Ringing & Migration Journal of the BTO Ringing Scheme

Ringing & Migration Volume 23 Part 1
Abstracts

Measurement of mass change in breeding birds: a bibliography and discussion of measurement techniques

SEAN A. RANDS1,2,3, ALASDAIR I. HOUSTON1 and INNES C. CUTHILL1
1 Centre for Behavioural Biology, School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK 2 Centre for Ecology and Conservation, University of Exeter in Cornwall, Tremough Campus, Penryn, Cornwall TR10 9EZ, UK 3 Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK

Studies detailing how energy reserves change over the course of the breeding season can give us valuable insights into environmental and physiological factors affecting the life-history strategies of birds. Here, we bring together a reference collection of studies that have measured reproductive mass changes in 132 species. We discuss how data collection, recording and reporting can be refined to offer a detailed insight into the evolution of avian reproductive strategies.

Movements of British Hen Harriers Circus cyaneus outside the breeding season

BRIAN ETHERIDGE and RON W. SUMMERS
Royal Society for the Protection of Birds, North Scotland Regional Office, Etive House, Beechwood Park, Inverness, IV2 3BW, UK

Hen Harrier chicks were wing-tagged in four regions in Scotland and in North Wales between 1990 and 1995, and resighted or recovered dead as fully grown birds during the non-breeding season (August to April) throughout Britain and Ireland, and on the Continent, until April 1997. Results were analysed in terms of the percentages of birds that carried out long-distance movements (over 25 km) and the extent of the long-distance movements. The percentages of first-year birds undertaking long-distance movements were related to natal area, sex and season. A higher percentage of first-year males in the East Highlands undertook long-distance movements than females. For first-year birds that made long-distance movements, there were significant effects of season and natal area, and interactions. Thus, longer movements occurred in winter and spring, and males from the North Highlands made the longest movements. Records on the Continent referred mainly to first-year males. For all age classes, the percentage of birds undertaking long-distance movements was related only to sex; males making a higher percentage than females. For those that made long-distance movements, there were effects of season, age and sex, and interactions. In autumn, the most distant sightings and recoveries were of first-year males, and the shortest were of adult males. The lengths and directions of movements taken by males and females from different natal areas were interpreted as due to the locations of upland natal areas relative to lowland wintering areas, and food availability in lowland and upland habitats affecting the sexes differently.

Phenology of Western Olivaceous Warbler Hippolais opaca and Eastern Olivaceous Warbler Hippolais pallida reiseri on stopover sites in Mauritania

VOLKER SALEWSKI and MARC HERREMANS
Swiss Ornithological Institute, CH – 6204 Sempach, Switzerland

Due to the problems of identifying the recently-split Western Olivaceous Warbler Hippolais opaca and Eastern Olivaceous Warbler H pallida reiseri in the field, the migration phenology, passage routes and wintering areas of the two species remain unknown. Both species were mist-netted regularly during autumn and spring migration on Mauritania and the migration phenology of the species in the western Sahara is described here for the first time. Autumn migration of Western Olivaceous Warblers through central Mauritania lasts from early August to early October. Passage at the coast started later and occurred during a shorter time period. The species does not seem to winter in central Mauritania. During spring migration, Western Olivaceous Warblers occurred from early March to early May. No birds were mist-netted in spring at the coast although some were present. The Eastern Olivaceous Warbler was mist-netted at the inland sites only. Only a few birds were mist-netted on autumn migration, which was between late August and early October. The species does not seem to winter in central Mauritania. During spring migration, Eastern Olivaceous Warblers were mist-netted from mid March until early May. There were no indications that the species breeds in central Mauritania.

