Mammals, fish listen to birds’ sounds


This video from North America is called Red-breasted nuthatch mini documentary.

From the Sydney Morning Herald in Australia:

When birds squawk, other species seem to listen

May 19, 2015

Christoper Solomon

Scientists believe bird calls are a sophisticated early-warning system alerting birds and other prey over wide areas to the presence and size of predators.

In the backyard of a woodsy home outside Missoula, Montana, small birds – black-capped chickadees, mountain chickadees, red-breasted nuthatches – flitted to and from the yard’s feeder. They were oblivious to a curious stand nearby, topped by a curtain that was painted to resemble bark.

Erick Greene, a professor of biology at the University of Montana, stepped away from the stand and stood by the home’s back door. He pressed the fob of a modified garage-door opener. The curtain dropped, unveiling a northern pygmy owl preserved by taxidermy. Its robotic head moved from side to side, as if scanning for its next meal.

The yard hushed, then erupted in sound. Soon birds arrived from throughout the neighbourhood to ornament the branches of a hawthorn above the mobbed owl, calling out “yank-yank” and “chick-a-dee”.

As a recorder captured the ruckus, its instigator grinned with delight. “For birds, this is like a riot,” Greene said afterward, adding that he heard “a whole set of acoustic stuff going on that’s just associated with predators”. The distinctions are subtle – “even good naturalists and birders can miss this stuff,” he added.

Studies in recent years by many researchers, including Greene, have shown that animals such as birds, mammals and even fish recognise the alarm signals of other species. Some can even eavesdrop on one another across classes. Red-breasted nuthatches listen to chickadees. Dozens of birds listen to tufted titmice, who act like the forest’s crossing guards. Squirrels and chipmunks eavesdrop on birds, sometimes adding their own thoughts. In Africa, vervet monkeys recognise predator alarm calls by Superb starlings.

Greene wants to better understand the nuances of these bird alarms. His hunch is that birds are saying much more than we ever suspected, and that species have evolved to decode and understand the signals. He acknowledged the obvious Dr Dolittle comparison: “We’re trying to understand this sort of ‘language’ of the forest.”

At his laboratory on campus, Greene, 57, plugged the recording of the pygmy owl fracas into a computer that he likened to an “acoustic microscope”. The calls appeared as a spectrogram – essentially musical notation. On the screen, they looked like a densely layered cake fallen on its side. One call may last only a second, but can have up to a dozen syllables. Parsing one of myriad encounters with a pygmy owl or other robo-raptors, even with the help of a computer, will take the researchers hours.

“It’s cutting-edge stuff,” said Jesse Barber, an assistant professor at Boise State University who studies animal acoustics. Greene is looking at communication “across large swaths of habitat, and this is really where the field has yet to go,” Barber said. “It’s a new frontier for animal communication work.”

Greene developed his fascination with birds and sound early on, growing up around Montreal as a “total nature nerd,” he said. As a boy, he listened to and played classical, jazz and Renaissance music. He recalled being “a harpsichord-playing, hockey thug, bird nerd.”

As a teenager, he met Peter and Rosemary Grant, then at McGill University in Montreal, whose studies of Darwin’s finches in the Galapagos Islands were groundbreaking. Offered a year-long job as their field assistant, he dropped out of high school and never returned.

That experience helped him gain admission to Dalhousie University in Nova Scotia. There he spent much time playing obscure Renaissance instruments like the crumhorn – “which sounds like a pig being slaughtered,” he said – before attending Princeton for his doctorate in ecology, evolution and behaviour.

“What I’m doing now is really a natural marriage of those sorts of interests,” Greene said of his interest in animal communication. “It’s nature’s music, in a way.”

He and his wife, Anne, met before college while studying birds 800 miles north of the Arctic Circle. Theirs is a science family: Anne teaches science writing at the university, and the couple has two grown daughters working in the field – one teaches at a charter school in Brooklyn that has an environmental-sciences theme, and the other is working towards a master’s degree in aquatic biology.

Greene has spent much of his career at the University of Montana studying the pas de deux of predator and prey. As part of this dance, most animals, including birds, have evolved alarm signals to warn of danger. Greene’s interest in the subtlest bird alarms developed several years ago while studying lazuli buntings.

The buntings occasionally stopped responding to the artificial calls he broadcast and instead dived into the bushes. “And then maybe four, five minutes later, a Cooper’s hawk” – a major predator of small birds – “would cruise by,” he said. Clearly, some signal was spreading among them.

So-called “seet” calls, peeps produced by many small songbirds in response to a raptor on the wing, are well-known to ornithologists. Conventional wisdom held that the calls dissipated quickly and were produced only for other birds nearby. However, that’s not what Greene noticed: chatter sweeping across the hillside, then birds diving into bushes.

Studying the phenomenon, he documented a “distant early-warning system” among the birds in which the alarm calls were picked up by other birds and passed through the forest at more than 45km/h. Greene likened it to a bucket brigade at a fire.

