VOL. 16 (8) DECEMBER 1996 339

AUSTRALIAN BIRD WATCHER 1996, 16, 339-343

Notes on the Diet of the Southern Boobook Ninox novaeseelandiae in

by A.B. ROSE, Associate, The Australian Museum, 6-8 College Street, , N.S.W. 2000 (present address: 61 Boundary Street, Forster, N.S.W. 2428)

This paper presents further data on the diet of the Southern Boobook Ninox novaeseelandiae from various locations throughout New South Wales, as a follow­ up to the note by Campbell & Rose (1996). It is a compilation from the examination of stomach contents of owls found dead on roads (treated here as 'road kills'), and of samples of regurgitated pellets from Boobook roosts, but does not include the stomach samples previously detailed by Rose (1973). The samples represent opportunistic collections of dead owls or pellets, mainly by National Parks & Wildlife Service staff. Many of the owl specimens were too damaged to sex and age by dissection. 'Immature' owls were those with skulls not fully pneumatised; 'subadults' were those that had not yet bred (oviduct not convoluted). The samples were treated according to the procedure previously described (Rose 1996), and the contents were identified by comparison with reference material and (for ) by reference to CSIRO (1970).

Road kills The stomach contents of each specimen are listed for the following 20 localities, in the order spring, summer (Boobook breeding season), autumn, winter (non-breeding season). (1) Yarras, Oxley Highway (north coast, 31 °25 'S, 152 °19'E), 30 September 1978 (N. Swanson): (), beetles (Coleoptera) including scarabs (Scarabaeidae), crickets/grasshoppers (Orthoptera), and a spider (Araneae). (2) Mt Colah, northern Sydney (33 °40'S, 151 °07'E), 14 November 1974 (ABR) : beetles including green scarabs, orthopterans including Black Crickets Teleogryllus commodus. (3) Galston (33 °39'S, 151 °03'E), 14 December 1980 (S. Foster): scarabs and longicorn beetles (Cerambycidae), a mole cricket (Gryllotalpidae) and moths. (4) near (33 °26'S, 151 °20 'E), 3 January 1975 (K. Blade): large black cockroach (Blattodea), many orthopterans including crickets (Gryllidae) and acridid grasshoppers, Christmas beetles Anoplognathus viriditarsus (Scarabaeidae). (5) Narrandera (34 °45'S, 146 °33'E), 4 January 1976 (R. Moffatt): a Common Starling Stumus vulgaris, a mantis (Mantidae) and beetles. (6) Kos~iusko National Park (32 °52 'S, 148 °30 'E), January 1979 (collector unknown): beetles. (7) Gloucester (32 °00'S, 151 °57'E), 7 January 1980 (D . Hardman), owl very fat with full stomach: three mole crickets (33 % by no.), a Black Cricket (11 %), a long-horned grasshopper (Tettigoniidae, 11 %) , a stick (Phasmatidae, 11%) and three Gum Longicorn Beetles Acrianome spinicollis (Cerambycidae, 33%) (n = 9 items). (8) Mt Ku-ring-gai, northern Sydney (33 °39 'S, 151 °08 'E), 28 January 1980 (ABR): orthopterans, a stick insect and a . AUSTRALIAN 340 ROSE BIRD WATCHER

(9) Yarrangobilly (35°39'S, 148°28'E), 12 March 1974, immature (R. McKinney): a male and four female huntsman spiders /sopedn sp. (26% by no.), a stick insect Didymuria violescens (Phasmatidae, 5%), a moth (5%) and 12 tettigoniid grasshoppers (Orthoptera, 63%) (n = 19 items). (10) Old Bar near Taree (31 °58'S, 152°35'E), 16 March 1978 (M. Dodkin): three tettigoniid grasshoppers, a Black Cricket, a Christmas beetle Anoplognathus sp. and moths. (11) Gloucester (32 °01 ,S, 151 °58'E), 11 Aprill972, subadult female (J. Gilchrist): a wolf spider Lycosa sp., a cockroach Laxta sp., moths and immature Black Crickets. (12) Booti Booti National Park south of Forster (32 °ll'S, 152 °3l'E), 6 April 1996, immature: a grasshopper Caedicia sp. and three large moths Abantiades hyalinatus (). There was an emergence of the moths on the night of 5 April (M. Bowen & D. Hackett pers. comm., collectors of the specimen). (13) Laguna south ofWollombi (33 °00'S, 151 °08'E), 16 May 1971 (ABR): mainly moths, a weevil (Curculionidae) and detritus. (14) Springwood (33 °42'S, 150°34'E), 3 May 1975, adult (K. Armstrong): moths, orthopterans, a beetle and a House Mouse Mus domesticus. (15) Grenfell (33°54'S, 148°l0'E), 15 May 1978, adult (R. Moffatt): a moth and four scarab beetles. (16) Fitzroy Falls (34 °38 'S , 150 °28 'E), 12 July 1974 (R. Moffatt): a spider, beetle, cockroach and moths. (17) Gunnedah (30°59'S, 150°15'E), 30 August 1974, adult (K. Blade): 10 moths and a wolf spider. (18) Ku-ring-gai Chase National Park (33°40'S, 151 °10'E), 18 August 1977 (S . Stephens): moths. (19) Asquith, northern Sydney (33°41'S, 151°07'E), 23 August 1978, adult (M. Ingram): a House Mouse, spider, cockroach, orthopterans and moths. (20) Dorrigo (30°20'S, 152 °43'E), undated 1976 (collector unknown): four mygalomorph spiders, three moths, and beetles including one longicorn Uracanthus sp. (Cerambycidae). Of these owls, three immatures/subadults had eaten only , two adults had eaten only arthropods and two adults had eaten arthropods and mice. Moths, beetles, orthopterans and spiders occurred with greatest frequency in Boobook stomachs (Table 1).

Pellets Pellets and pellet material were examined from the following 10 sites, again listed by season. (1) Armidale (30°30 'S, 151 °40'E), 20 October 1976: Boobook pellets collected by I. Archibald (an experienced bird-watcher, now museum curator, Darwin) contained Christmas beetles, several House Mice, a juvenile Rabbit Oryctolagus cuniculus, two House Sparrows Passer domesticus and a thornbill Acanthiza sp. (2) Marra Marra National Park north of Sydney (33 °-3 l'S, 151 °06'E), 12 December 1982: I found under a rock overhang the remains of pellets and moulted Boobook feathers. The pellets contained a Brown Antechinus Antechinus stuartii and insects including scarab beetles, a longicom beetle Phoracantha sp., cockroaches and moths. VOL. 16 (8) DECEMBER 1996 Diet of Southern Boobook in N.S .W. 341

Table 1: Frequency of prey types in the stomachs of road-killed Southern Boobooks (total 20) in New South Wales (various localities; see text). Prey n stomachs %frequency Moths 15 75 Beetles 12 60 Orthopterans 12 60 Spiders 7 35 Cockroach 4 20 Stick insect 3 15 Mantis 1 5 Weevil 1 5 Common Starling 1 5 House Mouse 2 10

