Stuart Sharp - Sheffield University

The February speaker was Stuart Sharp, a NERC-funded post-doctoral research associate in the Animal and Plant Sciences Department of Sheffield University, where he has conducted ornithological studies for about six years. His work at the department, together with his activities as a member of Sorby Breck Ringing Group, has included several large-scale ringing studies. On this occasion he told us about two such projects, namely studies of Waxwings and of Long-tailed Tits.

Ringing Waxwings requires operating in very public places, such as car parks etc., and therefore involves more interaction with the public than is usually the case when bird ringing. Stuart found that only a tiny minority of people who spoke to him had ever heard of ringing, or had any idea about what was involved. This was a bit worrying, not least because ringers rely on members of the public reporting any ringed birds that they find. (Stuart did however find that minders and owners of car-parks, supermarkets and other urban ringing sites were very happy to help, and he was never refused permission to operate in them.)

In general, most people who are aware of ringing activities think that the main purpose of it is to study migration, and it is sometimes suggested that we already know all about that ? so why keep ringing? Although ringing was indeed originally developed for studying migration, the main aim these days is to monitor avian population dynamics and identify the causes and consequences of population trends. Furthermore, migration patterns for many species remain poorly understood, and even in relatively well known species these patterns are changing all the time: it is unlikely that we will ever be able to say that we ?know all about? migration.

Ringing studies provide invaluable information about birds on an individual basis, allowing us to study such factors as local movement, longevity, changes in rates of birth and death, dispersal and behaviour. One big snag, however, is that recovery rates are often very low, and any generalisations can only be made with caution. So, how can recovery rates be increased? Answer: by using colour rings. This brings a massive increase in returns because the coloured rings are relatively easy to see with binoculars; the need to recapture individuals is thus removed, and re-sighting data can be collected by members of the public rather than by trained ringers alone. Waxwings are particularly good subjects for colour-ringing studies since they are very charismatic, and often become local celebrities: birdy and not-usually-birdy people will frequently make an effort to go and see them locally, and subsequently report or photograph them.

It is well known that Waxwings breed in northern Europe, and that they come to the UK in varying numbers each winter in response to poor conditions further north ? sometimes just a handful of birds, in other years huge irruptions involving hundreds or even thousands of individuals. However, little is known about the precise breeding origins of these birds, or what factors determine the scale of irruptions; even less is known about what they do after they have arrived. Studying Waxwings therefore provides useful insights into bird movements on both an international and local scale, as well as offering a model for how birds respond to climate change.

It is commonly believed that the birds initially arrive in the north-east, and move gradually south during the winter before migrating directly back to their breeding grounds. It is also known that there are popular hot-spots which are regularly used each winter, Sheffield being one of them. However, we do not know whether the same individuals come back to these hot spots each year, or whether a flock seen daily in one place comprises the same individuals each day. It was Stuart?s colleague Raymond Duncan in Aberdeen who first started ringing Waxwings in any numbers, but in spite of much effort, he got very few recoveries, hence his decision to embark upon a colour-ringing project.

Meanwhile, Stuart had been ringing small numbers of Waxwings in Sheffield: in the winter of 2002/3, he ringed 7 birds and had one return ? a bird recaptured in Norway, 9 months and more than 1000 Km later; in 2003/4, a further 7 birds again gave one return - this time a bird caught in Doncaster, 1 month and 27 Km later. These two returns were interesting in that the first showed an individual in a very different location the following winter, whilst the second showed a local movement during the same winter. However, this was just a tantalising glimpse of what was to come.

In the winter of 2004/5, there was a huge and unprecedented invasion of Waxwings to the UK, starting in October with a flock of over 1500 concentrated in a few trees in the town of Forres in the Highlands. This gave Scottish ringers the opportunity to catch and ring good numbers, but when these birds subsequently moved to Aberdeen, Raymond Duncan and his team started colour-ringing on an even bigger scale. As winter progressed, large flocks began to appear in Sheffield and Stuart also started trapping and ringing more birds than in previous winters (he operated principally in Walkley and Heeley Green at this early stage). When he found that several of these Sheffield birds had been colour-ringed in Aberdeen, he started searching through flocks with his binoculars and found several more colour-ringed individuals ? and realised that here was a unique opportunity to find out a lot more about this species.

During the course of that winter Stuart caught 261 Waxwings and colour-ringed 70 of them, half of which were subsequently re-sighted at least once; 9 birds had already been ringed elsewhere in the UK (mostly Aberdeenshire) earlier in the winter, and he also re-sighted 14 birds that had been colour-ringed by Raymond. One nice thing about Waxwings is that it is relatively easy to distinguish adults from first-year birds, and males from females, by plumage details. This meant that when Stuart received reports or photographs of colour-ringed individuals but exact colour combinations were unclear, his records of age and sex frequently enabled him to identify the individuals involved. So Stuart and Raymond now have a huge amount of data that has not yet been fully analysed; however even a casual inspection gives much interesting information.

It is clear that there was indeed a general southerly movement as winter progressed, but after initial movement in the first half of the season, individual birds were then more likely to stay in the same general area for the remainder of the winter. Thus all birds ringed in Sheffield after 1st February (and subsequently re-sighted) stayed in Sheffield until the spring, whereas birds ringed earlier in the winter were subsequently found elsewhere in the UK. Of the travelling birds, at least two were reported from Nottinghamshire, about 50 Km away, initially in March but then apparently remaining there until May; one was found in Worcestershire, about 140 Km away in March; and one was found in Kent, about 275 Km away in February. Furthermore, some birds moving in early winter soon returned to their original location: one bird colour-ringed in Aberdeen was sighted in Stirling and subsequently returned to Aberdeen in the space of a month; of three birds colour-ringed in Walkley, and re-sighted a few days later in Stockport, one returned to Sheffield (seen on the Parkway) within the same week.