Arctic Tern Study

The BTO have been putting together a series of identification videos and now and again I spend some time going through these to remind myself of key ID points on some potentially confusing species. They really are most useful and to date there are 27 videos covering over 60 species. This morning I was taking another look at the one titled: 'Taking a Look at Terns 1: Arctic and Common Terns.' These two species can be a little tricky if you are not sure what to look for. This prompted me to post a few of my Arctic Tern shots. When you have had a good look at these I recommend checking the BTO video by clicking on the following link:
http://www.bto.org/about-birds/bird-id/common-and-arctic-tern
These pictures were taken at the colony on Inner Farne in the Farne Islands, Northumberland. Whilst we were there we had good views of two breeding Roseate Terns but we had left by the time the Bridled Tern turned up!
The main ID features of Arctic Tern are: a blood-red bill without a black tip, which can be seen best on the third photograph. (The bill of a Common Tern tends to have a distinctive black tip and the bill of a Roseate appears to be all dark with a red base.) The throat, breast and belly tend to be washed grey and this forms quite a clear contrast with the white of the cheeks. This feature can be seen on the photos of the bird in flight as well as the perched birds. (This contrast is less obvious on Common Terns and not really present on Roseates.) Arctic Terns have very long tail streamers which extend beyond the wing tips when the bird is perched as you can see in the second photo. (The tails of Common Terns do not extend as far as the primary tips.)

Arctic Tern Sterna paradisaea   Adult

Arctic Tern Sterna paradisaea   Adult showing length of tail and contrast between the grey under-parts and the white cheek.

Arctic Tern Sterna paradisaea   Adult showing blood red bill.

The flight shots show that the flight feathers are translucent and almost pure white when viewed from below and the outer primaries have a neat black trailing edge. Common Terns would show a much broader diffuse black trailing edge to the primaries.

Arctic Tern Sterna paradisaea   Adult. Note the distinctive contrast of the cheek

Arctic Tern Sterna paradisaea   Adult showing the neat black trailing edge to the primaries.

Arctic Tern Sterna paradisaea   Adult - note the white, translucent flight feathers.

Arctic Tern Sterna paradisaea   Adult

Other ID features of Arctic Tern, useful for separating it from Common Tern, are its slightly smaller size, shorter legs, narrower wings, uniform pale grey upper-wings which lack the dark wedge found on Common Terns and its more bouncy flight. None of these features can be seen on these pictures and you really should see the birds side by side to benefit from some of these points so go and take a look at the BTO videos.

Nightjar Chicks

Last Saturday I drove down to the BTO headquarters in Thetford to attend the OSME general meeting, more of which later. After the event had closed at around 5.00pm I took some time to visit a part of Thetford Forest to take a couple of photos of Nightjar chicks. A friend was looking for Adders last week when he flushed a female Nightjar and in doing so he located the nest which contained two recently hatched chicks. So armed with a 400mm lens, so that I could shoot from a reasonable distance as well as a 70mm lens to get shots that shows the nest site, we strode purposefully into the forest!

Typical Nightjar habitat in Thetford Forest
 

It was particularly hot and as it was not yet really evening there was not much in the way of bird activity. A couple of Wood Pigeons flew over and a Yellowhammer was singing from a nearby pine as we approached the site. The female took flight as we neared the nest and pitched in to an oak about thirty metres away. She was obviously keeping an eye on us and we suspected that the male was probably resting up pretty close by too.

Nightjar chick - close-up

Not wanting to get too close or to be too long at the site I took pictures using the 400mm lens. The chicks had their eyes open and were both looking healthy and well. These birds prefer open areas in which to nest, especially lowland heath, clear felled areas in forests and young conifer plantations


Spot the chicks!

The nest (which really is a misnomer as there isn't one) is a slight scrape at most and more often just a suitable patch of ground as was this one - as can be seen in the photos.



Nightjar's nest!

 





Nightjar chicks at approximately one week old.

 The young rely on their cryptic camouflage and by remaining still to avoid being detected. I was told that when they are handled by licenced ringers they remain perfectly still and calm and do not need to be placed in bags as they are so sure of their invisibility they don't really think they are being handled at all...because nobody can really see them!



Nightjar chicks

Identification of Blyth's Reed Warbler

Over the past few years I have seen three Blyth's Reed Warblers in Britain and the last one, on Fair Isle in 2011, was mist netted and ringed and so I was able to get some in-hand shots of the bird. The photos have been sitting on my hard drive serving very little purpose since then. I thought I'd stick a few on my blog so that they are available for anyone wanting help with identifying putative Blyth's Reed Warblers or who just want to brush up their ID skills.
Blyth's Reed is an un-streaked Acrocephalus and as such is pretty difficult to identify as there are a number of other, very similar, un-streaked Acrocephalus warblers in the Palearctic region. Blyth's, Marsh and Eurasian Reed can all be told apart on song but the chances are a bird in the UK will be a first-winter bird in the autumn and will be silent. If it does call you are listening for a Lesser Whitethroat type 'tuk'  which is unlike the 'tcharrr' of a Eurasian Reed or the softer note of a Marsh warbler. So what do you look for in a Blyth's? They have a combination of relatively short primary projection and clear emargination on two of the primaries. O.K. if you have a bird in the hand but difficult in the field! The emargination on the primaries can be seen on the first photograph but it would not, I suggest, be of much use generally.

1st autumn Blyth's Reed Warbler Acrocephalus dumetorum  Fair Isle October 2011

In this second picture we can see that the wing is quite rounded, more so than in Marsh Warbler or Eurasian Reed Warbler. The bird has a short primary projection, about 50-60% of the length of the exposed tertials. According to Kennerley and Pearson in " Reed and Bush Warblers" Helm 2010, "The wing point is formed by p3 and p4, and p5 is often so close in length that just six closely spaced primary tips are visible on the closed wing, fewer than in Marsh and Eurasian Reed." This feature is clear on this bird and it is a particularly important identification feature

1st autumn Blyth's Reed Warbler Acrocephalus dumetorum  Fair Isle October 2011

In this third picture we can see that the bill is quite deep and broad based and so it appears to be more substantial than on Eurasian Reed Warbler but they tend to be about the same length. The bill of Marsh Warbler is slightly smaller. Guidebooks always point to the long, sloping forehead and the low angular crown, peaking just after the eye as a useful ID feature of Blyth's and again this feature can clearly be seen in these photographs. This bird has a clear open-faced expression that can also be a useful ID feature of Blyth's.

1st autumn Blyth's Reed Warbler Acrocephalus dumetorum  Fair Isle October 2011

Blyth's Reed lacks the hint of warm tawny-brown shading to the rump and uppertail coverts that you would expect on a Eurasian Reed Warbler and it is not as greenish as a Marsh Warbler's rump. The overall colour impression of this first-autumn bird is a cool olive-brown above with hints of warmer, browner tones in the wings and on the tail and pale below with a whiter chin and throat. On these pictures we can see that the supercillium is quite indistinct, especially behind the eye. It is quite poorly defined on this individual. Blyth's tend to have a supercillium that bulges in front of the eye but that is less prominent behind the eye and this gives the bird a bland appearance.



1st autumn Blyth's Reed Warbler Acrocephalus dumetorum  Fair Isle October 2011

This bird is showing very worn rectrices and fresh primaries. It is a classic first-winter bird in autumn: the tail feathers are browner than in an adult and the upperwing coverts, tertials and flight feathers are all brighter than in an adult. The first three photographs show that the upper mandible is grey with pinkish cutting edges whilst the lower mandible is a pale pink.



There are a number of confusion species. As well as Marsh and Eurasian Reed, Large-billed Reed Warbler Acrocephalus orinus is probably the most difficult to tell apart - fortunately not a problem in Britain...not yet!

Back on Fair Isle during the week of September 18th to 25th I witnessed a repeat performance as another Blyth's Reed was located, captured and ringed. This bird then hung around showing well on and off in a couple of crofters' gardens for the rest of the week. I took photos of the bird in the hand.

The next three photographs are of the 2015 bird.The gingery colouration on the primaries and secondaries is quite noticeable on this bird. Note the pale pink lower mandible. The wing length of this bird was 60.5 mm. I think that the wing length for Eurasian Reed Warbler lies between 65 and 70mm so the wing length of this bird is quite short in comparison.

Wot...no bins!

I've seen a good number of Ring-billed Gulls Larus delawarensis in North America but I've only ever managed to see a handful in the UK. Two reasons for this: firstly Ring-billed Gulls are pretty scarce; secondly I'm not much of a gull-watcher. Miserable evenings in the cold, wet, half-light sifting through half a billion Herring Gulls on a midlands reservoir is my notion of Hades. Likewise hanging around stinking land-fill sites trawling through a swirling mix of Black-headed Gulls, Lesser Black-backed Gulls and yet more Herring Gulls in upwards of twenty seven plumage variations leaves me a touch unfazed. So when I heard that a first summer Ring-billed Gull was showing well just twenty minutes from my house I decided to give this one a go.
When I arrived at Melton Mowbray Country Park the weather was just right - sunny, dry, warm and fairly still. I should get great views of this I thought. On opening the boot of the car I realised that I had not brought my bins. Stupid...stupid! A cardinal error. Fortunately my scope was in the car and I had a 400mm lens on my camera so I was not wholly without optics. If the bird is on the water I should be OK as I can scan with the scope. If it's flying about I've got no chance.

