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Ruddy retains egg in oviduct for five months

PHIL F. BATTLEY*•, WOUTER K. VAHL & BERNARD SPAANS

Department of Marine Ecology and Evolution,Royal Netherlands Institutefor Sea Research (NIOZ), PO Box 59, 1790 AB Den Burg, Texel, The Netherlands

Battley,P.F., Vahl, W.K. & Spaans,B. 2003. RuddyTurnstone retains egg in oviductfor five months. Study Group Bull. 101/102: 67-69.

A Ruddy Turnstonecaught in The Netherlandsin September2002 and held in captivityfor feedingexperi- mentswas euthanasedin mid-November,after concernabout what appearedto be a solidgrowth in its abdo- men.A necropsyrevealed that the was egg-bound,with a large,soft-shelled egg at the distalend of its oviduct.The egg+oviductmass of 16.5 g constituted14.9% of the bird's body mass(110.8 g). As the average startof egg-layingin the Baltic regionis from the end of May to mid-June,it is likely that this bird had been carryingthe egg matterfor aroundfive months.While egg-bindingis often fatal to ,this is clearly not alwaysthe case.However, unlike 17 otherTurnstones caught in October2002 the bird hadperformed no pre- basicmoult andhad extremelyworn plumage.The bird presumablysuffered secondary infections as a result of egg-binding.Carrying an extra 15.7-18.6% of the "egg-free"body mass may haveimposed a transportcost.

INTRODUCTION ance, and the extent of the pre-basic(post-breeding) moult was assessedby scoringdifferent feather tracts in the body As partof studieson interference in foragingwaders, W.V. and as old, moulting or new. Scoreswere summarisedfor the B.S. brought18 Ruddy TurnstonesArenaria interpresinto flight feathers(primaries, secondaries and tertials) and for captivityin September-October2002. Birds were caughtat contourfeathers (mantle, breast,upperwing coverts) such nightby mist-netin the western(1 bird, 27 September)and that an overall score of "old" or "new" means all feather eastern(17 birds,8 October)parts of the Dutch WaddenSea groupswere thatcategory, while "moulting"means that one and were held at the experimentalshorebird facilities at the or moregroups were in moult. Individualone was the heavi- RoyalNetherlands Institute for SeaResearch, Texel, The Neth- est bird at capture(117.2 g comparedwith an averageof erlands.In captivity,birds were trained to eatmaggots (Diptera 88.5 g for the otherbirds), but was the only bird that had not larvae)and to feed on periodicallyavailable feeding-flats. moulted any of its flight or contourfeathers (Table 1). Concerns were raised for one bird when we realised that it had a hardened abdomen, the cause of which was not clear. Necropsy results Moreoverthe bird' s plumagewas in poorcondition, suggest- ing thatit mightnot havebeen producing preen waxes. The The causeof the abdominalswelling was easily identified as bird was euthanased on 13 November 2002 to determine the an egg in the lower oviductadjacent to the cloaca(Fig. 1). cause of the swollen abdomen (particularly to discover The egg was approximately29 x 31 x 24 mm in size, with whetherthe apparentproblem had been inducedby condi- no hardenedshell. The egg contentswere largely solid and tions in captivity). In this note, we comparethe body mass yellowish,though a smallamount of yellowmaterial was still andmoult statusof thisindividual ("individual one") with the semi-liquid.There was a "vein" of dark material running restof the captiveTurnstones, and describethe unexpected down the centreof the egg. The contentshad an unpleasant necropsyresults, that the bird still hadan eggin its oviduct, odour. The oviduct was convoluted, thick and hardened,with roughlyfive monthsafter the main Turnstonelaying period. an averagewidth of 4.8 mm (mean of sevenmeasurements alonglength). At the proximalend of the oviduct,a separate SAMPLES AND OBSERVATIONS thickenedpart was separatedfrom the rest of the thickened oviductby a smalllength of"typical" thin oviductonly about Source of birds, body masses and moult 1 mm thick (L-shaped,13.7 mm x 13.0 mm alongthe arms, 8.0 mm deep). One loosewhite "ball" 4.0 mm acrossmay Most Turnstonesin the studywere caught by theringing group havebeen another egg follicle. The folliclesat theovary itself Stichting and W.V. at Schiermonikoog(53ø28'N, wereall 0.5 mm or lessin diameter(typical for northem-hemi- 06ø15'E) in the easternDutch Wadden Sea (Table 1). Indi- spherewaders in thenon-breeding season). The eggweighed vidualone was the only bird caught(by W.V. andB.S.) along 11.3 g, while the rest of the oviductweighed 5.2 g. 16.5 g of the dike at Den Helder in the westernWadden Sea (52ø57'N, the total body massof 110.8 g (14.9%) consistedof repro- 04ø43'E).Birds were weighed(_+ 0.1 g) on an electronicbal- ductive material.

