08 June 2018

A big jump in Hawfinch Longevity

With the influx of Hawfinch into southern Britain this winter, Jerry Lewis started one of his feeding sites much earlier than usual (in mid January) hoping to try and catch some of the visitors. Despite a decent sized flock of 40+ birds visiting the feeding site, they were mainly coming down to Hornbeam seed, rather than sunflower seeds. After two months, catching had been very slow (just 16 birds caught, at a rate of one every three hours), but after mid March it started to pick up. The largest catches began from mid-April onwards (as happens most years), averaging a 'finger numbing' two birds per hour. 

Despite problems at two of the feeding sites - sunflower seeds being taken by squirrels/wild boar (leaving few for the birds) and a road closure preventing access to a third site, it was Jerry's most successful year to date. By the time his 'catching season' was over he had caught 202 birds, which included 43 that had been ringed in previous years (plus a small number of same-season recaptures). It is unlikely that many (any) would have been continental birds, as migrants had generally left by early April in previous years.

Photo by Vaughan Thomas  Hawfinch NW31779, ringed 1 May 2008 and re-caught 5 May 2018 (10 years, 4 days later)

Five of his recaptures had originally been ringed in 2010, making them comparable with his current British & Irish longevity record of 8 years 1 month 22 days. One female, caught on 5 May 2018, topped these however, having been ringed on 1 May 2008, 10 years and 4 days earlier; a big increase in longevity. This bird was ringed in the northeast of the Forest of Dean - nr Cinderford, was caught twice in April 2010 - near Tintern in the Wye Valley (20 km SSW), before now moving to near Chepstow (7 km further SSW).

What seems to be surprising is how rarely the 2010-ringed birds had been re-caught (three had been caught once since ringing, the other two hadn't been re-caught at all). Jerry's next challenge is to try and understand why these long-lived birds are not re-caught more often.

17 May 2018

How long do Red-throated Divers live for?

Dave Okill of Shetland Ringing Group writes:

On  26 April 2018, Mick Mellor was doing a routine Beached Bird Survey for SOTEAG (Shetland Oil Terminal Environmental Advisory Group), when on Urafith beach, North Mainland, Shetland he found a freshly dead Red-throated Diver (RTD) that had a ring on it. He carefully noted the number and emailed me when he got home. 

Not remembering the number, I started to look back through old, almost fading, files and I found that I had ringed it as a large chick on a small remote lochan not far from Nibon, North Mainland, on 27 July 1985. At well over 32 years old, this individual was an old bird. Looking at the BTO longevity records, the oldest-known RTD was a bird ringed in Hoy, Orkney in July 1986 and last caught at the same location in April 2015, 28 years, 9 months and 7 days later; our bird clearly beats that by some margin! Searching through North American and other longevity lists, it seems that our bird is probably the oldest RTD yet recorded anywhere.

Ringed Dead Red-throated Diver, Urafirth Beach, Shetland. Photo by Mick Mellor.

As well as demonstrating essential information on migrations, movements and dispersal, ringing also gives us the ages of different species; both the average age and the maximum age of the oldest individuals. Longevity records usually creep up slowly, so an increase in the maximum age of RTDs by four years is a notable leap. I suspect that divers are long-lived birds and this record will be well beaten in time.

The ringing site and the finding place are only a few kilometers apart and it is likely that this bird was a male returning in spring to nest in its natal area. Male divers return to breed close to the area where they fledged; females disperse widely before they breed and Mainland-ringed females have been found many kilometers from their fledging loch, up to the North Isles and as far as Orkney. Orkney females have also been found breeding in Shetland.

Red-throated Diver. Photo by Manuel Schultz/BTO.

Over the years our bird will have traveled widely but we only know two points in this bird's life. To help us understand divers better, JNCC are promoting a project to discover what divers are doing, especially on their wintering grounds, now especially important with the proliferation of vast off-shore wind farms which displace wintering and moulting birds from their traditional areas. Birds from Orkney, Shetland, Finland and Iceland will be investigated.  

Editor's note: all recoveries of ringed birds help to further our knowledge, so if you find a bird ring, please report the details at www.ring.ac

12 April 2018

Birds of a feather, fly together

It's pleasing to have a flock of Siskins arrive in your garden, and thanks to ringing, we might know where they come from or go to, but can ringing tell us anything about the link between these individuals in the flock? A note in Bird Study by Juan Senar and Jeff and Allison Kew in 2015 revealed that the individuals in Siskin flocks have stable social bonds and move in stable social units.