1st Summer Ring-billed Gull Larus delawarensis Melton Mowbray

I set up my scope at the edge of the lake and scanned the few gulls loafing in the middle...Common Gull...Common...Common...Common....Common etc. All bloody Common Gulls. It's at this point that you realise how easy it is to string a bird. The temptation to turn an obvious Common Gull into a stringy Ring-billed was pressing. Bit more of a scan...Common...Common...Black-headed.

1st Summer Ring-billed Gull Larus delawarensis Melton Mowbray

Then bingo! A big, heavy Common Gull with a massive parallel sided pink bill with a black tip. Ring-billed. It was an aggressive individual; twice attacking passing Common Gulls. It stayed some distance away and I could only take a few record shots of it sat on the water. Ten minutes later it took flight along with the Common Gulls and I had to follow it through the camera lens as I had no chance of staying focused through the scope.

1st Summer Ring-billed Gull Larus delawarensis Melton Mowbray

I did manage to capture a few images as it was easy to keep on the right bird due to its mangled tail. In flight the bird looked bulkier and longer winged than the accompanying Common Gulls. In particular its head and bill were much stockier.

1st Summer Ring-billed Gull Larus delawarensis Melton Mowbray

 The pale wing panel on the secondaries was quite an obvious feature although it can't be seen on any of these pretty useless photographs! I couldn't pick out any dark crescents amongst the scapulars or any narrow pale tips to the tertials - as all of the guide books say you should. It is a birding education though looking at the differences between Common and Ring-billed Gulls. Side by side the differences are obvious but I doubt if they would be so with a lone bird.

1st Summer Ring-billed Gull Larus delawarensis Melton Mowbray

1st Summer Ring-billed Gull Larus delawarensis Melton Mowbray

 I'll probably have another bash at this bird tomorrow and try for some more worthwhile pictures and this time I'll take my bins!

Eight crows a day.

We spent last week on Anglesey in North Wales looking for migrants as well as getting in some much needed walking. We had some good numbers of common migrants with Swallows arriving in numbers on Monday 15th April - well over 100 during the morning around Breakwater Country Park - along with a few House Martins and Sand Martins. The 16th saw a fall of Willow Warblers with over twenty counted along with over thirty Chiffchaff. Sandwich Terns appear to be quite plentiful with over 40 at Cemlyn Bay on 18th April. There were four adult Mediterranean Gulls there too as well as a single Arctic Tern. We picked up a Common Tern at Newborough. On the 18th we were at South Stack where there was an impressive arrival of Northern Wheatears - birds were bouncing around on the heather in all directions. We estimated in excess of fifty birds.
But for me the week will be remembered mostly for the first time that I had seen eight species of crow/corvids in a single day - although I didn't manage to photograph them all.

On Sunday 14th we were walking around the lake at Rhosneigr when I caught sight of a Hooded Crow Corvus cornix battling against the gales that were blasting in from offshore. It was in the company of a couple of  equally knackered Carrion Crows and they soon struggled to ground near the northern shore of the lake. Hooded Crow - great...my first for Wales.

Carrion Crow Corvus corone

We had already seen plenty of Rooks at the southern end of Anglesey as we drove north along the A55 and Jackdaws were just about everywhere. Four species of 'crow' and because I was on Anglesey; one of the best places for Chough and Raven I figured that if I could catch-up with a Jay I'd manage all eight.


Jackdaw Corvus monedula

Raven Corvus corax - a friendly pair

Over to South Stack RSPB reserve on Holyhead Island - a guaranteed Chough site. Easy pickings! A couple of Chough flying by as soon as we got out of the car and Ravens flying over and calling. A volunteer warden in the RSPB visitor's centre told us later that there have been counts of up to 1 600 Ravens roosting in the Pine forests near Newborough!

Rook Corvus frugilegus

Magpies were seen, normally in pairs, throughout the day and those on South Stack were getting blown every which way. Just a Jay needed now!



Magpie Pica pica with the wind up its jacksie

We drove down to The Dingle near Llangefni - a picturesque, sheltered, wooded, welsh valley if ever there was one and as Bob's yer uncle a single Jay flew through the woods. I've not managed to get pictures of Jays as I find them pretty shy and skittish although noisy. Later this year we plan to bird western Scotland so I might get some shots of Hooded Crow but Jays might have to wait. Six species photographed so far and two to go - three if we count Nutcracker but I haven't seen one of those in the U.K. since the Staffordshire bird in 1991!

(Red-billed) Chough Pyrrhocorax pyrrhocorax

 

A Tale of Two Grebes

On Wednesday I drove down to Thetford Forest to spend some time looking for Golden Pheasants. I had planned to spend the last few hours of daylight on Wednesday and the first couple of hours on Thursday hoping to get some photographs of this elusive and fast-disappearing species. On the way down I passed Fen Drayton RSPB reserve in Cambridgeshire and as I knew that there had been reports of both Black-necked and Slavonian Grebes I figured it was worth a diversion. I had a walk around Ferry Lagoon looking for migrants first of all but there was nothing bar four Chiffchaff and a lone Blackcap but at the southern end of the lagoon I managed to locate the Black-necked Grebe feeding a fair way out. However, it soon started to move nearer to the bank where I had set up my gear and pretty soon it was close enough to take photographs. I had been watching the bird through the camera lens and so had a narrow field of view. Taking my eye away from the lens so that I could have a quick look through my bins I was surprised to see two birds more-or-less together. The second was the Slavonian Grebe and this had appeared from nowhere. Both birds were in summer plumage; the Black-necked complete and the Slavonian almost so this was a great opportunity to compare these two scarce grebes side-by-side. I had never seen these together in summer plumage before. I have seen them together in the winter on a number of occasions.

Slavonian Grebe Podiceps auritus - Fen Drayton

The first thing that struck me was that the Black-necked Grebe looked slightly larger than the Slavonian but this could have been the result of it sitting higher in the water compounded by its steep forehead and peaked crown as both of these birds overlap in size - the Slav often being the larger. Both birds were sporting golden-yellow ear tufts - the tuft on the Slavonian was a little more ragged. Both birds had amazing red eyes. Note the bill in the photograph of the Slav below - straight, quite small and tipped pale yellowish/horn. The bill of a Black-necked Grebe is all black, up-tilted and sharply pointed. This bill difference is a good feature for separating the two species.

Slavonian Grebe Podiceps auritus - Fen Drayton

Because the Slavonian Grebe was not yet fully moulted it looked a bit untidy. If you compare these photographs you will see what I mean. There were still some winter plumage white feathers on the chin and upper throat as well as the upper breast but it was clear that the front and sides of the neck were turning reddish - a key difference between the two species as the neck of the Black-necked Grebe is all black - hence its name! The flanks too still had signs of winter plumage and were not yet entirely deep red.

Slavonian Grebe Podiceps auritus - Fen Drayton

The rear of the two birds was different with the Black-necked showing a fluffy, almost Little Grebe, back end whilst the Slavonian had a more stream-lined lower in the water end which was white.
You can see this feature in the picture below, although the Slav is out of focus due to a narrow depth of field. You can also tell the difference in head shape. The Black-necked has a steep forehead with the crown peaking directly over the eye, whereas the Slav's crown is flatter and has a definite peak behind the eye. The Slavonian has a longer sleeker body and looks a bit like a small Great Crested Grebe whereas the Black-necked recalls a big Little Grebe - if you know what I mean!

Black-necked Grebe and Slavonian Grebe Podiceps nigricollis and P. auritus - Fen Drayton

The Slavonian Grebe followed the Black-necked Grebe all of the time that I was watching. They behaved as if they were a pair with the Black-necked leading. Also the Black-necked called a number of times as it approached the bank but I don't think I heard the Slavonian Grebe at all. Both birds were happily feeding and appeared to be settled, they have both been present for some time.

Adult summer Black-necked Grebe Podiceps nigricollis - Fen Drayton

No doubt as the Slav progresses with its moult it will become more spectacular but it will have a way to go before it can beat the beauty of the Black-necked Grebe seen in the following two shots.

Adult summer Black-necked Grebe Podiceps nigricollis - Fen Drayton

In this portrait shot of Black-necked Grebe the tiny all-black up-tilted and sharp-pointed bill along with the incredibly steep forehead peaking above the eye are obvious. Both of these features tell you that you have a Black-necked Grebe and not a Slavonian.

