Sooty Tern (Onychoprion fuscata) ringing data is available for download in either Microsoft Excel of Microsoft Access file formats:
Click Here for full application showing details of Breeding Colonies by Year
Open Google Earth file (407KB)To get Google Earth go to theGoogle Earth download page
Followlink to see page depicting the age and plumage development of Sooty Tern chicks.
Followlink to see poster. Comments please to John Hughes via the Personal Message facility on the Messageboard.
The population of Sooty Terns (Onychoprion fuscata) breeding on Ascension Island in the Atlantic Ocean was monitored over 17 years (19902007). This period spanned the programme of feral Domestic Cat(Felis silvestris catus) eradication from the island, which commenced in 2001 with the last Cat recorded in 2004. We report on the abundanceof Sooty Terns and Black Rats (Rattus rattus) before and after Cat eradication. The Sooty Ternbreeding population in the 1990s averaged 368 000 and Cats were killing Terns at an average rate of 33 adults per night. Following Cat eradication, adult Terns are no longer predated.However, egg predation by both Rats and Common MynasAcridotheres tristis has continued with Mynas destroying more eggs than Rats. Unexpectedly, we observed a change in Ratpredatory behaviour. Following Cat eradication, Rats have become a major predator ofSooty Tern chicks. Despite this change, the Tern population has shown a season-on-seasonincrease since Cat eradication, 48.8% in 2005, 8.2% in 2006 and 6.1% in 2007, and thebreeding population increased to 420 000 birds in 2007. Incubation success improved from66.0 to 84.4% during Cat eradication, before dropping down again to 67.9% after Cats wereeradicated and Rat control measures were introduced. Index traplines were set for Rats andRat numbers fluctuated widely immediately after Cats were eradicated but there were nosignificant differences that could be attributed to changes in Cat numbers. Ascension IslandSooty Terns breed every 9.6 months and juveniles defer breeding for seven seasons. Hence2008 is the first year in which an increase in the breeding Sooty Tern population directlyattributable to Cat eradication is likely to be detected. We conclude that long-termmonitoring is essential to guide conservation practice even in this relatively simplepredatorprey system.
To view the paper clickhere. Comments please to John Hughes via the Personal Message facility on the Messageboard.Sub-lingual oral fistulas are a condition firstreported in New Zealand Stitchbirds (Notiomystis cincta)in which a lesion develops on the periphery of the mandiblein the oral cavity and a fistula develops throughwhich the tongue protrudes. We report that it arises inanother species, the Sooty Tern (Onychoprion fuscata),breeding on Ascension Island in the south Atlantic. Wediscovered five adults with oral fistulas out of a total of13,664 adults and chicks ringed during 11 breeding seasonsover 13 years. Compared with other threats to theAscension breeding population of over 180,000 pairs ofSooty Terns, we report that oral fistulas are a minor threatto colony stability, especially because afflicted birds wereincubating eggs. Nevertheless, our findings suggest thatfurther investigations of whether the condition is sexlinked,of its pathogenesis, and of its causation wouldaugment our knowledge of the biology of Sooty Terns;such information might also have conservation implicationsfor our understanding of the condition in endangeredStitchbirds. We call upon ornithologists to report oralfistulas in other species, because it would seem unlikelythat these are the only two species predisposed to thecondition.
To view the paper clickhere.Sooty terns Onychoprion fuscata are one of the most abundant seabirds butbreeding populations in many colonies have diminished. Rapid sexing of sootyterns in the field could be crucial in advancing our understanding of theirreproductive biology, and in promoting conservation. However, sooty tern malesand females are identical in their plumage and, thus, difficult to sex in the field.Morphometric measurements were taken from 63 adult sooty terns breeding onAscension Island in 2005. A small blood sample was taken from the brachial vein todetermine the birds sex using standard PCR-based molecular techniques. Maleswere consistently larger in all morphometric measurements than females butconsiderable overlap between the sexes resulted in no single measurement being auseful discriminator of sex. A principal components analysis on a correlationmatrix of seven morphometric measurements indicated that the first principalcomponent (PC1) was a good body size axis explaining 40.5% of the variance inthe original matrix. The suite of head measurements all had high character loadingson PC1 and were, therefore, good indicators of the body size of sooty terns. Tarsuslength and wing length were less reliable predictors of sex. Discriminant analysesrevealed that a disciminant function incorporating head measurements and winglength allowed 77.8% of sooty terns to be sexed correctly based upon morphometricmeasurements alone. Further morphometric approaches to sexing should beexplored with sooty terns captured in subsequent years.
To view the paper clickhere.Populationsizeisdeterminedbythebalanceofbirthsanddeaths,andofimmigrationandemigration.InordertoinvestigatepopulationdynamicsoftheSootyTernOnychoprion fuscatuspopulationonAscensionIslandinthesouthAtlantic,wefocussedonthekeycomponentofimmigrationbymeasuringtheproportionsofphilopatricandimmigrantrecruitstothebreedingpopulation.TheSootyTerncolonyhadexpandedby7%followingtheeradicationofFeralCatsFelis silvestris in2003.Between1975and2002potentialrecruitstothebreedingcolonywereringedaschicksonAscensionIslandand incolonieselsewhere intheAtlantic.Searches for thesebirdsasadultsbreedingonAscensioncommenced inJune2002andcontinueduntilDecember2008.Ofthe600chicksringedonAscension,36(or6%)wererecruitedintothebreedingpopulationandofthe9,482ringedinothercolonies,onlyone(0.01%)wasfoundbreedingonAscensionIsland.Afurtherinvestigationofmorphometricmeasurementsrevealed thatSootyTernsonAscensionwere significantlydifferent from those fromneighbouringcolonies.The sampleofbirdsfromAscensionwasdrawnfromadifferentpopulationandispossiblyofapreviouslyunidentified,sub-species.WeconcludethatimmigrationtothebreedingpopulationonAscensionisminimalandthattheyareareproductivelyisolatedpopulation.
To view the paper clickhere.Masked boobiesSula dactylatra, like many other species of Sulidae, do not construct elaborate nests. However, their nest sites produce a characteristic 'nest signature'. We found that these nest signatures could apparently be seen in freely available satellite images (GoogleEarth) of the main island of Ascension in the south Atlantic. We verified that this was the case by comparing nest signatures detected on these satellite images with field reports of occupied nests. We found that the locations of these nest signatures determined from satellite images agreed closely with the coordinates of actual nests on the ground. We used this information to determine the position and size of a previously unreported masked booby colony on the island. Thus, we show that the presence and abundance of some species can be estimated using freely available satellite imagery if a suitable signature in the satellite image can be found. Regularly updated satellite imagery of target sites could also be used for population monitoring. While this would be expensive, initial evaluation of the technique for particular species or populations can be achieved using freely available images. We encourage wildlife managers to view their study sites on GoogleEarth for evidence of their target species.
To view the paper clickhere
