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VOL. 17 (1) MARCH 1997 25

AUSTRALIAN WATCHER 1997, 17, 25-33

Diet of the Tawny strigoides in Eastern New South Wales

by A.B. ROSE 1 and R.H. ELDRIDGE2

1Associate, The Australian Museum, 6-8 College Street, Sydney, N.S.W. 2000 (present address: 61 Boundary Street, Forster, N.S.W. 2428) 2State Forests of New South Wales, P.O. Box 100, Beecroft, N.S.W. 2119

Summary The diet of the Tawny Frogmouth Podargus strigoides in eastern New South Wales was determined from an analysis of stomach contents of 40 found dead (mostly road kills) . preyed predominantly on insects (especially , orthopterans, and caterpillars), but also some other arthropods (notably and ) and a few and mice. There was slight seasonal variation in diet composition, with orthopterans, moths and spiders less important in winter than in summer, and caterpillars, cockroaches, centipedes and small more important in winter than in summer. Frogmouths appeared to accumulate fat after the breeding season in preparation for periods of food shortage in winter. Some individuals appeared to suffer from poisoning when they metabolised that fat in winter.

Introduction The diet of the Tawny Frogmouth Podargus strigoides is reasonably well known in general terms, though with little quantification. This species is known to eat a range of terrestrial , supplemented by a few small terrestrial vertebrates including and frogs (e.g. Schodde & Mason 1980, Blakers et al . 1984, Barker & Vestjens 1989, Hollands 1991, Strahan 1994). Rose (1973) listed the contents of 11 stomachs from road-killed Tawny Frogmouths in eastern New South Wales. This paper presents the results for a further 29 Frogmouth stomachs, mostly from birds dead on roads (here also treated as 'road kills'). Those data are combined with the original 11 stomachs into an analysis of all 40 samples. An aim of the study was to determine whether there was any seasonal variation in diet composition. Evidence for pesticide poisoning was also considered (cf. Rose 1976, Fleay 1981).

Methods Dead Frogmouths were collected opportunistically in eastern New South Wales from 1966 to 1982, stored frozen, and their stomach contents preserved in alcohol. The prey items in the stomachs were examined under a hand-lens and binocular microscope, and identified with the aid of a reference collection and by reference to CSIRO (1970). Where possible, the number of individual prey items per species in the stomach was counted for each bird by counting skeletal parts. An assessment of body fat was also made using the technique described by Rose (1976). Regurgitated pellets or pellet/faecal material were collected beneath one Tawny Frogmouth roost and one active by ABR. The prey remains were analysed in the same manner as the stomach contents. Frogmouths found dead or dying in gardens, but uninjured, were dissected and examined for possible causes of death, including symptoms of pesticide poisoning (notably, prominent blood vessels showing in the skin; see Newton eta!. 1991, Rose 1996). One carcass (no. 14) was sent to Macquarie University for laboratory testing for pesticide residues.

