28 AUSTRALIAN FIELD ORNITHOLOGY 2009, 26, 28–32 Diet of the Nankeen Kestrel Falco cenchroides on Christmas Island MARTIN SCHULZ1 and LINDY LUMSDEN Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, 123 Brown Street, Heidelberg, Victoria 3084 1Present address: Scientific Services Division, Department of Environment and Climate Change, P.O. Box 1967, Hurstville, New South Wales 2220 (Email:
[email protected]) Summary. This note reports on the diet of the Nankeen Kestrel Falco cenchroides on Christmas Island (Indian Ocean) from remains located at perches in 2005 and 2008. The dominant prey item was the Giant Grasshopper Valanga irregularis. Other prey included the Christmas Island Swiftlet Collocalia linchi natalis and the introduced Grass Skink Lygosoma bowringii. The Nankeen Kestrel Falco cenchroides is a partially migratory and dispersive species (Olsen & Olsen 1987) that has expanded its range in recent decades, colonising far-offshore islands, including Lord Howe Island in the 1940s and Norfolk Island in the 1960s (Schodde et al. 1983; McAllan et al. 2004). On Christmas Island (Indian Ocean) the species first arrived in the 1940s and was initially present in low numbers in the north-eastern section of the island (Rumpff 1992). By the 1980s the species had expanded its range and significantly increased in abundance (H. Rumpff cited in Lumsden et al. 1999) and still appears to be increasing, although this has not been quantified (Lumsden et al. 2007). Until this species’ colonisation, the only resident raptor on the island was the Variable Goshawk Accipiter hiogaster. The successful establishment of the Kestrel has been associated with habitat alteration resulting from phosphate-mining operations, causing the creation of extensive open minefields.