An Unlikely Hero With Global Impact
Bats have been on Earth for more than 50 million years. With more than 1,400 species, they are the second largest order of mammals, and are widely dispersed across six continents. Globally, bats provide vital ecosystem services in the form of insect pest consumption, plant pollination, and seed dispersal, making them essential to the health of global ecosystems.
Today, bats are under unprecedented threat from widespread habitat destruction, hunting, accelerated climate change, invasive species, and other stresses. Without concerted international action, their populations will continue to fall, driving many species to extinction.
Bats are mammals that belong to the order Chiroptera (from the Greek cheir – “hand” and pteron -“wing”).
Bats are Important
Who needs pesticides when we have bats?
Scientists estimate that insect-eating, or insectivorous, bats may save U.S. farmers roughly $23 billion each year by reducing crop damage and limiting the need for pesticides. Most, on average, can eat up to half their body weight in insects, while pregnant or nursing mothers will consume up to 100 percent of their body weight each night.
Did You Know? The millions of Mexican free-tailed bats at BCI’s Bracken Cave in Central Texas help target an especially damaging pest called the Corn Earworm Moth (aka cotton bollworm, tomato fruitworm, etc.), that attacks a host of commercial plants from artichokes to watermelons.
Most flowering plants cannot produce seeds and fruit without pollination – the process of moving pollen grains from the male part of the flower (the stamen) to the female part (the pistil). This process also improves the genetic diversity of cross-pollinated plants. From deserts to rainforests, nectar-feeding bats that drink the sweet nectar inside flowers pick up a dusting of pollen and move it along to other flowers as they feed.
This role as a pollinator is critical for a wide variety of plants, such as giant cacti and agave, which, without bats, would not thrive. Bat pollination also plays a vital role in the cultivation of a host of commercial products, including balsa wood, carob, cloves, and durian fruit.
Vast expanses of the world’s rainforest are cleared every year for logging, agriculture, ranching, and other uses. And fruit-eating bats are key players in restoring those vital forests.
Regenerating clear-cut forests is a complex natural process, one that requires seed-scattering by many animals besides bats. Many fruit-eating animals drop seeds back into the ground, but these droppings typically occur within proximity to where they live. Night-foraging fruit bats, on the other hand, often cover vast distances each night, and many of these species are quite willing to cross clearings and typically defecate in flight, scattering far more seeds than animals such as birds across cleared areas. Seeds dropped by bats can account for up to 95 percent of the first new growth.
This ability to transport seeds is highly crucial — as the conditions left by forest clearings are often hot, dry, and unwelcoming to many types of plants. The seeds dropped by bats are often from hardy pioneer plants, whose first growth serves as shelter and cover for more delicate plants.
8 Amazing Bat Facts
- Bats are the only mammal capable of true flight.
- Tequila is produced from agave plants that in the wild rely on bats as their primary pollinators.
- The world’s smallest bat is the Bumblebee Bat measuring up to 29 – 33 mm (1.1 –3 in) in length and 2 g (0.071 oz) in mass as a full-grown adult.
- The world’s largest bat is the Giant Golden-crowned Flying Fox with a wingspan up to 6 ft!
- The oldest known bat was a male Brant’s myotis who lived at least 41 years.
- The fastest bat in the world is the Mexican Free-tailed Bat, flying in short bursts at speeds up to 100 mph!
- Of the 1,400+ species of bats in the world, only three are vampire bats that drink blood.
- Bracken Cave is the world’s largest bat colony. Located near San Antonio, Texas, USA, this is a summer maternity colony for up to 20 million Mexican Free-tailed Bats.
- Bat species are critically endangered (face imminent risk of extinction)
- Bat species are endangered
- Bat species are considered vulnerable
- Bat species are considered “Data Deficient,” an indicator that more conservation attention is necessary for these species
A dangerous time for bats.
As bat populations continue to decline worldwide, their potential for extinction only grows. While some of the challenges they face are endemic to their order, such as their slow gestation periods and diseases like White-nose Syndrome, the primary cause of their decline is human activity including:
- The ongoing destruction of natural habitats
- Hunting and persecution for sport and meat
- The growing use of wind-turbine energy
- The proliferation of harmful myths
Bats are among the slowest-reproducing mammals on earth for their size – On average, most species only give birth to one pup per year.
Bats are threatened
Global climate change is a major threat to the ecological integrity of our planet. The negative forces of climate change are often most severe on species already imperiled by habitat loss and other stressors. Integral to our mission to protect global bat populations is developing science-based strategies that address threats to bats around the world to prevent extinctions and faunal collapse.
Major threats that climate change poses to global bat populations:
- Mortality from increased severity and frequency of extreme weather events
- Flying foxes are dying in alarming numbers in Australia from extreme heat waves
- Bats on islands are threatened by severe tropical storms, especially when coupled with extensive habitat loss and persecution on islands.
- Increased aridity and drought reduce survival and reproductive success of bats
- Bats in arid and semi-arid landscapes have lower fitness during drought. The long-term consequences could result in range contraction of bat species and loss of bat diversity in arid and semi-arid regions of the world.
