Thursday, 20 June 2013

REVIEW: Barr & Stroud "Sprite" 10x50 Monocular

Simple question: can you get decent birding optics for less than fifty quid?  Simple answer: no, of course you can't – the whole idea is ridiculous...

(Image courtesy of The Dreadnought Project wiki)
Back in the 1920's, when Britannia really DID rule the waves, her Majesty's navy went to one place and one place only for the supply of binoculars, telescopes, and optical rangefinders – Barr & Stroud Ltd of Glasgow. Equipped with these beautiful (and largely hand-made) instruments, British diplomatic policy consisted of loading up the main armament and letting Johnny Foreigner know who was boss. But times have changed. There are no battleships left to impose order on the poor benighted heathen, and there are no companies left like Barr & Stroud either. These days your MG car is made in China, your Webley & Scott shotgun is made in Turkey, and this new range of B&S “Sahara” optics originate in South Korea – via a new import firm and a smart bit of re-branding to cash in on the famous name.

I have many pairs of binoculars – far too many, if I am honest.  And I can't look through any of them any more.  Recent illness left me with a medical problem called “strabismus” which means that I get double vision when using them.  Although this doesn't affect my daily life to any great extent, it is a nuisance when out birding.   What I really need is HALF a pair of binoculars – so when I saw this 10x50 device being advertised, I decided to grab one and test it.  Unlike most monoculars on the market today, the B&S 10x50 “Sprite” is exactly that – whereas most of them are really cut-down cheap spotting scopes.  It is a roof prism design and features fully coated lenses, BAK4 prisms and an off-axis focusing system.  Supplied are a captive front lens cover (at last!), rip-stop nylon pouch, and a mini-tripod – of which more later.

A quick trip out to my local nature reserve on a dull and overcast day – perfect for optics testing.   First impressions are more than favourable: this glass is GOOD.  Images are bright and punchy, and the colour fidelity is well-nigh perfect.  Field of view is also excellent at 103m/1000 – as good as anything in its class.  The teeniest trace of chromatic aberration could be detected on brightly lit subjects but even this is a lot better than usual.   For a 10x50, edge distortion is minimal.  Up against my old Zeiss 10x50 porros – which cost ten times as much – the B&S Sprite matched them on optical performance in every department.  Of course there is no “stereo image” impression with a monocular but we pretty much lost that years ago, when roof prisms became the standard layout.

So far, so excellent.  But what really impressed me was the ergonomics
and handling - someone has really put some thought into the design, and it shows.  The frame is polymer, for a total weight of 420g.  This is covered with a rubberised armour giving good grip.  The tube is fully waterproofed and even nitrogen purged (something we just never see at this price point) so fogged-up lenses will not be a problem.  Overall, the exterior moulding fits my (rather small) hands well, with my index finger falling naturally onto a focus control which is both light, and as smooth as a double-glazing salesman's patter.

I really like this thing.  It's not perfect: compact dimensions and 10x50 usually mean critical eye relief, for the laws of Physics cannot be altered, but at 17.5mm this is better than average.  The eyepiece has a four-position click stop arrangement with positive detents.  With my mismatched eyes I would have preferred an extra two stops, but this would have increased the overall length.  For normal people – and spectacle wearers – it should be fine.  The other imperfection is the included table-top tripod.   It's cheap and rattly and very nasty, and will probably stay in the box.

I also did some quick experiments with “digiscoping”, for which the Barr & Stroud monocular is surprisingly well suited.  Even with adapters, proper digital SLRs don't like it: the vignetting upsets their fancy metering unless pulled back to full manual control.  Much better results came with a Samsung Galaxy S3 phone: its autofocus was quite happy to look through the Sprite and it figured out the correct exposure with no adjustments at all.   A couple of extremely boring test shots are included here.

Digiscoped shot with Galaxy S3. The houses facing are exactly 220m away.

So what about the price?  Pacific-rim optics have come a long way in the last ten years and, in the medium price bracket, are now a match for anything made in Europe.   Last season, the same range of bins and monoculars was being brought in through Bresser in the USA and the equivalent model retailed at around £90.00.  The new importer has done some aggressive discounting and I bought this one (new and boxed) from Amazon for £49.00 including delivery, which is just a steal.   Even better, unlike some cheap instruments with their orange lenses and go-faster stripes, the “Sprite” 10x50s will not embarrass you down the bird hide: its black and green finish looks the business, and it still has that historic name on the side.  Truly “second kind of cool” and, if anyone asks – show them the receipt and watch their faces...

