20 November 2015

Choppy times for Manxies

Manx Shearwaters and their migration provide one of the most fascinating bird stories of the British Isles. They breed in inaccessible places and historically have been difficult to observe, let alone study, outside their breeding period. For this reason, the Manx Shearwater has been a mysterious species for ornithologists for many years. Luckily, technology, the Ringing Scheme and the fact that it is a long lived species have combined to provide us with a lot of information on the life history of the Manx Shearwater, including its distribution and behaviour in summer and winter.

The 300,000 breeding pairs of Manx Shearwaters in Britain & Ireland are distributed among about 50 colonies, the largest ones being Skomer in Wales and Rum in Scotland. Several thousand 'Manxies' are ringed by BTO ringers every year; the table below show the last five years from the Online Ringing and Nest Recording Report.

Most 'regular' recoveries of Manx Shearwaters are generated at their breeding sites, when they return to breed at the same colonies year after year. Since the BTO Ringing Scheme started, over 100 years ago, we have received about 1,000 reports of BTO-ringed birds from foreign countries, all except one on the Atlantic coast, most of them in Brazil, Uruguay and Argentina. 

Nowadays, the more exciting and revealings facts about the pelagic life of this species come not from ringing but from satellite and datalogger tracking. When the birds return to breed in their burrows on islands in Britain & Ireland, they can be fitted with special devices that are safe for the birds and give more detailed information about their movements and behaviour.

Researchers studying this species have been able to reveal where most 'Manxies' spend their winters and what routes they take to and from the breeding colonies. One such research project is led by T Guilford - some result from which, below, show the estimated routes and stopovers of 12 birds fitted with geolocators. 

Different colours indicate different birds, the 'lines' are joined dots and do not represent actual trajectories of the birds. 
Migration and stopover in a small pelagic seabird, the Manx shearwater Puffinus puffinus: insights from machine learning
T GuilfordJ MeadeJ WillisR.A PhillipsD BoyleS RobertsM CollettRFreemanC.M Perrins
Most of the South American reports occur between November and January, and the number of dead birds reported along the coasts of the Atlantic varies from year to year. So far this Autumn we have received 10 reports, a few more than we would expect. Many of the finders who kindly let us know about these Manx Shearwaters mentioned the stormy weather they have experienced on the other side of the Atlantic. These intense stormy periods may be linked to a strong 'El Niño' event in the Pacific, bringing unusual weather to many parts of the world including North and South America. 'El Niño' literally translates as 'the child', because this weather anomaly typically manifests around Christmas time when the birth of baby Jesus (the child) is celebrated. The graph below puts the 2015 'El Niño' event in context compared to previous strong 'El Niño' events.

The graph above shows how this year's event ranks in terms of severity compared to other strong 'El Niño' events. More information can be found at: http://www.srh.noaa.gov/tbw/?n=tampabayelninopage

It is also interesting to see how many birds have been reported washed up on the shores of the east Atlantic in the last two decades. 

In North America, Deaborah Kotzebue, who lives Texas, USA, found a Manx Shearwater in Gulf Shores, Alabama, washed up after a stormy period. She sent us some photographs to illustrate what the place is like

The other nine reports of Manx Shearwaters were of birds washed up on beaches in Brazil, South America. One of them was found on Campeche beach, Santa Catarina, by surfer Paulo Vieira. I asked Paulo if the weather had been particularly stormy and he replied "Yes, it has been very stormy  down here in Santa Catarina State, and southen Brazil in general. We are suffering the effects of 'El Niño', which produces a lot of rain during the Spring (above normal range). Since mid-September until early-November it has been raining a lot down here".

At the end of the wintering period we will give an update on Manx Shearwaters on the other side of the pond.

The Manx Shearwater was chosen as the bird of the month in September 2015. See the distribution map in the Atlas Mapstore.

