When it comes to locating a meal, insect-eating bats generally employ one of two foraging tactics: capturing prey in the air or snatching it from a substrate. Accordingly, the animals use different kinds of echolocation during these activities. Whereas aerial hunters tend toward longer calls with constant frequency, substrate-gleaning species generate short calls that sweep from low to high frequencies (FM echolocation). Less clear, however, is how effective the latter is at distinguishing the prey item from the substrate when the substrate contains clutter. Under such conditions, one would expect the background objects—leaf litter on the forest floor, for example—to produce their own echoes, which could mask those of the bats intended target. Now new research shows that bats have a third strategy for just this kind of tricky circumstance: they turn down the sonar and wait for the insect to reveal itself. The findings appear today in the journal Nature.
Raphaël Arlettaz of the University of Bern and colleagues studied the mouse-eared bats ability to obtain live and dead insects on clean and cluttered surfaces. As it turns out, the animals scored well when it came to capturing moving prey on both substrates and still prey on a smooth surface, but they labored to locate still prey on a complex surface. Additionally, the researchers found that bats attempting to pinpoint prey in the air or on smooth surfaces emitted so-called feeding buzzes. Those searching among the rubble, in contrast, emitted only faint calls or no calls at all for more than a second just before detecting prey. The scientists thus suggest that the bats listen for prey-generated sounds during this moment of silence, which would explain why they struggled to locate the dead prey in the leaf litter. "The low-intensity calls emitted during prey approach," the team writes, "may detect the immediate surroundings so the bats avoid colliding with obstacles or the ground."
According to the researchers, the study results indicate that echolocation does not provide a detailed picture of objects to substrate-gleaning bats. Indeed, when hunting among clutter, echolocation appears to render the bats "acoustically blind." This, they conclude, "suggests that FM echolocation is mainly adapted to orientation and capture of prey either in the open space or from simple backgrounds."
Kate Wong | Scientific American
Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel
Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences