Research Group (IWRB)

MONICA SHORTEN

East Gate, Old Castle Road, Salisbury, WiltshireSP1 3SF, UK

Citation: Shorten, M. 1975. Woodcock Research Group (IWRB). Study Group Bull. 15: 12.

The exasperatingWoodcock Scolopax rusticola is a 'fringe measurementsof bill length and central tail feathers, ex- species'amongst and waterfowl and woodland game, pressedas a ratio, allow adultmales and females to be con- and tendsto be neglectedin any group study.Woodcock fused: the best that can be done without dissection is to use enthusiastsare perhapsas odd and solitaryas the they the formula of Stronach, Harrington & Wilkins which have chosen,and the new Woodcock ResearchGroup of reducesthe probabilityof error to 28%: IWRB is strivingto flush someand induce flocking behav- iour. -0.2952 x bill length + 0.1566 x centraltail featherlength: [...] It seemsthat the occasionalWoodcock does get ringedby if greaterthan -8.3640 = male (72% correct),and theWSG - a total of five wasrecorded for 1974- thankyou, if less than -8.3640 = female (75% correct). TRG andHumber! The captureand ringing of this bird dur- ing its breedingseason really separatesthe men from the in their first twelve monthsafter hatchingmust be boys,yet thereis a greatneed for 600-700, mainly pulli or excluded,and this can be done by examiningthe tips and juveniles,to be ringedin the BritishIsles each year. It has proximaledges of theouter primaries (ragged outline on first not beenmet since 1935 (763 pulli) and the averageyearly years;smooth on olderbirds, at leastuntil April) andthe ter- total, including FGs on migration, has been about 30 in minal lighter bar on primary coverts(broader and browner recentyears with pulli averagingabout 8. So every young on young birds). This quick, simple methodcorrectly clas- Woodcockringed will be a help. The recoveryrate is 7.9%. sifies 95-98%. Any Woodcock ringed during migration Two yearsago Ib Clausager(Ka10, Denmark) published periodsor in the winter is worth suchextra recordsin the a goodguide to methodsof determiningthe age-classand sex notebook.But can anyonesex Woodcockpulli? of Woodcock from external features. Even very precise

The value of bill lengths of museum specimens in biometric studies

RON SUMMERS

CultertyField Station, Newburgh, Ellon, Aberdeenshire, UK

Citation: Summers, R.W. 1976. The value of bill lengths of museum specimens in biometric studies. Wader Study Group Bull. 17:10-11.

The measurementof bill, wing, or any other structureis a onedoes not experiencesuch a complexsituation as seen in useful techniquein the study of migration (Evans 1964). .One wouldtherefore expect the meanbill lengthsof However, the techniqueis fraught with problemswhich the freshlycollected birds and museumspecimens to be the make standardisation difficult. One of the difficulties is in the same. However, the table showsthat in the two species use of museummaterial. Standardbird text books give investigated, Arenaria interpresand Sanderling biometricdata based on museumspecimens but the applica- alba, the museum birds tend to have lower bill tion of thesemeasurements to the field situationis problem- lengths. In the Turnstonethe difference amountsto 5.4% atical; e.g. it has been shownthat wings of museumskins (males) and 4.4% (females).These differences were highly shrink (Vepsalainen 1968, Green & Williams 1973). Bill significantin the Tumstone,but not in the Sanderlingwhere length,however, is believedto be the leastvariable of the the samplesize is smaller(Table 1). The explanationfor the biometricmeasurements though the possibilitythat the bills difference betweenthe two speciesmay lie partly in the of museumskins shrink has not beeninvestigated. structureof the bill, for in the Tumstonethe rhamphotheca I havethe opportunityto measurea seriesof freshlycol- (the hornysheath) extends further beyond the bonepoint of lected birds and to comparethem with skins from various the bill. The Sanderlingon the otherhand has a roundertip SouthAfrican museums(Cape Town, Pretoria,Durban, East to the bonearound which the rhamphotheca fits moreclosely London).Being at the tip of it is likely that the birds (Figure 1). Shrinkageof the rhamphothecawill thereforebe of a given speciesare drawn from the sameorigin and that limited by the bone.

93 Bulletin 69 Special Issue July 1993