Adult summer Black-necked Grebe Podiceps nigricollis -Fen Drayton

 

A bit of a twitch!

Earlier this year I drove over to Beeley Moor in Derbyshire to look for a Great Grey Shrike Lanius excubitor that had been frequenting an old quarry for a couple of weeks. Needless to say I didn't locate the bird even though we put in a couple of hours searching. It was still there yesterday so this morning I fancied having another go even though it promised to be bitterly cold up on't' moors with an easterly wind howling in from Moscow. I expected a similar search and seek mission to the last visit and I was resigned to getting frozen and possibly not seeing the bird. As we approached the site my wife and I had the following conversation. "Are you going to park just here on the right?" "Yes, this is where I parked last time." "Good...'cus there's the Shrike by the gate." "!?!!*" Birding's like that! Ten minutes later it had flown off and despite searching could not be relocated. It might never have been there.

Great Grey Shrike Lanius excubitor Beeley Moor, Derbyshire

Whilst searching for the Shrike an Osprey flew directly overhead heading north. This was a bonus bird but hardly a surprise when you take into account all of the reservoirs that can be found in this area - along with the time of year.

Osprey Pandion haliaetus

That the idea of reservoirs popped into mind due to the Osprey then had us heading a little further south to try for one of the four reported Great Northern Divers at Carsington Water. Here we heard and saw our first Chiffchaffs of the year - 4 in total in a thirty minute spell. Hardly a record but nice to hear after all of the cold, snow, wind and stuff of the last few months. The divers were proving to be particularly difficult to locate but a couple of Redshank in full breeding kit were pretty obliging.

Redshank Tringa tetanus Carsington Water Derbyshire

 We eventually located just a single Great Northern Diver some distance away on the far edge of the reservoir. It was too far away to photograph and it was not that convincing a bird. Had I not known that it was probably one of the four that has been reported on and off for a month or two I would have seriously considered this one to be Black-throated. This picture is of a bird I photographed earlier.

Juvenile Great Northern Diver Gavia immer

Not a day to be remembered for migrants piling into the area but Great Grey Shrike, Osprey and Great Northern Diver just an hour away made it a bit of a twitch worth doing.

Ringing Tawnies

Today I had the pleasure of being invited down to March in Cambridgeshire to photograph young Tawny Owls as they were being ringed. The adult Tawnies were nesting in a purpose built 'Owl Box' set in a Walnut Tree in a large suburban garden. When I arrived the male was roosting, virtually out of sight, in an ivy-covered tree near to the house. When the sun is shining he is known to roost more in the open so as to enjoy the warmth of the sun. Not so today. The female bird was in the box keeping an eye on the three young inside. We knew that there were three young because the owners of the house and grounds have placed nest box cameras in and around the box and they keep a constant vigil on the birds. It was a proper Spring-Watch set-up.
An experienced, licenced qualified ringer from the BTO was present to ring the birds and ensure their safety. In fact everyone present seemed to be mindful of the birds' welfare above all else and the youngsters were not out of the box for more than quarter of an hour before they were safely back in their very smelly home.
 The female bird meanwhile was keeping an eye on things from a thick hedge at the back of the garden.

Three sibling Tawnies -' Los Tres Amigos'

In 2010 1,716 Tawny Owls were ringed in Britain. 1,439 of these were ringed in the nest like today's birds, 65 were juveniles, that is, birds in their first calendar year and 210 were adults. The remaining two birds were un-aged as it is often difficult to tell on plumage whether a bird is in its first year or older.
In 2011 1,655 Tawny Owls were ringed; 1,458 in the nest, 44 juveniles, 148 adults and five were un-aged.
Since 1909 until the end of 2011 47,010 Tawnies have been fitted with rings.

Young Tawny Owl  Strix aluco

Now here's the thing as we say: 2,550 of these have been recovered and these birds have provided some fascinating information. How old do you think a Tawny Owl can be? Ringing data  suggests that they average about four years. But the average is low due to the mortality rates of young birds - only about a third manage to get through the first year of life. Lots of young, inexperienced birds are killed by traffic on the roads. But a bird ringed at Malham Tarn in North Yorks on the 25th May 1967 was found freshly dead on the 7th November 1988. It was 21 years, 5 months and 13 days old!

