16 October 2014

Tay Bearded Tits on the move: can you help?

In the UK, the largest single population of Bearded Tits, also sometimes known as Bearded Reedlings, occupy the Tay reedbeds, in eastern Scotland. Over the 2014 breeding season, Tay Ringing Group have been working hard to monitor this important population, ringing an incredible 635 birds - and now these birds are on the move...

The Tay reedbed runs for 15km along the estuary, the largest continuous reedbed in the UK

Around this time last year, Iain Malzer conducted a radio-tracking study of these elusive birds, following them around the reedbed. He was intrigued when he found that none of them moved out of the Tay area during what is assumed to be a traditionally dispersive period. However, this year the picture is quite different. When the population reaches the huge numbers we’ve seen on the Tay this year, ‘Beardies’ sometimes undergo irruptive movements, flying in small flocks in all directions. By understanding the extent and drivers of these movements, we can observe how connected these birds are at a population level, how they remain stable genetically and how they colonise and occupy new areas of reedbed.

Photo (c) Amy Lewis
Typically though, this year Iain didn’t have any trackers on the birds, and so is now asking for help in finding these dispersing birds. As previous Demog Blog posts have suggested, the birds can turn up in the smallest patches of reed, so we are checking everywhere for sightings of colour-ringed birds. Already we’ve had reports from the Isle of May, Aberdeenshire and Loch Leven, but birds can move much further: the longest recovery within the UK was a 390km movement between Suffolk and Devon, and other records have even shown birds moving abroad. This is our chance to record the first long-distance movements from the Tay population.

Many of the birds ringed on the Tay have unique colour-ring combinations, allowing us to identify exactly who they are. Birds may have three colour-rings in any combination of red, orange, green, yellow, light blue, dark blue, white, grey and black. Reports of any sightings, colour-ringed or not, at your local reedbed will be an essential contribution to the understanding of the movement systems of these peculiar birds and their wider conservation.

One of the colour-ringed birds (a female) from the Tay reedbed
To report a sighting drop Iain an email or get in touch with us here at Demog Blog.

So if you're out over the autumn and winter, listen out for the unique ‘pinging’ of Beardies (have a listen on xeno-canto here) and let’s leave no reedbed unchecked.

14 October 2014

Technical wizardry helps monitor Merlins

For many of us who can’t enjoy this species on its breeding grounds in the moorlands and uplands, the Merlin (Falco columbarius) is a bird of autumn and winter when they can be spotted in the lower lands chasing Skylarks or other passerines. The BirdTrack graph below illustrates that pattern, with an obvious peak in October. An increase in sightings in October is potentially also due to the presence of passage migrants and the incoming winter population.

Merlin chart from BirdTrack
Recently, Roy Filleul, a birdwatcher and photographer from Jersey, captured images of a juvenile Merlin on the side of a pond. The following day we received a phone call from a member of the public reporting a Merlin that had been taken into care in the JSPCA (Jersey Society for Prevention of Cruelty to Animals). Unfortunately this was the same bird that had been photographed by Roy and, sadly, it didn’t survive due to injuries.

Merlin, by Roy Filleul
The bird in question was ringed in the nest last June in Lancashire, one of their strongholds (click here for top five counties for species in 2013). Although this Merlin didn’t travel a long distance or move in an unexpected direction, this is the first time one ringed in the UK has been found in the Channel Islands.

As you can see from the photograph, as well as being ringed, this bird was also PIT (Passive Integrated Transponder) tagged. These tags work in a similar way to Microchips for a dog or cat except that they are mounted externally (on a ring) rather than being inserted under the skin and are read by a receiver placed by the nest (by a licence holder). Metal ringing allows us to gather information on movements as well as survival; for example, it is possible to infer that when you stop catching a bird, that is normally caught year on year at a particular site, it has not survived (the principle behind the Retrapping Adults for Survival Scheme). As it is often very difficult to re-catch adult raptors, using a PIT tag allows us to follow a bird throughout its life to obtain data that categorically tells us the bird is still alive. If nests are monitored by a licensed nest recorder, levels of productivity over its lifetime can also be obtained from PIT tags. Unfortunately, as this bird died before returning to its breeding grounds, we will never know what information we might have gathered from this individual.

Currently in the online ringing database we have 54 recoveries of UK-ringed Merlins that have been found abroad, 35 of them in France. Also notable are the 31 Icelandic Merlins found in the British Isles, mostly recovered in Ireland. This reflects the fact that many British breeders winter on the continent and our remaining winter population is joined by winter visitors, predominantly from the Icelandic breeding population. See map of recoveries below.

Merlin recoveries map, from the online reports

07 October 2014

Looking out for Twite

As a breeding bird, Twite Linaria flavirostris has undergone a 19% range contraction in Britain since the 1968-72 Breeding Atlas (Balmer et al 2013). The stronghold for breeding Twite in England is the southern Pennines where the population has undergone declines possibly due to reduced availability of seed later in the breeding season (restricting second broods), reduced availability of suitable nesting habitat and moorland fires (RSPB England Twite Recovery Project). 

