The week prior to Halloween is officially designated as National Bat Week. In honor of this event, it’s worth considering some of the benefits bats provide to us.
Did you know there is a species of bat that lives nowhere in the world but within our state? It’s called the Florida Bonneted Bat, and occurs in only about 12-15 counties in south and central FL. These bats are so mysterious that we’re currently not even sure exactly where they occur. They are so rare that they’re listed as a federally endangered species.
The Florida Bonneted Bat lives nowhere in the world but Florida. Photo credits: Merlin Tuttle.
These bats were named for their forward-leaning ears, which they can tilt forward to cover their eyes. With a wingspan of 20 inches, they are the largest bats east of the Mississippi River: only two U.S. species are larger than they are, and these both occur out west.
We have been investigating the diet of Florida Bonneted Bats. To do this, we captured bats in specialized nets, and then collected their scat (called guano). Next, we processed the scat in a laboratory using DNA metabarcoding to determine which insect species the bats had recently consumed.
We found that the bats eat several economically important insects, including the following:
- fall armyworm (Spodoptera frugiperda)
- lesser cornstalk borer (Elasmopalpus lignosellus)
- tobacco hornworm (Manduca sexta)
- black cutworm (Agrotis ipsilon)
These insects are pests of corn, cotton, peanut, soybean, sorghum, tobacco, tomato, potato, and many other crops.
Furthermore, the bats did not eat these insect pests infrequently. In fact, 86% of the samples we examined contained at least one pest species. On average, each sample contained three pest species! This tells us that Florida Bonneted Bats should be considered IPM (Integrated Pest Management) agents.
Currently, a new student has begun investigating the diets of bats more commonly found in northern Florida, southern Georgia, and southern Alabama. By the time Bat Week 2019 rolls around we’ll have details on which insect pests these bats could eat on your property.
If you’re interested in helping bats or incorporating them into your Integrated Pest Management efforts, consider creating roosts for them (places where the bats can sleep during the day). Bats roost not only in caves, but also in cavities in trees, in dead palm fronds, and in bat houses.
Bats sometimes move into buildings when they can’t find the natural structures they prefer (caves and large trees with cavities).
All 13 species of bats that live in Florida sleep during the day and feed on insects throughout the night. Most of these bats sleep in natural structures such as trees and caves. But when the natural structures these bats prefer are limited or vandalized, the bats may move into buildings.
Bats are a great help to us. Each of them consumes hundreds of insects per night. Bats save growers billions of dollars annually by reducing insect pests. Some of the pests bats feed on include the damaging fall armyworm, cabbage looper, corn earworm, tobacco budworm, hickory shuckworm, and pecan nut casebearer. But both bats and humans are happier when not sharing living spaces!
If you or someone you know has a group of bats living in a building where they are not welcome, you have options. The safe, humane, effective way to coax a colony of bats out of a building permanently is through a process called an ‘exclusion’. A bat exclusion is a process that prevents bats from returning to a building once they have exited at sunset to feed. This is accomplished by installing a temporary one-way door. This one-way door can take many forms, but the most common is a sheet of plastic mesh screening (with small mesh size of 0.125 x 0.125 inches or less) attached at the top and along both sides of the sheet, and open on the bottom. Another option is to install slick tubes (such as clean caulk tubes) to such entry points. These temporary one-way doors should be attached over each one of the suspected entry/exit points bats are using to get in and out of the building.
It is illegal to harm or kill bats in Florida. However, excluding bats from a building is allowed if you follow practices recommended by the Florida Fish and Wildlife Conservation Commission (FWC). According to Florida law, all bat exclusion devices must be left in place for a MINIMUM of 4 consecutive nights with temperatures above 50⁰ F before each entry point can be permanently sealed to prevent bat re-entry. Also, it is unlawful in Florida to attempt to exclude bats from a building between April 15 and August 15, which is bat maternity season. This is when female bats form large colonies and raise young that are unable to fly for their first few weeks of life. If bats were excluded during this time period, young bats (pups) would die indoors.
Bats can be coaxed to leave a building by first identifying the bat’s entry points into the building, and then creating a temporary one-way door using plastic screening with fine mesh size over each of these entry points.
The steps for an effective exclusion are as follows:
- Identify the locations where bats are getting in and out of the building. Look for holes or crevices about the width of your thumb, often near the roofline, with brown staining on the exterior of the building and bat scat (guano, about the size of a grain of rice and brown in color) below.
- Fashion and install one-way doors at each suspected bat entry point. This can be done anytime between August 16 and April 14 – it cannot be done when bats have young pups, which is between April 15 and August 15.
- Leave all one-way doors in place for at least 4 consecutive nights with minimum temperatures above 50⁰ F so all bats leave through the doors and cannot re-enter. If any one-way door becomes ineffective during the 4 day period, begin again. You must be absolutely certain all bats have exited so you do not block any inside the building.