Results

Road kills and other dead birds Tawny Frogmouths were examined from the following localities ('road-killed ' AUSTRALIAN 26 ROSE & ELDRIDGE BIRD WATCHER unless otherwise stated). Specimens are listed by season (in the order spring, summer, autumn, winter). 'Signs of poisoning' in all cases refers to symptoms of pesticide poisoning as determined from autopsy, i.e. prominent blood vessels noted in the skin. l. Gosford area (33 °29 'S, 151 o 19 'E), 1 September 1972 (B. Cameron-Smith): stomach crammed full with 25 king crickets Australostoma sp., five centipedes Ethmostigma rubripes (one 15 em long) , one House Mus domesticus, four spiders (Araneida, one Deinopidae), six beetles (Coleoptera; two sc1.1rabs Scarabaeidae and one click Elateridae), one long-horned grasshopper (Orthoptera: Tettigoniidae), moths and a caterpillar (Lepidoptera); also feather fragments (probably its own) . 2. Heathcote (34 °05 'S, 151 °01 'E), 18 September 1972 (J. Somerlad), no fat, stomach almost empty: three species of beetle only. 3. Broken Bay Fitness Camp (33°33'S, 151 °17'E), 17 September 1975 (the Manager), stomach almost empty: beetle remains only, including weevil (Curculionidae). 4. Narrabri (30~0'S, 149°44'E), 26 October 1977 (P. Davies), fat: stomach full with three Spotted Grass-Frogs Limnodynastes tasmaniensis, cockroach (Blattodea) and beetle remains. 5. Turramurra, northern Sydney suburb (33°44'S, 151 °09'E), 1 November 1982 (ABR), found dead, uninjured, signs of poisoning: beetle remains including longicorn (Cerambycidae). 6. Pearl Beach (33 °32 'S, 151 °l8'E), 6 January 1975 (K. Blade), fat: stomach full with Christmas beetles Anoplognathus viriditarsus. and one A. porosus, one stick insect (Phasmatidae) 16 em long, one earthworm (Oiigochaeta: Lumbricidae), one huntsman lsopeda sp., two orthopterans (Gryllacrididae), lepidopteran scales. 7. Cowra (33°50'S, 148°45'E), 14 February 1974 (ABR): beetles including Anoplognathus sp., orthopterans and one spider. 8. Mt Colah, northern Sydney suburb (33 °40'S, 151 °07'E), February 1975 (ABR), stomach almost empty, fat: a few ground-up remains including orthopteran, beetle, and a phasmatid egg (4 mm). 9. Ku-ring-gai Chase National Park (33°38'S, 151 °14'E), 24 February 1975 (A . Norman), very fat: several king crickets Australostoma sp., one spider Nicodamus bicolor, two cockroaches (one Oniscosoma sp. and one Platyzosteria sp.), beetles including a large ground-beetle (Carabidae), bones of a , remains (Hymenoptera: Forrnicidae, probably the gut contents of the frog). 10. Frederickton near Kempsey (31 °02'S, 152°53'E), 20 February 1976 (M. Dodkin), very fat: two frogs (one a Leaf-green Tree-Frog Litoria phyllochroa), one , three orthopterali.s (one eumastacid, one tettigoniid, one mole-cricket Gryllotalpidae), one spider. [The Litoria frog had eaten two caterpillars, a homopteran nymph and several beetles including weevil and ground-beetle.] 11. Ku-ring-gai Chase road (33 °40 'S, 151 °10 'E), 18 February 1981 (D. Sharpe), fat: stomach full with one (Diplopoda), two huntsman spiders, one mantis (Mantidae), two long-horned grasshoppers, beetles including eight weevils and three cerambycids, two cockroaches (one Platyzosteria sp. and one Polyzosteria limbata). 12. Kosciusko National Park (36 °23 'S, 148 °35 'E), 3 March 1974 (R. McKinney), very fat: one Ethmostigma rubripes, two orthopterans (one Yellow-winged Locust Gastrimargus musicus, one unidentified), two large cerambycid beetles Eurynassa spinicollis. 13 . Ku-ring-gai Chase road, 4 March 1974 (ABR), very fat: stomach well 'furred' with caterpillar hairs, full with one spider, one mantis Orthodera ministralis, cockroach remains, caterpillars (arctiid and a larger 7 em long larva), four orthopterans (mole cricket, one eumastacid and two tettigoniids), balled-up grass. 14. Killara, northern Sydney suburb (33°46'S, 151 °10'E), 24 March 1975 (ABR), found sick (uninjured), later died (signs of poisoning), no fat: one mantis Didymuria violescens with eggs, one orthopteran, beetle remains. 15. Bellingen (30~7 'S, 152 °54'E), 30 March 1975 (I. Archibald), very fat: orthopterans including three locusts Austacris guttulosa, one beetle, one caterpillar and one (Gastropoda: Stylommatophora). 16. Macksville (30°43'S, 152°56'E), 30 March 1975 (I. Archibald), very fat: orthopterans (mainly eumastacids, seven crickets Gryllidae), beetles (mainly scarabs), and moths. 17. Royal National Park (34°05'S, 151 °05'E), 11 April1971 (J. Clunes), very fat: stomach full with four cockroaches (two Platyzosteria sp., one Laxta sp, one unidentified), one stick insect, one mantis Orthodera ministralis, two species of beetle, one moth, orthopterans, one spider. VOL. 17 (1) MARCH 1997 Diet of Tawny Frogmouth in N.S.W. 27

