Sperm Competition in Birds

[dieseltaylor]

Is not the book I am reading but the 2012 Birkhead book " Bird Sense" just loaned to me by a mate. Who incidentally also lent to me " The war of the Landing Craft" published 1976.

The "Bird Sense" book gets rave reviews and is full of interesting items like do birds have senses of smell, taste, and about hearing, seeing, emotions and magnetic sense.

I have hardly started but already I know that when nesting gannets can pack 70 to the square metre! Rather amusingly whilst scientist and ornithologists were debating whether birds had a sense of smell and working out how to prove it people prospecting for gas since the 1920's in the US already knew that a particular bird loved flying above natural gas vents!

Anyway details to follow.

[Michael Emrys]

Rather amusingly whilst scientist and ornithologists were debating whether birds had a sense of smell and working out how to prove it people prospecting for gas since the 1920's in the US already knew that a particular bird loved flying above natural gas vents!

Why would that impact the question of whether birds have a sense of smell? Natural gas is odorless, which is why commercial gas has an additive that gives it a distinct odor allowing leaks to be readily detected. In any event, the birds might be detecting it by other means. We know that many birds, such as condors and eagles can visually detect thermals. If the venting gas is of a different density than the surrounding atmosphere, the same thing would apply. And that's just one possible example.

Michael

[dieseltaylor]

I suppose odourless to humans might be more likely way to follow that thought - if it were true. : )

Fortunately I have now the detail. Union Oil Company of California had noticed in the 1930s that turkey vultures attracted to leaks in their natural gas pipleine. This was so useful they actually added more mercaptan to the pipes.

[Michael Emrys]

Ah, so it was the additive that attracted them.

Michael

[dieseltaylor]

Not from the book - which remains top of my reading list - apart from the others I have been reading : )

'Homing pigeons have remarkable navigational skills that allow them to find their way back to the loft when released from an unfamiliar location hundreds of miles away. To perform such a feat, they rely on various cues, such as odors and Earth's magnetic field . Yet, how birds and other animals obtain magnetic-field information has been a mystery. On page 1054 of this issue, Wu and Dickman report how this information is neurally encoded and suggest a candidate magnetic sensory organ in the inner ear of the pigeon Winklhofer

Magnetic Sense

Many species orient and navigate using aspects of Earth's magnetic field. Magnetic receptors have been found in the eyes, ears, and bills of birds, but there has been no clear evidence of the neural mechanism by which magnetic signals are translated into direction. Recording from the brainstem within conscious pigeons, Wu and Dickman (p. 1054, published online 26 April; see the Perspective by Winklhofer) reveal the presence of neurons in the pigeon's brain that encode the inclination angle and intensity of the geomagnetic field. Thus, pigeons—and perhaps other species—can develop an internal model of geopositional latitude to facilitate spatial orientation and navigation based on magnetoreception.

And if you go to the link you can read this extract:

Neural Correlates of a Magnetic Sense

Le-Qing Wu, J. David Dickman*

Department of Neuroscience, Baylor College of Medicine, Houston, TX 77024, USA.

Many animals rely on Earth’s magnetic field for spatial orientation and navigation. However, how the brain receives and interprets magnetic field information is unknown. Support for the existence of magnetic receptors in the vertebrate retina, beak, nose, and inner ear has been proposed, and immediate gene expression markers have identified several brain regions activated by magnetic stimulation, but the central neural mechanisms underlying magnetoreception remain unknown. Here we describe neuronal responses in the pigeon’s brainstem that show how single cells encode magnetic field direction, intensity, and polarity; qualities that are necessary to derive an internal model representing directional heading and geosurface location. Our findings demonstrate that there is a neural substrate for a vertebrate magnetic sense.

added

[Michael Emrys]

Seems like I recall reading some years back that there is some evidence that another cue they respond to has something to do with the angle of polarization of sunlight at different latitudes, but how exactly that would work I haven't a clue at the present time.

Michael

[dieseltaylor]

Just to shown how powerful and spreading the gas additive is:!!

22 January 2013 Last updated at 13:46 Foul smell complaints in Kent and Sussex after gas leak

A cloud of foul-smelling but harmless gas has leaked out of a factory in north-western France, drifting across the Channel and prompting complaints from Paris to south-eastern England.

The leak is blamed on a chemical factory in Rouen, and many residents compared the odour to diesel fumes.

Police in Kent and Sussex said they had received a large number of calls from people worried about the odour.

The gas is reported believed to be mercaptan, an additive to natural gas.

It leaked on Monday from a plant near Rouen, 75 miles (120km) north-west of Paris. Winds blew the cloud over northern France on Monday night and then into England on Tuesday.

