Australian Field Ornithology 2015, 32, 187–189 Nankeen Kestrel preys upon Western Bearded Dragon Graham R. Fulton School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia Email: [email protected] Summary. A Nankeen Kestrel Falco cenchroides was observed eating an apparently freshly killed Western Bearded Dragon Pogona minor at a beach in south-western Australia. The Kestrel twice flew low over the landscape for 25 m, carrying the slain dragon. The mass of the dragon (43 g) was calculated as 26% of the Kestrel’s mass (164 g). Kestrels taking, and carrying, lizard prey of this size may be uncommon. A range of invertebrate and vertebrate prey (mammals, birds and reptiles) has been recorded in the diet of the Nankeen Kestrel Falco cenchroides (Marchant & Higgins 1993; Johnstone & Storr 1998; Debus 2012). Vertebrates, particularly lizards, can make up a large proportion of prey by biomass (e.g. Olsen et al. 1979; Aumann 2001; Starr et al. 2004) and lizards may be taken more commonly than mammals, owing to the Kestrel’s diurnal habit (Dickman et al. 1991). Large lizards are reported less often and include small dragons (Agamidae), usually those such as Ctenophorus spp., up to ~27 g, but occasionally the Western Bearded Dragon Pogona minor (mean mass 31 g) (Marchant & Higgins 1993; Johnstone & Storr 1998; Aumann 2001; lizard masses from Meiri 2010). Western Bearded Dragon remains were reported from Kestrel pellets by Aumann (2001), but the prey size was undetermined. The report in Johnstone & Storr (1998) was derived from an observation by John Dell, in 1972, of a pair of Kestrels feeding a Western Bearded Dragon to their nestlings (R. Johnstone pers. comm.). Marchant & Higgins (1993) listed the Western Bearded Dragon, citing Barker & Vestjens (1989), who did not give the lizards’ sizes. Marchant & Higgins (1993) also listed the Eastern Bearded Dragon Amphibolurus barbatus (= Pogona barbata), citing Czechura (1971, p. 68) who simply stated, without reference, that ‘Bearded Dragon Lizards’ ‘seem’ to be included in the Kestrel’s diet. The largest prey items recorded for the Kestrel are a Spotted Dove Streptopelia chinensis (Pacher 2010) and Crested Pigeon Ocyphaps lophotes (Oliver 2004). Pacher (2010) reported that the Kestrel could not lift the Dove, but removed its head and carried this away, and Oliver (2004) reported the Kestrel managing laboured flight at ~10 m altitude while carrying the Pigeon. The following observation, of a Nankeen Kestrel carrying and eating an apparently adult Western Bearded Dragon, was made on 3 October 2014, 15 minutes before sunset at the central beach in Warnbro Sound, south-western Australia (32°20′S, 115°44′E). The study site (Warnbro Sound Beach) and bird survey methods are described elsewhere (Fulton 2010). Conditions were cool (~19°C) and overcast. This is a single incident in a long-term study of birds on this beach, currently in its ninth year. 188 Australian Field Ornithology G.R. Fulton Figure 1. Adult male Nankeen Kestrel with Western Bearded Dragon prey, Warnbro Sound Beach, south-western Western Australia, October 2014. Photo: Graham R. Fulton The Nankeen Kestrel is a moderately common bird at this site where it was observed in 142 of 817 surveys (GRF unpublished data). A survey consists of a walked transect of 4 km, 2 km on the beach and 2 km through the hind-dunes. The Kestrel, a male identified by the grey crown and tail, was first observed eating the slain Western Bearded Dragon on the ground ~25 m from the shoreline, ~5 m behind the first line of beach vegetation. The intact appearance of the dragon indicated that it was freshly killed. The Kestrel flew away with its prey only when approached within 15 m. It flew up a slight incline for ~25 m while carrying the dragon, and perched with it atop a low (~1 m) wooden post. As I approached within 10 m, the Kestrel flew again, above the short dune vegetation, with the dragon for ~25 m before descending ~1 m to land on the ground. The Kestrel did not appear to struggle by over-flapping or by showing any obvious labouring in flight. The mass of the Western Bearded Dragon was calculated from the photograph as follows. The Nankeen Kestrel’s length was ~31.7 cm (mean adult male length from Olsen & Olsen 1987). The mass of the dragon was calculated from its total length (~25.9 cm) by comparison with the Kestrel holding it. The dragon’s snout– vent length (SVL) was calculated from Cogger (2014), i.e. tail = 130% of SVL. Thus, SVL = 11.3 cm. The mass of the dragon (~43 g) was then read from a graph, drawn from a table of SVL versus mass (Craig et al. 2007). The male Kestrel’s average mass is 164 g in spring–summer (Olsen & Olsen 1987). Thus, the dragon was estimated to be 26% of the Kestrel’s mass. In this observation, an adult male Nankeen Kestrel (smaller than an adult female) took a Western Bearded Dragon. In previous reports of large prey taken, either the female Kestrel was implicated or the gender not given (e.g. Oliver 2004; Pacher 2010). This observation suggests that the dragon was killed by the Kestrel, and that the Kestrel could fly with its prey in an unlaboured fashion, although Nankeen Kestrel preys on Western Bearded Dragon 189 without gaining much altitude. However, there are few suitable perches, and the most suitable site to consume the dragon was probably on the ground. Reports in the literature of the Nankeen Kestrel taking this species of dragon are rare and do not state the size or mass of the dragon. Instances of adult dragons being taken by Kestrels are apparently uncommon or rare. Kestrels may not transport reptiles of this size because they can consume them where they are caught. The Kestrel in this observation flew only when approached by the observer. I thank Stephen Debus for his advice and support in writing this note, Ron Johnstone for his prompt communication, and referees Tom Aumann and Jerry Olsen. I thank Scott Thompson for identifying the Western Bearded Dragon. I acknowledge the Nyoongar people, the traditional owners of the land where this study was undertaken. References Aumann, T. (2001). An intraspecific and interspecific comparison of raptor diets in the south-west of the Northern Territory, Australia. Wildlife Research 28, 379–393. Barker, R.D. & Vestjens, W.J.M. (1989). The Food of Australian Birds, I: Non-passerines. CSIRO, Canberra. Cogger, H.G. (2014). Reptiles and Amphibians of Australia. CSIRO Publishing, Melbourne. Craig, M.D., Garkaklis, M.J., Hardy, G.E.S.J., Grigg, A.H., Grant, C.D., Fleming, P.A. & Hobbs, R.J. (2007). 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