Nebraska is home to a diverse population of bats, which are a significant component of the state’s wildlife and natural ecosystems. These small mammals are insectivores, consuming a large quantity of night-flying insects, including many agricultural pests and mosquitoes. Their presence across the state provides ecological and economic benefits through natural pest control.
Key Species Found in the State
Thirteen species of bats are recognized within Nebraska, generally categorized into two groups: cave bats and tree-roosting bats. The most widespread and commonly encountered is the Big Brown Bat (Eptesicus fuscus), a robust species found statewide and likely the most abundant. This bat often lives in colonies and tolerates colder temperatures than other species, frequently hibernating locally in structures like buildings.
The Little Brown Bat (Myotis lucifugus) is another common species, though its populations have faced severe declines due to disease. It is slightly smaller than the Big Brown Bat, and reproductive females often form maternity colonies in human-made structures. These colonies can number in the thousands, especially in areas like the Pine Ridge region where natural tree roosts may be limited.
Several migratory tree-roosting species are also common, including the Eastern Red Bat (Lasiurus borealis), the Silver-Haired Bat (Lasionycteris noctivagans), and the Hoary Bat (Lasiurus cinereus). The Hoary Bat is the largest species in the state, with a wingspan that can reach up to 16 inches. These “forest bats” are more solitary and primarily roost in the foliage of trees, often following river valleys like the Missouri and Niobrara.
The Northern Long-Eared Bat (Myotis septentrionalis) and the Tri-colored Bat (Perimyotis subflavus) are also present, and both are species of conservation concern. The Northern Long-Eared Bat is federally listed as threatened, largely due to disease, and prefers foraging and roosting in the interior of dense forests. The Tri-colored Bat, the smallest species in Nebraska, is more versatile in its habitat, utilizing both forest interiors and edges.
Daily Habits and Roosting Ecology
Nebraska bats are strictly nocturnal, emerging from their daytime roosts near dusk to forage and returning to rest before dawn. Their activity is focused on consuming flying insects, resulting in them eating between 25 and 125 percent of their body weight in insects each night. This high consumption rate means a colony of 150 Big Brown Bats can prevent the hatching of millions of agricultural pests, such as cucumber beetles, in a single season.
Bats use a sophisticated sensory system called echolocation to navigate and hunt in the dark. They emit ultrasonic calls, typically outside the range of human hearing, and interpret the echoes to determine the size, direction, and location of their prey and surrounding obstacles. Foraging often occurs along the edges of fields, near wooded areas, and over streams, maximizing access to insect populations.
During the active season, female bats gather in specific locations to form maternity colonies necessary for raising their young. Mating occurs in the fall, but females delay fertilization by holding the male sperm until late winter or early spring, ensuring the young are born when insect abundance is at its peak.
Most Nebraska bats give birth to a single pup annually, though the Eastern Red Bat may have two to four young. Maternity colonies seek out warm, enclosed spaces that function as incubators, commonly establishing themselves in attics, wall voids, behind chimneys, or in tree cavities. The young remain in the roost until they become capable of flight, typically around late July, at which point the colonies begin to disband.
Seasonal Movement and Hibernation Patterns
The arrival of fall triggers distinct seasonal behaviors as Nebraska bats prepare for the limited insect availability of winter. Species employ two primary strategies for winter survival: local hibernation or long-distance migration. Migratory species, including the Hoary Bat and the Silver-Haired Bat, are often solitary and fly south, sometimes covering great distances, though the specific wintering grounds for some remain largely unknown.
Other species, such as the Big Brown Bat, Little Brown Bat, and Tri-colored Bat, are residents that enter a state of torpor called hibernation within the state. Hibernation typically lasts from late October to early April, during which the bat’s body temperature drops to near the ambient temperature of its roost. The bat’s heart rate slows dramatically to conserve energy during this period.
These hibernating species seek out sheltered areas, or hibernacula, that maintain a stable, cool temperature above freezing. Natural sites include caves, mines, and deep rock crevices, but Big Brown Bats frequently use human-made structures, such as attics or wall voids in buildings. Disturbing bats during this period is detrimental because waking them causes them to burn through their limited fat reserves, which can lead to starvation before spring arrives.
Some hibernating populations in eastern Nebraska have been observed to travel north and east toward the Ohio Valley to find suitable overwintering sites. Research efforts are actively tracking bat movements along corridors like the Platte and Missouri River valleys to better understand these patterns. The distinction between species that migrate and those that hibernate locally is important for conservation efforts.
Conservation Status and Protection Measures
All bat species in Nebraska are considered protected, and it is illegal under state law to intentionally kill a bat. However, many populations face threats, with nine of the state’s thirteen species listed as at-risk under the Nebraska Natural Legacy Plan. The primary threat to cave-dwelling bats is White-Nose Syndrome (WNS), a disease caused by the non-native fungus Pseudogymnoascus destructans.
WNS was confirmed in Nebraska in 2017, following the detection of the fungus in Cass County mines as early as 2015. The disease affects bats during hibernation, growing on the skin and causing them to wake frequently. This rapid depletion of stored fat is necessary for survival, and mortality rates in affected hibernacula elsewhere have reached over 90 percent.
The Northern Long-Eared Bat is listed as a federally threatened species under the Endangered Species Act, primarily due to WNS. Efforts are ongoing to potentially list the Tri-colored Bat and Little Brown Bat as well, given their population declines. Migratory, tree-roosting species are generally safe from WNS, but they face a threat from wind energy development, as many are killed by turbine blades during seasonal movements.
Public involvement in conservation focuses on preventing the spread of WNS and minimizing disturbance to the bats. Individuals who enter caves or mines are encouraged to follow strict decontamination protocols to avoid carrying fungal spores between sites. Scientists are also exploring methods to combat the fungus, including probiotic applications and temperature adjustments within hibernacula to create environments less favorable to the pathogen.