Sunday, 7 October 2018

How not to get lost

How not to get lost


We have known for some years that birds and fish navigate across oceans and continents by using the earth's magnetic field as a compass - it is a truly astounding ability. However the assumption has been that the knowledge of where to go is either imprinted at birth or the magnetic signature of home is remembered. There was no actual learning to navigate. However what nobody has been able to explain is how this particular compass works. Until now.

I must admit I had always thought of the geomagnetic field, to give it its correct title, as an earth based phenomena; that shows how much attention I paid to science at school. The electrical currents created by the movement of the molten iron in the Earth's outer core radiate out into space. Without the magnetic field that creates deflecting the solar wind that would otherwise strip away the ozone layer, we'd all have been fried millions of years ago. It seems that birds are able to 'see' this magnetic field by way of a sort of avian heads up display.

It is, inevitably, more complicated than that but the conclusions of two separate studies in Sweden and Germany which found evidence of an unusual eye protein called Cry4 in European robins and zebra finches, have come to essentially the same conclusion. 

It seems that the Cry4 protein is sensitive to blue light and the ability to see the magnetic field relies on being able to see the blue wavelength of light within the field. So the protein creates a filter, or sort of gauze, over the birds' vision which enables it to identify magnetic north and navigate accordingly, the process enhanced by a greater production of Cry4 during the migration period.

The scientists at the University of Illinois at Urbana-Champaign have created a graphic that puts it all in a bit more context; look out for the defined arc and central black spot in the middle column of squares. Now all we need is for someone to check out salmon eyes .......

Father & Son Taster Days

As you will see from the video we have rather a surfeit of fish in the Nether Wallop Mill lake. I base my stocking numbers at the start of each year with a certain attrition rate, largely reflecting otters and people. We have had plenty of the latter but very few of the former. Sadly I think Kuschta, the star of The Otters' Tale has died - we have had just the one young otter who comes and goes.

Nether Wallop Mill
Trout frenzy!
So, with fish still to catch and half term coming up I'm running a series of special Half Day Father & Son (or grandparent/mother/daughter) Tasters. You have the choice of a morning or afternoon session, with full instruction and tackle provided.

The format will be based around an hour of casting tuition for the children (under 16's please) in a group of three whilst the parents relax. Then we'll all come together for some bug work before everyone fishes together for the remainder of the session, ending up with fish gutting and some fairly rudimentary fish biology. I am hopeful everyone will have a fish to take home.

The dates are October 20, 21, 25 and 27. The sessions start at 9.30am or 2pm. The cost is £125 for a Father & Son. To book click here, or call 01264 781988.

The rain is coming

Meeting with one of my river owners last week, who also happens to have an extensive farming operation in Berkshire, we got to talking about the weather and rainfall in particular.

He reminded me of an interesting statistic: whatever period you take since 1961 the southern England rainfall each year remains remarkably consistent at around 780mm annually. So on that basis be prepared for a wet run up to Christmas with six months of rain due to fall in the next three. 

You have been warned!

Life of a Chalkstream talk

It seems like forever since I last did one of my Life of a Chalkstream talks; it tends to be a winter thing so I guess the clocks must be changing soon.

My first of the 'season' so to speak will be at the Sir Harold Hillier Gardens near Romsey in Hampshire on Wednesday November 21st 2018. Unusually this is a lunchtime event at 12.30pm.

For tickets and information contact Terry Lewis

Photo of the Week

The River Itchen water meadows but perhaps not as you have ever seen them.

September feedback winner

It is a terrible thought but this is the penultimate draw of the year; next time it will be early November with everyone who has returned a report in the hat for the Simms pliers.

But for now it is Patrick Moore who fished twice in September, his trip to Barton Court coming out of the hat. The Fishing Breaks snood is on its way.


The usual random selection of questions to confirm or deny your personal brilliance. As ever it is just for fun with the answers at the bottom of the page.

1) This Sunday sees the running of Europe's richest horse race the Prix de l 'Arc de Triomphe. What was the Arc de Triomphe built to commemorate?

2)   Who is the Viking god of rain?

3)   At what speed does a large raindrop hit the ground?

Enjoy the weekend.

Best wishes,
Simon Signature 

Founder & Managing Director

Quiz answers:

1)     Those who fought and died for France in the French Revolutionary and Napoleonic Wars.
2)     Frey
3)     20mph

No comments:

Post a Comment