PROOF Australian Field Ornithology 2019, 36, 1–4 http://dx.doi.org/10.20938/afo36001004

Prey-caching in the Nankeen Falco cenchroides, and a review of caching in other Australian

James A. Fitzsimons1,2, Janelle L. Thomas3 and Stephen J.S. Debus4

1The Nature Conservancy, Suite 2–01, 60 Leicester Street, Carlton VIC 3053, . Email: [email protected] 2School of Life and Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood VIC 3125, Australia 3BirdLife Australia, Suite 2–05, 60 Leicester Street, Carlton VIC 3053, Australia. Email: [email protected] 4Division of Zoology, University of New England, Armidale NSW 2351, Australia. Email: [email protected]

Abstract. We describe two instances of a Nankeen Kestrel Falco cenchroides caching a House Mouse Mus musculus in winter: (1) beneath ground vegetation, and (2) beneath a clod of earth in a ploughed field. As caching is seldom reported in this or other Australian falcons, we review reports of caching by Australian falcons, and by Northern Hemisphere in which the habit is well studied.

Introduction The Kestrel landed on a slightly elevated mound covered with Rounded Noon-flower Disphyma crassifolium subsp. clavellatum on the edge of the bank of the Little River. Over Prey-caching, the hiding of food for later retrieval and the course of c. 1 minute, it attempted to push the mouse consumption, is undertaken by several families. under the noon-flower with its bill, then pulled it out and Caching helps make mealtimes more regular and repositioned it several times (see Figure 1). Eventually it increases efficiency by reducing the time required for left the mouse and flew a few metres. Here, it wiped the hunting (by storing prey when food is at a premium) fur off its beak on the ground. The mouse was not totally (Olsen 1995). Cached items may not necessarily be fully concealed. The Kestrel then went back to hunting by concealed, but simply out of sight of passing competitors hovering ~20 m away. No further observations were made that might steal the item. Vander Wall (1990) identified and we did not wait to see if the bird returned. published accounts of caching for 17 (Falco) species, and White et al. (1994, p. 230) suggested that In June 2012, SJSD observed an adult female Nankeen at least 21 species of Falco have been recorded caching Kestrel flying several low circuits within 1–2 m of the ground and that “It will probably be found to occur in most if not of a freshly ploughed paddock, carrying a mouse (most all falcon species” (Cade 1982 and Anderson & Squires likely a House Mouse on the basis of previous local raptor 1997 suggested similar). Significant research on this and owl dietary studies: Debus & Rose 2004; Debus et behaviour has been undertaken for American Kestrels al. 2006) at Tamworth, New South Wales. Crop fields and F. sparverius (e.g. Mueller 1974; Nunn et al. 1976; Collopy weedy road-verges adjoined the site just east of the city 1977; Bildstein 1982; Toland 1984) and Common Kestrels (at 31°07′42′′S, 150°59′26′′E). Initially, it was considered F. tinnunculus (e.g. Rijnsdorp et al. 1981; Masman et al. that she was looking for a place to land and consume 1986; Rejt et al. 2000). In Australia and New Zealand, the mouse, but she landed on a raised clod, placed the Marchant & Higgins (1993) in their general introduction mouse under the clod and immediately flew up to perch to the Family suggested that “Food may be on a power-pole, without the mouse. At the time House cached” (p. 326) but listed caching for only three species in Mice were abundant in the district, and Black-shouldered the species accounts: the Peregrine Falcon F. peregrinus Kites Elanus axillaris were also abundant (and breeding); (caching studied by Cameron & Olsen 1993), New Zealand the Kites (and other Kestrels) were often seen catching Falcon F. novaeseelandiae and F. berigora. mice during raptor fieldwork by SJSD throughout autumn Following the reviews of Marchant & Higgins (1993) and to spring of that year. White et al. (1994), Olsen (1995) noted observations of prey-caching by the Nankeen Kestrel F. cenchroides, and caching has also been reported for the Black Falcon Discussion F. subniger (Olsen 1995; Charley et al. 2014; Debus et al. Compared with global research (Toland 1984; Nunn et al. 2017). Considering the scarcity of published observations 1976; Vander Wall 1990; White et al. 1994), other than of caching in Australian falcon species, we document two the study by Cameron & Olsen (1993) for the Peregrine cases of this behaviour for the Nankeen Kestrel. Falcon, published records of prey-caching for Australian falcons are sparse and descriptions brief, and for few Observations species (Marchant & Higgins 1993; Olsen 1995; Charley et al. 2014; Debus et al. 2017). This is despite the statement by Marchant & Higgins (1993, p. 326) that “Food may be At c. 0915 h on 28 July 2012, JAF and JLT observed a cached” for Falconidae, and by Olsen (1995, p. 100) that Nankeen Kestrel flying low holding a House Mouse Mus “On occasion all Australian falcons... cache prey”. musculus [identified on the basis of photographs (Figure 1) and local faunistic knowledge], at the Western Treatment For the Peregrine Falcon, Marchant & Higgins (1993, Plant, Point Wilson, Victoria (38°00′12′′S, 144°34′52′′E). p. 311) summarised prey-caching as “Breeding pairs 2 Australian Field Ornithology J.A. Fitzsimons et al.