Two more recent examples of Siskins apparently travelling together between Britain and both Finland and Sweden provide even more evidence to reinforce the existence of social bonding between migrating Siskins.

Hugh Insley writes:

The moment you take a ringed bird out of a net and realise that the number on the ring is not one of your own, is always pleasing. When the ring has a foreign inscription the pleasure rises to excitement.

Swedish ring being examined. Photo by Sandy Davidson

Following several spells of easterly winds this March, I wasn’t entirely surprised to find that one of the Siskins visiting my garden feeders (green pin on map below) was carrying a Swedish ring and had been ringed as a 5,M (last years fledgling, male) on 25 April 2017 at Overboda, Västerbotten (63 deg 51 min N 19 deg 55 min E) 1,490 km ENE of Inverness (red pin on map below).

Swedish Siskin recoveries are not as frequent as might be expected from such a close neighbour. Up to 2016 there had been 38 Swedish-ringed Siskins reported here, with 110 BTO-ringed individuals recovered there. This compares with 105 from, and 172 to, Norway. So, even though another bout of easterlies had followed, I was quite surprised to catch another Swedish ringed Siskin, on 4 April and even more so to get a third the following day. What was really interesting was that the third bird’s ring, was only seven numbers different from the bird caught the previous day so that it was nearly certain that these two birds had been ringed at the same location and were travelling together. Both birds had been ringed on 23 July 2017 at Handol, Jamtland (63 deg 16 min N 12 deg 26 min E) 1,119 km ENE of Inverness (blue pin on map below).



An email exchange with Malcolm Calvert of the South Manchester Ringing Group, with whom I swap quite a number of Siskins, revealed that he had had a similar experience over the weekend of 22/23 February 2016 when one of six Siskins caught in his North Cheshire garden was an adult and was carrying a Finnish ring; the bird had been ringed at Pori, Satakunta, Turku and Pori (purple pin on map below) on 15 May 2015. The following day Malcolm caught another six, and was delighted to learn that one of these had been recaptured two months later on 29 April 2016 at Niinivisi, Kupio  Finland (yellow pin on map below), albeit some distance from the ringing location of the Finnish ringed bird caught in his garden (brown pin on map below). Finnish recoveries are even scarcer than those from Sweden with only four Finnish-ringed birds reported here and 28 BTO-ringed ones reported in Finland up to 2016.



Two male Siskins squabbling over seed. Photo by Desmond Dugan

Any foreign recovery is interesting, but to find two different examples of pairs and probably groups, of Siskins apparently moving together is remarkable. It seems likely that Malcolm’s two Finnish recoveries involving his Cheshire garden would have involved birds that had been wintering in Britain. The Swedish birds in my Inverness garden could also have been birds that had wintered in Britain, returning north with all the other Siskins which seem to move up into the Highlands in March and April. Many of these travel via the Manchester area, as evidenced by all the exchanges with the South Manchester Ringing Group, or perhaps they might have been the result of drift migration following all those easterly winds?

Siskins at a feeder. Photo by Desmond Dugan

Siskin was the sixth most-ringed bird in 2017 with in excess of 35,000 individuals ringed. Even so, or perhaps because of this effort, every year is bringing new knowledge to our understanding of these charismatic little garden visitors.

01 March 2018

Retail ringing

After undertaking years of training, bird ringers are in a privileged position to be able to catch birds. The information gathered through ringing is used to help answer some of the big questions in ornithology, such as why populations are changing and what routes birds take on their migrations.

Ringing often brings ringers into contact with people who know nothing about bird ringing, and commonly have little contact with birds, other than those in their garden. This is a great opportunity to educate and enthuse the public about the lives of birds, ringing and the BTO. Most of the time, bird ringing is encountered through television programmes like Springwatch, a ringing demonstration at a local nature reserve or even the ringing demonstration at the Birdfair, but occasionally it can be seen in the most unexpected places.

Rutland Birdfair ringing demonstreration. Photo by Sam Franks.

With the permission of the landowners, ringing sessions are held up and down Britain and Ireland; in supermarket car parks (for Pied Wagtails), city streets (Waxwing), waterways (swans and geese) or on the sea front (gulls and waders). Colour rings or flags are frequently used to identify birds that are ringed without the need for ringers to catch them again. This has the added bonus that anyone (not just ringers) can report colour-marked birds (see here for instructions on how to report a sighting of a colour-marked bird), as long as the species is known and the combination is read correctly.