18. Dome Road, Dorrigo (30 "21 'S, 152 °45 'E), 7 Aprill975 (M. Sawtell), very fat : six king crickets, two cockroaches, one weevil, four carabid beetles, two spiders and one large frog. 19. Carrathool (34°26'S, 145°27'E), early Aprill977 (R. Moffatt), I)O fat: beetles including one carabid, one cricket (Gryllidae) and eight centipedes Ethmostigma rubripes (one 12 em, three 10 em, two 8 em and two 6 em long) . 20. Coonabarabran district (31 °15 'S, 149°16'E), 23 May 1975 (A.K. Morris): three centipedes Ethmostigma rubripes, one (Scorpionida), beetle remains including one carabid, one bull-ant Myrmecia sp., caterpillar remains, one House Mouse. 21. Wagga Wagga (35°06'S, 147°17'E), 9 May 1977 (J. Brickhill), very fat: one frog, beetles including one carabid and one weevil, orthopterans, one spider, one centipede. 22 . Brisbane Water National Park (32 °27 'S , 151 °19 'E), lJune 1972 (J . Small) , very fat: one House Mouse, one snail (Gastropoda: Stylomrnatophora), two centipedes Ethmostigma rubripes, two caterpillars, beetles. 23. Hornsby, northern Sydney suburb (33 °41 'S , 151 °06'E), 1 June 1972 (J. Small): stomach empty. 24. Killara (33°46'S, 151 °10'E), 25 July 1975 (Mrs Boyd-Boland), stomach almost empty, found dead uninjured, signs of poisoning: some beetle and bug () remains and detritus. 25. Bobbin Head (33 °39 'S, 151 °09 'E), 22 August 1972 (T. Barratt), no fat, stomach almost empty : one cockroach, one beetle and one caterpillar. 26. Turramurra (33 °44 'S, 151 o09 'E), 5 August 1973 (ABR), little fat , stomach almost empty, found dead uninjured, signs of poisoning, and stomach infested with roundworms: fragments of wood and a little ground-up insect (beetles including two weevils, caterpillar hairs). 27. Wahroonga, northern Sydney suburb (33 °43 'S, 151°08 'E), 24 August 1973 (ABR), little fat , stomach almost empty, found dead uninjured, signs of poisoning: beetles, acridid grasshoppers, two small frog bones and an equal amount of vegetable matter all ground up together. 28. Stroud (32°26'S, 151 °58'E), 31 August 1974 (ABR), little fat: one frog Limnodynastes sp. , one House Mouse, two acridid grasshoppers, two cockroaches, three different beetles, one wolf spider Lycosa sp., one centipede, grass, leaves and seeds of Chickweed Stellaria media. 29. Near Gosford (33°26'S, 151 °l8'E), 28 August 1975 (ABR) , no fat: two whole cockroaches, two scarabs and other beetles, detritus. Overall, Tawny Frogmouths ate mostly insects (78% of items, in 95% of stomachs), ofwhich beetles (29% of items, 88% of stomachs), orthopterans (27% of items, 68% of stomachs), and moths and caterpillars (9% of items, 45% of stomachs) were most important (Table 1). Among the beetles, the weevils, scarabs and ground-beetles were most important. Among the orthopterans, the carnivorous (wingless) crickets and long­ homed grasshoppers were most important, followed by short-homed grasshoppers and winged crickets. Of the other insects ( 13 % of items), cockroaches were next in importance (7% of items, 35% of stomachs) and the remainder contributed little. Other invertebrates were of minor importance (18% of items), notably spiders (9% of items, 45% of stomachs) and centipedes (8% of items, 23% of stomachs); some of the latter were large. Vertebrates (4% of items, 25% of stomachs) were eaten in small numbers but contributed disproportionately by biomass, given that they weighed probably 10-20 g each compared with