Barr & Stroud “Sprite” 10x50 Specification
Magnification: 10x
Objective: 50mm
Minimum focus distance: 2.3m
Field of View @1000m: 103m
Prism type: BAK-4
Lens Coating: Fully Multi Coated
Exit pupil: 5mm
Eye Relief: 17.5mm
Tripod bush: Yes
Waterproof: Yes (Fully immersion tested 1m for 60sec)
Nitrogen gas filled: Yes
Case supplied: Yes (Nylon with belt loop)
Dimensions: 165x88x60mm
Weight: 420g

[All images except #2  (c) Wildlifewriter 2013]

Sunday, 16 June 2013

Great steaming piles of... bark?

Glesni chews some bark.
Image (c) Dyfi Osprey Project 2013

During this early part of their nesting season, the Dyfi ospreys – Monty and Glesni – have been bringing some strange items back to their nest.  As well as conventional materials, they have also been collecting dried cow pats, seaweed, and pieces of tree bark.  A lot of the bark appears to be silver birch, though other species have been sampled as well. Not only have they been collecting this stuff, but on occasion they have been eating it – and on camera, as well

As might be expected, this hasn't gone down very well with the legion of dedicated osprey fans.  They have been disapproving of the selected “nibbles”: ospreys eat fish and only fish, and birch bark and cow poo are not supposed to be on the menu.   So what's really going on...?

This is a kind of detective story.
Almost everything that animals do, they do for a good reason.  That reason might not be obvious to us, ensconced in our little anthropomorphic bubbles as we are, which is why we often misinterpret their actions.  But on other occasions, even a close and objective study of the behaviours cannot provide the correct answer: to get to THAT, we have to think outside the box – and even right outside the nest.  But first, let's define the problem. Fish, we are told, is an almost complete foodstuff in itself and ospreys shouldn't need anything else to sustain them.  That's what it says in all the books.  And here's the thing...

The books are quite right. They don't.

And yet is seems unlikely that Monty and Glesni are eating cow dung and chewing bark just because they like the taste.  I mean, would YOU? That means they must be getting something important from these things – something to do with nutrition or the maintenance of good health. And there, my dear Watson, is our first clue.   A second clue comes from something that cow pats and bark have in common, and that fish don't.   The cow dung consists of partly digested vegetable matter.  Once it has lain around for a while, and the urea and sulphide compounds have degraded or been leached out by the (very occasional) Welsh rain, it doesn't smell too niffy nor taste too acrid.   The birch bark includes an inner layer of woody cells (part of the cambium) which contains and transports many of the nutrients used by the tree during its own development.

Molecular structure of
unbound thiamine pyrophosphate
(c) Warwick University
There are some substances vital for life which animals (with a few rare exceptions) cannot synthesise for themselves.   One of these is vitamin B1, or thiamine.  Thiamine is important stuff: it is needed for the production of ATP, a molecule which supplies energy to the cells of the body, and also plays a role in the correct functioning of the heart, kidneys, and central nervous system.  Chronic B1 deficiency is a serious and potentially fatal condition in all animals, and in humans it has a disease name: Beriberi.

So perhaps the ospreys are getting this and other substances from direct ingestion of plant material, to supplement their typical diet.   If this is so...

Hold on just a cotton-picking minute there, Sherlock. Uncooked fish contains LOADS of B-complex vitamins. Everyone knows that!

And so they do. But some of them might contain other things as well. This is where we need to think outside the box (or nest) because the answer doesn't lie on the green pastures of Derwenlas, but out there in the grey waters of the Irish Sea...

Grey mullet
A favourite prey species of the Dyfi pair is the Atlantic grey mullet Mugil cephalus, which form more than 50% of their total catch.  Mullet are an ideal osprey food: rich in fats, protein and easy to catch because their habit is to feed at the top layer of the water-column.   There they graze on plankton – microscopic plants and animals – and small free-swimming crustaceans. It's been found [1] that mullet also contain quantities of enzymes called “thiaminases”.[2]  The thiaminase enzyme splits B1 molecules in situ, making them biologically inactive.  The amount of enzyme contained in mullet seems to vary seasonally and by location, and may depend on what the fish themselves have been eating. [3]

So this may be the answer to our little mystery: the wonderful mullet which ospreys adore also hides a sinister secret. By eating so much of it, the birds may actually be getting less available vitamin B1, because enzymes in the fish itself are blocking it. To redress their dietary balance, Monty and Glesni need to nibble at an alternative “top-up” source – one that is already part-processed (by tree or cow) but which doesn't contain any thiaminase. This would explain why other fish-eating birds, or other ospreys in different parts of the country, don't have to nibble on cow pats.

