01 October 2015

Phylosc's, Acro's and lovely lady Sylvia

Adam Homer writes:

The numbers of warblers ringed at Stanford Reservoir, Northants has increased significantly over the last 5 years. An annual habitat management plan allows us to control tall scrub which then allows low scrub and vegetation such as Brambles, Hawthorn, Sedge and Phragmites to regenerate. This as we all know is very important habitat for breeding birds such as warblers.

A site that is as far inland from any coastal observatory that you could get, Stanford Ringing Group prides itself on the numbers of warblers caught annually. Over 3,600 warblers were ringed in 2014 and already this year we have ringed nearly 3,800 and we still have October to catch a few more Blackcap and Chiffchaff.

With all these warblers ringed and eventually setting off on their migration we do receive a few reports of birds controlled (caught by another ringer >5km from ringing site) and we occasionally control birds ringed at other sites. Every spring we also retrap some of our returning warblers and to me that is what bird ringing is all about. That a small bird such as a Garden Warbler or Willow Warbler can fly a round trip of 3,000 miles and return to the site it has been breeding at for 10 years in a row is amazing!

Garden Warbler taken by Lee Barber (tail obscured)

One of these record-breakers was once again retrapped this year. It was a Garden Warbler that was ringed as an adult female on 2 July 2005. She then disappeared for two years, returning in 2008 and retrapped every year since. I was on holiday when she returned this year and was caught during two of our CES sessions. On 8 August she became the longest known BTO-ringed Garden Warbler at 10yrs and 37 days, breaking the longevity record for this species by 7 days*.













Garden Warbler












Lesser Whitethroat












Sedge Warbler






Grasshopper Warbler






Reed Warbler






Willow Warbler













As you can see from the table above, the numbers of warblers, particularly Blackcap and Chiffchaff, have increased significantly with Garden Warbler and Lesser Whitethroat also showing a positive upward trend.

*Eds - The longevity records will be updated when all the 2015 data has been sent to the Ringing Scheme and fully processed. This longevity record will then replace the previous longevity record... unless another ringer catches an older bird or Stanford Ringing Group catch this Garden Warbler again a few days older.

24 September 2015

Exceptional Siskin Surge

The Siskin movement this autumn has been exceptional, for both the early start and vast numbers involved, as indicated by BirdTrack. With the peak movement and arrival of continental birds still to come, numbers in the UK are expected to increase considerably.

BirdTrack Siskin reporting rate

Jeff Kew from Thetford, Norfolk writes:

This has been an exceptional September for Siskins in the UK, with large numbers being reported across southern Britain, due to a major irruption from Northern Britain.

Last autumn Siskins were fairly scare in Southern England with a few being reported on feeders in February and March, the usual peak time to see and ring this species. Reports from Scotland indicate a bumper cone crop last summer and consequently most Siskins stayed at home for the winter, this Autumn with dwindling food supplies the picture is very different.

In the Norfolk / Suffolk Brecks area we have not seen anything like the numbers coming to feeding stations in September since 2005.

In our Thetford garden we have already ringed 611 Siskins this month (in just 4 ringing sessions), with an amazing 368 caught on the 18 September.

One of the hundreds of Siskins recorded taken by Jeff Kew

We have had birds ranging from exceptionally light (10.4g) to exceptionally heavy (17.0g) - which presumably indicates a mix of recently arrived birds and birds with serious intent to travel much further south. The majority are juveniles, which appear to have done less post juvenile moult than our local breeders.

Post juvenile moult strategies are interesting with the amount of post juvenile moult being variable and probably linked to both fledging date and food supply. We believe unmoulted juveniles (3JJ) can reach us from Scotland.

Thinking back to what we saw in 2005 we had high numbers through September, followed by two recoveries in Spain in Navarra and on Mallorca - which could give an indication of where some birds of this years birds may end up this winter.

Greg Conway from Thetford Forest Ringing Group writes:

The extent of post juvenile moult is highly variable, with some typically retaining one, or more, old greater coverts along with juvenile tertials and tail feathers, whereas others replace all coverts, tertials and tail (see below).  However, there are also many in between that replace different numbers of tertials and tail, often symmetrically but not always centrally!

Juvenile Siskin with replaced greater coverts, tail and tertials - Greg Conway

Juvenile Siskin with replaced greater coverts and two inner tertials - Greg Conway
Juvenile Siskin that has replaced outer pair and 2 central pairs of tail feathers contrasting with juvenile feathers (pointed and browner) - Greg Conway

To better understand the mix of different migration and post juvenile moult strategies occurring this autumn, and add to long-term data collected from Thetford Forest, ​any ringers catching Siskins are encouraged to record the following biometrics (in addition to age/sex, wing & weight):

All birds if possible!
1) Number of unmoulted greater coverts (including those with zero)
2) Fat score (0-8 scale)​

And if time allows!
3) Tertial moult (record in IPMR moult card)
4) Tail moult (record in IPMR moult card)
5) Pectoral muscle score (0-3 scale)

08 September 2015

Nettlecreeper doing more than creeping

Mike Marsh writes:

On 4 July we controlled a German-ringed Whitethroat at Orfordness, Suffolk. The ringing information showed that this bird had been ringed earlier in the spring on the island of Helgoland, Germany and when I checked against the Online Ringing Reports I was surprised to find that this was only the second ringing movement of a Whitethroat between Germany and the UK, the other being in 1952.