Post-breeding dispersal, breeding site fidelity and migration/wintering areas of migratory populations of Song Thrush Turdus philomelos in the Western Palearctic

R. D. P. MILWRIGHT
17 Forehill, Ely, Cambridgeshire CB7 4AA, UK

Song Thrush Turdus philomelos ring recovery data gathered over 90 years in central, north and east Europe were analysed in their breeding zones and in 14 migration/wintering areas in Europe, North Africa and the Near East. Few post-breeding movements were over 20 km before the end of September. Subsequent- year breeding site fidelity was high in May to August. Migratory T p philomelos moved southwest in autumn on a broad front. Scandinavian and northwest Russian birds moved down the northwest coast of continental Europe arriving in large numbers in southwest France in October; many adults then moved on to winter in west Iberia. Those ringed in central Europe, from Switzerland to Belarus, tended to follow the Rhine–Rhône route to the French Mediterranean before dispersing to winter in east Iberia, the Balearics and Algeria. Southeast European birds moved to north and west Italy in the autumn/early winter, many adults moving on to Corsica or Sardinia. Birds breeding in the Netherlands and northwest Germany appear to have two migration patterns. A short-distance group dispersed through Belgium to northwest France in autumn/early winter, moving on to England and Wales in late winter. A long-distance group migrated to southeast Biscay in October, many then moving on in midwinter to west Iberia. Recoveries of birds ringed in the Netherlands and northwest Germany showed a change to a more sedentary population after 1989, raising the possibility that the less migratory T p clarkei has increased in abundance relative to T p philomelos in this area. Subspecific identification would be useful to assess future changes in range boundaries of philomelos and clarkei within northern Europe.

Autumn migration of Reed Buntings Emberiza schoeniclus in Switzerland

PATRICK SCHMITZ1 and FLORIAN STEINER2
1Department of Biology, Faculty of Science, University of Geneva, Switzerland
2Rue de Genève 60, 1225 Chêne-Bourg, Switzerland

To elucidate the migration strategies of Reed Buntings Emberiza schoeniclus migrating through Central Europe, we analysed data from 595 Reed Buntings ringed at La Touvière, Rhône River, Geneva, Switzerland, during the autumn migration from September to November 2004. These data were used to investigate age, sex, biometrics and body condition in relation to timing of migration. The overall sex ratio and the ratio of first-years to adult birds were 1:1 and 3:1, respectively, but there was a chronological sequence of young females, adult females, young males and adult males during the autumn. The mean bill depth varied during the study period with individuals migrating during October having deeper bills. The greater bill depth of males by comparison with other European studies suggests a more northeasterly origin of these birds, compatible with a leap-frog migration.

Wear and loss of rings used on Razorbills Alca torda – further caution in the estimation of large auk survival

PETER LYNGS
Christiansø Biological Fieldstation, Christiansø 97, DK-3760 Gudhjem, Denmark

On Græsholmen in the central Baltic Sea, 3,583 Razorbill Alca torda chicks were ringed with triangular Incoloy rings, and about half the birds were subsequently resighted. The resightings were used to calculate rates of turned rings, and 119 retrieved rings were used to calculate rates of wear and ring loss. At 1.7%, the rate of turned rings was much lower than reported among Common Guillemots Uria aalge in Britain, most likely because the Razorbill rings were fitted with soft wax at the time of ringing. The mean annual rate of metal loss of rings on birds for 3–9 years was 1.51%. Ring loss due to abrasion was 50% by year 14 with no ring lasting longer than 24 years, thus severely biasing survival estimations based on ringing data.

Migration patterns of two populations of Twite Carduelis flavirostris in Britain

ANDRÉ F. RAINE¹*, DAVID J. SOWTER2, ANDREW F. BROWN3 and WILLIAM J. SUTHERLAND¹
¹ Centre for Ecology and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK 2 5 The Grove, Penwortham, Preston, Lancashire PR1 0UU, UK 3English Nature, Northminster House, Peterborough PE1 1UA, UK

