24 November 2016

Migratory Moorhen?

BTO volunteer, Lawrence Potter writes:

"Whilst doing our monthly BTO WeBS count at Woodbridge, Suffolk, I noticed a moorhen feeding on the river alongside a pontoon as it looked to have a coloured ring. I asked my colleague (Robert Johnson) to have a look with his telescope and after about 10 mins of observation we got details on the ring; AE32. We were both intrigued with who was colour ringing Moorhen, wondering where it had been ringed, so we submitted it and the results were amazing!

The ringer, Carsten Lome writes:

We started colour ringing Moorhen and Coot in Norway in spring 2013. So far 104 moorhens have been ringed, 54 of them ringed this year. Nearly all have been caught in three cities; Oslo, Bergen and Stavanger. All of the birds in Oslo migrate, so are ringed during the summer only. The majority of the Moorhen in the other two locations are mostly caught during the winter. There have been a few movements between Bergen and Oslo, although how they tackle the mountains in between is unknown. We've also had one bird ringed in Bergen and found in Stockholm.

AE32 was ringed as a breeding bird in Oslo in July this year. Interestingly its partner was ringed last winter in the city centre of Bergen (300 km from Oslo)! Unfortuately they have exactly the same wing length, so sexing them is currently not possible. This pair had three young in their first brood and only two in the second brood, which had not fledged by the last time we visited this pond on 11 October but hopefully did so soon after.

For a species that is thought to be fairly resident, we have had three BTO ringed Moorhen found in Norway but this was the first Norway ringed Moorhen to be reported in Britain or Ireland. This is a distance of 1042 km in 120 days.

Colour of location: Purple - Originally ringed in Britain & Ireland; Orange - Found in Britain & Ireland

For more information on the WeBS counts for Moorhen click here.

There are colour ringing projects all over the country that need your sightings. In Suffolk alone there are Redshank, Black-tailed Godwit, House Sparrow, Herring and Lesser Black-backed Gull, Kittiwake, Peregrine and Mute Swan to name a few. A list of projects can be viewed at European Colour-ring Birding.

16 November 2016

Ringing and nest recording; the dream 'info team'

Monitoring nests for the BTO Nest Record Scheme gives us a really good estimate of the number of fledglings produced from the average nest each year, but this is obviously only the first part of the story - for breeding success to have an impact on the future population size, these young birds have to make it through autumn and winter to the following spring. By fitting rings to chicks in the nest and recapturing them as free-flying individuals, volunteers are able to follow their progress over this period. Calculating post-fledging survival rates from these data is actually very challenging as many young will move from the site in which they were raised and settle to breed in areas where there is a lower chance of them being re-encountered. However, those that are observed subsequently provide vital information on dispersal and settlement, key processes by which birds are able to change their ranges over time in response to changing climate and habitat quality.   

Brood of Blue Tit chicks. Photo by Mainwaring

Another big advantage of ringing nestlings is that the exact age of re-encountered individuals is known. Most songbirds have replaced all their juvenile feathers by the end of their first breeding season and, from this point onwards, it is impossible to determine how old they are. As age can have significant impacts on behaviour and breeding success, precise information is very valuable. Another certainty established by ringing chicks is the breeding population from which they originated, allowing researchers to determine which areas are net producers of young birds, and which may be population sinks.

Dave Leech studying Reed Warbler nests. Photo taken by Lee Barber

The totals presented in the Ringing Report show that in 2015 alone, over 167,000 nestlings (termed 'pulli') were ringed across Britain and Ireland. In almost all cases, the chicks ringed in each brood would have belonged to the same species, but there are exceptions, as Ian Wrisdale explains:

On a relatively large site of former gravel pits, I run nest box monitoring scheme, a Constant Effort Site (CES) and conduct autumn/winter ringing between October and December. To avoid the possibility of winter flooding, the ringing activities move from the reedbed of the CES, to an area of scrub/young woodland on the opposite side of the site for the winter. Due to the site being a Site of Special Scientific Interest (SSSI), all of the ringing activities are in accordance with agreements with Natural England. The agreed purpose of the winter ringing is to catch winter thrushes; however, it usually entails catching many tits. Whilst the outcome of the nest boxes is usually recorded as, “Nest Empty”, the winter ringing serves to confirm this outcome, monitor the movement of the birds around the site and allows some comparison of breeding productivity with post-fledgling survival.

The reedbed and wet willow scrub of the CES. Photo by Ian Wrisdale

During the last two seasons I have had two mixed broods of tits sharing the same nest box. In both cases, the brood comprised several Great Tits and a single Blue Tit. It is usual to assume that a single Blue Tit would struggle to survive with such competition but, in both of these cases, there was no sign of a dead Blue Tit in the nest box and the outcome was recorded as, “Nest Empty”, assuming at least a partial success. The Blue Tit in question this year was ringed on the 28 May, at the same time as the seven Great Tits with which it shared the nest. But its survival was not confirmed until it was recaptured during the first of the winter ringing sessions, on the  02 October 2016. Whilst I was pleased and surprised to be able to confirm its survival, it was a small, possibly female, individual (wing 60mm, mass 9.8g), making its successful competition against the Great Tits seem all the more remarkable.

Winter ringing in woodland scrub. Photo by Ian Wrisdale

It is unlikely that I will be able to catch it during the breeding season, unless I can agree, with Natural England, to conduct some summer ringing sessions at the winter site or catch it on the nest, but it would be interesting to see if it goes on to breed successfully, or will it think it's a Great Tit.

Eds - If you are a ringer and regularly ring resident species at a site during the winter, it would be worth considering if you are able to find and record the nests of these species. Even getting in touch with your local nest recorder could be beneficial. As this post demonstrates, the quality of the data can be dramatically increased.

04 November 2016

Fire with red and yellow

It has been an exciting time in the Demography team over the past month, with data and news arriving in earnest. In terms of bird migration, the winds were coming from the east, bringing rare birds with them to our shores, as described in the BTO Bird Migration Blog.

Yellow-browed Warbler featured very highly last month, with another bumper year, see BirdTrack reporting rate graph below. At the beginning of October, Fair Isle Bird Observatory counted 72 and Cape Clear Bird Observatory managed to ring its 60th Yellow-brow of the autumn. West Cornwall Ringing Group have also been doing very well for this species with 56 ringed so far this autumn.

The Online Ringing and Nest Recording Report shows recoveries for Yellow-browed Warbler are few and far between, with exchanges only occurring between Britain and Ireland and the Channel Islands, Norway and the Netherlands. This year however, we have heard that one was caught at Brownstown Head, Ireland wearing a Russian ring! Hopefully we will get all the data soon.

Yellow-browed Warbler, taken by Lee Barber

Another autumn visitor is the Firecrest and we have just received the ringing details of a Firecrest recaptured a few years ago by the Teifi Ringing Group wearing a Belgium ring. This bird had travelled 566 km in two months and 10 days.

Whilst migration of small passerines is starting to reduce, thoughts now move to the influx of winter birds such as thrushes and Waxwings. Redwing in particular have been arriving in large numbers, and some ringers are getting close to 1,000 birds ringed this autumn. We will have to wait and see if our 2016 ringing total for Redwing beats the 11,743 ringed in 2015, but it is looking good so far.