Ringing & Migration Journal of the BTO Ringing Scheme

Ringing & Migration Volume 23 Part 2
Abstracts

Survival rates of adult Reed Warblers Acrocephalus scirpaceus at a northern and southern site in England

CHRIS B. THAXTER1*, CHRIS P.F. REDFERN2 and RICHARD M. BEVAN1
1School of Biology, Ridley Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
2School of Clinical Medical Sciences, Paul O’Gorman Building, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK

Mark–recapture ringing data from Wicken Fen in Cambridgeshire and Gosforth Park in Newcastle upon Tyne were used to estimate adult survival rates in a southerly and a northerly population of Reed Warblers in England. The computer program MARK was used to estimate survival and recapture rates, adjusted for transient birds, with respect to sexes at each site. Expressed as percentages, survival rates between 1988 and 2004 at the northerly Gosforth Park site were 60.3 ± 6.0 (se) for males and 54.9 ± 10.3 for females. Survival rates at the southerly Wicken Fen site between 1995 and 2004 were 32.9 ± 16.0 for males and 52.0 ± 22.4 for females. Rainfall in the Sahel region of West Africa did not account for variation in survival rates over time at either site and did not correlate with variation in adult Reed Warbler abundance in the UK. At both Wicken Fen and Gosforth Park, Reed Warbler populations increased during the study periods. At Wicken Fen, new recruits due to immigration had a greater contribution to population growth than survival of adults returning to the site, whereas at Gosforth Park the reverse was found.

Migration of a Peregrine Falcon Falco peregrinus over water in the vicinity of a hurricane

M.J. MCGRADY1*, G.S. YOUNG2 and W.S. SEEGAR3
1Natural Research Ltd, Am Rosenhügel 59, A-3500 Krems, Austria 2 The Pennsylvania State University, Department of Meteorology, 503 Walker Building, University Park, PA 16802, USA 3Soldier Biological and Chemical Command, Aberdeen Proving Ground, MD 21019, USA

Peregrine Falcons Falco peregrinus migrating over the Gulf of Mexico have limited perching opportunities and can encounter weather that impedes southward movement. In 1998 we tracked via satellite a migrating second-year female Peregrine during 79 days from Assateague Island, Virginia, USA, to inland Venezuela, and related its movement to local weather conditions, especially during its crossing of the Gulf where it encountered weather affected by Hurricane Mitch. We document Peregrine migration in extreme weather conditions and highlight the importance of tailwinds and updraughts, especially during the water crossing – even for a Peregrine, which is not adapted for soaring flight. Analyses of the large pool of data from migrating Peregrines fitted with satellite-received transmitters in relation to weather are lacking.

Annual survival rates of adult male Corsican Nuthatches Sitta whiteheadi

JEAN-CLAUDE THIBAULT*1 and STEPHANIE JENOUVRIER2
1Parc Naturel Régional de Corse, B.P. 417, F-20184 Ajaccio, Corsica
2Centre d’Études Biologiques de Chizé, F-79360 Villiers en Bois

The endemic Corsican Nuthatch Sitta whiteheadi population is small and currently restricted to mountain forests of Corsican Pine Pinus nigra laricio. An estimate of annual survival rate is an important parameter to allow evaluation of extinction risk. Adult Corsican Nuthatches were colour-ringed and resighted on territory in the Ascu Valley, central Corsica, from 1998 to 2005. Mark–recapture methods were used to estimate the annual apparent survival rate of male Corsican Nuthatches as 0.616 (95% CI 0.524–0.700), the best model being independent of time. The longest lifespan recorded for any individual was five years and seven months. During the study, there was no strong evidence that annual survival was affected by the variation in a key food source, Corsican Pine seeds.

Natal philopatry and local movement patterns of Twite Carduelis flavirostris

ANDRÉ F. RAINE¹*, DAVID J. SOWTER2, ANDREW F. BROWN3 and WILLIAM J. SUTHERLAND¹
¹Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK 25, The Grove, Penwortham, Preston, Lancs PR1 0UU, UK 3English Nature, Northminster House, Peterborough PE1 1UA, UK

The Twite Carduelis flavirostris is classified as a red-listed bird of conservation concern in the United Kingdom. Successful conservation initiatives will depend on an understanding of local movement patterns and natal philopatry as these will be important in determining how likely the species is to colonise new nesting areas. Natal philopatry was studied in twelve breeding colonies in the South Pennines Special Protection Area using an intensive colour-ringing programme. Of twenty birds colour-ringed as nestlings and relocated in a subsequent breeding season, half had returned to their natal colony. Seven had moved to adjacent colonies while the remaining three had moved up to 12.1 km away. Local movement patterns were studied by colour-ringing birds at two feeding stations outside the breeding season. These birds did not necessarily breed in adjacent colonies in subsequent years but rather dispersed throughout the South Pennines. In the post-breeding season, before winter migration, adults and first-year birds moved extensively throughout the study area. During this time, certain key feeding sites were utilised by individuals from widely dispersed colonies. The observed pattern of natal dispersal and local movements within the South Pennines suggests that historical breeding sites can be recolonised if appropriate breeding conditions are restored.