(3) Dharug National Park near (33 °23'S, 150°59 'E), January 198 1: Boobook pellet remains from a sandstone cave, collected by R. Conroy, contained a House Mouse, beetles, orthopterans and moths. (4) Grafton (29°4l'S, 152 °56'E), March 1982: material collected beneath a Boobook roost by D. Fahey (conveyed by G. Clancy) contained insects, a Gould's Wattled Bat Chalinolobus gouldii, a Bush Rat Rattus fuscipes, three House Mice and five House Sparrows. (5) Lake Innes near Port Macquarie (31 °30 'S, 152 °53 'E), April 1981: I found four Boobook pellets which contained (a) Black Cricket; (b) and (c) Black Cricket and House Mouse; (d) Black Cricket, House Mouse and beetle. (6) Ku-ring-gai Chase National Park (Little Shark Rock, Cowan Water 33 °35'S, 151 °l2'E), Aprill983: I found what appeared to be a Boobook pellet containing crab (Decapoda), millipede (Diplopoda) and beetles including a weevil. (7) Lion Island, (33 °33 'S, 151 °l8'E), 2 June 1981: I found under a rock overhang the dried carcass of a Boobook (presumed roost occupant) and a pellet that contained beetle, ant (Formicidae) and Eastern Water Dragon Physignathus lesueurii (scales, of presumed juvenile lizard). At the roost in January 1982 a pellet contained beetles, skink scales and a bronze-cuckoo Chrysococcyx sp. (8) Little Cattai Creek north-west of Sydney (33 o33 'S, 150 °55 'E), 28 June 1983 : I located a Boobook roost under a rock overhang. The owl's pellets contained a small bird and insects including moths, orthopterans, cicadas (Cicadidae) and beetles (among them scarabs and cerambycids). Amongst the dust were similar insect remains, a small bird and the jawbones of seven species of mammal: five Brown Antechinuses, a Feathertail Glider Acrobates pygmaeus, a juvenile Common Ringtail Possum Pseudocheirus peregrinus, a Bush Rat, a House Mouse, two Gould's Wattled Bats and a Lesser Long-eared Bat Nyctophilus geoffroyi. It is possible that the roost had been occupied previously by a different species of owl, although no feathers were found . (9) Thirlmere Lakes National Park south of Sydney (34 °l4'S, 150 °31 'E) , June 1982: pellets collected from a rock overhang by R. Kinnish, who saw a Boobook at the roost, contained insects (including beetles, moths and a stick insect), a spider, a House Mouse, a Sugar Glider Petaurus breviceps and a Gould's Wattled Bat. On 25 July 1983 Kinnish collected from this roost a further 10 pellets which contained a Common Dunnart Sminthopsis murina (4% by no.), two Brown Antechinuses (8%), a Bush Rat (4%), a bat (4%), a Common Myna Acridotheres AUSTRALIAN 342 ROSE BIRD WATCHER

Table 2: Frequency of prey types in pellet samples (n = 12 pellet collections) of the Southern Boobook from eastern New South Wales (various localities; see text). Prey n samples %frequency Small marsupials 3 25 Bats 3 25 Rodents 7 58 Juvenile rabbit 1 8 Common Myna 1 8 Small birds 5 42 Reptiles 2 17 Crab 1 8 Millipede 1 8 Spiders 2 17 Beetles 11 92 Moths 5 42 Orthopterans 4 33 Cockroaches 1 8 Stick insect 1 8 Cicadas 1 8 Ant 1 8

tristis (4%), another bird (4%), six beetles (24%), four moths (16%), an orthopteran (4%), a spider (4%), and six unidentified insects (24%) ( n = 25 items), or 20% mammals, 8% birds and 72% arthropods by number. However, these items represent c. 95% vertebrate prey by biomass, from mammal weights in Strahan (1983) and assuming 100 g for the myna, 20 g for the other bird and 1 g per . (10) Dharug National Park (33 °20'S, 151 °05'E), 12 August 1985: pellets collected by G. Clancy, and which appeared to be from a Boobook, contained a Bush Rat, a House Mouse and beetles. Of the foregoing pellet samples (total 12 pellet collections), arthropods occurred in all 12 (predominantly beetles, orthopterans, moths and spiders), reptiles in two (17%), birds in five (42%) and mammals in eight (67%) (Table 2). In addition, at Morgans Cave in Benambra State Forest near Albury (35 °48 'S, 147 °03'E), in October 1978, I found Barn Owl Tyto alba and Boobook moulted feathers at a roost site. At the roost were remains of beetles, moths, orthopterans and other insects, parrot, finch, Yellow-footed Antechinus Antechinus jlavipes, juvenile Common Ringtai1 Possum, Eastern Pygmy Possum Cercanetus nanus, Feathertail Glider, House Mouse, Black Rat Rattus rattus and juvenile Rabbit. With two owl species using the roost over time, it is impossible to attribute the prey remains to one rather than the other although the larger items were less likely to have been taken by the Boobook.