Although it is hard to work out why a Whitethroat should be moving from Germany to the UK at this time of year it is interesting to note how similar the movement of the bird was to the one 63 years earlier. Both birds had been ringed off the NW German coast in late April/early May and then controlled in East Anglia in late June/early July, and the movements were 483km/WSW/54 days compared with 468km/W/59 days.

German ringed Whitethroat by Dave Crawshaw and several photos of the ring that have been merged to see full ring number

Ring number - 90212927
11-05-2015   ringed: Helgoland, Helgoland, GERMANY  54 10’N  07 55’E
04-07-2015   controlled: Orfordness, Suffolk  52 05’N  01 34’E
                         483 km WSW  -  54 days

Ring number - 9435010
29-04-1952   ringed: Wangerooge-Ost, East Friesland Islands, GERMANY  53 47’N  07 58’E
27-06-1952   controlled: Cley-next-the-Sea, Norfolk  52 57’N  01 03’E
                         468km W  -  59 days

Eds - Nettlecreeper is a local name of the Whitethroat. 'Controlled' is when a ringer catches a previously ringed bird, usually that he/she hasn't put on originally.

27 August 2015

How to get up close to a ringer

Gary Clewley writes:

Another year and another Birdfair at Rutland Water has come and gone. The bird ringing demonstration proved to be very popular again with people (and especially families) regularly able to get up close and see the process of ringing first hand. In total, around 175 birds from over 20 species were ringed or recaptured over the course of the weekend. This gave us the opportunity to show people how ringers are able to identify and age birds in the hand as well as explaining why ringing and nest recording are essential for monitoring how and why populations are changing.
Great way to get close and learn about our 'British' birds - Stephen McAvoy

Some species do tend to steal the show however, and the Lesser Whitethroats were particularly popular and also quite relevant to this year’s theme at Birdfair; protecting species in the Eastern Mediterranean. With their easterly migration route, there could be a good chance the Lesser Whitethroats which were ringed could be passing through the Eastern Mediterranean soon.

Lesser Whitethroat taken by Morris Rendall

There was a promising start to the event, when at 8:55 am on the Friday morning, the very first bird in the nets was actually a Sparrowhawk! Unfortunately in this case the bird proved too quick for the ringers and managed to free itself within seconds. So it was an especially pleasant surprise when another adult male Sparrowhawk found its way into the nets on the Sunday morning and even better it already had a ring on. This bird was originally ringed at Rutland Water in 2012 and we now know it is still going strong. A very lucky crowd were able to watch the ringers process the bird.

Adult male Sparrowhawk - Dawn Balmer
Sparrowhawk getting efficiently processed while a lucky crowd watch on - Dawn Balmer
Perhaps the most unexpected bird of the weekend was a House Sparrow (and perhaps a sign of the times since this species has seen a substantial decline in recent years) which is the first ever caught during the Birdfair ringing demonstrations.

Unfortunately, we also had our fair share of unfavourable weather over the weekend so there were times when we were unable to safely catch birds. But nonetheless there were ringers on hand to answer questions and even ‘ring’ some people with the wristbands we had available (if you were ringed you can find out your story here).

The ringing demonstration stand. You can tell where the bird is by the crowd - Stephen McAvoy

It is always a privilege to be able to ring birds and even more so at an event like this. It requires a lot of planning and I would just like to thank all those ringers who volunteered their time to help with the demonstration again for all their hard work, in particular the Rutland Water Ringing Group, as well as everyone who came along to see us.

Eds - There are ringing demonstrations run at various sites across the UK by individual ringers or groups however the BTO, in collaboration with the RSPB, are running their next event on Sunday 30 August at the BTO headquarters from 10 am until 3 pm (catching weather dependent).

07 August 2015

Owl and raptor mid-season update

That annual Barn Owl breeding success is influenced by peaks and troughs in abundance of field voles, the species' main prey item in many areas, is hardly news to Barn Owl recorders. But after seeing some of the lowest levels of nesting activity in memory in 2013, followed by record productivity in 2014, many might be wondering just when they'll next get an 'average' season. Not in 2015 it seems: anecdotal reports so far suggest Barn Owl productivity has been much lower than expected, though other species seem to have followed on better from last year's bumper season.

Poorer than predicted Barn Owl breeding

Back in February, Barn Owl expert Colin Shawyer predicted that, provided spring conditions remained mild, the exceptional number of 2014 fledglings would mean good recruitment of young breeding birds, but also that though egg-laying could be expected at the usual time in late-April/early-May, a decline in vole numbers from their 2014 peak would result in smaller brood sizes and fewer fledglings this year.