16 November 2015

Out of Africa... and into Norfolk, for a 13 gram bird

Oliver Fox writes:

Monitoring of wintering passerines is one of the main objectives of the Kartong Bird Observatory (KBO), a project run by volunteer ringers in the south of The Gambia, West Africa. Situated on the Atlantic coast close to the Senegalese border, the Kartong wetlands were formed relatively recently as a result of wet-season flooding of disused sand mines and form part of the Allahein to Kartong coast IBA.

Palearctic passerines being processed at Kartong Bird Observatory taken by Colin cross

The wetland reedbeds and surrounding scrub provides an excellent wintering site for many Palearctic passerines, and mist-net surveys have highlighted the importance of the site for Western Olivaceous Warblers, Common Whitethroats, Subalpine Warblers and Common Nightingales in particular. In dry years the area provides refuge for Sahel-dependent species, such as Western Orphean Warblers and Woodchat Shrikes, when conditions further north become unfavourable. Located on a promontory extending into the Atlantic, the site is also well placed to observe passage migration of Blackcaps and Garden Warblers moving south in October and November and Willow Warblers moving north in early Spring.

Wintering Reed Warblers are regularly encountered at Kartong, both in the Typhus reedbeds and the dry coastal and Acacia scrub that surrounds the wetlands. A proportion of those ringed at Kartong seem to be faithful to the wintering site, with five birds recaptured the winter after ringing and one bird returning to Kartong in two successive winters.

Reed Warbler about to be released at Kartong taken by Oliver Fox

News from the BTO has been received that a Reed Warbler ringed on 18/01/14 at Kartong was recaught at Hilgay Wetland Creation, Norfolk on 11/08/2015 BTO's Graham Austin, only 29 km from BTO HQ. There were several BTO staff members on the expedition in 2014, so it seems fitting that the bird was caught in Norfolk a few months later.

This is the sixth Reed Warbler ringed at KBO to be recaptured back in Europe during the summer months, with three having been previously recaptured in Spain, one on Guernsey and one in Surrey. Similarly, the ringing teams at Kartong have recaptured two Spanish and one British & Irish-ringed bird in the last few years, showing the migration pattern of Reed Warblers from Western Europe to the coast of West Africa.

Details of this latest recovery can be found on the Recoveries and Controls page of the KBO website.

29 October 2015

The Goldrush: update

After the big influx that we reported previously on the Demog Blog, and on our very own BTO Bird Migration Blog, things have calmed down somewhat after the initial rush (see BirdTrack chart below). For our ringers however, it's time to start inputting all that data scrupulously collected including age, sex, date, time, location, wing length, weight and fat and muscle scores. 

Goldcrest reporting rate by BirdTrack

Once the BTO receives the data, they will be loaded and the ringer/finder should receive the details about these birds within a few days (as long as the original ringer has submitted the ringing data). If it's a foreign-ringed Goldcrest, the BTO will contact these schemes and exchange information. Just this morning we received a file from Daphne Watson from the Isle of Wight who caught a Belgian ringed Goldcrest and the details arrived with the Belgian Ringing Scheme only 3 hours later (isn't technology brilliant!). They send us the ringing details and we then pass the information onto Daphne.

Unusually pale Goldcrest lacking it's dark pigments taken by Euan Ferguson and Carmen Azahara

Pale Goldcrest compared to a more usual one, taken by Euan Ferguson and Carmen Azahara

Below is a map of the origins of all the Goldcrests ringed abroad that have been caught in Britain & Ireland within the last couple of weeks! There are bound to be a few more and they will arrive in due course, ready for the Online ringing report to be published next year.

Some of the origins of these Goldcrests are very notable, as we have only received a handful of reports from these locations in the last 106 years (it also takes a lot of Goldcrests to get a handful). For example this was the 15th Belgium-ringed, the eighth Polish-ringed and sixth Lithuanian-ringed Goldcrests reported here. Click on the red point to find out how many reports of Goldcrests there have been from each county.

22 October 2015

Getting collared by a goose

Geese are one a special group of birds that can divide people's opinion in the same way that city pigeons or urban gulls can. Many assume that geese stay in the same place year after year, especially the ones that are fed in parks and urban areas. No one really knows for sure however and ringing is uniquely set up to be able to find this out.

