Slender-billed Curlew: have we been looking in the wrong places?
Scientists from the RSPB have carried out stable isotope analysis on feathers from juvenile Slender-billed Curlews Numenius tenuirostris to identify potential breeding areas, and found that these areas may be significantly further south than previously thought.
Previously the only known breeding area of Slender-billed Curlew was from the Omsk province, western Siberia.
This has led some to hope that new searches could lead to its ‘rediscovery’.
The data from juvenile Slender-billed Curlew feathers (donated from museums across the globe) and data from feather samples of other wader species from locations in Russia and Kazakhstan, collected by expeditions led by Geoff Hilton, now with WWT, was used to compare with large scale hydrogen isotope maps. A ‘calibration equation’ was produced which enabled the locations the juvenile Slender-billed Curlews grew their primary feathers to be identified.
The results suggested that the breeding range may have been centred in the steppes of northern Kazakhstan and part of southern Russia, between 48°N and 56°N. This is considerably further south of the known breeding range and in a different habitat zone, being more in drier steppe than the forest steppe habitat in the Omsk area.
It seems possible that the records from the Omsk area may be atypical for the core range of the species and any future searches for the species may be better targeted at the Kazakh steppes.
If it is extinct, the identification of the breeding sites may help understand the reasons for the species' decline and help learn wider conservation lessons.
15 March 2017
Journal reference: Buchanan G B, Bond A L, Crockford N J & Kamp J. 2017. The potential breeding range of Slender-billed Curlew Numenius tenuirostris identified from stable-isotope analysis. Bird Conservation International, DOI: 10.1017/S0959270916000551
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