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!

02 September 2014

Minsmere mega demo

Steve Piotrowski writes:

Waveney Bird Club operate regular ringing demonstrations to the public at Minsmere RSPB, Suffolk. This is the BTO’s second biggest annual ringing demonstration event of the year, with the Bird Fair at Rutland Water perhaps commanding a greater audience. The purpose of our demo is to explain bird migration and to allow Minsmere's visitors (especially children) to see birds in the hand. The Minsmere demonstrations have proven to be extremely popular with hundreds of people attending each session, some staying for the whole day. 

Collecting valuable data while educating the next generation - Jez Blackburn
The demos are managed by Waveney Bird Club (WBC), which has been responsible for ringing studies on the reserve’s birds for over ten years. The trapping areas are set in different habitats; woodland, reedbed and scrub, to produce a great diversity of species. Carl Powell is WBC’s principal demonstrator and he explains to his audience the migration habits of each bird species, how and why birds are ringed and the benefits of ringing as a conservation tool. The audience is both invited and encouraged to ask questions.

Steve Piotrowski - Jez Blackburn

This year has been exceptional, with record numbers of birds being processed at the ringing table.  With this summer’s final demonstration and training session event on the 4th September still to come, we have already processed over 1,400 birds. This summer’s highlight was a reasonable passage of migrants at the end of August. Many warbler species passed through Minsmere and a proportion were trapped and ringed to determine their destination, stopping off points, longevity and causes of mortality.

Young male Sparrowhawk and a young male Thomas Barthorpe - photo by Ian Barthorpe
The list of warbler species encountered was most impressive and included: Chiffchaffs, Willow, Reed and Sedge Warblers, Common Whitethroats, Lesser Whitethroats and Blackcaps.  The icing on the cake were two Wrynecks (a small migrant woodpecker that formerly bred in Suffolk) that were trapped (two of the four on site). However, it was the bigger birds, such as the three Sparrowhawks, a Kingfisher and seven Green and three Great Spotted Woodpeckers, that caused the most excitement at the ringing table. We also became reacquainted with some old friends, such as a Marsh Tit and a Blue Tit, that were first trapped at Minsmere in 2009 and are still going strong today. Small birds rarely live more than three years so these “old-timers” are doing well.

Wryneck - Chris McIntyre

Last Thursday, we were delighted to welcome Ellie Zantboer from Ipswich to the ringing demonstrations. Ellie is 11-years old and has been ringing under close supervision since she was eight. As children form most of the audience, Ellie was invited to give a ringing demonstration, which she did with confidence and a great deal of skill. Ellie said "I ringed twelve birds including two Long-Tailed Tits and a Chiffchaff and I loved showing the other children how it was all done!". What was really amazing was how the children immediately communicated with her, asking her questions that they may have been reluctant to ask an adult.

Ellie Zantboer (right) demonstrating ringing to visitors - Paula Zantboer
If you would like to see a ringing demo, the next ringing session will be at Minsmere on 04 September.