Steve Christmas and Jamie Dunning started a new project to monitor this population in 2014 and are seeking help looking for colour ring re-sightings. Birds will be on their breeding grounds between April and September but previous monitoring projects and information from ring recoveries suggest that the birds from the Pennines population winter (October to March) on the North Sea coasts between the Wash and the Thames (Wernham et al 2002). In total, there have been six UK based Twite colour ringing projects registered with the European colour-ring birding website although not all of these are still operating. Details of the colour ring combinations used for this project are described by Jamie below.

Jamie Dunning writes:

The South Pennines are the last bastion for resident breeding Twite (Linaria flavirostris) in England and are therefore home to a very important population of these birds (which belong to the endemic ssp. pipilans). Following on from historic research done by Andy Brown, David Sowter, AndrĂ© Raine, Sean Gray et al, Steve Christmas and I have started a colour ringing project on this species this year. As with the previous research, we will monitor movements as well as population dynamics and productivity over the coming years.

Female Twite. Photograph by Edmund Fellowes.
As with all colour ringing projects, publicity is key to getting data back in the form of re-sightings! The Twite we are ringing in the Pennines are being fitted with plain colour rings. We are fitting a single colour ring on the left leg over the standard BTO metal ring and two colour rings on the right leg. The colours used in our project are as follows:

Black (N)
White (W)
Pale Blue (P)
Blue (B)
Green (G)
Orange (O)
Yellow (Y)
Red (R)
Metal (M)

We have ringed approximately 100 birds in 2014 so far. Any birds seen with a combination of the above should be reported to Steve Christmas at: se.christmas@ntlworld.com or myself at: jamiedunning8@googlemail.com. Either of us would be more than happy to give any further information or answer any questions you may have. We would be very grateful if any sightings of birds that are not part of our project could be reported to the appropriate research group (www.cr-birding.org). [As well as replying to you they will inform their ringing scheme of the sighting, adding to the knowledge of this species' movements.] - Eds

For further information on Twite in the South Pennines see the RSPB’s project pages on what they are doing in the way of conserving upland habitat for birds.

Thanks for reading!

Balmer, D.E., Gillings, S., Caffrey, B.J., Swann, R.L., Downie, I.S. & Fuller, R.J. (2013) Bird Atlas 2007-11: the breeding and wintering birds of Britain & Ireland. BTO Books, Thetford.
Wernham, C.V., Toms, M.P., Marchant, J.H., Clark, J.A., Siriwardena, G.M. & Baillie, S.R. (eds) (2002) The Migration Atlas: Movements of the birds of Britain and Ireland. T. & A.D. Poyser, London.

19 September 2014

Capping off a busy breeding season

Over the last couple of weeks we have been hearing of large numbers of Blackcaps being ringed (www.bto.org/ringing), predominantly at sites in western and central parts of the country. Ringing migrants on passage provides a reliable indicator of the number of birds moving through an area and helps to improve our knowledge of migration routes and the rates at which birds move. British & Irish breeders are known to migrate south through the country between July and September whilst continental birds wintering here show north-westerly movements across Britain & Ireland during September and October (Wernham et al 2002). The stories below appear to show a southerly movement of Blackcap suggesting that the majority of these birds are UK breeders (migrant birds tend to travel down the eastern and southern coasts (Wernham et al 2002)). The large numbers of birds encountered may be an indicator of a successful breeding season, a welcome event for a species that experienced its worst breeding season on record in 2012. but may also result from a more synchronous movement, with a higher than average proportion of the population travelling simultaneously. The ratio of juvenile to adult birds caught could help us to determine which explanation is more likely.

Despite the poor breeding season in 2012, nationally, Blackcap numbers are increasing and their range is expanding northwards. Breeding Bird Survey data show that Blackcap has increased in abundance by 137% over the past 20 years (download the latest BBS report from www.bto.org/bbs). Data from another BTO survey, Garden BirdWatch (www.bto.org/gbw) show that our migrant Blackcaps are currently moving out of gardens. The data suggest they won’t return in any numbers until the wintering populations move into gardens in November. 

Female Blackcap. Photograph by Liz Cutting.

Peter Fearon rings in North Liverpool and writes:

We ring at a relatively urban site in North Liverpool - Rimrose Valley Country Park - the site is a long, thin country park separating different housing estates. This former rubbish dump has grown to be a diverse habitat for breeding and migrant birds, especially Blackcap. This summer, it wasn't until Sunday 31 August that I was able to get out with my reliable band of trainees to ring at one of our sites on Rimrose. We were rewarded with our biggest catch at the site of over 130 birds ringed, with 52 of these being Blackcap. We were able to set up another session the following Thursday and managed to catch a further 35 Blackcap, only one being retrapped from the previous session indicating a significant turnover. The following weekend (6 & 7 September) however, it was a different matter with two sessions completed but only 25 Blackcap ringed. It would seem that there was a significant movement of Blackcap in this week and it was a shame that the weather prevented us from surveying their movement through some of our other sites. I think that it is interesting to note that we had ripened blackberries in mid-July and most of our sites are now devoid of any soft fruit other than the elderberries.
Mick Townsend rings at Stanford Reservoir on the Leicestershire-Northamptonshire border and writes:

