LONGEVITY of the CRESTED TERN Sterna Bergiiln SOUTH AUSTRALIA
Total Page：16
File Type：pdf, Size：1020Kb
Corella,2008, 32(2): 35-37 LONGEVITYOF THE CRESTEDTERN Sterna bergiilN SOUTHAUSTRALIA M. WATERMAN'andM. D. MURRAY'3 r"DebmarPark", 28 GordonAvenue, St. Agnes, South Australia 5097 '17 AshmoreAvenue. Pvmble. New SouthWales 2073 'Correspondingauthor Received:25 January2007 Recoveriesof aliveand deadCrested Terns Stema bergii, banded as chicksat the colonieson Stonywell,Hallway, Troubridgeand Penguinlslands in SouthAustralia, have shown that birdscan surviveas longas 32 years.Although mostbirds were breeding between ,&-18 years old, several breeding birds ol 19-29years were also captured. INTRODUCTION Watermane, al. (2003)described two typesof dispersalof Crested Tem Stema bergii chicks from their natal islands in SouthAustmlia. Recoveriesfrom the southemcolonies were mainly eastwardsaround southeasternAustralia to as far nofh as southemQueensland, whereas those from coloniesaround the Gulf St.Vincent and Spencer Gulf weremostly within these gulf regions.Chicks were bandedregularly at two localities: Stonywell Island and Halfway Island in the south of the Coorong from 1962-1983, and Troubridge Island at the southem end of the Yorke Peninsulafrom 1966-1975 afi 1985-2003.These colonies were also searchedfor banded breedingadults, and the dataobtained ftom the retapped birds, together with those from other recoveries of birds banded as chicks,from theseand other colonies,have given information on the longevity of Crcsted Terns. METHOD Birds were bandedwith aluminium bandssupplied by the Australian Bird and Bat Banding Scheme.Banded breeding adults were capturedwith a hand-netwhen sitting on eggs dudng late incubationor on youngchicks beforc they disperced aroundthe colony. At Stonywell and Halfway Islands searchesfor bandedadults were madein 17 of the 22 years.Howevel intensivesearches were not attemptedbecause the islands were visited when it was best for banding chicks, and brceding birds were not accustomed to the presenceof humans.At Troubddge Island searches Figure 1. Satellite ihage of the Crested Tern studJ area along commencedin 1999 and havebeen intensive since 2002. This the SouthAustralian coastline. was possible becausethe birds werc accustomedto the presence Imaqecourtesy of NASA'ttsibleEarth'( http ://risibleearth,nata. goy/). of humansand the island was visited at an appropriatetime. The Troubridge data in this paper includes that up to 2004. Data ftom Recoverieswere classifiedas breeding,alive or deadbirds. PenguinIsland, which wasvisited less ftequently, arc alsogiven. Alive birds werecapturcd away from a breedingcolony, In this The data from other South Ausralian colonies are that for birds group are included the few that werc shot, becauseat the time rccoveredwhen 19 yeals or older they werc alive and healthy, A major effort has been made from the 1980s to read band numbersof birds in the wild with The adult birds capturedwere either of known agebecause telescopes.Only data supportedby recoveriesfrom elsewhere they had been bandedas chicks, or of unknown age because havebeen accepted, as the small bandsused on CrestedTems, they had beenbanded as breedingadults. All chicks were aged with the band lumber around the band, are difficult to read. A from the first of March for reasonsgiven previously (Waterman full discussionon the care requiredwhen using binocularsor er a/- 2003).Thus, they were one-year, two-year, three-year etc., telescopesto read bands, which were larger and especially being within their fifft, second,third year etc. of the annual designed for this purpose, on Silver GtIIs Larus nonbreedingand breedingcycle. Data from chicks recovered novaehollandiaeis given by Ottawayet al. .(1984).Birds that before I March, i.e. 0-yearold, arenot includedin the analysis. were alive but iniuredor exlaustedwere classifiedas dead. 35 36 M. Watermanand M.D. Muriiayj Longevity ot theCrested Tern Sfema berg, in SouthAustralia Corella32(2) TABLE 1 Age-distributionsof CrestedTerns in SouthAustralia Age (years) Locality Banded Recovered 3-yeargroupings as '7-9 Totals l-3 4-6 10-12 13-15 16-18rg 20 21 22 23 24 25 26 27 28 29 30+fr StonywellI./ chicks breeding Halfway I. 66 lo4 82 22 32 l6* 323 Troubridge I. chicks breeding 45 116 6l 50 123 4 I t2 StonywellI./ adults breeding Halfway I. 20 25 I 55 PenguinL chicks breeding l5 2l 3 48 OtherIs** chicks brceding*** 22| chicks alive 13 18 lll II 130 StonywellI./ Halfway I. alive I 51 21 16 lr 96 TroubridgeI. chicks alive 28 39 PenguinI. chicks alive 46 I rr 21 63 StonywellI./ chicks 275 Halfway I. 33 2l l5 334tl3l t l 394 Troubridge I. chicks dead 155 l3 218 PenguinI. dead 113 1161 l* 182 OtherIs chicks dead 11 2 Totals 24 12 26 6 2 4 | 2 2 2 2 2 + +. two were capturedon Penguin Island I bandsread wrth a telescope ** " OtherIslands = Bird I., RockyIs., GooseI. andBaudin Rocks 30 vears2 months xxx breedingon TroubridgeIsland "" 32 years2 months RESULTS Island and Rocky Islet were captured breeding on Troubridge