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Lilac Breasted Roller

Newsflash | Announcement

PLEASE DIARISE THESE DATES FOR THE REMAINDER OF 2016 WNC MEETINGS

THURSDAY, 23 JUNE
THURSDAY, 18 AUGUST
THURSDAY, 17 NOVEMBER (inc. AGM)

by Richard Wadley

In this age of car-borne GPS systems, with their invariable pseudo-Japanese-American female direction advisors – the ultimate dumbing down of map reading – it’s increasingly difficult to find anyone who can actually read a real map.

This sad fact was brought home to us late the other afternoon as we reached the T-junction of the Bakkers Pass road with the old tar road to Lephalale via Bulgerivier. We were flagged down by an occupant of a very small car, while his companion, the driver, sat panic-stricken and hunched over the dashboard, desperately punching instructions into the GPS mounted on the windscreen.

“Which is the quickest way to Bela-Bela?” the man asked, looking hopefully at the strip of dusty corrugated track we had just negotiated in our bakkie.

“Well”, I replied, casting an eye at the bright blue midget parked in the shadow of one of my wheels, “this road could eventually take you to Bela Bela, but it certainly isn’t the quickest way – and it won’t be simple either, especially in ..er... that”.

This news was communicated to the perspiring GPS operator-cum-driver, who, judging from his wild gesticulations (he was French) and stabbing motions towards the instrument on the windscreen, evidently still believed otherwise.

“And”, I added, as a final deterrent, “the road hasn’t been maintained for years, it’s full of dongas and is frequented by crazy young game rangers who drive their employers’ 4x4s at reckless speeds along it, forcing other users into the bush”. (The bit about the dongas isn’t true).

That image sank in, and even though the car was a hired model (it had the little give-away red sticker on the top left corner of the windscreen), I could see they were having second thoughts.

 “What should we do then?” cried the passenger – and it was evident that this was not the first time on this trip they’d been led astray by that digital siren. “We must be there this evening!”

“I’m afraid you really would do best to go back through Vaalwater and on to Modimolle, even through the awful roadworks”, I replied sympathetically. “Turn right at the first robots in Modimolle and you’re almost there”.

The fellow clearly agreed – and had obviously already suggested this option to his techno-captive friend, because he repeated my advice with just a hint of – you know – ‘I told you so’ smugness.

The driver shrugged resignedly, said something rather unpleasant to the GPS lady (French is such an expressive language) and fired up his Korean steed. The passenger leapt in and, spitting grit onto my bumper, they screamed off.

In the direction of Bulgerivier.

Truly.

I wonder where in Botswana they eventually ran out of gas...

Back in the real world, anyone who has had to try and find a position using a topographic map and a compass will know that this is not quite as straightforward as it might at first appear. The reason is that our maps are (nearly always) orientated so that the top of the map points towards the North Pole, also known as True North (TN); whereas the compass needle, on the other hand, points towards the Magnetic North Pole (MNP), which, it turns out, is somewhere else entirely. (The MNP is that imaginary point where the axis of the Earth’s magnetic field points vertically into the Earth’s surface.) Worse, the MNP does not remain in one position, but is migrating around, depending on whimsical changes in the Earth’s magnetic field.

The result is that if one wants to convert a magnetic compass bearing relative to MNP to a direction on a map, it is necessary to know how to adjust that magnetic bearing to one that refers to TN.  The difference between the two is called the magnetic declination; and, this number varies both through time and according to where you happen to be on the Earth’s surface.

According to Wikipedia, studies have shown that the MNP has been wandering in a generally north-westerly direction for most of the last century, during which time it has moved over 1100 km; and currently, it’s moving at a faster pace, over 40 km per year. This means that anyone needing to convert a magnetic compass bearing to an accurate bearing on a map needs to know the current magnetic declination at the location concerned.

Well, help is at hand: that marvellous institution funded by the American taxpayer, the National Oceanographic and Atmospheric Administration, or NOAA (a neat acronym don’t you think?) has a very user-friendly website on which you can punch in your own latitude and longitude and get – instantly – the current magnetic declination for your site. Just like that. For free. No sultry voice trying to lure you down a lonely track. Just the faint refrain of “Star Spangled Banner”.

In late June 2012, for example, the magnetic declination for Vaalwater (latitude 240 17’ 30” South; longitude 280 07’ 00” East) was:  -150 28’ 02”, increasing at about 1’ per annum. The minus sign means that the MNP is to the west of TN; so you would need to add 150 27’ 55” to your compass bearing in order to get the direction on a map. You could use the same figure for anywhere in the Waterberg and not be more than a couple of minutes out - for now.

In case you’re interested, the website is www.ngdc.noaa.gov . Click on “Geomagnetic Calculators” and you’ll be taken to a screen inviting you to enter your latitude and longitude co-ordinates. Where to get those? From your GPS of course!

Birding

The Waterberg is home to hundreds of bird species, of which 21 are threatened.

Expanses of water, wetlands, cliffs, mountains and plains offer a variety of habitats.