Barbastelle

What is barbastelle?

The term barbastelle refers to either of two species of bats belonging to the genus Barbastella and the vesper bat family, Vespertilionidae.¹

These bats are distinguished by their short, wide ears that are joined together on the forehead. Their physical characteristics include long, dark fur with tips that appear white or gray, a body length of approximately 4–6 cm (1.6–2.4 inches), and a weight ranging from 6–10 grams (0.2–0.3 ounce).¹

Regarding their distribution and behavior:

• Species: B. barbastellus is found in Europe and North Africa, while B. leucomelas inhabits the Middle East and Asia¹.
• Habits: They are considered relatively heavy fliers that live either alone or in small groups, typically roosting in trees or buildings.¹
• Lifecycle: They hibernate in caves from fall through spring.¹

Like most bats, they utilize echolocation to navigate and locate prey.²³

How do bats use echolocation to navigate in the dark?

Bats navigate and hunt in the dark using echolocation, a sophisticated biological sonar system. By emitting high-frequency sound pulses—often well above the range of human hearing—through their nose or mouth, they create sound waves that reflect off objects in their environment.²

When these sound waves hit an object, such as an insect or a physical obstacle, the echoes return to the bat. By interpreting these returning signals, bats can determine an object’s direction, distance, velocity, and size. Their specialized ears and auditory systems are highly sensitive to these high-frequency echoes, allowing them to distinguish between multiple targets and background noise with remarkable precision.²³

The process typically occurs in three phases:

• Search: The bat emits pulses at a steady, slower rate to scan the environment.²
• Approach: Upon detecting a target, the bat increases its pulse rate and adjusts the frequency to focus on the object.²
• Terminal: During final interception, the bat emits extremely rapid, short pulses to track the target’s precise movements.²

What are some other animals that use echolocation to find food?

Beyond bats, several other animals utilize echolocation to navigate and procure food in environments where vision is limited:

• Toothed Whales and Porpoises: These aquatic mammals (suborder Odontoceti) use a series of high-frequency clicks—ranging from 50,000 to 200,000 hertz—to hunt fish and navigate murky waters. Because sound travels faster in water, they require these higher frequencies to achieve the same level of object discrimination as bats.⁴³
• Birds: Two specific groups of birds use echolocation to navigate in total darkness, typically within caves:
  • Oilbirds: These birds emit audible, rapidly pulsated clicks (around 7,000 hertz) to navigate their cave environments.³⁵
  • Swiftlets: Certain species of cave-dwelling swiftlets also employ echolocation³.⁵
• Other Mammals: Echolocation is suspected in shrews and sea lions, though current scientific evidence for these species remains limited.⁴³

Interestingly, the development of high-frequency sensitivity in both microchiropteran bats and some toothed whales is an example of convergent evolution, as both groups independently evolved a nearly identical molecular structure for the Prestin gene to facilitate this ability.³

Why do some bat species hibernate in caves during the winter?

Some bat species hibernate in caves during the winter as a vital adaptation to survive adverse conditions when food sources, such as insects, are scarce. Caves provide a stable, cool, and humid environment that remains above freezing, which is essential for these animals to maintain their state of hibernation.⁶⁷⁸

To prepare for this period, bats increase their body weight by 50 to 100 percent in the fall by storing energy as fat. During hibernation, they enter a state of torpor characterized by significantly reduced metabolic activity, lowered body temperature, and slowed heart and respiration rates. This “turning down the thermostat” allows them to conserve energy for months.⁶⁷

Additionally, hibernation is integrated into the reproductive cycle of many bats. Males and females typically mate in the fall when they are at their nutritional peak. In most species, the female stores sperm throughout the winter, with fertilization occurring only after she awakens in the spring. While caves offer necessary protection, they are also where bats face threats like white nose syndrome, a fungal disease that disrupts their hibernation and leads to fatal energy depletion.⁶⁹¹⁰