The Shame of Eggers.

I have spent the summer enjoying watching the Sparrows and Tits bring their young to the bird feeder on my terrace. Many people think it's unnecessary to feed the birds during the summer but food shortages can still occur even at this time of year and if this happens during the breeding season, then the extra food can help the chicks survive. The once plentiful House Sparrow is now on the RSPB red list which means they are globally threatened. I am happy to have to supported them feeding their young this year.

I was horrified to read on the RSPB website that an automated photograph had been taken of a hand reaching into the nest of a stone-curlew they were monitoring on Salisbury Plain in Wiltshire. Although there is no direct evidence that the eggs were taken, evidence on the ground and the birds behaviour suggests that the eggs never hatched and were infact stolen. I thought the sport of egging had died away with the Victorians. (hand photo taken from RSPB website)

The Stone-curlew is a nationally rare species and the RSPB with support from Natural England has spent more than 20 years working with farmers and land owners, including the Ministry of Defence, to reverse the historical decline of this unique and evocative bird of the Wessex chalk downland (Stone Curlew photo and text from RSPB website).

What is wrong with these people?

A quick search on google to try and find out what drove these people to do such pointless things brought me to an article on the BBC website by Katie Law on Why do people steal birds' eggs?

It seems there is a small community of egg collectors to which the ownership of rare birds eggs is an obsession. In 2006 the Cleethorpes home of Richard Pearson was raided by police and the largest egg haul ever recovered was found. More than 7,000 eggs, including 653 belonging to the UK's most protected species. Officers also found 59 dead birds in a freezer in his garage. Pearson, 41, was sentenced to 23 weeks in prison. Early this year Gregory Wheal of Coventry was sentenced to his second prison sentence for egg theft and has eight previous convictions. (Picture shows RSPB's Mark Thomas with the recovered eggs from Richard Pearson in 2006 from the BBC).

The loss of eggs is devastating for rare species of birds. Pearsons collection included nearly 40 black-necked-grebe's eggs. The RSPB estimates there are only between 40 and 60 breeding pairs in the UK. In addition golden eagle's eggs were amongst the collection, which are known to only have one offspring every year. "Despite common belief that rare bird eggs are worth thousands of pounds on the black market, this isn't the case. There's no real monetary value," says Mark Thomas, an investigations officer for the RSPB.

So what's the big thrill?

The chase

Birds take great care where they lay their eggs and they deliberately choose hard-to-reach spots such as cliffs, marshes, trees and rooftops, to build their nests and protect their young from predators. The BBC conclude that this, it seems is part of the problem because for eggers it’s about the thrill of the chase of outsmarting the birds, the wardens and the authorities, to track down the nest, to take the eggs, dispense with the living material inside, to proudly carry home the trophy and to add it to the secret collection.

Outsmarting the birds?? Have they considered the size of the birds brain in proportion to mans!

The Trophy

Mark Thomas told the BBC that an egg represents the memory of the daring expedition that produced it - up to Scotland, over moors, abseiling down cliffs to reach nests.

So why not take up extreme sports and buy yourself a camera?

The Hunt

A self confessed egger on Radio 5 said "I don't feel any guilt as regards to cruelty to the birds, because it's almost a blood sport without the blood. A crime without consequence"

The absence of blood does not remove the cruelty nor the consequence.

It is now illegal in Britain to take birds eggs from the wild and to possess or sell them and from 2000 custodial sentences were introduced for these offences. It is hoped that the discoveries of large collections of eggs have come to an end because as the law has strengthened, more collectors have been jailed.

So the good news is, the RSPB say "Whereas 10 years ago we might have two to three hundred reports per bird breeding season of egg collector activity, now that's right down to maybe 50 reports in a typical year."

If they don’t get caught by the authorities then let’s hope they come to the same fate of Colin Watson, an infamous egg collector who fell to his death stealing eggs in 2006.

Civil Twilight in Bergen.

Mum came to visit in June and after a top evening in the Potato Cellar she couldn't believe how light it was when we were walking home and she noticed it was midnight.

The sun had set but it must have been hovering less than 6 degrees below the horizon as objects on the ground were clearly visible without artificial light.

Daylight Hours and the High Latitudes

There is no better time than the passing of the midsummer solstice to get to grips with daylight hours in the higher latitudes. Living in Norway it’s a subject that I’m asked time and time again about from those residing at lower latitudes.

If you want to compare daylight hours between two cities then the U. S. Naval Observatory website has a neat little page where you can input latitude and longitude and output the sun rise and set times for the year. I have chosen Bradford, England (W001 45, N53 47) which is the city of my birth, Bergen, Norway (E005 20, N60 20) which is currently my home town and Barcelona, Spain (E002 09, N 41 23) for comparison and because it also starts with a B - see map below that shows the different cities within their time zone. Purple is GMT and yellow is GMT + 1.

