Short Notes: Extension of breeding activity for Rodrigues Warbler Acrocephalus rodericanus PDF
Preview Short Notes: Extension of breeding activity for Rodrigues Warbler Acrocephalus rodericanus
. Extension of breeding activity for Rodrigues Warbler Acrocephalus rodericanus DaveA. Showier La Roiisserollede^odnguesAcrocephalusroclericamis, especemenacee, estendemiquea Rodrigues. Line des lies formant I’archipel des Mascareignes, situee dans le sud de LOcean Indien. I’n jmenile. observe pendantqu’iletaitnourri parunadiilte, le30avril 1999, etaitestime a\'oirquitte le nid moins de cinq jours auparavant. Ceci est de 6 a 8 semaines plus tard que les dates d'enx'ol constatees auparavant. II estpossible que la saison de nidificationsoit plus tardixe pendant certaines annees ou qu’il y ait plus d’une nidification par an, selon les conditions meteorologiques ou I'abondance de noLirriture. T heEndangeredRodriguesWarblerdcrocep/?c////s annual production per pair xxas. on axerage. far rodericanus is endemic to the Indian Ocean higher than that ofthe same pair prior to transloca- island of Rodrigues. A juvenile Rodrigues Warbler tionk observed being fed by an adult in xvoodland at St On Rodrigues, inaddition tothexxarbler. xxinter- Gabriel (central Rodrigues), on 30 April 1999, was breeding of Rodrigues Fody Foiidiajlavicaus. the estimatedtobefewerthanfivedaysoutofthenest.Its only other extant endemic bird, has also been ob- bill length was approximately three-quarters that of served'. Interestingly, xxinter breeding is almost theadultfeedingit,ithadobviousgapeflanges,some Linknoxvn for pas.serines on the txxo more xxesleiiy down on the lower throat and the tail xvas c25 mm Mascarene islands. .Mauritius and Reunion, xxhere long. This is 6-8 weeks later than any previously nestingseasonsarexxellknoxxn(R.Salfordperscomm observed Hedging date. The fledging period of 2001). Cheke (pers comm 2001) suggests that xxinter Rodrigues Warbler is unknown, but is probably cl4 breedingisanadaptationtothemuchle.sspredictable daysLThefledgingperiodofitsslightlylargerconge- xveather precipitation patterns in Rodrigues, xxhen it ner,SeychellesWarblerA.sechellensisis 18-20daysf xvoiild be an advantage to be able to make effective Backdatingindicatesthatthebirdhatchedsometime use of Lin.seasonal rainfall, as the main rainy .sea.son during the second week of April. The incubation often does not arrix’e. Eurther ecological .studies on period of Rodrigues Warbler is also unknown, but Rodrigues are required to examine the reproductix'e Seychelles Warbler incubates for 18 daysk On this strategies and breeding success of both of the en- basis,theegg-layingdatewouldhavebeenc25March, demic passerines. at the start ofthe Southern Hemisphere winter. It is possiblethatinsomeyearsthebreedingseasonmay Acknowledgements be extended orbreedingmayoccurmore than once Many thanks to Anthony Cheke for his thoughts on perannum, ega pairofwarblers nestedtwice in the thewinterbreedingofthetxvoendemicpasserineson 1974-75seasonandtwobroodsisperhapsthenormf Rodrigues, and Roger Safforcl for comments on the Breedingactivityispresumablylinkedtoweather draft manuscript. conditions and food availability. Examples can be drawn from the findings of extensive research into References the breeding biology of Seychelles Warbler. On its 1. Cheke, A.S. 1987. Obserx^ations on the surxaving nativeislandofCousin,wherefoodavailabilityvaries endemic birds of Rodrigues. In: Diamond, A.W. seasonally. Diamond^ found that the species bred (ed)StudiesofMascareneIslandBirds. Cambridge, twice inmostyears (once inthewetandonce inthe UK: Cambridge University Press. diy season), apparently using rainfall frequency to 2. Diamond,A.W. 1980.Seasonality,populationstruc- predict peak abundance in insect food. Eurther, ture and breeding ecology ofthe Seychelles Brush KomdeuA was able to test the hypothesis that sea- Warbler Acrocephalus sechellensis. Proc. UPan- Afr. Orn. Congr.-. 253-266. sonalchangesinfeedingconditionsareanimportant proximatefactorcontrollingreproduction, following 3. Komdeur,J. 1996. Seasonal timingofreproduction in a tropical bird, the Seychelles Warbler: a field translocation ofsome pairs (as a conservationmeas- experimentusingtranslocation./.Biol.Rhythms11: ure) to Aride, an island with high year-round food 333-346. availability. Here,birdsprolongedtheirreproductive season, increased the annual numberofbroods and E-mail: [email protected] 64-BullABC Vol9No 1 ShortNotes
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