Australian Field Ornithology 2020, 37, 44–47 http://dx.doi.org/10.20938/afo37044047

Some vertebrate prey of Barn Owls Tyto alba sumbaensis on Sumba and Rote, Indonesia

Jerry Olsen1*, Stephen Debus2, Susan Trost3, Leah Tsang4 and Harry Parnaby4

1Institute for Applied Ecology, University of Canberra, Canberra ACT 2601, Australia 2Zoology, University of New England, Armidale NSW 2351, Australia 344 Wybalena Grove, Cook ACT 2614, Australia 4Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney NSW 2010, Australia *Corresponding author: [email protected]

Abstract. The diet of the Barn Owl Tyto alba sumbaensis is little known in Wallacea. Samples of pellets from nests in a church in an urban setting on Sumba and in a forested, limestone cliff setting near Nembrala (Nemberala) on the small island of Rote (Roti), off Timor, were collected in July 2001 and July 2002, respectively. The Sumba sample contained the remains of rodents (three Black Rats Rattus rattus, four Pacific RatsR. exulans and one probable House Mouse Mus musculus) and birds (17 Eurasian Tree Sparrows Passer montanus). The sample from Rote contained the remains of 30 small fruit- (24 Geoffroy’s Rousettes amplexicaudatus and six that were probably also this species).

Introduction invertebrates according to availability, and non-mammalian (or non-rodent) prey can be prevalent in the diet on islands The name used for the Australasian population of the (e.g. del Hoyo et al. 1999; König & Weick 2008; Romano Barn Owl complex by BirdLife Australia (2019) is Tyto et al. 2020). The diet of the Barn Owl on Wallacean islands alba although Aliabadian et al. (2016) and Uva et al. is little known. Fitzsimons (2010) noted, at a cave roost of (2018) showed that the Australasian population, along rosenbergii on Sulawesi, many pellets that could not be with the Indian and South-East Asian population, should accessed for collection. A cave deposit of pellets attributed be recognised as a separate species T. javanica (including to rosenbergii contained the remains of rats (Muridae), Australian subspecies delicatula and others in Melanesia/ shrews Sorex sp. and a microbat (Microchiroptera), and Oceania). The taxon inhabiting Sumba in the Lesser that owl taxon is known to prey on rats (del Hoyo et al. Sunda Islands, T. j. sumbaensis, is basal in the javanica/ 1999). Cave deposits of avian remains (quail Coturnix sp., delicatula clade (Jønsson et al. 2013; Aliabadian et al. button-quail Turnix sp. and passerines) on Timor were 2016), suggesting that it has been sympatric with settled attributed to Barn Owls (Hawkins et al. 2019). Indonesian peoples for many centuries. Unlike Barn Olsen et al. (2009) and Olsen (2011) provided a brief Owls in Australia, which normally nest in tree-hollows, account of some presumed prey species based on a Barn Owls in Indonesia commonly nest in churches cursory examination of pellet contents from Sumba. Here and other buildings and in caves in cliffs (Olsen 2013). we detail the contents of those pellets, and the contents of The T. javanica complex, as recently proposed, also pellets from Rote (Roti) Island also in the Lesser Sundas now includes the Sulawesi Barn (or Masked) Owl (Nusa Tenggara) (Figure 1). There are three other owl T. (j.) rosenbergii as only subspecifically distinct, albeit a species on Sumba—Sumba Hawk-Owl Ninox rudolfi, Little dark morph, as also applies to the Taliabu Masked Owl Sumba Hawk-Owl N. sumbaensis and Eastern Grass Owl T. (j.) nigrobrunnea (Jønsson et al. 2013; Uva et al. 2018). Tyto longimembris (see Olsen et al. 2002, 2009; Olsen Globally, as in Australia (e.g. Debus et al. 2004), Barn 2011). On Rote, off the south-western tip of Timor, there is Owls specialise in preying on small terrestrial , one other owl, the Rote Boobook Ninox rotiensis (Verbelen although they take a range of other vertebrates and 2010; Gwee et al. 2017).

Figure 1. Location of Sumba and Rote, Indonesia. Is = Islands. Vertebrate prey of Barn Owl in Indonesia 45