Following a recent large decline in range and numbers, the Twite Carduelis flavirostris is a red-listed bird of conservation concern. An understanding of the species’ movements between wintering and breeding areas is essential to underpin effective conservation. The migration patterns of two populations of Twite were examined: those breeding in the South Pennines and those wintering on the west coast of Lancashire and Cumbria. This was achieved by carrying out an intensive colour-ringing study on the two populations between 2003 and 2005. Birds breeding in the South Pennines wintered predominantly on the east and southeast coasts of England. However, a small number migrated to the west coast of England. Furthermore, large flocks of predominantly South Pennines-bred individuals overwintered in the South Pennines. From the single previous recovery, northwest-coast birds were also thought to originate from the South Pennines. However, resightings from this study suggest that these birds breed primarily on the west-coast islands of Scotland, with smaller numbers breeding on the Scottish mainland. Some interaction occurred between northwest-coast and South Pennines birds, with several birds ringed on the northwest coast found wintering during the same or subsequent year on the coast of Lincolnshire. Two birds ringed in the South Pennines were found breeding elsewhere in subsequent years: one in Scotland and one in Wales. This study has shown that, despite a small amount of cross-dispersal, these two populations have entirely different wintering and breeding grounds, and should be treated discretely for the purposes of future conservation management plans.

Autumn migration of passerine long-distance migrants in northern Morocco observed by moon-watching

GUDRUN HILGERLOH1, JAN WEINBECKER² and PAVEL ZEHTINDJIEV³
1Institute of Zoology, Ecology, Johannes Gutenberg-University Mainz, D-55099 Mainz¸ Germany ²Am Freibad 1, D-26419 Schortens¸ Germany ³Institute of Zoology, Bulgarian Academy of Sciences, blvd. Tsar Osvobodeltel 1, Sofia 1000, Bulgaria

The aim of this study was to test two different models of migratory orientation in passerines passing through the Iberian Peninsula. One model predicts a change of direction in southern Europe and the other predicts that migration follows an arching route through Europe and along the West coast of Africa. Measurements of migration direction were obtained by moon-watching at three sites in Morocco: Témara and Âin-el-Âouda, situated in the coastal region of Rabat, and near Douyèt, 150 km further east. There was no statistically-significant difference between the directional distributions of migrants in the coastal region and the inland site. Overall, the mean migration direction of 211° is consistent with the model that passerines passing through the Iberian Peninsula take an arching route through southwestern Europe and along the African West coast. Thus, an endogenous change of direction, previously demonstrated experimentally for the Garden Warbler Sylvia borin, may occur gradually along the migration route.

Biometrics and wing moult of migrating Red-rumped Swallows Hirundo daurica in Greece

JEREMY D.WILSON1, TRIANTAPHYLLOS AKRIOTIS2, DAWN E. BALMER3, LES HATTON4 and SHIRLEY MILLAR4
18 Keith Marischal Steading, Humbie, East Lothian EH36 5PA,UK 2Department of Environmental Science, University of the Aegean, Karantoni 17, Mytilini, Lesvos, GR 81100 Greece 3BTO, The Nunnery, Thetford, Norfolk IP24 2PU, UK 4Edenvale, Lydox Cottages, Dairsie, by Cupar, Fife KY15 4RN, UK

Published data describing the biometrics, moult and fat loads of migrant Red-rumped Swallows Hirundo daurica are scarce. Here we present data on wing and tarsus length, tail measurements, abdominal fat scores and weight for a sample of 457 birds captured at a reed-bed roost during autumn migration through the island of Lesvos in the Aegean Sea. Biometrics were similar to those reported from smaller samples of museum skins but with a greater range of values for several measures. Tail length and tail-fork length in adult birds were not markedly bimodally distributed, suggesting either that females were rare in the sample captured or that use of the sexing criteria proposed by Svensson (1992) should not be applied to the population migrating through this area. The majority of birds carried fat loads, and these were significantly larger in adult than in first-year birds, suggesting that adults might have been in better condition prior to long-distance migration. Moult of the inner primaries was found in 16.4%, and of tertials in 8.2% of adult birds. Its frequency varied significantly between years, but did not vary with size, mass or fat score.

SHORT NOTE

Validity of ageing Wrens Troglodytes troglodytes on fourth primary spots

ROBIN M. WARD1* and CHRIS DU FEU2
1Species & Populations, Wildfowl & Wetlands Trust, Slimbridge, Glos GL2 7BT, UK
266 High Street, Beckingham, Nottinghamshire DN10 4PF, UK

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