- Immediately after removing the one-way doors, permanently seal each hole to prevent bats from getting back inside.
For detailed instructions on how to conduct a bat exclusion, see this video that features interviews with bat biologists from the University of Florida, FWC, and the Florida Bat Conservancy: How to Get Bats out of a Building.
For additional information on Florida’s bats, visit University of Florida’s bat advice or FWC’s bat website.
Remember, if you have a colony of bats roosting indoors that you want to exclude, you must either act within the next few weeks or else wait until the middle of August to coax them out. Bat maternity season in Florida runs from April 15 to August 15, and during this time no one can attempt to exclude bats from a building.
Bluebirds are very energetic birds. If you enjoy watching wildlife in your yard, now is a fantastic time to put up a few bluebird houses. You might gain hours of entertainment watching all the hard work these small birds put into gathering materials to build nests and gather food to feed their chicks.
In the Panhandle, bluebirds begin in March to create their first nests of the year. They carefully weave a basket of pine needles and twigs, and line it with fine grasses. Photo by Holly Ober.
March is when bluebird nest-building begins in the Panhandle. Believe it or not, these enterprising birds are likely to continue building nest after nest from now through July or even August!
The reason we can observe bluebirds more closely than many other birds is because they prefer to nest in cavities situated in open, sunny locations. These birds readily use nest boxes because natural cavities in clearings are quite scarce.
If you’re considering putting up a nest box to attract bluebirds, be aware that these birds are rather fussy when it comes to selecting nest boxes. They prefer structures that are approximately 4”x4”x9” or 5”x5”x9”. These structures could be rectangular, cylindrical, or wedge-shaped. It’s best if the entrance hole is 1.5” in diameter, and located about 5” above the floor of the box. Each house should be mounted on a pole 4-8’ above the ground.
We have been conducting an experiment the past few years to determine which of three common nest box designs local bluebirds prefer. The three types of houses we tested were:
- traditional wooden rectangular house (4”x4”x9”)
- Gilbertson (cylindrical houses made of a PVC tube with a wooden floor and roof)
- Peterson (wedge-shaped houses made of wood and covered in metal, with a sloping floor and roof).
We tested bluebird preferences for 3 types of houses: the traditional rectangular wooden house (left), the Gilbertson (cylindrical house of PVC, center), and Peterson (wooden wedge-shaped, right).
We put up 18 houses during the summer of 2013 and have been keeping track of the number of nest attempts, eggs laid, and chicks fledged ever since. The ambitious birds using these 18 houses have fledged 124 chicks during the past three years! The standard rectangular wooden houses have performed best, with bluebirds laying an average of 8.3 eggs per house per year, and fledging 4.3 chicks per house per year. The other two house types performed similarly, with bluebirds laying an average of 4.3 eggs per house per year in each. An average of 2.4 chicks fledged from each of the Gilbertson houses each year, whereas 1.8 chicks fledged from each of the Peterson houses each year.
Regardless of which type of house you choose to put up for bluebirds, be sure to place the houses at least 100 yards apart. These birds are very territorial and will not allow other bluebirds to nest nearby.
Christmas trees can provide benefits to wildlife long after they have served as holiday decoration indoors. Credits: IFAS photo database.
Americans purchased approximately 30 million live Christmas trees last year. If you plan to have a live tree this winter, and you’re wondering what you could do with your tree once it has finished its role as holiday decoration in your home, read below. Rather than simply dragging your tree to the curb for the waste disposal truck to pick up, you could prolong the life of your holiday tree by repurposing it to benefit wildlife.
YOUR TREE COULD PROVIDE FOOD FOR WILDLIFE
Many of the needles may have dropped from your Christmas tree as it dried out while indoors, but the branches should still be intact. This means your tree could be used as a frame to present food for wildlife. After removing your indoor decorations, consider propping the tree up in your yard (perhaps using the same stand you used indoors), and adorning the branches with food enjoyed by wildlife visitors. Some low-budget options include mesh bags filled with bird seed (black oil sunflower seed, safflower seed, and thistle (nyjer) are favorites of many common backyard birds), pine cones smeared with peanut butter, home-made suet cakes, and strings of fruit such as apple slices, orange slices, or grapes. If you choose this option, beware that you may attract not only birds, but mammals such as squirrels, raccoons, opossums, and others.
If you’d like to watch your wildlife visitors, be sure to attach the food items with string so that the animals must eat the food at the site of the tree rather than carrying it away to eat or store elsewhere out of view. Consider using a biodegradable string (i.e., cotton) to secure the food items to your tree so you can eventually compost the tree without worrying about needing to remove the string.