We are just about as far from the coast as you can get, yet we have just experienced the most extraordinary event in the 39 years of ringing at the site. On Monday 1 September the weather forecast was not promising at all with rain due about 10am so I decided to go for a 5am start. I erected six nets in the hope of a few warblers, Blackcaps and Chiffchaff being my target. The rain came early and by 8:30am I was taking the nets down with only 46 birds caught, not a great morning but I at least caught nine Blackcaps. Tuesday dawned and I was full of hope for a much better day and I was at the reservoir for 3:45am. As the time arrived for the first net round I could hear Blackcaps ticking away in the bushes so off we set. The first round total was 163 birds caught, 96 being Blackcaps. The rest of the day continued in the same vain with lots of Blackcaps caught in each round of the nets. We finished on 331 birds caught and of these 298 were new, 214 being Blackcaps. The following day saw another 198 birds caught, 118 of which were Blackcaps. This time we had a control and the BTO tell me the ring was issued to a ringer in Doncaster. The fourth day was a quieter day all round with only 96 birds caught, 47 of which were Blackcaps. The Blackcap rush didn’t stop there though and on the 6 September, we caught 119, on the 8 September we caught 150, on the 9 Sept we caught 101, on the 11 September we caught 111 and on the 16 September we caught 94. At this time of year we usually catch fewer than 30 a session! Blackcap numbers for the month so far are a staggering 994, we have only managed just over 700 for the year in the past.

Site locations - pink: Rimrose Valley Country Park, turquoise: Stanford
Reservoir, green: Swindon STW, orange: Salisbury Plain
Map tile courtesy of National Park Service.

Matt Prior rings on Salisbury Plain and writes:
The North Wilts RG has two teams led by Matt Prior and Graham Deacon. The Salisbury Plain is an area of grassland the size of the Isle of Wight but it has dotted patches of scrub that are very important for migrating warblers on their way back to their wintering grounds in southern Europe and Africa. We have ringed much higher numbers of Blackcaps than ever before suggesting that they have had a very good breeding season. Over the years the Blackcaps that we ring tend to get recovered along the south coast between Sussex and Devon. Blackcap totals are as follows: 24 August – 147, 31 August – 245, 6 September – 160, 7 September – 192, 8 September – 194, 10 September – 161, 13 September – 99 making a grand total of 1198! A further 309 Blackcaps have been ringed in just two ringing sessions at Swindon STW, a 9 hectare nature reserve owned by Thames Water. This compares with two sessions in the same period at the same site in 2013 when 104 Blackcaps were ringed. This year, we recorded Blackcaps breeding in a wide variety of locations where we wouldn’t normally find them such as in tiny areas of scrub on farmland.

To date, we have not heard any similar stories from the east of the country; feel free to leave a comment if you have anything further to add to the story!

Wernham, C.V., Toms, M.P., Marchant, J.H., Clark, J.A., Siriwardena, G.M. & Baillie, S.R. (eds) (2002) The Migration Atlas: Movements of the birds of Britain and Ireland. T. & A.D. Poyser, London.

12 September 2014

Swallows fledge young at a natural site

Ian Kerr writes:

A thriving Swallow population has long been a feature of my regular patch on Holy Island, Northumberland and 2014 has proved to be by far the best year since I started nest recording and ringing the species a decade ago.

This year around 75 nests, most of them around the village, harbour and at St Coombs Farm, fledged at least 260 young. Many pairs produced two broods with a small number of nests producing a third brood, although it was impossible to say if the same pairs were involved. Whatever the circumstance, the 2014 breeding season far surpassed the previous record year of 2009 when 56 pairs fledged around 150 young.

Juvenile Swallow - Jill Pakenham

Excitingly, for the first time a pair used a natural site, the first record of its kind for Northumberland. This nest was in a crevice under an overhanging turf at the top of an eroding low boulder clay bank near Emmanuel Head, the eastern most point of our tidal island. At high tides the waves would have been just eight feet below the nest. The nest was discovered by a friend, George Moody, summer warden for Lindisfarne’s Little Tern colony. When I visited the site a few days later these birds had disappeared but there were large amounts of droppings indicating the chicks had fledged. When I climbed up I found a fully-feathered dead chick in the cup which must have perished at about the time its siblings fledged.

The white droppings making this nest more obvious - Ian Kerr

Swallows using natural nesting sites are very rare in Britain although obviously at one time in the remote past they must have been the norm. Keith Bowey knows of a nest in County Durham in the early 1970s which was situated on the side of a horizontal branch on a Beech tree in Sunderland and Martin Davison reported Swallows nesting near the entrance to a sea cave near Oban on the west coast of Scotland. I will certainly be checking the bank site next spring in case these birds return.

Editor's comment - we also heard that Mark Lawrence found two Swallow nests on cliffs in Devon this year. Luckily, he found them in time to ring them!