(a) (e)

(b) (f)

(c) (g)

(d) (h)

Figure 1. Nankeen Kestrel caching a House Mouse under Rounded Noon-flower at Werribee, Victoria. Sequence follows alighting with prey (a), initial placement of prey (b), and multiple attempts repositioning prey (c–g), before final cache position was determined (h). Photos: Janelle L. Thomas Prey-caching in Nankeen Kestrel 3

cache excess food recovering it usually later in the same concealed but sometimes the Kestrel spends time pushing day; cache hidden on cliff-edge, holes or stick-nest”, and grass over the cache”), there are no other published this is supported by the observations of Cameron & Olsen records of caching for Nankeen Kestrels. Considering that (1993), Turner et al. (1993) and Olsen (1995). the Nankeen Kestrel is one of Australia’s most commonly For New Zealand Falcons, Marchant & Higgins (1993, recorded (Olsen et al. 1993), the paucity of caching p. 282) suggested that they “Cache prey throughout records (Marchant & Higgins 1993; White et al. 1994; year; caching also recorded in juveniles from 7 weeks”, Hollands 2003) suggests either that this is not a common citing Lawrence & Gay (1991) and L. Barea, although activity for this species, possibly less so than Northern Fox’s (1977) work was the source of the ‘year round’ Hemisphere kestrels (e.g. American Kestrel and Common observations. Fox (1977, p. 165) observed: Kestrel), or that it is seldom reported. The possible global differences in kestrel caching might also reflect dietary If not satisfied the Falcon occasionally would extract the prey differences, e.g. Northern Hemisphere species in cool- and adjust it or hide it somewhere else. The commonest locations for caches were small 30–100 cm high bushes (see temperate zones prey heavily on vertebrates (e.g. White Plate 7.3), the prey being thrust in from above or from the et al. 1994), whereas the Australian species in warmer side. Tussocks, tree-stumps and small 3–4 m trees were also climates often prey on arthropods (e.g. Marchant & Higgins used. Although high trees might be used in forest habitat, no 1993), which may be less profitable for caching. caches above 3 m were found in this study. Neither Marchant & Higgins (1993) nor White et al. Lawrence & Gay 1991 (p. 180) observed prey-caching by (1994) reported prey-caching for the F. this species in a “clump of astelia (Astelia sp.), where it hid longipennis or Grey Falcon F. hypoleucos, and we could the food. Two different clumps of astelia were used”. find no further instances in the literature. For the Brown Falcon, Marchant & Higgins (1993, p. 241) The breeding season is the most common time for prey- stated: “Also caching prey caught for young in disused nest caching in falcons (Olsen 1995) and our observations of for 2 h (Anon. 1907)”. Anon. is really Ford (1907, p. 200), Nankeen Kestrels caching were at the start of the nominal who also found breeding season for this species (Marchant & Higgins Once there seemed to be an extra supply of lizards, as the 1993) (searches for breeding events were not conducted male took one and left it on an old nest 100 yards away for at Werribee, but were observed in the Tamworth district in two hours, when he came back for it. spring 2012). White et al. 1994 (p. 230) in their summary of Bollen (1993, pp. 21–22) described an instance of caching the Falconidae stated that by a female Brown Falcon at the end of the incubation In nearly all seasons, most caches are to be found in period: conspicuous locations, such as prominent clumps of grass she collected the prey item [Common Starling Sturnus in a field, unused nests or other obvious locations in trees, or vulgaris], flew about 70 m away from the nest tree and conspicuous ledges or nooks on cliffs and buildings. appeared to drop the item into a grass tussock. She then For the better-studied kestrels in the Northern Hemisphere, flew back to her perch without the prey. grass tufts are favoured as cache sites (e.g. Clegg 1971; Mooney (1982) also observed prey-caching of a Common Nunn et al. 1976; Collopy 1977). The behaviour of the Starling by a Brown Falcon on a rocky foreshore outcrop, Nankeen Kestrel in our observations is similar to that of just above high-tide level. McDonald (2003, 2004) found Northern Hemisphere kestrel species. For the Tamworth that female Brown Falcons frequently cached larger prey incident, SJSD speculates that there were more catchable items (at the Western Treatment Plant) if chicks could mice around than a Kestrel could immediately consume, not consume them in one sitting and suggested that this and that her low flight was to memorise the spot (in a behaviour “demonstrates that the practice is widespread rather featureless dirt paddock) where she hid the mouse and common throughout the entire breeding season” (which was perhaps surplus to her immediate energy and that “cached prey was usually used to feed offspring requirements). Considering the significant research on immediately prior to sunrise and after dark, periods when prey-caching that has been undertaken for falcon species c hunting was not likely to be successful” (M Donald 2004, (and particularly kestrels) in the Northern Hemisphere, p. 5). further research is required to determine the relative Marchant & Higgins (1993) did not specify caching in importance of this behaviour in Australian falcons. Black Falcons, but Olsen (1995, p. 101) noted that the species was “seen storing prey in the wall of a farm dam during winter”. Charley et al. (2014) observed breeding Acknowledgements Black Falcons prey-caching: at three sites in horizontal We thank Jonny Schoenjahn and an anonymous referee for hollow limbs in the nest-tree, one on the ground at the base helpful comments on a draft of this manuscript. of a eucalypt near the nest-tree, and one in the hollow of a dead tree near the nest-site. Debus et al. (2017) similarly observed cache sites in a branch fork in the nest-tree, in a References hollow limb near the nest-tree, and in an undetermined site Anderson, S.H. & Squires, J.R. (1997). The Prairie Falcon. in a large eucalypt in the nest area. Both studies observed University of Texas Press, Austin, Texas, USA. retrieval of cached prey. Bildstein, K.L. (1982). Prey concealment by American Kestrels. Raptor Research 16, 83–88. Besides Olsen’s (1995, pp. 101–102) photograph and Bollen, C. (1993). Breeding behaviour and diet of the Brown description (“Nankeen Kestrels push lizards under a rock, Falcon Falco berigora on the southern tablelands of New South hide a mouse in grass at the base of a log or stuff it into Wales. Australian Bird Watcher 15, 19–23. a crotch of a tree”, “In this case the mouse was barely Cade, T.J. (1982). The Falcons of the World. Collins, London. 4 Australian Field Ornithology J.A. Fitzsimons et al.

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