This Caterpillar Makes Noise the Same Way a Tea Kettle Does

By Laura Geggel, Senior Writer | February 26, 2018 06:00pm ET

Caterpillars aren't known for being noisy — except, perhaps, for the chomping sounds they make while munching on leaves — but hawkmoth and sphinx moths are far rowdier, producing clicks, whistles and other sounds when attacked by hungry predators.

However, it wasn't immediately clear how some of these voracious insects were making such weird noises — in particular, the Nessus sphinx hawkmoth caterpillar (Amphion floridensis), which emits a faint cry that sounds like a mix between spitting and static.

Now, researchers have solved that puzzle: the brownish-red caterpillars create sound the same way that jet engines roar and tea kettles whistle, they said. [Meet the Colorful Nocturnal Moths of 'Mariposas Nocturnas' (Photos)]

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Motor-boat noise makes fish bad parents, leading to the death of their babies

Date: June 6, 2017

Source: University of Exeter

Noise from motorboats is making fish become bad parents, and reducing the chance of their young surviving, research led by marine experts at the University of Exeter has shown.

The sound of motorboat engines disturbed coral reef fish so acutely it changed the behaviour of parents, and stopped male fish properly guarding their young, feeding and interacting with their offspring.

The research, which involved playing recordings of natural reef noise or intermittent motorboat noise around 38 fish nests over 12 days, found that the death-rates of baby fish exposed to boat engine noise increased significantly, with six of the 19 boat-noise nests suffering complete mortality.

The Exeter University led team of marine biologists say that noise from boats is a 'global pollutant', distracting fish and making them unable to properly protect their young from predators. They believe motorboat noise should be factored in when trying to protect fish stocks and manage fisheries.

Dr Steve Simpson, an expert of the impact of noise on marine life at the University of Exeter.

"This study raises important implications for managing the noise of the 100,000s of motorboats used around the world in coral reef environments. We are now considering acoustic quiet zones and corridors, and exploring how engine and propeller development can reduce the impact of this globally prevalent pollutant."

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Assessing noise in Southern California whale habitat

Date: April 11, 2017

Source: NOAA Fisheries West Coast Region

A new study assessing the underwater soundscape off Southern California found that blue, fin and humpback whales experience a range of acoustic environments, including noise from shipping traffic as well as quieter areas within a national marine sanctuary. The study appeared in a special issue of Endangered Species Research focusing on ocean noise.

"Our research provides a framework that can be used to evaluate how shipping traffic affects acoustic environments and a tool to explore existing and future management strategies," said Jessica Redfern, a research biologist at NOAA Fisheries' Southwest Fisheries Science Center in La Jolla, Calif., and the lead author of the study.

Other authors include scientists from NOAA's Office of National Marine Sanctuaries and Office of Science and Technology, the National Park Service and private consulting companies. The analysis is a case study in NOAA's Ocean Noise Strategy Roadmap, which describes methods of measuring and assessing the impacts of ocean noise.

Blue whales feed in Southern California waters from about June to October, while humpback whales feed in the area from March to November and fin whales have been found there year-round. Underwater shipping noise occurs at low frequencies and these three species of large whales are low frequency hearing and communication specialists. Therefore, the potential for low frequency noise to mask communication has been identified as a primary concern. The study used U.S. Coast Guard data on ship traffic from 2009 to estimate sound levels throughout Southern California waters, including areas south and west of Point Conception and in the Channel Islands National Marine Sanctuary.

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Frog-hunting bats have ‘cocktail party effect’ workaround In noisy environment, hunters shift from listening for croaks to using echolocation – via Herp Digest

Science News by Susan Milius, Science News 9/15/16

Humankind is loud, and research already suggests that birds alter their singing in urban noise. Now tests show that bats listening for the frogs they hunt switch from mostly quiet eavesdropping to pinging echolocating when artificial sounds mask the frog calls. That way, the bats can detect the motion of the frogs’ vocal sac poofing out with each call, researchers report in the Sept. 16 Science.

That switch in sensory tactics could make bats the only animals besides people shown to react this way to interfering din in the classic cocktail party scenario, says study coauthor Wouter Halfwerk of Vrije University Amsterdam. People straining to hear each other over the cacophony of a party can get a boost in communication by paying attention to each other’s mouth movements. He points out that watching someone’s lips lets people tolerate about an extra 20 decibels of tipsy shrieking and shouting.

Conservation biologists worry about the effects of human racket on other residents of the planet. Other researchers, for instance, found that noise interfered with pallid bats’ success in hunting insects on the wing. The fringe-lipped bats (Trachops cirrhosus) in the new study, however, specialize in frogs instead of insects. Hungry bats listen to frog choruses and swoop out of the darkness to carry off a male chirping his advertisements for a mate. “A talking pickle” is what Halfwerk calls the frog.

Researchers tested 12 wild-caught bats in outdoor flight cages in Panama. Bats perching (upside down, of course) in cages were perfectly willing to make a grab at robotic frogs deployed in the cages. The robofrogs, modeled by an artist on the túngara species the bats naturally hunt, sit motionless but can on command start inflating a specially constructed balloon in time with broadcast calls.

In this setup, interfering noise changed normal hunting. When researchers broadcast sounds that partially masked the main frequency of telltale frog calls, bats waited longer than normal to strike and also strongly preferred pouncing on a robofrog that was inflating his sac instead of an identical frog squatting nearby with a deflated sac. Recordings of bat noises from the perch showed that the hunters were pinging fast echolocation sounds instead of mostly listening for the pickle to betray its location.

Even with the strategy switch, the bats aren’t completely making up for the noise nuisance, Jinhong Luo at Johns Hopkins University points out. A sensory biologist, he has tested noise effects on other bats but was not involved in this project. Looking at the new data, he notes that frog-eating bats in echolocating mode are slower to leave their perches and swoop than bats in eavesdropping mode. He also cautions about generalizing to the other 1,300-plus bat species. Many of them are already using echolocation to hunt insects and may not have a backup prey-finder method when noise complicates their foraging. 

Citations

D.G.E. Gomes et al. Bats perceptually weight prey cues across sensory systems when hunting in noise. Science. Vol. 353, September 16, 2013, p. 1277. doi: 101126/science.aaf7934.

Further Reading

J.P. Bunkley and J.R. Barber. Noise Reduces Foraging Efficiency in Pallid Bats (Antrozous pallidus). Ethology. November 2015, p. 1116. doi: 10.1111/eth.12428.

W. Halfwerk et al. Negative impact of traffic noise on avian reproductive success. Journal of Applied Ecology. Vol. 48, February 2011, p. 210. doi: 10.1111/j.1365-2664.2010.01914x.

S. Milius. A coast-to-coast picture of America’s cacophony of sounds. Science News. Vol. 187, February 21, 2015, p. 32.

S. Milius. Noise made by humans can be bad news for animals. Science News. Vol. 187, February 21, 2015, p. 22.