Table 1

Diet of the Tawny Frogmouth in eastern New South Wales 1966-1982, from the stomach contents of road-killed birds and others found dead, incorporating the data of Rose (1973); 40 birds in total. Data are presented as the minimum number of prey individuals (n) and percentage of these in the pooled sample, and the number (n and % frequency) of stomachs in which those items were found. Prey individuals StoTfUlchs with prey Prey species n % n % Coleoptera (beetles) Curculionidae 25+ 8 11 28 Scarabaeidae 11+ 3 7 18 Carabidae 10+ 3 7 18 Cerambycidae 6 2 3 8 Elateridae 2 (1 2 5 Tenebrionidae 1 (1 1 3 indetenninate 37+ 12 30 75 total 92+ 29 35 88 Orthoptera (crickets/ grasshoppers) Gryllacridoidea 39+ 12 7 18 Tettigonioidea 15+ 5 12 30 Acridoidea 12+ 4 8 20 Grylloidea 11 3 5 13 indetenninate 8+ 3 8 20 total 85+ 27 27 68 Lepidoptera (moths): adults 11+ 3 11 28 larvae 18+ 6 13 33 total 29+ 9 18 45 Blattodea (cockroaches) 23+ 7 14 35 Phasmatidae (stick insects) 6+ 2 4 10 Mantidae (mantises) 6 2 6 15 Hemiptera (bugs) 1+ (1 1 3 Pergidae (sawflies): larva 1 (1 1 3 Fonnicidae () 1 (1 1 3 Dermaptera (earwigs) 1 (1 1 3 Unidentified insect 1 (1 1 3 Total insects 246+ 78 38 95 Araneida (spiders) 28 9 18 45 Scorpionida () 1 (1 1 3 Chilopoda (centipedes) 25 8 9 23 Diplopoda () 1 (1 1 3 Oligochaeta (earthworms) 1 (1 1 3 Stylommatophora: slug 1 (1 1 3 snail 1 (1 1 3 Frogs 10 3 7 18 Mice 4 1 4 10 Total vertebrates 14 4 11 28 Total prey items 318+ Plant matter/detritus 8 20 Empty/near empty 11 28 VOL. 17 (1) MARCH 1997 Diet of Tawny Frogmouth in N.S.W. 29

78+ 72+ 133 35 (8) (8) (15) (9) 100 [2l Beetles 80 Orthopterans D Moths ci c Caterpillars >- 60 • .0 D Other insects "0'?- rz:l Spiders 40 8 Centipedes [!] Other invertebrates Vertebrates 20 •

0 Spring Summer Autumn Winter

Figure 1. Seasonal variation in the diet of road-killed Tawny Frogmouths: % prey items by no. for main prey categories. Sample sizes are total no. of prey items (total no. of stomachs in parentheses) for each season. For 'other insects' and 'other [non-insect] invertebrates', see Table 2.

the importance of vertebrates in winter, probably disproportionately so because of the greater biomass value of individual vertebrates. Including the data of Rose (1973, 1976), Frogmouths with empty or nearly empty stomachs were distributed thus: spring four (50%), summer one (13%), autumn nil, winter six (67%; two completely empty). Birds that were fat or very fat were distributed thus: spring two (25%), summer five (63%), autumn 12 (80%), winter one (11 %, on 1 June).

Nestlings The following were found dead on the ground, although there were no high winds at the time to blow them out of . Both showed signs of poisoning. 1. Wahroonga area (33°43'S, 151 °08'E), 27 October 1974 (ABR): beetle remains and detritus. 2. Mt Ku-ring-gai (33 °39 'S, 151 °08 'E), same date, different nest (P. Lucas-Smith): stomach empty. About five other nestlings found on the ground under nests, after high winds, were alive; they werehand-reared by wildlife carers.

