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
Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard
New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State University
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Power and Electrical Engineering
15.12.2017 | Materials Sciences
15.12.2017 | Life Sciences