The information rippled ahead of a predator minutes before it flew overhead, giving prey time to hide. Moreover, while raptors can hear well at low frequencies, they are not very good at hearing at six to 10 kilohertz, the higher frequency at which seet calls are produced. “So it’s sort of a private channel,” he said.

Greene turned to chickadees, which are highly attuned to threats. When one sees a perched raptor nearby, it will issue its well-known “chick-a-dee” call, a loud, frequent and harsh sound known as a mobbing call because its goal is to attract other birds to harass the predator until it departs.

In 2005, Greene was an author of an article in the journal Science that demonstrated how black-capped chickadees embed information about the size of predators into these calls. When faced with a high-threat raptor perched nearby, the birds not only call more frequently, they also attach more dee’s to their call.

Raptors tend to be the biggest threat to birds nearest their own size because they can match the manoeuvrability of their prey. So a large goshawk might only merit a chick-a-dee-dee from a nimble chickadee, while that little pygmy owl will elicit a chick-a-dee followed by five or even 10 or 12 additional dee syllables, Greene said.

The researchers next showed that red-breasted nuthatches, which are chickadee-size and frequently flock with them in the winter, eavesdrop on their alarm language, too.

Greene, working with a student, has also found that “squirrels understand ‘bird-ese’, and birds understand ‘squirrel-ese'”. When red squirrels hear a call announcing a dangerous raptor in the air, or they see such a raptor, they will give calls that are acoustically “almost identical” to the birds, Greene said. (Researchers have found that eastern chipmunks are attuned to mobbing calls by the eastern tufted titmouse, a cousin of the chickadee.)

Other researchers study bird calls just as intently. Katie Sieving, a professor of wildlife ecology and conservation at the University of Florida, has found that tufted titmice act like “crossing guards” and that other birds hold back from entering hazardous open areas in a forest if the titmice sound any alarm. Sieving suspects that the communication in the forest is akin to an early party telephone line, with many animals talking and even more listening in – perhaps not always grasping a lot, but often just enough.

Greene says he wants to know not only the nuances of that party-line conversation, but also how far it stretches across the landscape – and who else is listening.

If chickadees indeed issue alarm calls that indicate the size and thus the danger of their predators, how many other species of birds – robins, crows – hear and evaluate those alarms based on their own body size? Perhaps a big Steller’s jay hears a chickadee’s frantic alarm in the face of a little pygmy owl and says, in effect, “I’m not worried”, Greene said.

Conversely, does the same jay hear a half-hearted chickadee alarm and suddenly perk up, understanding that this means a threat now lurks nearby for a bigger bird?

Here is where the stuffed animals come in. The researchers are using predators of different sizes – the owl, Cooper’s hawks, sharp-shinned hawks, goshawks – to elicit responses. Back at the lab, Greene pointed to the alarm call on the spectrogram in response to the pygmy owl.

“All of these notes are acoustically very different, and they might have different meanings,” Greene said. “Sound humans hear simply as ‘chick-a-dee’ actually could contain information differentiating between a Cooper’s hawk and a pygmy owl. We know birds hear this as if it’s slowed down,” he said.

Weatherfish enemies are northern pikes, hedgehogs, herons …


This video is about European weatherfish, Misgurnus fossilis, mating.

Translated from the Dutch RAVON ichthyologists:

Tuesday, May 19th, 2015

Hedgehogs, rats and herons like eating European weatherfish, which is evident from transmitter research by RAVON. This loach is also high on the menu of the purple heron in the Natura 2000 area Zouweboezem. It was suspected that the northern pike, the main freshwater predator fish, also likes to devour weatherfish, but evidence for this was lacking, until …

Recent research in Hungary (pdf, 0.4 MB) shows that in water with a big weatherfish population, the diet of pikes in the spring may consist for more than 90% of weatherfish. Probably the nocturnal loach, which normally hides during the day, during the reproduction period is easy prey as they swim along the banks by day.

Recently, also in Brabant province in the Netherlands, proof was found of a northern pike eating a weatherfish.

Opah fish are warm-blooded, new research


Opah

From NOAA National Marine Fisheries Service in the USA:

May 14, 2015

New research reveals first warm-blooded fish

21 minutes ago

New research by NOAA Fisheries has revealed the opah, or moonfish, as the first fully warm-blooded fish that circulates heated blood throughout its body much like mammals and birds, giving it a competitive advantage in the cold ocean depths.

The silvery fish, roughly the size of a large automobile tire, is known from oceans around the world and dwells hundreds of feet beneath the surface in chilly, dimly lit waters. It swims by rapidly flapping its large, red pectoral fins like wings through the water.

Fish that typically inhabit such cold depths tend to be slow and sluggish, conserving energy by ambushing prey instead of chasing it. But the opah’s constant flapping of its fins heats its body, speeding its metabolism, movement and reaction times, scientists report in the journal Science.

