![\"Image](\"http:\/\/pages.vassar.edu\/sensoryecology\/files\/2016\/02\/Daubentons-bat-resting-on-wood.jpg\")
<\/a>Image of Daubenton’s bat, Myotis daubentonii<\/p><\/div>\n
Echolocation is type of sensory system in which an animal can generate biosonar signals to detect and locate objects. \u00a0Hunting bats are one of the mammals that utilize this system in order to locate prey. Daubenton\u2019s bats,\u00a0Myotis daubentonii<\/i>, are small to medium-sized bats that live in Europe and some parts of Japan and Korea, where they live in wooded areas within close vicinity of a body of water, such as a river or stream. \u00a0They are insectivores and tend to hunt just after twilight and into the night. \u00a0The can produce sounds between 35-85 kHZ, and use calls to locate potential prey.<\/p>\n
Because bats have the ability to fly, they have multiple planes in which they can hunt. \u00a0In a study done by\u00a0Hugal and Ratcliffe, they\u00a0divided\u00a0this potential hunting area into\u00a0two different \u201cdimensions;\u2019 over water and in the air. \u00a0Water-trawling is considered a 2-dimensional hunting ground, because all insects the bats would prey on in this environment are located just above the surface of the water, creating one plane for the bats to hunt on. \u00a0Aerial hunting is considered 3-dimensional hunting because insect prey can travel in any direction.<\/p>\n
In this study,\u00a0Hugal and Ratcliffe\u00a0investigated the differences in sound duration and its proxy to task difficulty.\u00a0 The researchers then\u00a0divided the type of biosonar signals emit into two categories; \u2018buzz I\u2019 and \u2018buzz II.\u2019 \u00a0Buzz I calls consisted of approximately 90 calls a second at a higher frequency, while buzz II calls were produced around 160 calls a second at a lower frequency. \u00a0This gives the bats the largest frequency range to detect prey. \u00a0They tested that the type of call and duration would change depending on the hunting strategy and the amount of attention the task required. They predicted that hunting in a 2D environment would elicit more buzz II, and that buzz I calls would be used to would be used for aerial, moving prey. \u00a0This is because call sequences of multiple short bursts, increase the amount of information that the bat receives. \u00a0This gives the bat more and more precise information, the closer it gets to its prey, allowing it to zero in for the kill, especially when the prey target is stationary. \u00a0Longer calls send a larger stream of signals, allowing for more real-estate to be interrupted. \u00a0This is more beneficial for moving prey or prey that is at a greater distance.<\/p>\n
Their results supported their hypothesis that more difficult tasks, i.e. aerial hunting, would result in longer vocalizations, and greater energy output. \u00a0This, they suggest, is proxy for how difficult a task is. \u00a0Closer prey requires shorter signals, and therefore less energy output. \u00a0As Figure 2A (below) shows, the further away the bat is from the prey, the lower the time interval between vocalizations.<\/p>\n
<\/a>Call (pulse) intervals, attack distances, SSGs, spectrograms and oscillograms for attack sequences. Hulgard, Katrine, Ratcliffe, John M. “Sonar sound groups and increased terminal buzz duration reflect task complexity in hunting bats.” Nature, 2016. 21500 (2016). doi:10.1038\/srep21500.<\/p><\/div>\n
These findings have important implications in understanding how bats\u2019 sensory systems have evolved to make them successful in their environment. \u00a0Their usage of an array of biosonar vocalizations allows them to detect prey in specific hunting environments, and their selectivity of call type depending on the hunting environment is telling of the complexity of this system and deters previous assumptions that vocalizations were independent of one another. \u00a0It also demonstrates that bats are able to utilize the information they receive form this type of signaling in real time. \u00a0Further studies should be done as to how the water reflects signaling back to the bats, and whether the acoustics of water affect the signals.<\/p>\n
Hulgard, Katrine, Ratcliffe, John M. “Sonar sound groups and increased terminal buzz duration reflect task complexity in hunting bats.” Nature, 2016. 21500 (2016). doi:10.1038\/srep21500.<\/p>\n
“Daubenton’s bat.” \u00a0Wildscreen Arkive. \u00a0Web 17 Feb. 2016.\u00a0http:\/\/www.arkive.org\/daubentons-bat\/myotis-daubentonii\/<\/p>\n","protected":false},"excerpt":{"rendered":"
Echolocation is type of sensory system in which an animal can generate biosonar signals to detect and locate objects. \u00a0Hunting bats are one of the mammals that utilize this system in order to locate prey. Daubenton\u2019s bats,\u00a0Myotis daubentonii, are … Continue reading