The Health Protection Agency (HPA) and police said reports had started coming in from Surrey, and London Fire Brigade had received 25 calls by Tuesday afternoon. Complaints also came from residents in Hampshire.

Kent Fire and Rescue Service has advised residents to keep doors and windows closed if they had concerns, or were elderly or asthmatic.

But area commander Martin Adams said there were no serious concerns and he urged people not to call the fire service.

Mercaptan is an organic compound containing sulphur, known for its strong, unpleasant odour.

'Unpleasant aroma' One resident in Cheriton, east Kent, said there had been reports of a strong smell in Ashford, Lydd and Hythe.

Tania Bartlett told the BBC that people "all over Facebook" were talking about it.

And Canterbury resident Andrew Roberts said: "Just stuck my head out of the back door here in south Canterbury - strong smell of fuel oil in the air."

Sussex Police said it had been receiving reports of a gas smell along the East Sussex coast.

The force said Kent Police had also received a larger number of calls.

In a statement, a Sussex Police spokesman said: "We understand that this smell emanates from an accidental factory discharge in Rouen.

"The smell is from an additive to the gas which has an unpleasant aroma but is not toxic and there is no danger to the public."

'Rotten eggs' A spokesman for the Environment Agency said officers were responding to reports of an unpleasant odour.

He said: "We understand that a factory in Rouen has reported a leak of a harmless chemical which is added to natural gas to make it detectable.

"We expect that this is causing the smell but we are working with partners locally to rule out other potential sources."

He added: "The odour is detectable at very low concentrations and should dissipate naturally over time."

The HPA said in a statement: "The smell drifting over Southern England today poses no risk to public health.

"The odour, which is similar to rotten eggs, has been noticed by people mainly in Kent, East and West Sussex and some parts of Surrey."

It said the non-toxic chemical which had blown across the Channel would also have been diluted before entering the air over England.

Good thing its not poisonous given the spread must be several hundred square miles.

I was looking at some more info on the sense of smaell and yet again find that it was a known and then unknown fact. This is faintly amusing ...

Just as in ourselves, these

passages comprise delicate scrolls of tissuecovered

bone (easily broken during fights

and nose-reshaping). The more complex the

scrolling, the greater the surface area for

smell detection. In the 1960s, an American

woman with the wonderful name of Betsy

Bang, who was drawing specimens for her

anatomist husband, noticed that in three

species where there was some behavioural

evidence that they had a sense of smell, the

kiwi, Snow Petrel and the Turkey Vulture, the

nasal conchae were much more convoluted

than in other birds.

http://www.bto.org/sites/default/files/u23/downloads/publications/bird-table/BT69_LR_12-13.pdf

[dieseltaylor]

Update

If you own Lubizol shares .....

22 January 2013 Last updated at 15:15 French Lubrizol factory struggles to stop foul gas leak

Staff at a chemicals factory in north-western France are working to stop a gas leak that has spread a foul smell to Paris and south-east England.

French Ecology Minister Delphine Batho said she was heading for Rouen, where the factory is located, to oversee operations to deal with the leak.

Thousands of people, from as far away as Paris and London, have complained of nausea and headaches.

The gas is reported to be mercaptan, a harmless additive to natural gas.

It leaked on Monday from a plant run by a French subsidiary of the US chemicals manufacturer Lubrizol near Rouen, 75 miles (120km) north-west of Paris.

Winds blew the cloud over northern France on Monday night and then into England on Tuesday.

Ms Batho is cutting short a visit to Germany to a visit to supervise operations to stop the leak.

Tuesday evening's French Cup football match between Rouen and Marseille has been postponed because of the stink.

"We did not want to find ourselves with 10,000 fans two kilometres from the factory and with no means of confining them or evacuating them if necessary," local government official Florence Gouache told AFP news agency.

A senior executive at the factory, Pierre-Jean Payrouse, said stopping the leak could take until the evening. There is no word on the cause.

[SlowMotion]

Seems like I recall reading some years back that there is some evidence that another cue they respond to has something to do with the angle of polarization of sunlight at different latitudes, but how exactly that would work I haven't a clue at the present time.

Michael

Found this

http://www.bbc.co.uk/news/science-environment-17855194

[dieseltaylor]

Good link slomo

For those who might be barred from the site:

27 April 2012 Last updated at 11:42 Magnetic fields light up 'GPS neurons', scientists say

By Jason Palmer Science and technology reporter, BBC News

Researchers have spotted a group of 53 cells within pigeons' brains that respond to the direction and strength of the Earth's magnetic field.

The question of how birds navigate using - among other signals - magnetic fields is the subject of much debate.

These new "GPS neurons" seem to show how magnetic information is represented in birds' brains.