1 Departmentof Mathematicsand Statistics, University of Otago,PO Box56, Dunedin,New Zealand, e-mail: philbattley@ quicksilver.net.nz * Correspondingauthor

67 Bulletin 101/102 A ugust/December 2003 68 WaderStudy Group Bulletin Table1. Captureand biometric characteristics ofRuddy brought into captivity atthe NIOZ in September-October 2002.Birds werecaught atDen Helder (site 1) or Schiermonnikoog (site2). Old and new feathers correspond tosummer and winter plumage respec- tively(see text for moredetails).

Moult status

Individual Site Date Mass(g) Flight Contour

1 I 27-09 117.2 old old 2 2 08-10 97.3 moulting moulting 3 2 08-10 92.8 old moulting 4 2 08-10 88.8 moulting moulting 5 2 08-10 82.9 moulting moulting 6 2 08-10 85.2 new moulting 7 2 08-10 95.0 moulting new 8 2 08-10 90.0 moulting moulting 9 2 08-10 98.5 moulting moulting 10 2 08-10 83.1 new moulting 11 2 08-10 77.2 old moulting 12 2 08-10 97.0 new moulting 13 2 08-10 91.9 moulting moulting 14 2 08-10 78.0 moulting new 15 2 08-10 75.5 new moulting 16 2 08-10 92.4 moulting moulting 17 2 08-10 87.5 new moulting 18 2 08-10 91.3 new moulting

Body mass changesover time DISCUSSION Knowingthe mass of reproductivematerial in individual Ratherthan being a problemresulting from captivity,the one's abdomen,we cancompare total body mass and "equi- swellingin the Tumstone' sabdomen was an old egg that had valent"body mass without the egg mass over the period of notreached maturity. The egg was smaller than the normal theexperiment (9 Octoberto 11 November;Fig. 2). The sizeof Turnstoneeggs (41 x 29 mm; Cramp& Simmons massof individualone trackedthe changesin the groupas 1983),and there was no signof a hardenedeggshell. The a whole,but while the total body mass was one of theheavi- contentswere largely solid, implying the egg had been there estin thegroup, the mass without reproductive material was for sometime and gone rotten. The vein of darkmaterial in generallyatthe lower end of the range. The egg mass added theegg suggests it was fertilised, so the egg had probably an extra 15.7-18.6%to the total "egg-free"mass over the beenin the oviductsince the breedingseason in June.As periodcovered in Fig. 2. egg-layingin theBaltic region (the probable source of

A

5:0....

Fig.1. Solidifiedeggmass inthe abdomen ofa inNovember 2003. (A) Opened abdomen showing thelarge, round eggin the opened abdomen. (B)Egg and oviduct removed from the bird. The scale on the ruler is in mm. Photos: Jeroen Reneerkens.

Bulletin101/102 August/December2003 Battley et aL: Ruddy Turnstone retains egg in oviduct 69

180

--•-- in•rmidual one: total mass --0-- bxrmidualone: egg mass sublracled 160

140

o o o o o o

i i i i i i i 0 5 10 15 20 25 30 35

day since start of experbnent

Fig. 2. Comparison of body masses of individual one and other Turnstones in captivity. Individual one's total body mass, and body mass with the mass of egg and oviduct (16.5 g) subtracted, are shown as circles joined by lines. Box plots summarise the body masses for the other 17 birds (boxes enclose the 25%, 50% and 75% quartiles, whiskers denote the loth and 90th percentlies, and outliers are shown as small hollow circles).

