Ringing & Migration Journal of the BTO Ringing Scheme

Ringing & Migration Volume 22 Part 3
Abstracts

[ For abstracts from Ringing Group Reports click here ]

Sex differentiation of Corn Buntings Miliaria calandra wintering in northern Spain

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

A discriminant function was developed for sex differentiation of Corn Buntings Miliaria calandra wintering in northern Spain. The function, y = 0.136A + 0.288W - 26.837, where A is wing length in mm and W is body weight in g, gives positive values for males and negative values for females. The error of this function was 3.9% lower than other published biometric criteria for sex differentiation in Corn Buntings.

Feather lice (Mallophaga) of the Irish Dipper Cinclus cinclus hibernicus

Ú. DOYLE¹*, A.C. CROOK², P. SMIDDY³ and J. O’HALLORAN¹
¹Department of Zoology, Ecology and Plant Science, University College Cork, Ireland ²Centre for the Development of Teaching and Learning, University of Reading, UK ³Ballykenneally, Ballymacoda, Co Cork, Ireland

Forty Dippers Cinclus cinclus hibernicus were caught and deloused in southwest Ireland in 2003. Two species of lice (Mallophaga) were recorded; Philopterus cincli and Myrsidea franciscoloi. Both these species are known ectoparasites of the Dipper, yet these records were the first for Ireland. The incidence and infestation rates reported in this study were significantly greater than those recorded in Dippers from two studies in Wales and Germany.

Biometrics, ageing, sexing and moult of the Blue Chaffinch Fringilla teydea teydea on Tenerife (Canary Islands)

EDUARDO GARCIA-DEL-REY1* and ANDREW G. GOSLER2
1Departamento de Ecologia, Facultad de Biologia, Universidad de La Laguna, 38206 La Laguna, Tenerife, Canary Islands, Spain 2Edward Grey Institute of Field Ornithology, Department of Zoology, South Parks Rd, Oxford OX1 3PS, UK

The Blue Chaffinch Fringilla teydea is one of a few Palearctic species for which biometric data are lacking from the field; we address this issue here. Blue Chaffinches were caught by mist net, at ten sites on Tenerife (Canary Islands), and measured. Data on biometrics and moult using standard methods are presented, and observations on mass variation in relation to time of day and body size are reported for the first time. Wing length, bill length, bill depth & tail were greater in adults and first year birds than juveniles whilst tarsus and mass were the same. The species shows a clear sexual dimorphism in size except for bill length. The duration of primary moult was estimated to be 66 days for adults. For first year birds (in their second-calendar year), the mean starting date of primary moult was 25 days earlier than adults and was completed after 109 days.

Estimating the age of Corncrake Crex crex chicks from body weight and the development of primary feathers

RHYS E. GREEN* and GLEN A. TYLER
Royal Society for the Protection of Birds and Conservation Biology Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK

Two methods for ageing Corncrake Crex crex chicks are described. Data on the body weight of chicks of known age, from broods of radio-tagged females, were used to produce a formula for determining the age of chicks of unknown age. This method was, however, prone to error for chicks older than about 22 days after hatching. An alternative method, based on the ratio of the length of the waxy sheath on a primary feather to the maximum chord wing length, was developed using measurements of captive-bred chicks of known age. This method performed well for chicks aged 22-45 days old, but required testing on wild chicks before application because of possible effects of captive rearing. Estimates of the age of wild chicks from both weight and primary development indicate that the two methods gave similar results and, hence, that the latter method was useful for chicks older than 22 days.

Capturing Jack Snipe Lymnocryptes minimus with mobile horizontally held nets

MICHEL LEPLEY¹*, PIERRE DEFOS DU RAU¹, MICKAËL VEILLɹ, OLIVIER PINEAU² and JEAN YVES MONDAIN MONVAL^1
1Office National de la Chasse et de la Faune Sauvage-ONCFS, CNERA Avifaune Migratrice,
Le Sambuc, 13200 Arles, France. ²Station biologique de la Tour du Valat, Le Sambuc, 13200 Arles, France

The biology of the Jack Snipe Lymnocryptes minimus is poorly known and recent estimates of its population size are contradictory. To encourage ringing and marking studies of this cryptic species, we tested and improved a trapping technique in the Camargue during winter and migration periods. This capture method consists of walking with a horizontally-held net across sites where Jack Snipe regularly occur to catch birds that are flushed from beneath the net. We compared the catching rates of a 5 m x 10 m net and a 10 m x 10 m net. A total of 40 Jack Snipes was caught during 48 hours of trials with the two nets. Of the total number of individuals flushed, the average capture rate was 23% with the small net and 49% with the larger one, this difference being statistically significant. This method, therefore, appears to be appropriate for catching good numbers of Jack Snipe.

Autumn migration of the Broad-billed Sandpiper Limicola falcinellus on the southern Baltic Coast

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

Broad-billed Sandpipers Limicola falcinellus were counted and trapped in Puck Bay on the southern Baltic coast in autumn. The number of arriving birds varied greatly between years. The observed pattern was not completely convergent with data gathered at Ottenby, Sweden, 220 km north of Puck Bay. It seems that within years these two stop-over sites might be used by different groups of migrants with the majority of birds that stopped in southern Sweden being able to fly over the Polish coast, making their next stop somewhere closer to the wintering grounds. Adult Broad-billed Sandpipers migrated in the second half of July, and juveniles in August and the first half of September. There were no significant differences in biometrics between adults and juveniles. Morphometric variables were not correlated with date in either age group. Hence, the assumption of earlier departure of females from the breeding grounds was not supported. On average, Broad-billed Sandpipers gained 1.6 g/day in body weight, with a maximum value of 4.0 g/day (from 29 g to 33 g after one day). The theoretical flight range of Broad-billed Sandpipers departing from the Puck Bay region ranged between 1,300 and 1,400 km. Thus, it seems that the majority of Broad-billed Sandpipers are able to reach the northern Black Sea coast, which is one of the most important stop-over sites, in one flight.