Spring arrivals of migrant waders in Iceland in the 20th century

HUGH BOYD¹* and ÆVAR PETERSEN²
¹National Wildlife Research Centre, Environment Canada, Carleton University, Ottawa, Ontario, Canada K1A 0H3 ²Icelandic Institute of Natural History, Hlemmur 3, IS – 125, Reykjavik, Iceland

Records of first sightings of Icelandic-breeding waders and high-Arctic passage migrants have been made in most parts of Iceland since 1902. Two sets of records of first sightings are used here to analyse temporal changes in arrival dates during the 20th century and the effects of weather conditions. First sightings became earlier in the first half of the 20th century, as local spring temperatures increased. They ceased to do so after 1960, when temperatures were decreasing slightly, though the associations between arrival dates and annual temperatures were weak. In years with more than five records for a species, the earliest sightings were 5–9 days before the median dates of all first sightings. Though earliest sightings were delayed in cool Icelandic springs, those median dates showed little correlation with local spring temperatures. Six species arrived later when the winter or spring values of the North Atlantic Oscillation (NAO) were high, but seven species showed no significant associations with the winter NAO. Sightings tended to be later in springs in which westerly or cyclonic systems were prevalent over Ireland and Scotland. First sightings in Iceland were substantially later than in the Outer Hebrides, though in closer synchrony with the peaks of passage there than with arrival and passage dates in Shetland and north Norway. Sustained observations at a few key sites should be useful in tracking the responses of waders to variations in climate and other environmental changes.

Biometrics of Citril Finch Serinus citrinella in the west Pyrenees and the influence of feather abrasion on biometric data

DANIEL ALONSO1 and JUAN ARIZAGA1,2 *
1 Department of Vertebrates, Aranzadi Sciences Society, Zorroagagaina 11, 20014 Donostia, Spain 2 Department of Zoology and Ecology, University of Navarra, Irunlarrea 1, 31080 Pamplona, Spain

Biometric data are an essential component of studies into the breeding biology of bird populations. Citril Finches Serinus citrinella in the Pyrenees mainly feed on pine seeds, and coniferous habitats in the west Pyrenees are of significant conservation importance. The aim of this study was to increase our understanding of morphological variation in Citril Finches breeding in the west Pyrenees, north Iberia, within a region of grasslands and woodlands of Scots pine Pinus sylvestris. Individuals (1,118) were mist netted, ringed and measured. Wing and tail length were influenced by feather abrasion, particularly in juvenile birds. Overall, male Citril Finches were larger than females for all structural and flight-feather measurements (wing, tail, tarsus and culmen length, bill depth and width and lower mandible length), and adults were larger than young birds (except for tail length, culmen length and bill depth). There was significant year-to-year variation for all measurements apart from tail length, but the reasons for this are unknown. Principal Components Analyses (PCA) were used to analyse wing and bill morphology. Adult birds had narrower, more pointed wings than young birds, and the wing shape in males was more pointed than in females. There were only sex-specific differences in bill morphology, with males having more robust bills. We obtained a discriminant function to classify the sex of birds before their post-juvenile moult.

SHORT NOTE

Sexing Corn Buntings Miliaria calandra by discriminant function: a comment

JOHN H. MORGAN
Chemin de Laval, F-11160 Cabrespine, France

SHORT NOTE

Sexing Corn Buntings Miliaria calandra by discriminant function: a reply

F. CAMPOS1*, M. HERNÁNDEZ2, J. ARIZAGA2, R. MIRANDA2 and A. AMEZCUA2
1Universidad Europea Miguel de Cervantes, Carretera de Segovia s/n, E-47012 Valladolid, Spain
2Department of Zoology and Ecology, Faculty of Sciences, University of Navarre, E-31080
Pamplona, Spain

Papers from Ringing Group reports

IAN R. HARTLEY
Department of Biological Sciences, Lancaster University, Lancaster LA1 4YQ, UK

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