Chick-Provisioning and Other Behaviour of a Pair of Torresian Crows Cmvus Orru

207 AUSTRALIAN FIELD ORNITHOLOGY 2005, 22, 207-209 Chick-provisioning and other Behaviour of a Pair of Torresian Crows Cmvus orru DAVID SECOMB 21 Aberdeen Street, Katanning, Western Australia 6317 (Email: [email protected]) Summary Observations near Coffs Harbour (New South Wales) on one afternoon in week 3 of the nestling phase revealed that the presumed female Torresian Crow Corvus orru brooded for 35% of observation time (2.3 h), and both sexes fed the nestlings at a combined rate of 3.0 deliveries/ h ( n = 7). Both sexes defended the nest against potential predators, and the female performed an undulating return flight, with calling, after evicting a raptor. Introduction The breeding behaviour of the Torresian Crow Corvus orru has been studied (Rowley 1973), though in less detail than for some other Australian corvids, and little information has been added since then (Debus 1996). This paper describes an opportunistic observation of the parental behaviour of Torresian Crows on the North Coast of New South Wales in October 1996, made during a study of the Forest Raven C. tasmanicus (Secomb 2005b ). Study area and methods Observations of one Torresian Crow nest were made for 137 minutes on one day (26 October) on a small rural property near the village of Valla (30°36'S, 152°58'E), 40 km south of Coffs Harbour, NSW, between 1503 and 1720 h. As crows are shy around the nest, observations were made with the aid of a 20x telescope from a house 400 m away. The adults were sexed on the basis that only female Corvus species incubate or brood (Rowley 1973). The nest was in the top of one of a stand of three Hoop PinesAraucaria cunninghamii, used by the Crows for nesting in several consecutive years (S. Robinson pers. comm.). The pines are on a small creek that has several small dams along it. The surrounding area is cleared grazing land, orchards and macadamia plantations, with a 1-ha forest remnant 100m from the nest and a wide forest corridor (dominated by Blackbutt Eucalyptus pilularis, Tallowwood E. microcorys and Turpentine Syncarpia glomulifera) 400 m from the nest. Results Parental behaviour The two or three young Crows were about half-grown ( -25 days old, from Rowley 1973). The female brooded in stints of 12, 30, 2 and 4 minutes (35% of observation time), the last two stints being disrupted by intruders (one unidentified, the second a Grey Goshawk Accipiter novaehollandiae). Both adult Crows fed the young: the female at 1520 h, male at 1534 h, female at 1539 and 1548 h, sex unknown at 1626 h, female at 1640 h, and male at 1703 h ( = seven feeds in total), giving a combined rate of 3.0 deliveries/h. The adults often landed low in the tree then worked their way up the branches, through thick foliage, to the nest. After feeding the young, the female took 2-3 minutes to settle on the nest. Twice, the male AUSTRALIAN 208 SECOMB FIELD ORNITHOLOGY remained about 20-50 m from the nest during the female's extended absence. At 1532 h the male, with an object in his bill, flew to the ground in the nest area, but was subsequently seen without anything in his bill. At 1626 h an adult flew to the same point and gathered food from under grass, then took the food to the young. This foraging site appeared to be a cache. Calling was heard six times during the afternoon: female four times, male once and both together once. Twice, calling was related to nest-defence, three times apparently in defence of territory against other Torresian Crows, and once as the female departed from the nest and landed elsewhere when the male arrived to feed the young. Territorial defence Twice, Laughing Kookaburras Dacelo novaeguineae were vigorously chased when close to the Crows' nest. On one occasion the male chased a Kookaburra for 50 m and followed it, calling, for a further 50 m. On another occasion both Crows displaced and chased two Kookaburras. The female joined with other Torresian Crows and Australian Magpies Gymnorhina tibicen in chasing a Grey Goshawk. The pursuers were first seen 600 m from the nest, but after 5 minutes and nearer her nest (100m), the female Crow left and closely followed the group of mobbing birds to 300 m from the nest. She returned with undulating flight, calling with three well-spaced long oh notes as she folded her wings to her body. Meanwhile the male had landed 50 m from the nest, just before she left, but he did not assist in the chase. Once, the female left the nest and flew 400 m to the forested area to the north, calling often with drooped wings as she flew. For long periods (ranging from 15 to 45 minutes) at least four other Torresian Crows were heard in the forest, during which there were three possible responses from the breeding pair. On all occasions the pair was at the forest edge, perhaps a territory boundary. Discussion These observations extend previous information (Rowley 1973; Debus 1996) on the parental, defensive and display behaviour of the Torresian Crow. This species appears to resemble the better-known large, resident corvids (Australian Raven Corvus coronoides and Forest Raven) in these aspects of its biology, although the undulating 'currawong' display-flight is characteristic of the crows (Little C. bennetti and Torresian) rather than the raven group (Debus 1996; Higgins et al. 2006). Most corvids, including Torresian Crows, are known to cache food for later recovery (e.g. Ley 1995; Secomb 2005a; Higgins et al. 2006). Caching appears to play a significant role in the provisioning of nestlings (Secomb 2005a,b). Acknowledgements Thanks to S. & N. Robinson for kindly allowing the observations on their property, Barbara Lake for lending a telescope, Stephen Debus for assistance with a draft, Andrew Ley and Darryl Jones for reviewing it, and to Mary for her continual support. VOL. 22 (4) DECEMBER 2005 Parental Behaviour of Torresian Crow 209 References Debus, S.J.S. (1996), 'Crows and ravens', pp. 263-281 in Strahan R. (Ed.), Finches, Bowerbirds & Other Passerines ofAustralia, Angus & Robertson, Sydney. Higgins, P.J., Peter, J.M. & Cowling, S.J. (Eds) (2006), Handbook ofAustralian , New Zealand and Antarctic Birds, vol. 7, Oxford University Press, Melbourne. Ley, A.J. (1995), 'Recovery of cached food by Torresian Crow', Australian Bird Watcher 16, 77. Rowley, I. (1973), 'The comparative ecology of Australian corvids. IV Nesting and rearing of young to independence', CSIRO Wildlife Research 18, 91-130. Secomb, D. (2005a), 'Arboreal foraging and food-caching by the Forest Raven C01vus tasmanicus', Australian Field Ornithology 22, 67- 71. Secomb, D. (2005b), 'Breeding biology and behaviour of the Northern Forest Raven C01vus tasmanicus bore us', Australian Field Ornithology 22, 126-136. Received 20 March 2005 • .

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