- Changes in timing of migration and potential for phenology mismatch between bats and critical food resources during critical life stages
- Species of insectivorous and pollinating bats that undergo long-distance migrations and depend on seasonal timing of food resources to fuel migrations could be negatively impacted by shifts in phenology of available resources (e.g. flowering plants or seasonal insect abundance).
Climate change is a global problem necessitating a global solution, but local interventions and targeted actions play a critical role in protecting species from its adverse effects. Effective conservation strategies must address current and future impacts from climate change, including creating resiliency and mitigating the threats of extreme weather events, increased drought, and shifts in phenology and habitat suitability. Our work to protect bats includes strategies that promote climate adaptation, mitigation, and identifies key research needs. Specifically, Bat Conservation International takes action by:
- Promoting Climate Adaptation for Bats
- Securing resilient habitats for imperiled bats threatened by climate change
- We protect critical habitat refugia for island endemic bats vulnerable to increased severity and frequency of tropical storms (e.g. Fiji, Jamaica)
- We provide safe roosting structures for endangered species in hurricane-prone areas (e.g. Florida bonneted bat)
- We protect subterranean roosts to provide habitat resiliency for bat communities
- Protecting and restoring habitat networks for migratory species experiencing shifting phenology
- Our Bracken Cave preserve protects the largest known colony of Mexican free-tailed bats during the summer maternity season and now also protects a growing population of bats overwintering in Texas
- We restore agave plants in desert and montane habitats across the migratory range of nectar-feeding bats in Mexico and the US-Mexico borderlands to provide climate resilient corridors for migratory pollinating bats
- Securing resilient habitats for imperiled bats threatened by climate change
- Supporting Climate Mitigation Solutions
- We invest in researching solutions that reduce bat fatalities at wind energy facilities; supporting renewable energy development that is sustainable and does not negatively impact biodiversity while producing carbon-free energy
- Leading Research to Inform Conservation Priorities in a Changing Climate
- We partner with the North American Bat Monitoring Program to determine status and trends of bats, including range shifts, to inform local to continental conservation planning
- Mortality from increased severity and frequency of extreme weather events
The loss of natural habitats remains the most widespread peril for bats worldwide.
Forest habitat, which many bats use for roosting and foraging, are disappearing at an alarming rate — the result of timber harvests, clearings to make room for farm crops, mining operations, cattle pastures, and cities. The danger is even more significant for tropical rainforests, home to the richest diversity of bat species.
Caves and abandoned mines also serve as roosts for many species, with countless numbers of bats being driven out due to inappropriate guano mining or thoughtless tourism. This is especially prevalent during the winter months when large numbers of bats hibernate in caves and mines. If roused from hibernation, such as by human disturbance, bats can burn through the stores of fat they need to survive the winter.
In many parts of the world, bats are victims of casual killing, the result of harmful myths and misplaced fears. In Latin America, whole colonies of beneficial bats are routinely slaughtered, the victims of a mistaken belief that all bats are vampires. (In reality, only three of the more than 1,400 bat species feed on blood, and all are in Latin America.)
In regions such as Southeast Asia and the Pacific islands, large fruit-eating bats are hunted, both for local consumption and commercially for markets and restaurants. Some bats are also used in traditional folk medicines.
White-nose Syndrome (WNS) is a fungal disease that has been continually responsible for the death of millions of bats in North America since it was first discovered in a single cave in New York in 2006. The condition is causing massive population declines for multiple hibernating bat species – resulting in one of the most significant losses to wildlife in the past century. Named for the telltale white fuzzy growth on the nose, ears, and wings of infected bats, WNS repeatedly rouses bats from hibernation, causing them to consume their winter fat stores — which often can result in starvation before spring.
Bats with the disease symptoms of WNS are found in 34 U.S. states and 7 Canadian provinces. To date, 13 bat species have been found with WNS disease symptoms, including two federally endangered species, the gray bat and Indiana bat. The Northern long-eared bat was listed as federally threatened due to the rapid decline of this species from WNS. Thankfully, not all species are impacted the same way by WNS, with some appearing more resistant to the disease than others. Scientists are working to determine the conditions that contribute to a bat’s susceptibility and for potential treatments.
Bats affected with WNS do not always have visible fungal growth. Sometimes, they simply display unusual behavior such as flying outside during the day in near-freezing weather. As a result, in winter, you may see dead or dying bats on the ground or in buildings or other structures. If you encounter one, do not handle it!
The dramatic growth of wind energy throughout much of the world has also taken a considerable toll on bats, with scientists estimating that hundreds of thousands are killed each year in the United States alone. This mortality is due to both collisions with the spinning blades of wind turbines and rapid pressure change at turbines that can rupture blood vessels.
Between 2000 and 2011, an estimated 650,000 to 1.3 million bats have died from collisions with wind turbines in the United States and Canada (Arnett and Baerwald 2013). Additionally, as many as 400,000 estimated fatalities may have occurred in 2012. Migratory bats, such as hoary bats and silver-haired bats, make up a large part of these casualties.