Pellets and pellet/faecal material 1. Roost site, Lake Innes near Port Macquarie (31 °30 'S, 152 °53 'E), April 1981, pellets (ABR): beetles (mainly scarab but some weevil and carabid), a cockroach leg, mantid ootheca (egg­ case) and the leg bone of a frog. 2. Active nest, Coomba Park road (32 °18'S, 152 °28 'E) near Forster (4 December 1984), remains (pellet and/or faecal material possibly disintegrated by ants present at the site): orthopterans, beetles, one millipede and scales of a small . Evidence of pesticide poisoning ABR noticed an obvious decrease in the number of road-killed Tawny Frogmouths in the northern Sydney suburbs since the early 1970s, suggesting a local population decline. Concurrently, he had been finding or receiving specimens found dead or AUSTRALIAN VOL. 17 (1) 30 ROSE & ELDRIDGE BIRD WATCHER MARCH 1997 Diet of Tawny Frogmouth in N.S.W. 31

Table 2

Diet of the Tawny Frogmouth in eastern New South Wales (from Table 1) by season. Numben in parentheses are number of samples per season, n = no. of prey items, s = no. of stomachs. Percentages are % by no. and % frequency llf occurrence in stomachs, respectively.

Prey Spring (8) Summer (8) Autumn (15) Winter (9) . n % s % n % s % n % s % n % s % Beetles: weevils 1 1 1 13 15 21 2 25 7+ 5 7 47 2 6 11 scarabs 3 4 2 25 3+ 4 2 25 3+ 2 2 13 2 6 11 carabids 1 1 1 13 1 1 1 13 8+ 6 5 33 cerambycids 1 1 1 13 3 4 1 13 2 2 I 7 elaterids 2 3 2 25 tenebrionid 1 (1 1 7 indeterminate 12+ 15 8 100 4+ 6 4 50 12+ 9 II 73 9+ 26 7 78 total beet! es 20+ 26 s 100 26+ 37 7 88 33+ 25 14 93 13+ 37 7 78 Orthopterans: gry llacridoids 25 32 I 13 5+ 7 2 25 9+ 7 4 27 tettigonioids 4 5 3 38 4+ 6 3 38 7+ 5 6 40 acridoids 2+ 3 2 25 7+ 5 4 27 3+ 9 2 22 grylloids 2 3 2 25 9 7 3 20 indeterminate 2+ 3 1 13 6+ 5 6 40 total orthopterans 29 37 3 38 15+ 21 8 100 38+ 29 14 93 3+ 9 2 22 Moths: adults I+ I I 13 3+ 4 3 38 7+ 5 7 47 larvae 2+ 3 2 25 5 7 2 25 7+ 5 6 40 4+ 11 3 33