Young Tawny Owl showing wing in pin

Do Tawnies move about or are they faithful to one place? The bird at Malham was found close to where it was ringed so we know that it spent over 21 years cleaning up the mice and voles in the Malham Tarn area. But a nestling ringed in Torbol in the Highlands on 4th of May 1987 was hit by a car on 23rd November 1987 687 km away near Pemby Forest in Dfyed!
Two other birds have lived beyond 19 years and two more have lived to be over 20 years. Others have been recovered at distances of 202km, 205km and 217 km away from their ringing sites. All  of this we know because of the successes of the BTO ringing scheme.

Young Tawny Owl
Relaxed, safe and ready for ringing

 Tawny Owls lay 2 to 3 eggs and incubate for 30 days and the young fledge after a further 35 - 39 days so this pair must have laid early to mid February. In 2000 it was estimated that there were 19,000 breeding pairs of Tawny Owls in Britain. Three more have now been safely ringed and we wait to see if there is any news of them in the future.
You can check out all of the ringing information at the BTO web site here: http://www.bto.org/volunteer-surveys/ringing/ringing-scheme
Or statistics on Tawny Owls here:  http://blx1.bto.org/birdfacts/results/bob7610.htm

 

You can't keep a good Cormorant down!

I've just been reading a paper published in the Journal of Ornithology titled: "Licensed control does not reduce local Cormorant Phalacrocorax carbo population size in winter." It's another of those scientific studies carried out into human-wildlife conflicts which, to my mind, are becoming more and more prevalent. The current proposals for a badger cull being the latest. This paper, written by D E Chamberlain, G E Austin, S E Newson, A Johnston and N H K Burton says it all, more-or-less, in the title.
Here's the thing: Cormorants Phalacrocorax carbo have increased on inland waters in Britain causing conflicts with fishing interests - fishermen. Because of this several countries have introduced control measures; either lethal (shooting) or non-lethal (scaring the birds!). The paper states that "Human-wildlife conflicts are at the root of many current conservation problems and occur when requirements of wildlife overlap with those of human intersts." There's a surprise, I bet you could name a few in Britain alone - birds of prey, badgers, ruddy duck, fox, corvids! Measures to resolve such conflicts may include both lethal and non lethal control of wildlife. From the scarecrow to the gun. Cormorants are the source of human-wildlife conflict where their populations are increasing both due to damage to trees from guano - some fine examples of this at Attenborough Nature Reserve in west Notts - and potential impacts on fish populations.

Cormorant  Phalacrocorax carbo

 "Within Europe, the Great Cormorant Phalacrocorax carbo population has shown steep increases over the past few decades. This is particularly true of the subspecies P. carbo sinensis which is the most numerous in the northern parts of continental Europe and has rapidly expanded its range and population." The coastal breeding subspecies, P c. carbo has also started to move to inland freshwaters during the winter - all bad news for the fishemen and the roost trees. In the UK, in order to prevent serious damage to fisheries from Cormorant predation, licences have been made available since autumn 1996 for limited control of Cormorant populations by shooting. The authors of this paper have analysed data  - particularly from WeBS (Wetland Bird Survey) Core Counts from 1988 to 2009 and in a detailed description of the methods used to collect and analyse this data stretching over half-a-dozen A4 sides come to the conclusion that~: "Based on the results here, there is no evidence that Cormorant removal at local scales has had an effect on longer term population size at a site level - put simply, killing Cormorants in one winter did not appear to impact upon numbers at a site level in the next winter."

Cormorant Phalacrocorax carbo Taken at a local Country Park - Where the fishermen fish.

Breeding adult Cormorant Phalacrocorax carbo - Rutland Water

The authors suggest five possible reasons why killing Cormorants at a given site does not mean a fall in population during the following winter. One - killed Cormorants are simply replaced by other birds moving in from other areas. Two - significant disturbance caused by shooting may cause dispersal which may lead to apparent population increases. Three- control was not carried out on WeBS sites and birds may have moved there for refuge. Four - licenced control may be sought in anticipation of increased Cormorant predation prior to enhanced fish stocking which attracts more Cormorants. Five - licences granted at short notice in response to local increases in Cormorant numbers would suggest that control measures are undertaken in areas with the greatest growth rates, but also that such measures do not have significant impacts on the increasing local population. All very thought provoking and stuff that adds an extra dimension when you are looking at Cormorants on your local freshwaters.

The paper concludes that "We therefore suggest that the English winter Cormorant population as measured by the Cormorant index is not negatively influenced by control measures, but we need to add the caveat that not enough is known about the population outside WeBS sites, which are poorly monitored."
What lessons can we learn from this with regards to the Badger culling?
Visit: http://www.bto.org/volunteer-surveys/webs for information on the Wetland Bird Survey and how you can join in.