Subsequent early visits to Barn Owl nest boxes revealed much less activity than expected. In late May, Colin visited 25 boxes that had contained 16 active nests in March 2014, only to find just eight with signs of adults present and three clutches of eggs. Non-breeding females were found to be underweight, suggesting that, whether caused by recent wet weather affecting foraging or simply the scarcity of voles, birds were late getting into breeding condition.

By mid-June, reports on the NRS Forum were sounding similar. Alan Ball, Bob Sheppard and Keith Bowden, in Lincolnshire, had checked most of their boxes and found four Barn Owl pairs on eggs or chicks. On the same date in 2014, they had been monitoring 200 nests. Frank Mawby, in Cumbria, Peter Wilkinson, in Cambs, and David Garner, in Cambs, were also reporting low breeding occupancy, and an apparent shortage of prey. Bob Danson, a recorder in Lancashire, commented that food larders had disappeared after the very beginning of the season, in contrast to 2014 when piles of six and seven voles were common.

A single Barn Owl chick at 20-25 days. In 2015 there have been many reports of broods sizes dropping to just one or two chicks. Photo by BTO.

In mid to late July, when Barn Owl chicks are often ready for ringing, there were reports of brood sizes of three and four having reduced to just one—Mike McDowall in East Lothian, David Garner in Cambs and Frank Mawby in Cumbria all ringed single chicks. By the time Bob Danson had ringed his latest brood on 3 August, just eight of the 23 nests he had found so far in his 80 boxes had produced chicks, and his ringing total had reached only 18.

Better Barn Owl news has come in from elsewhere: Nigel Lewis at Salisbury Plain observed a good proportion of boxes with clutches of eggs in May and Judith Smith, in Manchester, has ringed several healthy broods of four and five chicks, including some in new boxes. Geoff Myers, in Lancashire, reported that good numbers of both early and later laying Barn Owl pairs had successfully reared broods and that by 24 June he had ringed a brood of six and several broods of five—very advanced compared to elsewhere.

Tawny Owl, Little Owl and Kestrel fortunes

There have been mixed reports for other box-nesting owl and raptor species that tend to be well-monitored by ringers and nest recorders. Alan Ball, Keith Bowden and Bob Sheppard reported that they had ringed just six Tawny Owl chicks in their boxes in Lincolnshire, compared to 130 in the same boxes in 2014. On the other hand, Bob Danson, in Lancashire, encountered 17 nests in 30 boxes—his second best annual total after last year—from which 26 chicks fledged, including four broods of three. Bob noticed that rats made up a higher proportion of prey in his Tawny Owl boxes, along with baby rabbits.

Several recorders have spoken of Little Owls doing well this year, a species that is obviously less dependent on rodent prey. Alan Ball, Keith Bowden and Bob Sheppard monitored 65 nests and ringed 100 chicks, compared to 80 nests and 188 chicks in 2014. Bob Danson's 70 Little Owl boxes saw occupancy increase to 16 pairs in 2014, from 12 in 2014 and 7 in 2013. He recorded 36 fledged young altogether, including a brood of five and two broods of four.

Two recently fledged Kestrels photographed by Wilf Hockney, who accompanied Steve Baines on several of his Kestrel box rounds this year. 

Kestrel reports have also been positive. Steve Baines monitors 20 boxes in Chelmsford, Essex, and 13 had pairs this year, one of his highest occupancy rates, though he noted that clutch sizes were down relative to 2014: clutches of five and four but no sixes, and that the number of chicks fledged overall (36) was slightly lower than 2014. Bob Danson reported a similarly successful season for Kestrels in Lancashire and noted more bird prey in boxes than usual, including a Swallow. In contrast, Alan Ball, Keith Bowden and Bob Sheppard had monitored only 6 nests by mid-June, compared to 150 at the same time in 2014.

Late season comeback?

Although the breeding season has now finished for Tawny Owl and Little Owl—bar perhaps a few exceptionally late nests—there will still be a proportion of Kestrels tending to chicks, and of course there is the question of whether we will see any Barn Owl second broods or late-season nesting attempts in previously empty boxes. As Dave Leech has pointed out in a recent interview for Radio 4, this might happen if non-breeding females have managed to get into breeding condition, although Colin Shawyer has observed that vole numbers appear to remain very low. Either way, good data on the extent of late and repeat broods is essential for assessing Barn Owl productivity, which is why those late-season box checks are so important...

The BTO Nest Record Scheme is one of the ways in which raptor populations are monitored in Britain & Ireland. These results are complemented by periodic single-species surveys and, in Scotland, by the Scottish Raptor Monitoring Scheme.

Many thanks indeed to: Steve Baines, Alan Ball, Keith Bowden, Bob Danson, Wilf Hockney, Nigel Lewis, Frank Mawby, Mike McDowell, Geoff Myers, Colin Shawyer, Bob Sheppard, Judith Smith, Peter Wilkinson