YOUR TREE COULD PROVIDE SHELTER FOR WILDLIFE
If you’re tired of seeing your holiday tree in its upright position, consider taking it outdoors, laying it down, and heaping other vegetative debris loosely on top to form a ‘brush pile’. Brush piles are mounds of woody vegetation created specifically to provide shelter for wildlife.
The lower portions of a brush pile can offer cool, shaded conditions that allow small mammals such as rabbits to hide from the weather and from predators. Meanwhile, the upper portions can serve as perch sites for songbirds. The entire pile may be used as resting sites for amphibians and reptiles. In yards with few understory trees or shrubs, and at times of year when many trees and shrubs have limited foliage, these brush piles can provide much-appreciated cover for many kinds of wildlife.
YOUR TREE COULD PROVIDE SHELTER FOR FISH
Your retired Christmas tree could be used to make long-lasting habitat improvements for fish. In artificial ponds with little submerged vegetation, the addition of one or more Christmas trees could upgrade the quality of refuge and feeding areas for fish. Small fishes may hide among purposely submerged Christmas trees for protection, and larger fishes may follow them. If you’ve got an artificial pond on your property, consider adding discarded trees to create a place where fish can hide and find food, and also to concentrate fish for angling. Simply secure a cinder block to your holiday tree using heavy wire or thin cable and place it far enough from shore that water covers the top of the tree by a couple of feet. When constantly submerged, Christmas trees can persist for many years underwater.
Not only can your tree offer enjoyment to you when decorated with lights and ornaments indoors, but it can also allow you to provide post-holiday gifts to the wildlife and fish on your property.
Brazilian free-tailed bat (Tadarida brasiliensis) eating a corn earworm moth (Helicoverpa zea).
If you think you’d prefer a world without bats, we present to you three reasons to reconsider. Most negative stereotypes about bats are untrue. The reality is that bats benefit us in numerous ways. Here are a few facts that may convince you we should be thankful for bats rather than fearful of them.
1. INSECTS WOULD BUG YOU MORE IF WE HAD NO BATS
Over two-thirds of the 1,240 species of bats that roam the earth’s skies feed on insects. These aerial acrobats cruise over forests, grasslands, waterways, and crop fields, assisting us by consuming nighttime insects. Bats collect insects using a variety of innovative approaches: some scoop them from the air with their wing or tail membrane and transfer them to their mouths; others nimbly pluck insects off surfaces such as leaves, tree trunks, or even water. These bats are our allies, as they drastically reduce the number of pests that would otherwise bite us or damage our crops. It’s estimated that bats help North American farms save around $23 billion a year. If all bats were lost, the resulting damage to crops due to the insects bats formerly kept in check is estimated to be $74/acre across the US.
2. SOME FOODS AND DRINKS MIGHT BECOME RARE IF WE HAD NO BATS
If you like tropical fruits like mangoes, papayas, guavas, bananas, or figs, you should be thankful for bats. Many bats in the tropics and sub-tropics pollinate and disperse seeds in ecosystems ranging from deserts to rainforests. Bats in the desert visit columnar cacti and agaves, ensuring pollination of the plants responsible for making tequila. Bats in the rainforests help regenerate new forests and ensure availability of many locally-consumed and highly-nutritious fruits.
3. BATS CAN HELP US SOLVE MEDICAL PUZZLES
Bats possess many unique biological adaptations that hold clues vital to solving human health issues. Bats have already made notable contributions to the medical community. The special blood thinning enzymes found in the saliva of vampire bats has helped us understand how to prevent blood clotting during open-heart surgery. The adaptations bats have for seeing in the dark are being studied to see if they could provide insight useful for assisting people who have limited vision.
Despite the many ways bats help us, they remain misunderstood by many. Fear of bats, called chiroptophobia, is the result of negative stereotypes about bats. Most of these stereotypes are downright untrue. First, there’s a common belief that bats get caught in people’s hair. This is highly unlikely: if a bat is agile enough to catch an insect the size of a gnat in flight, it can certainly steer clear of a human head. Second, there’s a common fear that all bats have rabies. In fact, rabies is quite rare among bats, and much more common among raccoons and foxes in Florida. Third, despite the portrayal in movies of bats as aggressive towards humans, bats are in reality not likely to bother people. In fact, they’re generally far more afraid of you than you are of them.
If you’d like to help bats (and perhaps get some free control of insect pests in your area), consider building or buying a bat house for your property. Also consider leaving dead and dying trees in your yard if they’re not a safety hazard, avoid trimming dead fronds off your palm trees, and retain Spanish moss. All of these locations (tree cavities, dead palm fronds, and Spanish moss) offer roosting habitat for bats. By promoting bat habitat, you may boost local bats and find you have fewer insect pests nearby.