii) animals classified as game or fur-bearing animals, and (iii) those species protected by state or federal law.
[Please note: the section highlighted above is Dr Parkhurst's added emphasis, not a part of the actual Code language]
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