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.

Garden Bird Photography

Not a particularly exciting blog today but it's been so long since I added a new post and I have been taking photographs of birds feeding in the garden. I was out for nearly six hours waiting to take shots of Magpies and not a one ventured anywhere near the house or showed any interest in the bait on the lawn. Normally these birds are aggressive and quick to take any advantage of bits of food left lying about...but not today. So I was left taking pictures of those birds that did have the nounce to come and get easy food. Now I don't normally give Wood Pigeons a second glance but over the past year or so I've seen many pigeon species from the continents of both South America and Africa and some of them have been fabulous - such as Bruce's Green Pigeon but I reckon that seen close the humble Wood Pigeon can give most a run for their money.

Wood Pigeon Columba palumbus

Wood Pigeon Columba palumbus

 This Collared Dove is also quite striking in a pigeony/dovey kind of way even though these can be quite aggresive towards each other and most other species in the garden. There were two of these today and they were constantly giving each other grief.

Collared Dove Streptopelia decaocto

Just over twenty species came into the garden to feed, most of which were to be expected. A male Blackcap has been feeding here for five or six weeks and over the past two weeks he has been in full song. This is the only sign of spring I've had this year as it seems to be constantly damp, grey and miserable. The Blackthorn hedges hereabouts show no signs of ever wanting to bud. And as I write this there is a warning of severe snow in parts of Britain!
The biggest surprise was this none-breeding-plumaged female Reed Bunting (possibly 1st Winter)taking seeds from below one of the feeders. The bird was sporting a brown rump which is indicative of females, the rump of a first-winter male would be grey, although it can't be seen on these photos.

1st W Female Reed Bunting Emberiza schoeniclus

1st W Female Reed Bunting Emberiza schoeniclus

 

1st W Female Reed Bunting Emberiza schoeniclus

This is the first time that I have been able to photograph this species in the garden. It's not a rare bird, although numbers are falling, but it's nice to add a 'first for the garden photo' type photo.

Falconry and Owls


 Over the weekend we visited a country fair in north Notts primarily so that I could shoot some close-ups of owls because there is always, always a tent full of owls at these type of events. Normally they are common British species such as Little Owls, Barn Owls and Tawny Owls but quite often there is a chance of getting a picture of an Eagle Owl or a Great Grey. I was not to be disappointed as there were at least two such tents at this event! One held three or four owls - the most interesting to me was a Great Horned Owl Bubo virginianus. This owl is probably the most widespread owl in North America but why does one end up in a tent in Notts? Why this species?



Great Horned Owl Bubo virginianus

Likewise in another tent I came across this White-faced Scops Owl or Northern White-faced Owl Ptilopsis leucotis a sub-Saharan African species.

White-faced Scops Owl


Also present was this Eurasian Eagle Owl Bubo bubo which is widespread across the Palearctic region. So three different owls from completely different regions of the planet. Why these? I know absolutely nothing about keeping owls or where one gets them from but there must be certain species that are easier to keep in captivity than others. Some owls must be almost impossible to keep fit and healthy under captive conditions whilst others do well. I presume that all of the birds on show were captive bred and that over time you just know which birds will thrive and which won't.

Eagle Owl

The diurnal birds of prey which were present were captive bred and bought. I know this as a falconer was openly bemoaning the fact that he was not allowed to take wild birds for himself to train up and show. He was saying this through an open mic. to everyone present. For 4 000 years, he said, man has been hunting with falcons, all of which were taken from the wild and it has had no impact on wild numbers and it never did nobody no harm!! He was complaining that he had to buy captive bred birds - at a cost and that they sometimes flew away. Excuse me! Again, falconry is a subject I know nothing about, but birds sometimes flying away I would have thought was a risk you take when you...fly birds!
Now the next question I want to ask is why are so many falconer's birds hybrids? Apart from the ubiquitous Harris Hawk Parabuteo unicinctus which I always see in any falconer's tent (apparently because it is a good bird for beginner falconers to train) all of the other big falcons seem to be cross-breeds. Gyrs, Peregrines, Lanners and Sakers especially seem to be let loose on each other to merrily produce all kinds of (presumably infertile) offspring.  Is this deliberate artificial selection by the falconers: are some hybrids more docile than pure breeds?
This one for example has a lot of Gyr Falcon in it but I don't think it's a pure bred Gyr

Gyr and....?

And what's this? There was no label that I could see near this bird. Perhaps I didn't look properly. It looks to have some Peregrine in it and also some Merlin! It was getting on for the size of a Peregrine. Would these two species mate? Any answers please in the comments box below.

Peregrine and....?

Harris Hawk Parabuteo unicinctus

Bateleur Teratopius ecaudatus



Crested Caracara Caracara cheriway

 

The Crested Caracara Caracara cheriway and the Bateleur Teratopius ecaudatus two species from different continents were both surprise "Country Fair" birds for me. I can't imagine either of them being falconers' birds. How could you train a Bateleur? Is it possible? How would you feel if one of those flew away? And that Caracara would need some very careful handling.
I presume that these birds were on show purely to entertain and educate the public. Then again they might be flown by falconers. Either way I wouldn't like to think that these were being taken from the wild!
All of these pictures were taken at the country fair. The Gyr type bird was being flown but the others were all tethered.