That warm-blooded advantage turns the opah into a high-performance predator that swims faster, reacts more quickly and sees more sharply, said fisheries biologist Nicholas Wegner of NOAA Fisheries’ Southwest Fisheries Science Center in La Jolla, Calif., lead author of the new paper.

“Before this discovery I was under the impression this was a slow-moving fish, like most other fish in cold environments,” Wegner said. “But because it can warm its body, it turns out to be a very active predator that chases down agile prey like squid and can migrate long distances.”

Gills show unusual design

Wegner realized the opah was unusual when a coauthor of the study, biologist Owyn Snodgrass, collected a sample of its gill tissue. Wegner recognized an unusual design: Blood vessels that carry warm blood into the fish’s gills wind around those carrying cold blood back to the body core after absorbing oxygen from water.

The design is known in engineering as “counter-current heat exchange.” In opah it means that warm blood leaving the body core helps heat up cold blood returning from the respiratory surface of the gills where it absorbs oxygen. Resembling a car radiator, it’s a natural adaptation that conserves heat. The unique location of the heat exchange within the gills allows nearly the fish’s entire body to maintain an elevated temperature, known as endothermy, even in the chilly depths.

“There has never been anything like this seen in a fish’s gills before,” Wegner said. “This is a cool innovation by these animals that gives them a competitive edge. The concept of counter-current heat exchange was invented in fish long before we thought of it.”

The researchers collected temperature data from opah caught during surveys off the West Coast, finding that their body temperatures were regularly warmer than the surrounding water. They also attached temperature monitors to opah as they tracked the fish on dives to several hundred feet and found that their body temperatures remained steady even as the water temperature dropped sharply. The fish had an average muscle temperature about 5 degrees C above the surrounding water while swimming about 150 to 1,000 feet below the surface, the researchers found.

While mammals and birds typically maintain much warmer body temperatures, the opah is the first fish found to keep its whole body warmer than the environment.

A few other fish such as tuna and some sharks warm certain parts of their bodies such as muscles, boosting their swimming performance. But internal organs including their hearts cool off quickly and begin to slow down when they dive into cold depths, forcing them to return to shallower depths to warm up.

Warmth provides competitive edge

Satellite tracking showed opah spend most of their time at depths of 150 to 1,300 feet, without regularly surfacing. Their higher body temperature should increase their muscle output and capacity, boost their eye and brain function and help them resist the effects of cold on the heart and other organs, Wegner said.

Fatty tissue surrounds the gills, heart and muscle tissue where the opah generates much of its internal heat, insulating them from the frigid water.

Other fish have developed limited warm-bloodedness (known as regional endothermy) to help expand their reach from shallower waters into the colder depths. But the opah’s evolutionary lineage suggests that it evolved its warming mechanisms in the cold depths, where the fish can remain with a consistent edge over other competitors and prey. Recent research has found distinctive differences among opah from different parts of the world, and Wegner said scientists are now interested in comparing warm-blooded features among them.

“Nature has a way of surprising us with clever strategies where you least expect them,” Wegner said. “It’s hard to stay warm when you’re surrounded by cold water but the opah has figured it out.”

NOAA research surveys off California have caught more opah in recent years, but biologists are not sure why. Current conditions may be favoring the fish, or their population may be growing. Opah are not usually targeted by fishermen off California but local recreational anglers and commercial fisheries occasionally catch the species. The opah’s rich meat has become increasingly popular in seafood markets.

“Discoveries like this help us understand the role species play in the marine ecosystem, and why we find them where we do,” said Francisco Werner, director of the Southwest Fisheries Science Center. “It really demonstrates how much we learn from basic research out on the water, thanks to curious scientists asking good questions about why this appeared to be different.”

Explore further: Warm bodied fishes found able to swim farther and faster than cold bodied fish

More information: Whole-body endothermy in a mesopelagic fish, the opah, Lampris guttatus, Science.

Journal reference: Science

Grey herons feeding, video


This video is about grey herons in the Netherlands. They have caught big prey; like an eel, a mole and a rat.

Brook lamprey mating season, video


In spring, it is brook lamprey mating season.

Nel Appelmelk made the video of these brook lampreys on 14 April 2015 in the Koppelsprengen stream near Ugchelen village in Gelderland province in the Netherlands.

Irish basking shark videos


This 20 April 2015 video is called Basking Shark – GoPro – West Cork – Ireland.

From Breaking News.ie:

Amazing underwater footage of basking shark off West Cork

24/04/2015 – 09:04:50

It seems you can’t move for basking sharks around our coast at the moment. Recently, we shared the video of a close encounter with one of the gentle giants off Dingle.

This video is called Kayaking Dingle with Basking Shark 16 April 2015, Irish Adventures.

And now there’s been another video uploaded to YouTube – this time off the coast of West Cork.

The guys who captured the footage were fishing out on the water when they noticed the basking shark. Using a GoPro camera, they managed to film the shark underwater, emerging from the shadows and swimming alongside their boat.

They estimated the shark to be six metres in length.