A computer method for resolving mixed normal distributions

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

Biometric data collected by bird ringers can often be a mixture of two normal (ie Gaussian) distributions, for example, due to sexual size dimorphism, population differences, or species differences. Here, I present a computer-aided solution for identifying the means, standard deviations and mixing proportion of two groups where the data are mixed. When distributions are unimodal and no other information exists, the program tests the two-component model generated versus a normal distribution. Further developments are possible and the program is made freely available for this purpose. When the method was applied to published wing length data used to sex birds, means were closely comparable with values deduced from sexing by dissection. For most wing length distributions examined, a two-component model is a better descriptor of the observed frequencies than a normal distribution. Statistical testing of the separate components by parametric methods will be efficient and more powerful than testing the unresolved distribution.

Evidence of prenuptial moult in the Little Bittern Ixobrychus minutus

FRANCESCO PEZZO1, 2 * and ANDREW G. GOSLER1
1Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK 2Dipartimento di Scienze Ambientali “G. Sarfatti”, Università di Siena,Via P.A. Mattioli 4, 53100 Siena, Italy

Evidence for a partial prenuptial moult in the Little Bittern Ixobrychus minutus is reported for the first time, and is based on both live and museum specimens. The prenuptial moult, which is probably undertaken in the African winter quarters shortly before the spring migration, involves body feathers and often some innermost secondaries. The moult pattern is discussed in the context of the Ardeidae and compared with those of other Ixobrychus species. Current ageing criteria are also reconsidered.

Wing moult of Eastern Olivaceous Warblers Hippolais pallida reiseri at stopover sites at the southern fringe of the Sahara

VOLKER SALEWSKI*, MARC HERREMANS and THOMAS STALLING
Swiss Ornithological Institute, 6204 Sempach, Switzerland

Recent research on the systematics of the genus Hippolais led to the proposal to split Olivaceous Warbler Hippolais pallida into Western Olivaceous Warbler H opaca and Eastern Olivaceous Warbler H pallida with the subspecies pallida, elaeica, laeneni and reiseri. Here, we present data on postnuptial primary moult in relation to age, for H p reiseri from five sites in southern and central Mauritania in late summer and autumn, 2003. Adult birds showed either interrupted primary moult or had not yet started to moult their primaries. First year birds were either not moulting in September or were actively moulting primaries in October. We suggest that some adult birds start primary moult on the breeding grounds and interrupt moult for migration. On the wintering grounds, adult birds either resume interrupted primary moult or moult their primaries completely. First year birds do not start primary moult on the breeding grounds but moult their primaries completely on stopover sites at the southern fringe of the Sahara prior to further southward migration. We discuss possible problems with this hypothesis and conclude that further research is needed to verify some of its assumptions.

Biometrics and sex identification of the Rose-Coloured Starling Sturnus roseus

MARCO ZENATELLO1* and JÁNOS BOTOND KISS2
1Istituto Nazionale per la Fauna Selvatica, via Ca’ Fornacetta 9, 40064 Ozzano Emilia BO, Italy 2Institutul National de Cercetare-Dezvoltare Delta Dunarii, Str Babadag 165, 8800 Tulcea, Romania

Biometric and plumage data on breeding Rose-coloured Starlings Sturnus roseus showed that the species is partially sexually dimorphic in size and plumage colour. Both sexes develop a brood patch, although it is most frequently found in females. Although males are generally more intensely coloured than females, there is much age-related overlap in colouration which makes sexing difficult. A discriminant equation based on wing and tarsus lengths was produced to provide an additional tool for sex classification.

Sexing, ageing and moult of Buzzards Buteo buteo in a southern European area

IÑIGO ZUBEROGOITIA1*, JOSE ANTONIO MARTÍNEZ2, JABI ZABALA3, JOSE ENRIQUE MARTÍNEZ4, IÑAKI CASTILLO5, AINARA AZKONA5 and SONIA HIDALGO5
1EM Icarus sl apdo 106, E-48940 Leioa, Bizkaia, Spain 2C/ Juan de la Cierva 43 (ST 100), El Campello, 03560 Alicante, Spain 3Department of Zoology and Animal Cellular Dynamics, Science Faculty, University of the Basque Country, E-48480 Bilbao, PO Box 644, Spain 4Departamento de Ecología e Hidrología, Universidad de Murcia, Campus de Espinardo, E-30100 Espinardo, Murcia, Spain 5Sociedad para el Estudio de las Aves Rapaces (SEAR), Karl Marx 15 4º F, E-48950 Erandio, Spain

In order to obtain a reliable method for sexing and ageing Buzzards Buteo buteo breeding in southern Europe, 115 birds from a wildlife rehabilitation centre and 43 trapped birds were measured, sexed and aged over four years (2000-2003). Dead birds were sexed by examining their gonads, and live birds by the presence of a brood patch. Wing length, minimum tarsus width and body weight were the only variables which differed significantly between the sexes, although there was much overlap for the wing length and weight. Buzzards with less than 7 mm minimum tarsus width were male and those greater than 7.9 mm were female. Birds did not complete moult in one year, moulting less than 60% of the flight feathers in one season. The first and the second moult followed a pattern, but afterwards moult was unpredictable and totally asymmetric. Also, half the females and 33% of males had started to moult within 30 days of their chicks hatching. These results differ from those published for Buzzards from northern Europe. The size and moult pattern depend on factors such as prey availability and migratory status, which in turn vary between areas. We therefore suggest caution when considering the moult strategies, ageing criteria and sexing criteria published for other countries.

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