Figure 4. Barn Owl nest-cliff on Rote, Indonesia. Photo: Jerry Olsen

The small island of Rote (Roti) lies 12 km south of the south-western end of Timor. It is 45 km long, 10–15 km Figure 2. Lutheran Church in Waingapu, Sumba, wide, and has an area of 1226 km2. It is low-lying, with Indonesia. Barn Owls entered and left through a maximum elevation of 440 m, and is formed entirely of the top tower. A Barn Owl is just visible on the coralline limestone. It is a patchwork of open land and forest left. Photo: Jerry Olsen & Susan Trost and, on the coast, has extensive mangroves. Large areas of forest have been cleared but patches of undisturbed dry forest remain (Verbelen 2010; Verbelen et al. 2017). Like Sumba, it has a wet and a dry season, with ~1100 mm of annual rainfall. JO and ST collected and examined (on site) prey remains from a previously occupied nest-site/roost in a cave in a limestone cliff in dry forest near Nembrala (10°53ʹS, 122°50ʹE) on 15 July 2002 (Figure 4). Villagers said that the nest had previously held a single Barn Owl nestling that was taken by the villagers and eaten. The Sumba prey remains were photographed and left in Waingapu, and the Rote prey remains were also photographed (separated skulls and postcranials). Rodent remains in the pellets from Sumba were identified by the Figure 3. Barn Owl inside the Waingapu church, Sumba, late Ken Aplin (Australian National Wildlife Collection, Indonesia. Photo: Jerry Olsen & Susan Trost Canberra, Australia, and later the Smithsonian Institution, Washington DC, United States of America) and marked on annotated colour photographs, with scale bar (steel rule in Study areas and methods mm), of the individual skulls and/or paired jaws separated from the dissected pellets. Separated bird skulls in the The island of Sumba, 210 km long and with an area of same photographs of the pellet sample were similarly ~12,000 km2, lies at 10°S and 120°E in the Lesser Sundas identified by LT, from comparison with relevant skulls in chain south of Flores and Sumbawa in south-eastern the finch families Estrildidae and Passeridae (e.g. Java Indonesia (Figure 1). At 1225 m, the highest point is Sparrow Lonchura oryzivora, other relevant Lonchura spp.) Gunung (Mount) Wanggametii. The island experiences a in the Australian Museum collection. Prey remains (entirely winter dry season around May to November, and a summer of bats) in the pellet sample from Rote were identified by wet season around December to April. The annual rainfall HP from a colour photograph of the separated skulls (with is between ~500 mm on the southern coast and ~2000 mm scale bar as above). In both samples, the minimum number on the inland hills (Monk et al. 1997). Nineteen Barn Owl of prey individuals was counted from skulls and mandibles pellets were collected from an occupied roost- and nest- visible in the photographs. Separation of all material from site in a church tower (Figures 2–3) in the main town of pellets was not complete; only skulls and large bones were Waingapu by JO and ST in July 2001 and dissected and extracted for identification, as an incomplete sample of the examined on site. diet at these two nests. 46 Australian Field Ornithology J. Olsen et al.

Figure 5. Skeletal material extracted from the Barn Owl pellets from Sumba, Indonesia. Photo: Jerry Olsen & Susan Trost

Figure 6. Skeletal material extracted from the Barn Owl pellets from Rote Island, Indonesia. Photo: Jerry Olsen & Susan Trost Vertebrate prey of Barn Owl in Indonesia 47

