Corella,1988 12(2): 53-56 CRESTEDTERNS Sterna bergii ON SOUTHERNGREAT BARRIER REEF ISLANDS. 1985-1986

T. A. WALKER p.O. QueenslandNational Parks and Wildlife Service, Box 5391,Townsville Mail Cenrre,eld. 4810

Reteivcd 18 Februarl, 1987

INTRODUCTION commonly observed speciesof tern and on most of The Crested Tern Stelna bergri is one of the the rocky islands they were the only species mostcommonly observed terns around the coast seen. Nesting was observedon two rocky islands of Australia.Information on the distributionand (Eshelby Island, East Rock) and nine coral brcedingon islandson the southernhalf of the islands(Table 1). As well as this. a Crested Tern GreatBarrier Reef is presentedhere for the 1985- 1986breeding season. There have been no previous surveysattempting to coverthis areaalthough there are reportsof nestingon the Capricorn,Bunker and Swain Reefs groups of islands(Kikkawa 1976,Walker and Jones1986).

-. METHODS sEA

Approximately 150 continentalislands and -cF- -r rocks betweenHolbourne Island (19'43'S) and O. .r the Keppel Group (23'15'5) were surveyedat least o/ oncebetween October 1985 and March 1986 .c et1,swrtn oe lligltle 1) All 23 coral cay islands except for Riptide Cay were surveyedtwo to four times betwcenDecember 198-5 and May 1986. In additionother lessextensive surveys have 100 been carried out from 1983 to 1987 in local 0 regionsof the southernGreat BarrierReef. The KIIOMETRE g only known tern nestingsite that wasnot visited was Riptide Cay where Crested Terns were reportednesting in November1976 (Limpus and l.yon 1981).

Fig\rre 1. Localiry map showing the positia s of aI islancls and grcups of islands(.) Islandsa-k cotrcspondto RESULTS those listed in Table 1; l, Holboulne I; m, Litle CrestedTerns were present Grcss! L; n, Pelicdn Rock.; o, Riptide Cal; p, throughoutthe Notuh Reef L; q, Wilson L; r, Noth West I.; s, whole of the surveyarea. They were the most LLttlfMusgrure L: t, Tem L T.A. Walker:CrcstedTerns on GreatBarrier Reef islands Corela 12(2)

TABLE 1 CrestedTern nestingsites in the 1985-1986bteeding season.

Tcms Number of Clutch Nesting Dilte Sites Prcscnl Clutches Stage Species a EsheLby 24Dec. muliiple >7 000 3 560 E BT b East Rock 27Dec. all over >400 243 E.C BNT c Bell Cav 14Feb. eastend 285 91 E.C,U CN >,100 200 CN d BacchiCay l7 Feb. l 000 200 U BB.LCT e Frigate Cay 2t) I E CN,RT f Price Cay 19Feb. I 400 329 U.E CN,BB.LCT 38 E CN,BB g Masthead 11Dcc. north side 116 58 L RT.BNT.LCT h Erskine 10Dec. north sidc > I00 80 E BT i Onc Tree 1,1Dec. >?00 E BT j Fairfax (east) 8 Jan. 200 60 C BB k LadyElliot ll Dec. northeaslside >5 000 3 50t1 E.C BT,CN,BNT.SG Abbreviations:E. eggs;C. downychicks; U. unfledgedfeathered juveniles; BB. Brown Booby;BT, BridledTern; SG, Silver Gull; RT, RoseateTern; LCT. LcsserCrested Terni BNT, Black-napedTcrn; CN, CommonNoddy.