Plotted in Graph 1 are the sunrise and sunset times for Bergen, Bradford and Barcelona, the sudden vertical translation of the curves depict day light saving. The graph shows that for us in Bergen in the depths of winter the sun rises at 09.45 and sets at 15.29 giving us only 5 ¾ hours of daylight. In the height of summer however the sun rises at 04.10 and sets at 23.10 giving us 19 hours of daylight. As expected, the graph shows that at the higher latitudes (Bergen) the daylight hours are shorter in the winter time and longer in the summer time. It also shows there is less variation in daylight hours as you move closer to the equator.

Graph 1
However a couple things are odd in the graph. I would have expected the curves to lie equal proportion between each other throughout the year and to cross only at the equinox. This is the case for the Barcelona and Bergen curves, but not for Bradford. In the summer the sun rises in Bradford around the same time as in Bergen but it sets around the same time as in Barcelona. The inverse relationship holds for the wintertime. In addition, the switch in the length of daylight hours should occur on the equinox all over the world but in Bradford this date is staggered either side of the equinox in comparison to the other cities.

The reason for this behaviour can be explained by plotting the sunrise and sunset times normalised to the true local time, that being noon when the sun is directly overhead or the same as moving the cities to the same longitude (GMT) (Graph 2). It then becomes clear that the reason that the daylight hours in Bradford do not behave as expected in Graph 1 is due to the time zones and where a city lies within that zone. Bergen and Barcelona lie in the west of their time zone but Bradford lies in the east of the previous time zone. The map shows that there isn't a huge distance between Bradford and Barcelona laterally but there is one hour time difference.

Graph 2 - note daylight saving is not applied.
Now the curves behave as I would expect. Also plotted are the number of daylight hours that each city receives throughout the year.

What is interesting to observe is that on the equinox all locations on earth receive the same amount of daylight and if you calculate the amount of daylight each city receives throughout the year then each city receives exactly the same.













Twilight

The first graph (no 1) shows that the sun sets in Bergen at 23:10 at midsummer but I know from experience of living in Norway that it is light way past this time The graph shows daylight hours which is when the sun is above the horizon and it doesn't include the effects of twilight. Due to the earth’s shape, tilt and orbit around the sun, the duration of twilight varies greatly with the time of year and with latitude from a few minutes in equatorial regions to hours in polar regions. It is that which makes the difference for those residing at higher latitudes in the summer.

Twilight is the period of time when the sun is below the horizon but the earth is not completely lit nor completely dark. It can be divided up into 3 distinct intervals: civil twilight, nautical twilight and astronomical twilight based on the position of the sun in degrees below the horizon. The definitions of these intervals are shown in the Table below. The observations on the ground can be obscured due to light pollution and atmospheric conditions.

The most important interval for us is civil twilight which is the time that the sun is less than 6 degrees below the horizon, but more importantly it is the time that the horizon can still be seen clearly visible and terrestrial objects are easily perceptible without artificial light.

At high latitudes during the summer time the sun never goes below 6 degrees below the horizon and a continuous civil twilight exists. At the poles, twilight can be as long as two weeks at the equinox (white nights), while at the equator, it can go from day to night in as little as twenty minutes. At temperate-zone latitudes, twilight is shortest around both equinoxes, slightly longer around the time of the winter solstice and more longer during late spring and early summer.

Graph 3- note daylight saving is not applied.

Graph 3 illustrates that at midsummer in Bergen there are 2 hours from civil dawn to sun rise and from sun set to civil dusk. If we were to apply daylight saving to these times then in there would only be 1 hour of Nautical Twilight between 12.30am and 01.30am. Although we do not technically have 24 hour daylight this explains why it feels like we do.

It is wonderful having so much daylight in the summer. It means that after work you can go for a hike in the mountains, go climbing or out in the kayaks and still get home before dark. To live close to the equator would mean much less variation in daylight length throughout the year, so although you wouldn’t have to live through the long dark winters that we get at higher latitudes it would also mean you wouldn’t get the fantastic long summers either. In contrast, to live further north than Bergen would be simply a waste of daylight as we still need to go to bed and any dalylight past 11pm would be better rationed out during the winter.

For me I think Bradford and Bergen are close to being the perfect location in terms of daylight hours through the year. Perhaps somewhere inbetween - close to a latitude of N60 would be spot on.. where could that be?

The Common Gull

The Common Gull is a medium sized gull (adults are 40-46cm long). They look very similar to the Herring Gull but are smaller and have a shorter, more tapered bill of a more greenish shade of yellow. The bill often has a poorly-defined blackish band near the tip. The body is grey above and white below. The legs are greenish-yellow.

The Common Gull is found all through northern Europe and you are probably most familiar with this bird trying to steal your fish and chips! I spotted it from my window as it joined in the cherry gorging frenzy.