No shit, Sherlock?

None at all Watson. Pass me my violin, there's a good fellow....

[1] Source: Cornell University Dept of Animal Sciences
[2] NEOPYRITHIAMINE AND THE THIAMINASE OF FISH TISSUES R Sealock & J White; J. Biol. Chem. 1949 181: 393-403.
[3] Or it is possible that this could be an evolving anti-predator adaptation. Other marine organisms use vitamin-busting enzymes as part of their chemical weaponry. Ferns - especially bracken - contain large amounts of thiaminase, which helps them to deter browsing herbivores.

Tuesday, 11 June 2013

The Puzzle of Portmore Lough

The view from the lower hide is oddly familiar, yet rather strange. We overlook a freshwater lake surrounded by low-lying wetlands of fen carr and unimproved grassland. Summer waterfowl chase each other around the shoreline, while nesting terns and gulls are busy on a couple of nearby nest rafts. The sky is big and open, though a few birch and alder trees stand to our left. It's sunny and getting rather hot out there. But where are we? It could be Cambridgeshire or somewhere else in East Anglia, or even northern Germany. But listen... from beyond the high ground on the far side of the lake, the sound of racing motorcycle engines drifts down from the roads where morning Qualifying is already under way. Behind the hide, a squadron of military transport helicopters is wheeling down from an air force station towards the army barracks about twelve miles to the south. Wherever we are, it's a long way from Norfolk...

This is the Portmore Lough nature reserve in Northern Ireland, and you can bring me here to die.

Gulls and terns at Portmore Lough
(c) Wildlifewriter 2013
On the first sunny weekend of the whole summer, more than 20,000 visitors have arrived at the Oxford Island centre down the road, and their car parks are already overflowing – yet here we have the place to ourselves. Like most fenlands it's remote and difficult to access, although RSPB who have the management of the reserve area, have done a lot of work on paths and boardwalks since last year. Wellington boots are no longer obligatory. This type of wetland habitat is rare in Ireland but, where it exists, Nature takes full advantage. As biodiversity hotspots go, the place is almost incandescent: 317 species of insects at the last count, including bembidion clarki and a colony of rhinoceros beetles found nowhere else. Tree sparrows Passer montanus are nesting in boxes by the upper boardwalk. On the water, common terns are still incubating: testament to the late spring and their difficult migration this year, but the black-headed gull chicks have hatched over the weekend. They stagger among the tern nests, trying to find their feet and avoid being pecked at the same time. The project to increase lapwing breeding is also paying off and numbers are already up on last year.

Anything could appear here – and usually does, if you time it right. In spring and autumn, the big-ticket items are passing through: ospreys are regular visitors, though none have stayed to nest as yet. It would be an ideal place for them, with perch and pike abundant in the water and minimal human activity. Short-eared owls feel secure enough to hunt in broad daylight and, after dark, rare Daubenton's bats are active along the gullies and hedgerows. By winter, internationally important numbers of wildfowl roost overnight on the lough, safe from ground predators and humans disturbance. Whooper swans and some Bewick's will be here, with gadwall and pochard occupying the cheap seats at the front.

Up at the observation platform, local birder Paul Toner is catching a few afternoon
Juv female marsh harrier, Portmore Lough, Jan 2012
(c) Ed O'Hara
rays and we stop to ask what the “craik” is: in January last year, Paul, Ed O'Hara and the local group recorded (and photographed) marsh harriers on the reserve – a good tick anywhere but big potatoes for Ireland where they are never regular. We talk about ospreys again, and the issues about getting planning permission for a nest platform. Bureaucracy will have its due course, and nothing will speed it up. A few other enthusiasts wander in and, as ever, the conversation turns to the mystery of the Lough itself: why is it here, and why is this place so different from the surrounding landscape?

No-one knows. The lake itself is almost circular, which is an odd thing for a natural formation. It is certainly not glacial in origin, as existing textbooks claim.
Google Earth 2013
Old maps and written descriptions from the sixteenth century make no mention of it, and recent core samples have confirmed that there was no large body of water present at that time, yet one seems have appeared - almost overnight - around the mid 1580's. It's even been suggested (quite seriously) that an airburst meteorite might have exploded there, excavating the circular depression in which Portmore now lies, but leaving no physical trace of what would surely have been a spectacular event at the time...

You'd think someone would have noticed.

RSPB Portmore Lough, Aghalee, County Antrim.
N 54.570768, W 6.299629
Open year round. Parking, wheelchair access.
Ph: 028 9049 1547