Sounds like trouble

Shall I flap the alarm?

Image courtesy of Fir0002/Flagstaffotos

In his writings on sexual selection, Darwin devoted equal space to non-vocal and vocal communication in birds. Yet, in the years that have passed since his death, the research community has given almost no attention to non-vocal communications. This, particularly when compared to the extensive attention that bird calls have received, is a great shame. Darwin called the sounds that birds made with their feathers and feet "instrumental music" and speculated that they used these sounds to send valuable signals to one another. That hypothesis is very old and has never been tested. Now, a team is revealing that one species of pigeon creates a unique warning sound with a single wing feather when fleeing danger.

The new work was all conducted through a clever mix of video and feather-removal experiments that were able to demonstrate that a highly modified primary feather on the wings of the crested pigeon produces a distinct note during each flap of the wing. Crucially, the note changes with wing beat frequency which means that pigeons fleeing danger produce a sound that is different from pigeons that are merely taking off in a relaxed manner. You can read more in The Economist article that I wrote on this here.

Antibiotic resistance on fish farms

Looks clean but what's in the food?

Image courtesy of Narek75.

We know that antibiotic resistance genes commonly appear in bacteria living in the muck below fish farms. Until recently, the assumption was that antibiotics used to prevent disease in these farms were the key force behind the high concentrations of resistance genes in the bacteria living below them but in 2014 a study challenged that notion by revealing that farms in parts of the Baltic, where antibiotics have been banned for years or were never used, still had sediment below them that was crawling with resistant strains of bacteria. That finding along with several others left researchers scratching their heads as to how the resistance was getting there. Now a new experiment is revealing that the food being used to feed farmed fish is where most of these resistant genes are coming from.  

The researchers behind the work knew from past studies that antibiotics had often been detected in poor quality fish food but, when they looked through the literature, they could find no studies that analysed whether fish foods on the markets were actually carrying bacteria in them with resistant genes. Curious, they analysed a bunch of commonly used fish food products and, voila, there they were. The team uncovered a whopping 132 unique resistant genes in five different fish food products. And the reason these genes are there? The fish food products are being made in facilities where sanitation is poor and genetic material in chopped up fish that are being prepared to be made into fish food are not getting heated enough to be destroyed. Friggin unbelievable.  You can read more in The Economist article that I wrote on this here.

T test

Many studies show that testosterone male animals more aggressive but how the hormone affects human decision making has, surprisingly, had little attention. Keen to take a closer look, a team ran the largest human testosterone behavioural experiment ever conducted and randomly administered a single dose of either testosterone or a placebo to a sample of 243 men. They then measured the participants' performance on both the Cognitive Reflection Test, a long used exam that assesses a person's capacity to monitor their own intuitive judgments and override them when appropriate, and a mathematics test which functioned as a control.

The researchers guessed that testosterone would increase participants’ tendency to rely on their intuitive judgments, reduce inhibition of incorrect responses and thus impair their Cognitive Reflection Test performance compared to those who were given the placebo. They expected the maths test results to not be affected. This is precisely what they found. Mathematics scores from both placebo and testosterone groups were nearly identical. However, Cognitive Reflection Test scores in those dosed with testosterone were a staggering 50% those of the placebo group.  You can read more in The Economist article that I wrote on this here.

Driven by digestion

Heartless beast.

Image courtesy of Steve Childs.

Sea spiders are an ancient group of animals that have a number of odd traits. Perhaps the most notable is that many of them either have teeny tiny hearts or no hearts at all. This has led many researchers to question how they get their blood to move around their bodies but, to date, nobody has been sure. Now a new experiment is revealing that they manage this vital task with guts... literally. Peristalsis, the process that moves food through our intestines, appears to be the primary force that swishes oxygen-carrying blood around the bodies of sea spiders. You can read more in The Economist article that I wrote on this here.

Colour me dangerous

Captured bandit.

Image courtesy of Jakob Vinther.

The "bandit mask" is a common colour pattern found on the faces of animals living in the open plains. With nowhere to hide, these species depend upon their mask communicating the important message that they are not to be messed with. In the case of the badger and the wolverine, the message is a simple "do not judge me by my size, I will rip your arms off." In the case of the skunk and the teledu, the message is "touch me and I will nauseate or blind you with nasty juices stored in my anal glands!" Many birds, including kingfishers, osprey and falcons also have dark bands covering their eyes both to prevent prey animals from spotting their dark eyes staring at them before an attack and to reduce glare from intense sunlight. Thus, it is fascinating that a new study is revealing that the dinosaur Sinosaurpteryx had a bandit mask on its face too. 

The new research revolves around a pigment analysis that was conducted on three exceptionally well preserved fossils of Sinosaurpteryx. While the species is known as one of the many toothy, meter-long and semi-feathered kin of Tyrannosaurus rex found in the Jehol formation of China, details about how it led its life have remained unclear. The assumption was that it lived as a forest ambush predator since the Jehol was once heavily forested but the colouration patterns on Sinosaurpteryx challenge that notion. Aside from the presence of the bandit mask, which needs to be easily seen by would be predators to be effective and would not function terribly well in a dense forest, Sinosaurpteryx also shows some lovely evidence of counter-shading. Counter-shading involves an animal having a light coloured belly and a dark back that helps mask the three-dimensional shape of its body by reducing self-shadowing, decreasing conspicuousness and thus helping to avoid detection by both predators and prey alike. Like the mask, counter-shading would be of little use in a dense forest and, indeed, it is rarely seen in such environments.