Cockroaches 4+ 5 3 38 4 6 2 25 10+ 8 6 40 5 14 3 33 Phasmatids 2+ 3 2 25 4 3 2 13 Mantids 2 3 2 25 4 3 4 27 Bugs I+ 3 11 Sawfly larva 13 Tawny Frogmouth Ant (1 7 Plate 4 Photo: N. Male Earwig I I 1 13 Indeterminate insect 1+ I I 13 consistent with organochlorine pesticide poisoning as Total insects 59+ 76 8 100 57+ 79 8 100 104 78 15 100 26+ 74 7 78 described by Fleay (1981) and/or Newton et al. (1991). Upon laboratory analysis at Macquarie University, Spiders 7 9 3 38 10 14 7 88 10 8 7 47 3 11 dieldrin and traces of three other were found Scorpions 1 (1 I 7 in the single bird analysed (no. 14) that had showed Centipedes 8 10 2 25 14 11 5 33 3 9 2 22 Millipede 13 the relevant symptoms (D. Mowbray pers. comm.). Earthworm 13 There had been much spraying around houses and Slug (1 7 gardens for Funnel-web Spiders Atrax robustus, and Snail 3 II ABR noted insects and other arthropods wandering around in the open for a day or so before dying - Frogs 3 4 I 13 3 4 2 25 2 2 2 13 2 6 2 22 easy prey for a nocturnal bird, which could then suffer Mice I I 1 13 I (1 I 7 2 6 2 22 secondary poisoning. Total vertebrates 4 5 2 25 3 4 2 25 3 2 3 20 4 11 3 33 Discussion Total 78+ 72+ 133 35 The results of this study agree closely with the literature on the Tawny Frogmouth's preference for dying in gardens with no injurie~ but wi~h symptom~ of poisoning (~s describ~d), nocturnal, mainly terrestrial arthropods (e.g. Schodde suggesting a new cause of mortality possibly responsible for .the d~clme . The birds still alive when found (nos 26, 27) were lethargic and lay with wmgs spread, then & Mason 1980), and indeed are a subset of the extensive prey list in Barker & Vestjens (1989). died with convulsions. Five birds (sites 5, 14, 24, 26 and 27) showed symptoms However, the results do not agree closely with the AUSTRALIAN 32 ROSE & ELDRIDGE BIRD WATCHER

statement that the Frogmouth preys mainly on 'scorpions, spiders and centipedes' (Tasmania: Mooney in Blakers et al. 1984). It is likely that there is regional variation in diet according to local prey availability, e.g. insects may be rare in Tasmania in the cooler months. Furthermore, a possible source of bias in this study is that road­ killed birds may have been preying on insects that were attracted to street lights (or vehicle headlights) and fell stunned on roadways. A notable feature of the birds was the stomach lining sometimes well 'furred' with caterpillar hairs, a feature otherwise common only in cuckoos (ABR pers. obs.). Such a feature is further evidence that the Frogmouth takes some prey types avoided by most insectivores (Schodde & Mason 1980). The small snake (scales) recorded in this study is a 'new' dietary record for the Tawny Frogmouth. Pellet and other prey material found under roosts/nests was generally a subset of that found in stomachs, suggesting that such material may accurately reflect the Frogmouth's diet. A captive bird regurgitated pellets, but such material is rarely found in the field (ABR pers. obs.), perhaps because pellets consisting mainly of arthropod material disintegrate rapidly. The unlikelihood of finding pellets, and perhaps a low search effort for them by bird-watchers, would explain why the Frogmouth has been said not to produce pellets (Schodde & Mason 1980). The diet data presented here are consistent with the view that the Tawny Frogmouth preys opportunistically on whatever nocturnal, terrestrial, moving prey it can snap up in its wide bill, according to local and seasonal prey availability, by perch hunting and swooping to the ground (e.g. RHE pers. obs., Schodde & Mason 1980). However, some of the insects taken are arboreal, winged and flying forms, and the Frogmouth may sometimes make short snatching or hawking flights to foliage, branches or air (e.g. Schodde & Mason 1980, Hollands 1991). Physiologically, the Frogmouth is characteristic of a sit-and-wait predator (McNab & Bonaccorso 1995). Its foraging behaviour deserves further study, for example by nocturnal observation of hunting methods. The data on seasonal variation in diet generally agree with the conclusion of Schodde & Mason (1980) on seasonal differences, except that the birds in this study took more spiders in summer than in winter. The seasonal variation in diet is probably a reflection of seasonal availability of prey types, rather than active selection on the Frogmouth's part. A possible interpretation of the specimen data is that Tawny Frogmouths lay down fat post-breeding (summer and autumn) to tide them over lean times in winter when food may be scarce; when drawing on that body fat in winter they then metabolise any organochlorine pesticides stored in that fat and suffer the ill effects (see also Fleay 1981). Organochlorine pesticides are now banned in Australia. The number of road kills in winter (nine birds, 26% of the 35 road kills) shows that the Frogmouth remains active through the year (see also Debus in press), contrary to the suggestion of McCulloch ( 197 5) that the species may hibernate or become torpid in cold weather. From a limited study, McNab & Bonaccorso (1995) also found no evidence that the Tawny Frogmouth undergoes torpor at ambient temperatures down to 6 oc. However, all the winter specimens of Frogmouths in this study were from mild coastal areas where the birds may not need to become torpid. Furthermore, the data do not rule out the possibility that Frogmouths can enter daily torpor on the coldest days, at high latitudes or altitudes, when food is scarce. A peak of road kills occurred in autumn (15 birds, 43% of road kills), and may partly represent dispersing immature birds which probably suffer heavy mortality. Tawny Frogmouths seem highly susceptible to being killed on roads (e.g. Schodde VOL. 17 (1) MARCH 1997 Diet of Tawny Frogmouth in N.S.W. 33