Island, five from 19-21 years old and one at 26 The intermittent searchesfor bandedbreeding birds, even at years respectively. the most frequentlyvisited colonies,have greatly limited how thesedata can be presented. On Stonywell Island, 866 birds were bandedas breeding adultsand the agedistribution of the 55 that wererecaptured is The age-distributions of all birds of known age are given in also shown in Table l There was a decline in the number Table l. There was a rapid increasein the number breeding after retrappedafter 4-6 years.Given that all were probably older five years and a decline after 16,18 years. The r€latively than 4-6 yearswhen banded,then, the bird capturedafter 16 fewer number of 13-15 year birds at Troubridge Island yearscould well havebeen over 21 yea6. reflects a reducedbanding of the chicks which would have produced these cohorts. Two birds from Stonywell Island Five birds were recovered alive afbr 19-24 years, and one were found breeding on Penguin Island when 21 years old. after 28 years.The band of anotherwas read with a telescope Three Troubridge birds were found breeding on Troubridge when the bird was 30 yearsand 2 monthsold. Deadbirds were Island after 28 and 29 years. In additiol, chicks from Bird recoveredafter 19-32 yearc. June2008 M. Watermanand M.D. Munayi Longevity of theCrested Tern Sterna berg,il in SouthAustralia 37 DISCUSSION ACKNOWLEDGEMENTS Brcedingbirds between4-12 yealswere the most abundant Over the yearsmany havehelped in this studyin SouthAustralia and therewere still many in the 16-18 and 19-21 year groups, and we are indebtedto the following assistants:paul Bradbrooke, after which numbersdeclined. A few were as old,2't-29 yearc Morris Collins,Steve Collins, William Collins,David Connell.Clavton (Table l). The only study of CrestedTems elsewherewith Cross.Leigh Foreman.Oliver Fuller.John Jenkins,Jim Jonarian, Beverly Langley,Keith Masson comparabledata has been that of Cmwford et al. (2002) in and Roy Masson. The considerable effortsofClive Minton andhis colleaguesof theVictorian Wader Study SouthAftica. Their extensivedata shows movementbetween Group in readingband numbers with telescopesare much appreciated. colonies,as reportedby Cerick et al. (1957) in New South Wales, Dunlop and Stor (1981) in Wcstem Austalia, and We wish to thank Dr Brad Page and Lachlan Mcl-eay, who is Watermanet al, (2003)in SouthAustralia, and full recruitment continuingthis study on Troub dge Island, for the data collectedin to breedingby six years extendingto 2l years. The South 2003and 2004. Walter Boles ofthe Aust alian Museumkindly assisted Australiandata are basically similar but extendthe breedinglife with literaturcsearches. to 29 yean. The true age distributionof older breedingbirds The constantsupport of the Australian Bird and Bat Banding will be determinedin the next years, in a continuingstudy in Schemeis greatll appreciated.and we wish to LhankDarid Drynanfoi South Australia with intensivesearches for birds banded as his assistance. chicks. It is to be hoped that iltensive searchesof other breedingcolonies will continuewhile bandedpopulations are R"EFERENCES available. The value of careful sight-readingof bands is Anon. (1999).Recovery Round-ttp. Corella 23.76. demonstatedin Table l. Anon. (2000).Recovery Roand up. Corella24..72. Anon. (2002).Recovery Round-up. Cor"l/a 26: 60. Recoveriesof alive and dead birds away from colonies Anon. (2005).Recovery Round\p. CorcIla29.. IO0. supportthe pattem of longevity of breedingbirds. The recent Anon. (2008).Recovery Round-up. Cordlla 32: 48 recoveryof a bird bandedon PenguinIsland, SA in December Carrick, R., Wheeler, W R. and Murray, M. D. (1957). Seasonal 1975 and recovereddead at Point Ricardo.Vic. in Februarv dispersaland mortality in the Silver Gull, aarus novae-hollandiae 2008extends the krown longevityfor thisspecies to 32 years. Stephens, and Crested Tern, Sterna bergii Lichtenstein, in 2 months (Anon. 2008). Thesedata a.refurther supportedby A$tlralia. CSIRO Wildlife Research2: 116-144. recoveriesfrom colonies elsewherein Aushalia: Broushton Crawford.R. J. M., Cooper,J., Dyer B. M., Upfold, L., Venter,A. D., Whittington,A. Island(21 years)and Five Islandse2 yea$) in New South J.. Williams, A. J. and Wolfaardr,A. C. (2002} Longevity,inter-colony movements and breeding Wales; Corner Inlet, Victoda (20 years); Green Island, of CrestedTems in SouthAfrica. tmrl 102.265-273. Tasmania (23 years) (Anon. 1999, 2005, 2OOO, 2OO2 Dunlop,J. N. andSton, c. M. (1981).Seabird Islands, No. I l t: Camac rcspectively).Clearly, the CrestedTem in Australia is a long- lsland,Westem Australia. Corella 5:71-74. lived bird. These older birds may make a sisnifrcant Ottaway,J. R., Canick, R. andMunay, M. D. (1984).Evaluation of leg contributionto populationstability. bandsfor visualidentification offreeliving silver galls.Journal of Fie ld Ornitho logy. 55: 287 -3O8. Waterman,M., Murray, M. D. and Connell, D. (2003).Dispersal of Crcsted Tems Sterna bergii from colonies in South Australia. Corella27:93-101. .