Discussion The stomach contents, and other prey items definitely attributable to the Boobook (pellet sites 1-5, 7, 8 [pellets only] and 9), confirm the dietary preferences of this species and slightly extend the known prey list (cf. -Schodde & Mason 1980, Green et al. 1986, Barker & Vestjens 1989, Hollands 1991, Campbell & Rose 1996). Invertebrates predominated in the stomach samples year-round, with a few small vertebrates present in summer, autumn and winter and no seasonal pattern in dietary composition evident. Vertebrates predominated by biomass in the pellets, although VOL. 16 (8) DECEMBER 1996 Diet of Southern Boobook in N.S.W. 343

invertebrates were also abundant in some samples; again there was no clear seasonal pattern, with the time of pellet deposition in some cases unknown or only approximate. The apparent discrepancy between the stomach and pellet samples suggests that some of the pellet collections may not accurately reflect what was eaten. Possible reasons for the differences are: (a) pellets consisting wholely or mainly of invertebrate remains may break down more quickly and be less likely to be found or collected; (b) pellets with obvious vertebrate remains may in some cases be selectively collected as more interesting; (c) the road-killed owls may include many inexperienced juvenile or immature birds forced into marginal habitats where they subsist on invertebrates, whereas the pellets from desirable roost sites (e.g. rock overhangs) may be from adult owls; (d) some of the pellet samples may have been deposited by more than one owl species. Perhaps, also, owls foraging along roads often concentrate on insects attracted to lights, hence a possible bias in stomach samples from road-killed birds. In support of age-related differences in diet, as suggested by the road-killed owls in this study, is the fact that three juvenile Boobooks (in Rose 1973) had eaten only invertebrates. Against the possibility of pellet misidentification is the fact that the Boobook was previously known to take mammals up to rat and juvenile Rabbit size and birds up to Common Myna and parrot size (Lawrence 1959, Green et al. 1986, Barker & Vestjens 1989). The Morgans Cave sample illustrates that great care is needed in assigning pellet samples to an owl species without strong corroborating evidence of the owl's identity, because more than one owl species may use a desirable roost site (such as a cave) over time. Of the pellet samples discussed, pellet site 8 (Little Cattai Creek) contained mammal remains possibly attributable to another owl species, but most of those mammals are known in the Boobook's diet and the juvenile Ringtail Possum would be equivalent to a rat or juvenile Rabbit. Even allowing for possible misidentifications of owl pellets, it is apparent that the Boobook is a capable predator of vertebrates even if it does mostly eat invertebrates.

Acknowledgements Thanks are due to N.S.W. National Parks & Wildlife Service rangers and others who provided specimens, and to S. Debus for much work in rearranging this information for publication. I gratefully acknowledge the facilities provided by the Australian Museum. References Barker, R.D. & Vestjens, W.J.M. (1989), The Food of Australian Birds. 1. Non-passerines, CSIRO, Melbourne. Campbell, B. & Rose, A.B. (1996), 'Diet of the Southern Boobook Ninox novaeseelandiae on the north coast of New South Wales', Aust. Bird Watcher 16, 349-351. CSIRO (1970), The Insects of , Melbourne University Press, Melbourne. Green, R.H., Rainbird, J.L. & McQuillan, P.B. (1986), 'Food of the Southern Boobook Ninox novaeseelandiae', Tas. Nat. 86, 1-3 . Hollands, D. (1991), Birds of the Night, Reed, Sydney. Lawrence, S.A. (1959), 'Boobook Owl carrying mynah', Aust. Bird Watcher 1, 180. Rose, A.B. (1973), 'Food of some Australian birds', Emu 73, 177-183 . --(1996), 'Notes on the diet of the Barn Owl Tyto alba in New South Wales', Aust. Bird Watcher 16, 327-331. Schodde, R. & Mason, I.J. (1980), Nocturnal Birds of Australia, Lansdowne, Melbourne. Strahan, R. (Ed.) (1983), The Australian Museum Complete Book of Australian Mammals, Angus & Robertson, Sydney. Received 1 May 1996 •