With wind-generated energy expected to expand from the current 82,000 MW to 224,000 MW by 2030 (U.S.DOE Wind Vision 2015), the impact on bat populations from this build-out could be devastating unless solutions to minimize fatalities are developed and implemented.
Our collaboration with the Bats and Wind Energy Cooperative (BWEC) has led to meaningful research suggesting practical solutions to reduce bat mortality. Other research has focused on trying to understand what makes bats more susceptible to wind turbine collisions, be it some attraction to turbines themselves, or that they somehow affect geographic features bats use during migration.
Thank Bats For That Margarita
Do you enjoy tequila? Without bats, we might not have any. Tequila is produced from the agave plant, which relies primarily on bats to pollinate its flowers and reproduce. So next time you order a tequila, be sure to raise your glass to the pollinating bats that helped to make it possible!
All The Better To Hear You
Bats are famous for their ability to navigate and hunt by listening to the echoes of their ultrasonic calls, known as echolocation. Some bats often have bizarrely elaborate faces, with intricately shaped flaps called noseleaves around their nostrils, which can help them to “see” in the dark by using their sonar in different ways.
Eating insects is the most common diet among bats worldwide — a major benefit for our farmers. However, the role many of nectar-feeding bats play is just as important. Bats, like the Northern Blossom Bat (Macroglossus minimus) from Australia, pollinate the flowers of plants that produce nectar. Scientists believe that many plants have evolved to attract bats, as they can carry significant amounts of pollen in their fur.
Bats Hear Everything
Fishing bats have echolocation so sophisticated that they can detect a minnow’s fin, as fine as a human hair, protruding only two millimeters above a pond’s surface. And African heart-nosed bats can hear the footsteps of a beetle walking on sand from more than six feet away!
Vampire Bats? More Like Stroke Prevention Bats
Only three bat species (vampires) feed on blood, and only one targets mammals. Limited to Latin America, scientists have discovered a potent anticoagulant in vampire bat saliva, which the bats use to keep blood from clotting, that has been developed into a medication that helps prevent strokes in humans.
Bats, humans, and health.
Simply left alone, bats are harmless and highly beneficial. They are fascinating creatures, vital to the balance of nature around the world. Like most wild animals, bats prefer to avoid contact with humans. But in situations where bats and humans come into close proximity, it is important to understand how to prevent negative outcomes for humans and bats.
Here are several scenarios that might bring bats and humans together:
- Bats sometimes accidentally fly into a home or business through open doors or windows
- Bats might take advantage of an existing small opening into an attic, wall space, or chimney, and roost in structures where humans live or work
- Sick, injured, or even dead bats sometimes fall to the ground where humans live
In each of these situations, we discourage the general public from handling bats. See below for information about possible health risks that may apply.
Bats and Human Health
Bats and Infectious Disease
We fully embrace the “One Health” movement, which recognizes that conservation biologists and public health officials confront the same ecological problems. As stated in the “executive summary” of the “One Health” Initiative, “the convergence of people, animals, and our environment has created a new dynamic in which the health of each group is inextricably interconnected”.
Research has revealed that more than 60 percent of emerging infectious diseases are zoonotic, meaning they can be communicable from animals to humans, and bats are not exceptional among wildlife as potential sources of human disease. Over the last decade, increased surveillance and improved techniques for disease detection have implicated bats as likely reservoirs and vectors for a growing list of pathogens that can affect humans and domestic animals.
These include Marburg, Nipah, Hendra, SARS-like coronaviruses, flu virus, a panoply of lyssa viruses including rabies, and most notably, Ebola.
Rabies is a preventable viral infection of the central nervous system in mammals. Bats, like most mammals, can contract the rabies virus, but the vast majority never do. When bats do get rabies, they eventually die from the disease and do not “carry” the virus indefinitely without themselves getting sick.
The virus is typically transmitted by the bite of an infected animal – anyone bitten by a bat (or any other wild or unknown domestic animal) should seek immediate medical attention. People can, in rare instances, contract rabies if infectious material, such as saliva from a rabid animal, gets into their eyes, nose, mouth, or a wound.
The U.S. Centers for Disease Control and Prevention provides information about Rabies here
Histoplasmosis is a respiratory disease caused by a fungus that grows in soil enriched by animal droppings, including those from bats. Ninety percent of all reported cases in humans come from the Ohio and Mississippi River valleys and adjacent areas where warm, humid conditions favor fungal growth.
The disease is rare or nonexistent in most of Canada and in the far northern and western United States. The majority of cases are asymptomatic or involve flu-like symptoms, though some individuals become seriously ill, especially if exposed to large quantities of spore-laden dust.
To be safe, avoid breathing dust in areas where there are animal droppings; if you must clean an area of bat or bird droppings, wear a respirator that can guard against particles as small as two microns.
The U.S. Centers for Disease Control and Prevention provides information about Histoplasmosis here