& Mason 1980). In addition to the 35 road-killed birds examined over 15 years, a further 42 mainly road-killed birds passed through ABR's freezers (from the same geographical area) without processing, owing to time constraints. The only cause of mortality recorded by ABR, other than road casualties and possible poisoning, was a single cat kill. Nestlings seem susceptible to being blown out of nests during high winds. This study, by taking advantage of a ready source of data, has demonstrated the value of making full use of road-killed specimens of a common species. A deliberately destructive sampling method was therefore avoided, while still obtaining data on a nocturnal bird that is otherwise difficult to study.

Acknowledgements We thank the National Parks & Wildlife Service rangers and other people (named above) for providing the specimens. We also thank Dr D.K. McAlpine, Curator of Insects at the Australian Museum, for assistance with identification of the stomach contents, and David Mowbray, Macquarie University, for conducting the pesticide analyses. We also gratefully acknowledge the facilities provided by the Museum, and S. Debus for revising an early (undergraduate report) version of this paper by RHE. Drs Stuart Cairns and Mary Notestine (Zoology Dept, University of New England) assisted with graph preparation and information on insect biology, respectively, and Dr Mark Brigham (University of Regina, Canada, Visiting Fellow to UNE) and Rod Kavanagh (State Forests of N .S.W.) commented helpfully on the manuscript.

References Barker, R.D. & Vestjens, W.J.M. (1989), The Food ofAustralian Birds. I. Non-Passerines, CSIRO, Melbourne. Blakers, M., Davies, S.J.J.F. & Reilly, P.N. (1984), The Atlas of Australian Birds, Melbourne University Press, Melbourne. CSIRO (1970), The Insects of Australia, Melbourne University Press, Melbourne. Debus, S.J .S. (in press), 'Vocal behaviour of the Southern Boobook Ninox novaeseelandiae and other nocturnal birds', in Czechura, G.V. (Ed.), Proc. Australasian Raptor Assoc. Conference, Currumbin, 1996. Fleay, D. (1981), Looking at , Boolarong, Brisbane. Hollands, D. (1991), Bin!s of the Night, Reed, Sydney. McCulloch, E.M. (1975), 'Variations in the mass of captive Tawny Frogmouths', Aust. Bird Bander 13, 9-11. McNab, B.K. & Bonaccorso, F.J. (1995), 'The energetics of Australasian swifts, frogmouths, and ', Physiol. Zoo/. 68, 245-261. Newton, I., Wyllie, I. & Asher, A. (1991), 'Mortality causes in British Barn Tyto alba, with a discussion of aldrin-dieldrin poisoning', Ibis 133, 162-169. Rose, A.B. (1973), 'Food of some Australian birds', Emu 73, 177-183. --(1976), 'Mass of wild birds of the order ', Aust. Bird Bander 14, 50-51. --(1996), 'Notes on the diet of the Barn 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.) (1994), Cuckoos, Nightbirds & Kingfishers ofAustralia , Angus & Robertson, Sydney . Received 19 June 1996 •