Waxwings enjoying the berry bushes. Photo by Jeff Baker

Occasionally, perfectly healthy birds do get into trouble and end up in places they don't want to be. If they are lucky, the bird identifies the exit and promptly flies out, but sometimes this doesn't happen due to the nature of the building (a large warehouse or a shop with automatic doors for instance). This can lead to store alarms having to be left unset, which has implications for their insurance and can be stressful for the owner. This is where a ringer's ability to catch birds safely can be invaluable.

Ringers across the country regularly step in to help catch the Blackbird in the warehouse, the Blue Tit in the shopping centre or the Robin at the wedding venue (as we have posted previously). Here at BTO HQ, we do not get that many phone calls about birds trapped in Thetford, Norfolk (where we are based), but today was the exception. The caller informed us that: "There is a Robin trapped in Poundland and it can't get out!!!! We've tried everything, including herding it towards the door, but it keeps flying back into the store!".

Robin doing a bit of light shopping in the afternoon. Photo by Lee Barber

Conveniently coming up to lunch time, Lee Barber had the opportunity to nip out and try and release the bird back into the wild. He recounts: it is a strange feeling putting a mist net up in Poundland, with customers wandering around and a Robin flying over their heads, moving mostly unseen. After a quick assessment of the Robin's behaviour and its preferred area in the store, and whilst managing the customers, I quickly put a short mist net up. Within 15 minutes I'd caught the adult Robin, which was promptly ringed and released outside (after a quick health check).

Robin safely in the hand ready for release. Photo by Lee Barber
As this is something that the BTO doesn't do routinely, we must say a huge thank you to all the ringers that we've contacted who have dropped everything to help a bird in need. Some of the locations have been very challenging due to the height of the building, access, and other obstacles in the way, but there is usually a happy ending; sometimes the bird has even left the building of its own accord before the ringer gets there.

15 February 2018

The Joy of Nesting Birds

Hazel Evans writes:

This week (14th – 21st February) is the BTO’s 21st National Nest Box Week.  Each year we encourage anyone who is interested, to put up nest boxes locally. I’d like to delve in to some of the different aspects for why this is such a wonderful thing to do, and how we can make the most of them.

The first and most obvious reason is to give birds a place to raise their young. In areas of human habitation it can be harder for birds to find places to nest, so putting up a nest box is a good way to ensure there is somewhere for the birds to use. There are many external factors which may affect the outcome of a nesting attempt, but we can offer them a good place to start. You may also choose to put out some appropriate nesting material in the nearby trees and bushes, or grow some plants to encourage insects. Non-native plants in gardens have been found to be a potential detriment to our local birds, they do not provide as much food, because non-native plants may not be able to host as many caterpillars as native plants, so this may be something to consider.
 
Robin feeding it's young. Photo by John Harding

The second reason why putting up a nest box can be important is monitoring. One of the BTO’s strongest assets is the data it has collected through organising monitoring schemes, and the Nest Record Scheme (NRS) is no exception. Now running for over 75 years, close to two million records of nesting birds throughout the UK have been sent in for over 200 species. This includes data from open nesting birds and nest boxes, both of which are highly valuable. As long as the NRS Code of Conduct is adhered to, we can safely record the progress of nesting attempts by counting the number of eggs and chicks and recording the outcome of the attempt and submitting data to the NRS.

Blue Tit fledgling. Photo by Christine M Matthews

The third reason I value nest boxes very highly, is the intrigue and excitement they can provide. Anyone can put up a nest box and monitor what’s inside it and in turn benefit from watching the behaviour of the birds. Interactions with the natural world have been shown to help relieve depression, anxiety and stress. We are living in a time where it is easy to lose touch with the natural world and many children aren’t getting experiences with nature; having a nest box in your garden is an inspiring way to learn about the natural world. Monitoring nests is not something that should be taken lightly but with the knowledge that the data is going to a good cause, it's something we can experience great joy from.

Now is the time when garden birds are just starting to prospect nesting sites in preparation for the approaching spring, so the sooner you can get a box up the better, whether you build it yourself or buy it from the garden centre. There are many bird species which use nest boxes, so if you have a bit more space then you may want to put up a larger nest box, for a Kestrel or owls.

Once used, it is a great idea to clean out old nests the following winter to allow for a fresh start in the spring. To comply with legislation, nests should only be cleaned out between 1 August and 31 January.