'fern cggshcll was found in a Black-naped Sterna area (Lesser Crested Tern Sterna bengalensis, sumatlana colony on North Reef Island (5 shearwaters Puffinus sp.. Brown Booby Sa/a February 1986) and a Crested Tern eggshellwas leucogaster and Frigatebirds FreSald sp.) suggests found in a Black-napedTern colony at Holbourne that a changehas occurredin seabirdpopulations lsland (24 December 1985). Observations from since Marshall's visit in 1933-1934 (Marshall flights over the area suggestedthat nesting might 1934). have occurred on Tern Island, east of Mackay. This island could not be visited for confirmation in 1985-1986but a desertedCrcsted Tern egg was Nesting occurred in 1985-1986on the southern found there on 19 January 1987. offshorecoral caysand on nearshorerocky islands in the north of the suruey area. This nesting dis- tribution is similar to that of Black-naped Terns DISCUSSION and Roseate Terns S/enra dougalli (W alker 1986, 1988). In contrast with these specics Crested Crested Terns have prcviously bccn found to be Terns were also observedwell away tiom known abundant in some regions of the southern Great nesting sites. It is probablc therefore that some Barrier Reef (for refcrencessee Kikkawa 1976). small to moderate sized Crested Tern breeding The present survey is in agreement with these colonies on rocky islandswere not located. Two observationsand extendsthe distribution to large further minor nesting sites were identified in the regions that have not previously been examined. following season(1986-1987) on Pelican Rock in Thc only disagreement is in the Whitsunday ShoalwaterBay (30 terns and four nestswith eggs Group where Crested Terns were classifiedas a on 5 November 1986)and on Little GrassyIsland rare species in the summcr of 1933-1934by north of the Whitsunday Group (20 terns and two Nlarshall (1934). Two other bird surveys ol the nestswith eggson 22 November 1986). Whitsunday and Cumberland Islands (Brown 1949, Roberts 1957) recorded Crested Terns as being common. In fact Crested Terns were the Brceding in the Capricorn-Bunker region onlv soeciesof tern seen in June 1948. In 1985- (Table 1, g-k) and on the rocky islands(Table 1, 1986tirey were the most frequently observedsea- a&b) is highly seasonal and occurs between bird throughout this area. Comparison of abun- November and March. Each island has basically dance of other seabird speciesin the Whitsunday a single nestingof Crested Tcrns during a season June,1988 T. A. Walker CtesledTernson creat BarrierReef islands

(or none ar all) althoughthere may be rome re- (MacGlllivray 1928),Wilson (MacGillivray 1926), la)rng b) unsuccessfulbirds. There can be more North Reef (Walker and Domm 1986),and Norih than one colony presentwith overlappingnesting West (Embury 1933) were regularly visited datesbut.as.u rule once nestingis cdmp-ieredoi throughoutlhe yerr and nestingwould nut hrvc an rslrndrt d()esnol occuragain until thc lollow- beenoverlooked. lng year. North West Island is of particular interest ln contrast, nesting colonies may be found becauseunlike other islandsin the Capricorn and throughout the year on islandsin the Swain Reef Bunker Groups it has leral cats and does not region (Table 1, c-f) though numbers are lower in support coloniesof ground-nestingterns. Embury wrnter (Walker and Jones 1986).The explanation (1933) described how wild cats ravagcd large 'southern for this differencebetween regions may be related colonies of Crested Terns on Barrier to seasonalchanges in abundanceof food or to Reef islands'in the late 1920's.North West Island seasonalchanges in temperature. Annual varia- is the only knowD southern Great Barrier Reef OnS ln scawater temperature are greater at island with feral cats and, as Embury lcd islands near to the mainland than at the Swain ornithological expeditions to this island (Mac- Reefs (Brandon 1973). Gillivray 1931)and made claim to holding a lease there (Qld. Govt. Archives). it is apparent that The number of nests on Swain Reefs islandsat this is the island to which his observationsrefer. any time was lowcr than in the Capricorn-Bunker The cats were eradicatcdin 1985(except for onc and north Whitsunday regions (Table 1) but that cscaped capture until 1987) trut Crested becauseof the year-round breeding at the Swains Terns did not rcturn to nest in 198-5-1986or in Group the annial difference betw;en the regions 1986-1987.This may take time becauseof present is not as great as thc data suggest. nesting site lidelitl' to nearby islandsor it may bc On coral cay islands nesting turtles may crawl discouragedby the large numbers of campers(up through tern colonics causing considerable to 15t))that now visit North West Island. damagc in summer. It is notable that the two It is possible using the survey results to make largest Crested Tern colonies on cays were at an appraisal of thc total summer population of Lady Elliot Island and One Tree Island where the CrestedTerns on the southernGreat Barrier Reef lcast interferencefrom turtles occurs(turtles can- during 1985-l9lt6. There appeared to bc 9 000 not dig nests in the shingle on these cays). Birds birds in the Capricorn-Bunker region. 8 000 in nestingoutsidc of the tuftle nestingseason in the the Eshelby Island region. 5 000 in thc Srvain SwainsGroups avoid such disturbance. Reefs region and nraybe 2 000 elsewhereon the Prior to thc 19U5-1986season, Crested Tern inner shelf giving a total of 24 000 birds. nesting had not been reported on East Rock, Eshelby Island, Bacchi Cay or Erskine Island. The hrst three of these islands probably support ACKNOWLEDGEMENTS regular nesting each year. Erskine Island did not Surveys of thc Capricorn, Bunker and Swain have any colonies in the three years prior to the Reefs cays were funded by OueenslandNational 1985-1986season but nesting occurred again in Parks and Wildlife Service.I thank Menna Joncs the following1986-i987 season. lbr help with the February1986 survey at the There were three islandsin the SwainGroup, SwainReefs. Thomas,Bylund and Gannetislands, where nest- ing has previouslybeen reported(Walker and Jones1986) but whcre ncstingwas not found in REFERENCES the presentsurvey. These islands could have had Brandon.D. E. (19?3).Waters of the Great Barrier Rec[ colonicsat timcsothcr than on thedates for which Province.1, BioloS,vand Geology of Coial Reefs.Vol. L theywere surveyed in Februaryand April. There Ed. by Jones.O. A. andEndean. R. pp. 187-232.Academic were also four islandsin the CapricornBunker Prcss,New York. Brown,A. G. (1949).Noies of somebirds of the Whitsunday Groupswhere nestinghas been observedprevi- Croup, Ouccnsland.Lnw 19:11 19. ously but where nestingwas not found in the Embury,E. M. (1933).The CreatBarrier Reef. The Shake- presentsurvev. These islands.Lady Musgrave spearHead Press. Sydney. T.A. Walket:CrcsledTernson c.eat BarrierReel istands Cotella12(2)