Canada Geese taken by John Harding

One particular issue people have is that when geese moult during June or July, they drop all their flight feathers simultaneously and become flightless. Due to the fear of predation they remain very close to bodies of water for the month or so while they regrow their feathers. Geese can cause serious habitat degradation in certain locations like the reed beds at Hickling Board, Norfolk (.pdf) and understanding more about the reasons behind this can improve the situation for geese and people.

On our BTO Nunnery Lakes reserve, Thetford, Norfolk we have several fishing lakes and the geese usually choose the lake that has fencing around it. The downside of this decision is that the geese quickly eat all the accessible food and they have to be moved out onto another lake. During this process the geese are ringed, and in 2012 our ringers started to add uniquely coded plastic neck collars to Greylag and Canada Geese as part of the Hickling Broad project.

Canada Goose AEL - taken by Neil Calbrade

Neck collars are a safe marking method for large geese and have been used widely in previous studies on species such as the migratory Pink-footed Goose and White-fronted Goose, allowing individuals to be identified when on water as well as on land. This is particularly important if you are investigating moulting birds, where seeing their legs are an issue. Due to the size of the goose's head the collars actually have quite a lot of room inside to move around.

Greylag FHA bringing up the next generation - taken by Janet Foster

Since 2012, we have had a fantastic response from BTO staff, volunteers and members of the public who have submitted sightings of any geese with neck collars to www.ring.ac, specifying the species, combination on the colour ring, location (ideally with a grid reference) and the date.

The map below shows the sightings that we received between summer 2012 to summer 2014 away from the reserve itself. As you can see they did indeed go into town but also they explored the surrounding waterways and lakes.

What is amazing however, is after the summer of 2014 the geese were spotted much further away from the BTO reserve, see map below. The reason for this are under investigation and some individuals regularly return to the BTO after making these 'unusual' movements. Being able to identify each individual on the water should help us answer some interesting questions like 'do geese moult in the same place every year', 'do they winter in the same locations' and 'why do they move'.

If you do see a neck collared goose, please report it via www.ring.ac and you will receive information on the movements of that particular goose and at the same time increase our understanding of these birds.

13 October 2015

The Goldrush

With all the excitement of the Yellow-browed Warbler influx at the moment, from Shetland to Cornwall, it could be easy to overlook the fact that Goldcrest is also doing very well (see the reporting rates on BirdTrack below). Weighing about 6g, this tiny bird was thought to ride on the backs of Woodcock to our shores (as they arrived at a similar time to Goldcrest) from Scandinavia and the Continent because they wouldn't be able to make it on their own; hence the old name of 'Woodcock pilot'. We now know this is not the case and they can make these massive migrations all on their own.

Ringers all over the country have been catching large numbers of Goldcrest with 150 ringed at Landguard Bird Observatory and 485 ringed at Spurn Bird Observatory over the last three days. This would be a small fraction of the number of birds actually moving through, as the 1,000+ estimate at Gibraltar Bird Observatory on one day can testify.

We have heard that a few have been caught wearing rings from different countries, for example the Mid Lincs Ringing Group caught a Goldcrest ringed in Denmark and a Polish-ringed bird was caught by Tees Ringing Group and Sandwich Bay Bird Observatory caught a Dutch and Latvian ringed Goldcrest. Mike Marsh and his team from Orfordness Nature Reserve managed to catch 109 Goldcrest last Sunday (11 Oct) and one of them was ringed on 6 October at Falsterbo Ringing Station, Sweden! Amazingly, the ring number was TM3052, which, if you put this as a grid reference on an OS 1km map, is only 15km from where the bird was caught. We don't believe this Goldcrest was pre-programmed to go here!

Goldcrest from Sweden. Image of ring taken by several photos of ring merged. By Dave Crawshaw

There are bound to have been more foreign Goldcrest captures over the past few days so feel free to share your stories below in the comments box.