However, the study reported by Science leaves open the question of how they actually sense the magnetic field.

David Dickman of the Baylor College of Medicine in the US set up an experiment in which pigeons were held in place, while the magnetic field around them was varied in its strength and direction.

Prof Dickman and his colleague Le-Qing Wu believed that the 53 neurons were candidates for sensors, so they measured the electrical signals from each one as the field was changed.

Every neuron had its own characteristic response to the magnetic field, with each giving a sort of 3-D compass reading along the familiar north-south directions as well as pointing directly upward or downward.

In life, this could help the bird determine not only its heading just as a compass does, but would also reveal its approximate position.

Each cell also showed a sensitivity to field strength, with the maximum sensitivity corresponding to the strength of the Earth's natural field.

And just like a compass, the neurons had opposite responses to different field "polarity" - the magnetic north and south of a field, which surprised the researchers most of all.

"People had reported in the past, in a 1972 paper in Science, establishing that birds do not seem to respond to the polarity of the magnetic field, yet here we have neurons that are in fact doing that," Prof Dickman told BBC News.

"That's one of the beautiful aspects of what we've identified, because it shows how single brain cells can record multiple properties or complex qualities in a simple way."

'Be puzzled' Several hypotheses hold that birds' magnetic navigation arises in cells that contain tiny chunks of metal in their noses or beaks, or possibly in an inner ear organ.

However, the most widely held among them was thrown into question recently when researchers found that purported compass cells in pigeon beaks were in fact a type of white blood cell.

Another theory suggests that a magnetic sense may come about in receptors in birds' eyes. When exposed to light, the theory says, molecules called cryptochromes undergo a fleeting change in their atomic makeup whose length depends on their alignment with a field.

The new work throws this latter possibility into question, as it would work equally well with a north- or south-pointing field.

Asked what an outsider should think, given that the recent results conflict with the two most plausible explanations for birds' remarkable navigation abilities, Prof Dickman said "be puzzled, because I am".

"We're leaning toward a third receptor in the inner ear, and we're doing experiments to try to determine whether it is in fact a receptor or not."

Henrik Mouritsen of the University of Oldenburg in Germany regards the current results with caution.

"[Magnetism-sensitive neurons] must be in the brain in several places... and maybe Dr Dickman has found them. If he has, it's a very, very important finding, but only time will tell," he told BBC News.

"There have been lots of claims of something similar to this, and so far every one has turned out to not be independently reproducible."

Both researchers concede that more than one mechanism may be at work in bird navigation - in their eyes, beaks or ears - and Prof Dickman said he is looking forward to getting to the bottom of it.

"That's what makes this whole field exciting, because there are these competing ideas out there and now, since we've discovered regions in the brain that are actually responding to the magnetic field, it intensifies our search for the receptor and how it might work."

[SlowMotion]

Since this is a wargame forum:

https://lh3.googleusercontent.com/-mOWMdbb6aPw/UQKIclTqaNI/AAAAAAACfeQ/JgeRBqTEOcY/w497-h373/3%2Bunreaded%2Bmessages.png

[dieseltaylor]

Nice : )

This weeks Economist reports that dung beetles steer by the Milky Way at night!

......Under a full moon the beetles took an average of 21.4 seconds to reach the moat. On a moonless, starry night, their speed was somewhat reduced, but not significantly so. However, under overcast conditions, when neither moonlight nor the stars were visible, the beetles took an average of 117.4 seconds.

Curious as to what it was in the sky that the beetles were using to navigate, the team moved their arena inside the Johannesburg planetarium and reran their experiments. As they report in Current Biology, the beetles presented with a full starlit sky, including the Milky Way or just the Milky Way, took statistically the same amount of time to exit the arena (43.3 seconds and 53.3 seconds). Under a sky full of dim stars they were only a little slower (65.2 seconds). This, speculates Dr Warrant, is because they were still able to spot the cluster that forms the Milky Way.

When allowed to see only the 18 brightest stars or immersed in total darkness, the beetles took more than twice as long to exit the arena. The team now wonders how many other animals might be able to use the glowing strip of light created by the Milky Way to guide them.

[SlowMotion]

I tend to be more amazed about nature discoveries like that above than latest hitech news.

Even though I recently posted a video showing artificial bird flying it's quite far from being able to do things like this:

https://lh3.googleusercontent.com/-BpB21BtdOjU/UPReEDR-LgI/AAAAAAAA24c/j0x46nnNR8I/w497-h373/mon%2B%25282%2529.gif

[SlowMotion]

or this:

https://lh5.googleusercontent.com/-5Ht3fdmMaAA/UQNkjHrp7BI/AAAAAAACkbQ/BjCSnmiJygY/w497-h373/qpPXy.gif