Wadden Sea birds;Speek and Speek 1985) startson average stances,it is somethingof a mysterywhy the apparentgrowth from 31 May (Denmark),7 June(Gulf of Bothnia)to 13 June was not noticedearlier. B.S. swearsthat the swellingwas not (Finnmark)(Glutz von Blotzheimet al. 1977), it is likely that presentwhen the bird was caught, but the condition of the the egg had been in the abdomenof the bird for up to five egg suggeststhat it had remainedfrom the breedingseason. months. The smaller thickenings in the oviduct may well As the oviductitself was solidified,the egg itself is unlikely have been other developingeggs. to have moved along it. A possibilityis that changesin the Egg-binding,where an egg becomesstuck in the oviduct, size of the digestive organs or general body condition is common,especially in cage-birds.Causes include low lev- changedthe layoutof the abdomen,so that the eggmass was els of vitamins A and E as well as selenium and calcium. Low further up underthe sternumwhen caught. levels of vitamin A can lead to thickening of the mucosal epitheliumof the oviductand thickenedmucus, while defi- ACKNOWLEDGEMENTS ciencies of vitamin A, selenium and calcium can result in poor muscletone (Olsen & Orosz 2000). As a consequence Thanks to the Stichting Calidris wader-ringing group for the egg is unableto be movedalong the oviduct. catchingmost of the Turnstones,Brett Gartrell (Instituteof In wild birds,egg-binding is oftenassociated with second- Veterinaryand Biomedical Sciences, Massey University) for ary infectionsthat kill the bird, or if the egg is still present information,and HumphreySitters and Sue Moore for use- during the next breedingseason, egg impactionmay occur ful comments. when more eggsenter the oviduct and result in death.If the eggs rupturesinto the abdomen,peritonitis can set in and REFERENCES lethal secondaryinfections can occur. Our individual sur- vived despitethe egg in its abdomen,had migratedto the Cramp, S. & Simmons, K.E.L. (eds). 1983. Birds of the Western non-breedinggrounds, was not starving and could still eat Palearctic.Volume III: to . Oxford University Press, Oxford. and defecate.However, there was apparentlya physiologi- Glutz yon Blotzheim, U.N., Bauer, K.M. & Bezzel, E. (eds). 1977. cal costinvolved in retainingthis reproductivematerial. This Handbuch der V6gel Mitteleuropas, volume 7, (2. Turnstonewas the only bird in the samplethat had not under- Teil). Akademische Verlagsgesellschaft,Wiesbaden. goneany moultbefore capture, and was the only bird thatdid Marks, J.S. & Underhill, L.G. 1994. Moult, massand migration of a not then initiate or carry on moult of different feathergroups handicappedBristle-thighed . Ardea 82: 153-156. in captivity.The likely causeof the delayedor skippedmoult Olsen, G.H. & Orosz, S.E. (eds). 2000. Manual of Avian Medicine. St. was a secondaryinfection, though costs of carrying 16.5 g Louis, Mosby Inc. Speek, B.J & Speek G. 1985. Thieme's vogeltrekatlas.Thieme & Cie, of extraweight may alsohave been involved. Retarded moult Zutphen. in a poor condition Turnstone was recorded by Underhill Underhill, L.G. 2002. A handicappedRuddy TurnstoneArenaria inter- (2002), who noted similar findings for an injured Bristle- pres losesmass and delays primary moult. Wader Study Group Bull. thighed Curlew Numenius tahitiensis (Marks & Underhill 98: 44-45. 1994) and two parasite-infectedRed KnotsCalidris canutus Underhill, L.G., Earl6, R.A., Piersma, T., Tulp, I. & Verster, A. 1994. (Underhill et al. 1994). Knots (Calidris canutus)from Germanyand South Africa parasitized by trematode Cyclocoelummutabile. Journal far Ornithologie 135: While the causeof the swellingin the abdomenwas iden- 236-239. tified readily and was not due to the experimentalcircum-

Bulletin 101/102 August/December 2003