Ringing & Migration Journal of the BTO Ringing Scheme

Ringing & Migration Volume 23 Part 3
Abstracts

Grasshopper Warbler Locustella naevia autumn migration – findings from a study in southeast Britain

NICHOLAS J. BAYLY* and STEPHEN J.R. RUMSEY
The Wetland Trust, Elms Farm, Pett Lane, Icklesham, Winchelsea, East Sussex, TN36 4AH, UK

This study examines the migratory behaviour of Grasshopper Warblers Locustella naevia on the south coast of Britain with respect to phenology, fuel loads, stopover behaviour and potential flight ranges. Data were derived from 5,455 mist-net captures gathered over 10 years between July and October at the Pannel Valley Reserve, East Sussex. For the majority of captures and recaptures, fat score, wing length and body mass were recorded. Data from recaptures were used to calculate fuel deposition rates and stopover durations, whilst fat scores and body masses were used to calculate fuel loads and potential flight ranges. The majority of birds were carrying moderate fuel reserves and very few birds refuelled at the reedbed site; indeed, many appeared to remain at the site for just one day. Estimated flight ranges suggest that most birds were capable of flying to the southern half of France. Therefore it is suggested that British birds typically accumulate fuel north of the south coast, possibly at or close to their breeding grounds, and do not refuel until reaching southern France. This is supported by the pattern of birds recovered abroad. That birds stop at the south coast at all is attributed to the English Channel acting as a barrier to onward flights.

Biometrics of the Southern Grey Shrike Lanius meridionalis in relation to age and sex

FRANCISCO GUTIÉRREZ-CORCHERO1, FRANCISCO CAMPOS2, M. ÁNGELES HERNÁNDEZ1 and ANA AMEZCUA1
1Department of Zoology & Ecology, Faculty of Sciences, University of Navarre, E-31080 Pamplona, Spain 2European University Miguel de Cervantes, c/ Padre Julio Chevalier 2, E-47012 Valladolid, Spain

The biometrics of Southern Grey Shrike Lanius meridionalis and differences from the closely related Great Grey Shrike L. excubitor are poorly characterised. The aim of this study was to describe sex and age variation in external biometric measurements for the nominate Southern Grey Shrike L. m. meridionalis in a population from northern Spain. In total, 174 Southern Grey Shrikes were ringed, measured, and sexed by molecular techniques. The overall biometry of the shrikes was summarised by Principal Components Analysis (PCA). There were significant differences in size between sex and age classes. We observed a sexual dimorphism in size, with adult males the largest and yearling females the smallest. According to the PCA, only the first principal component showed significant sex and age differences, and these were related to the tail, wing, third primary, white on primaries and white on rectrices. According to these data, and at least in terms of biometry, the Southern Grey Shrike is more similar to the Loggerhead Shrike L. ludovicianus than to the Great Grey Shrike.

Biometrics of Ruffs Philomachus pugnax migrating in spring through southern Belarus with special emphasis on the occurrence of ‘faeders’

NATALIA KARLIONOVA1, PAVEL PINCHUK1, WLODZIMIERZ MEISSNER2 and YVONNE VERKUIL3
1Institute of Zoology, Belarussian National Academy of Sciences, Academichnaya Str. 27, 220072 Minsk, Belarus 2Avian Ecophysiology Unit, Department of Vertebrate Ecology & Zoology, University of Gdansk, al. Legionów 9, 80-441 Gdansk, Poland 3Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, PO Box 14, 9750 AA, Haren, The Netherlands

In spring, the Ruff Philomachus pugnax passes through European inland sites in large numbers. Birds from eastern and western parts of the breeding range may differ in biometrics, but data on this species in eastern Europe are scarce. The aim of this study was to describe the biometrics of Ruffs migrating through southern Belarus in spring. In 2004, 242 birds were sexed by DNA analysis. Three birds sexed as males had female plumage but wing lengths intermediate between females and breeding-plumage males, and were identified as cryptic males or ‘faeders’. Between 2001 and 2005, 2,237 Ruffs were ringed at the study site (1,310 males in breeding plumage, 911 females and 14 faeders). There was a strong seasonal variation in sex ratio. For adult Ruffs wing length was the best predictor of sex. Total head length and tarsus-plus-toe length distributions overlapped slightly between the sexes. There was evidence for slight bimodality in the distributions of wing, bill and tarsus-plus-toe length in non-faeder males and in wing and bill length distributions for females. Mean wing lengths of Ruffs passing through the Belarus study site were similar to those birds from other locations in Europe and North Africa, but different from birds from South Africa, Yamal and the middle Lena River, suggesting that Ruffs have at least two different breeding populations.

Different timing of autumn migration of two Ringed Plover Charadrius hiaticula subspecies through the southern Baltic revealed by biometric analysis

WLODZIMIERZ MEISSNER
Avian Ecophysiology Unit, Department of Vertebrate Ecology & Zoology, University of Gdansk, Al. Legionów 9, 80-441 Gdansk, Poland

Ringed Plovers were trapped in Puck Bay (southern Baltic) between 1983 and 2002 during autumn migration. In adults a clear decrease of mean wing and bill lengths occurred between the third decade (ten-day period) of July and the first decade of August. A similar pattern was observed in juvenile wing lengths, whereas a sharp decline in mean bill length occurred later, between the second and the third decade of August. These changes in biometrics suggested that the larger birds passing through the study area in July belonged to the hiaticula subspecies and late migrants (adults caught from the beginning of August and juveniles caught from the third decade of August) were of the tundrae subspecies. This was supported by comparison of mean measurements of these early and late migrants passing through Puck Bay with data from other areas where only either hiaticula or tundrae occur. These data were used to compare the biometrics of adults and juveniles of each subspecies.

Bird ringing in Britain and Ireland in 2005

JACQUIE A. CLARK, ROBERT A. ROBINSON, SUE Y. ADAMS, MARK J. GRANTHAM, KATE RISELY, DAWN E. BALMER, JEREMY R. BLACKBURN, BRIDGET M. GRIFFIN, JOHN H. MARCHANT and VIOLA KIMMEL
BTO, The Nunnery, Thetford, Norfolk IP24 2PU, UK

This is the 69th annual report of the British Trust for Ornithology’s Ringing Scheme, covering work carried out, and data received, in 2005. Important research on Oystercatchers Haematopus ostralegus in North Wales showed that survival of adults, recruitment of juveniles and mass of both adults and juveniles were lower during winters when there was mechanised dredging for shellfish. A study of weight changes of House Sparrows Passer domesticus in autumn and winter found that they spread their weight gain through the day, thus potentially decreasing their risk of predation, but increasing their risk of starvation. Data gathered as part of the Constant Effort Sites (CES) Scheme showed an annual increase in adult numbers for five species (one migrant and four residents) and an annual decrease for five species (four migrants and one resident). Productivity was variable with 11 species having above-average productivity and 13 below-average. Work began to develop methods to produce annual survival trends by integrating CES data from the 350 sites that have taken part in CES over the last 21 years. Data for 110 Retrapping Adults for Survival (RAS) studies were submitted. Over 13,000 Swallows were ringed as part of the Swallow Roost Project, which ran until 2006. The total number of birds ringed (873,581) was exceeded only in 2004 and was a 12% increase on the mean of the previous five years (2000–04). The recovery total (12,658) was the second highest in the last decade, being exceeded only in 2004, and was 9% higher than the mean of the previous five years. A total of 236 selected recoveries are presented in the report. They include unexpected movements and others that confirm suspected or known migration patterns.

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