Results and discussion Almeida, F.C. (2019). Geoffroy’s Rousette Rousettus amplexicaudatus. In: Wilson, D.E. & Mittermeier, R.A. (Eds). The photographic pellet sample from Sumba Handbook of the Mammals of the World, Volume 9: Bats, p. 85. (Figure 5) contained Black Rat Rattus rattus [n = 3: two adults Lynx Edicions, Barcelona, Spain. BirdLife Australia (2019). Working List of Australian Birds v.3. (~180 g) and one immature (~50 g)], Pacific RatR. exulans Available online: www.birdlife.org.au/conservation/science/ [n = 4, including three adults (~40 g)], one probable House taxonomy (retrieved 9 December 2019). Mouse Mus musculus (~18 g), and 17 sparrows Passer sp. Debus, S.J.S., Olsen, J. & Rose, A.B. (2004). Diet of the Barn Owl [here assigned to the Eurasian Tree Sparrow P. montanus Tyto alba in north-eastern South Australia. Corella 28, 40–42. (~24 g), the only sparrow species occurring on Sumba, del Hoyo, J., Elliott, A. & Sargatal, J. (Eds) (1999). Handbook of and abundant around the Owls’ roost-site]. One pellet the Birds of the World, Volume 5: Barn-owls to Hummingbirds. contained the skulls of three sparrows, but otherwise no Lynx Edicions, Barcelona, Spain. further quantification was possible (weights from Trost Fitzsimons, J.A. (2010). Notes on the roost sites of the Sulawesi Masked Owl Tyto rosenbergii. Forktail 26, 142–145. et al. 2008 and other published sources), and the sample Gwee, C.Y., Christidis, L., Eaton, J.A., Norman, J.A., Trainor, C.R., included only vertebrate prey. Verbelen, P. & Rheindt, F.E. (2017). Bioacoustic and multi-locus The photographic sample from Rote (Figure 6) consisted DNA data of Ninox owls support high incidence of extinction and recolonisation on small, low-lying islands across Wallacea. entirely of small fruit-bats (Megachiroptera: Pteropodidae; Molecular Phylogenetics and Evolution 109, 246–258. n = 30). These were mostly (n = 24), if not all, Geoffroy’s Hawkins, S., O’Connor, S. & Louys, J. (2019). Taphonomy of bird Rousettes Rousettus amplexicaudatus, a species known (Aves) remains at Laili Cave, Timor-Leste, and implications for to occur on Rote (Rookmaaker & Bergmans 1981). The human-bird interactions during the Pleistocene. Archaeological remaining six skulls also appeared to be of that species. and Anthropological Sciences 11, 6325–6337. Generic identification is possible from skull characters Jønsson, K.A., Poulsen, M.K., Haryoko, T., Reeve, A.H. & evident in the image, but species identification is inferred Fabre, P.-H. (2013). A new species of masked-owl (Aves: Strigiformes: Tytonidae) from Seram, Indonesia. Zootaxa , from the geographic location where only one species of 3635 51–61. Rousettus has been recorded (Rookmaaker & Bergmans König, C. & Weick, F. (2008). Owls of the World. 2nd edn. Helm, 1981). The fauna of Timor and Rote is poorly known, London. although other small fruit-bats ( sp., Long- Mahirta, Aplin, K.A., Bulbeck, D., Boles, W.E. & tongued Nectar Bat Macroglossus minimus), microbats Bellwood, P. (2004). Pia Hudale rockshelter: A terminal and large fruit-bats ( sp., sp.) occur on Pleistocene occupation site on Roti Island, Nusa Tenggara Rote (Mahirta et al. 2004). Geoffroy’s Rousette is a colonial Timur, Indonesia. In: Keates, S.G. & Pasveer, J.M. (Eds). cave-roosting species, ~60–106 g, and its colonies can Modern Quaternary Research in South East Asia 18, pp. 361–394. A.A. Balkema, Leiden, The Netherlands. reach thousands of individuals (Almeida 2019). Monk, K.A., De Fretes, Y. & Reksodiharjo-Lilley, G. (1997). Our findings are generally consistent with knowledge of The Ecology of Nusa Tenggara and Maluku. Periplus Editions, the Barn Owl’s dietary spectrum globally, particularly that Hong Kong. Olsen, J. (2011). Australian High Country Owls. CSIRO Publishing, on small islands where the Owl may prey heavily on species Melbourne. other than rodents, according to availability (cf. del Hoyo Olsen, J. (2013). Do Australian Barn Owls nest in barns? Boobook et al. 1999; König & Weick 2008; Romano et al. 2020). 31, 36. However, there is little other information for Indonesia with Olsen, J., Trost, S. & Myers, S.D. (2009). Owls on the Island of which to compare our samples from Sumba and Rote (small Sumba, Indonesia. Australian Field Ornithology 26, 2–14. mammals, a microbat and small birds known or inferred Olsen, J., Wink, M., Sauer-Gürth, H. & Trost, S. (2002). A new for Sulawesi and Timor: see above). Concentration on Ninox owl from Sumba, Indonesia. Emu 102, 223–231. Romano, A., Séchaud, R. & Roulin, A. (2020). Global small fruit-bats on Rote, albeit an abundant species, in the biogeographical patterns in the diet of a cosmopolitan avian possible absence or scarcity of non-flying small mammals, predator. Journal of Biogeography 29, https://doi.org/10.1111/ may be noteworthy, although there are many records jbi.13829 globally of microbats as Barn Owl prey. It is not known if Rookmaaker, L.C. & Bergmans, W. (1981). Taxonomy and microbat or other small or invertebrate remains were in the geography of Rousettus amplexicaudatus (Geoffroy, 1810) detritus in the samples from Sumba and Rote. Predation on with comparative notes on sympatric congeners (Mammalia, colony-roosting small fruit-bats may be functionally similar Megachiroptera). Beaufortia 31, 1–20. to the well-known Barn Owl habit of preying on communally Trost, S., Olsen, J., Rose, A.B. & Debus, S.J.S. (2008). Winter diet of Southern Boobooks Ninox novaeseelandiae in Canberra roosting passerines such as sparrows, although the fruit- 1997–2005. Corella 32, 66–70. bats are substantially heavier than sparrows. Uva, V., Päckert, M., Cibois, A., Fumagalli, L. & Roulin, A. (2018). Comprehensive molecular phylogeny of barn owls and relatives Acknowledgements (Family: Tytonidae), and their six major Pleistocene radiations. Molecular Phylogenetics and Evolution 125, 127–137. We acknowledge the late Ken Aplin for identification of rodent Verbelen, P. (2010). First field observations of Ninox remains, and thank Les Christidis (then at the Australian Museum) (novaeseelandiae) rotiensis on Roti island, Lesser Sundas, and Janette Norman (Museum Victoria) for their assistance. We Indonesia. BirdingASIA 13, 85–89. also thank Colin Trainor and Chris Pavey for comments on a draft Verbelen, P., Trainor C.R. & Dossche, V. (2017). Rote Island, and suggestions of additional literature. Indonesia: An emerging hotspot of avian endemism. BirdingASIA 27, 57–73. References Aliabadian, M., Alaei-Kakhki, N., Mirshamsi, O., Nijman, V. & Roulin, A. (2016). Phylogeny, biogeography, and diversification Received 23 January 2020, accepted 5 March 2020, of barn owls (Aves: Strigiformes). 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