Kikkawa,J. (1976).The birdsof rhe GreatBarricr Reef. /n Roberrs,P. E. (1957).Notes on birds of rhc Cumberland Biologyand Geology of CoralReefs. Vol. 3. Ed. by Jones. Isiands,Ema 57r303-310. O. A. andEndean. R. pp. 279-341.Academic Press, New Walkcr,T. A. (1986).Black-naped Terns Stetna sumatrana on the southernGreat Barricr Reef, 191t5-1986.Cofela l0: Limpus,C. J. and Lyon. B. J. (1981).Seabirds breeding on 123-124. the S*'ain Reefs,Oueensland. Corclla t I0l-105. Walker, T. A. (1988).Roseate Tens ,Sternadouqalli on sovth- MacGillivray.W. D. K. (1926).Birds of the Capricorn ern Great Barrier Reef islands, 1985-1986.Corella 12: Islands.Ea, 25:229-238. 56-58. Maccillivray.W. D. K. (1928).BirdJife of the Bunkerand Walker,T. A. andDomm, S. B. (1986).The birdsof North CapricornIslands. Emu 21. 230-249. Reef Island. Qld. Nat. 26199-102. Maccillivray.W. D. K. (1931).A May visitto lhe Capricorn Walker,T. A. andJoncs, M. E. (1986).Scabird Islands Nos. Islands.Emlr 30t 2'70-2'76. 164-167.Frigate Cay; Bylund Cay; PriceCay; BelJCay. Marshall,A. J. (1931).A surveyof the bird-faunaof cetain Corclla loi 91-91. islandsof the Whitsundat Passagenorth Queensland.tm 34:36-44.

Corella,198B, 12(2): 56-58 ROSEATETERNS Sternadougalli ON SOUTHERNGREAT BARRIER REEF ISLANDS, 1985-1986

T. A. WALKER

QueenslandNational Parks and Wildlife Service, P.O. Box 5391,Townsville Mail Centre.Qld 4ill0

Reetrcd16 O'rober,1986

INTRODUCTION STUDY AREA AND METHODS In recent decadesthe DoDulationsof the Roseate Tern Sterna dougalii have declined Approximately 150 continental islands and precipitouslyin Europe, South Africa and No h rocks betweenHolbourne Island (19"43'5)and Americawhere it is consideredto be a threatened the Keppel Group (23"15'5)were surveyedat species(Nisbet 1980). In Australia, Roseate least once between October 1985 and March Terns nest on islandsoff the westerncoast of 1986.The region is shown in Figure 1. AII 23 WesternAustralia and off the easterncoast on coral cay islands except for Riptide Cay were the Great Barrier Reef. Breedingrecords on survevedtwo to four times betweenDecember theseislands are relativelyfew and therehas not 1985and May 1986.Included amongst the sur- previouslybeen a widespreadregional suruey, veyedislands were all known tern nestingsites Someislands appear to be preferredfor nesting exceptfor Riptide Cay, Reid Islandand Creek but largeyearly variations in sitesand numbers of Rock (Kikkawa 1976).There are no recordsof birdsoccur (Hulsman 1984). RoseateTern nestingon thesethree islands.