Australian Field Ornithology 2020, 37, 44–47 http://dx.doi.org/10.20938/afo37044047 Introduction The name used for the Australasian population of the Barn Owl complex by BirdLife Australia (2019) is Tyto alba although Aliabadian et al. (2016) and Uva et al. (2018) showed that the Australasian population, along with the Indian and South-East Asian population, should be recognised as a separate species T. javanica (including Australian subspecies delicatula and others in Melanesia/ Oceania). The taxon inhabiting Sumba in the Lesser Sunda Islands, T. j. sumbaensis, is basal in the javanica/ delicatula clade (Jønsson et al. 2013; Aliabadian et al. 2016), suggesting that it has been sympatric with settled Indonesian peoples for many centuries. Unlike Barn Owls in Australia, which normally nest in tree-hollows, Barn Owls in Indonesia commonly nest in churches and other buildings and in caves in clifs (Olsen 2013). The T. javanica complex, as recently proposed, also now includes the Sulawesi Barn (or Masked) Owl T. (j.) rosenbergii as only subspecifcally distinct, albeit a dark morph, as also applies to the Taliabu Masked Owl T. (j.) nigrobrunnea (Jønsson et al. 2013; Uva et al. 2018). Globally, as in Australia (e.g. Debus et al. 2004), Barn Owls specialise in preying on small terrestrial mammals, although they take a range of other vertebrates and invertebrates according to availability, and non-mammalian (or non-rodent) prey can be prevalent in the diet on islands (e.g. del Hoyo et al. 1999; König & Weick 2008; Romano et al. 2020). The diet of the Barn Owl on Wallacean islands is little known. Fitzsimons (2010) noted, at a cave roost of rosenbergii on Sulawesi, many pellets that could not be accessed for collection. A cave deposit of pellets attributed to rosenbergii contained the remains of rats (Muridae), shrews Sorex sp. and a microbat (Microchiroptera), and that owl taxon is known to prey on rats (del Hoyo et al. 1999). Cave deposits of avian remains (quail Coturnix sp., button-quail Turnix sp. and passerines) on Timor were attributed to Barn Owls (Hawkins et al. 2019). Olsen et al. (2009) and Olsen (2011) provided a brief account of some presumed prey species based on a cursory examination of pellet contents from Sumba. Here we detail the contents of those pellets, and the contents of pellets from Rote (Roti) Island also in the Lesser Sundas (Nusa Tenggara) (Figure 1). There are three other owl species on Sumba—Sumba Hawk-Owl Ninox rudolf, Little Sumba Hawk-Owl N. sumbaensis and Eastern Grass Owl Tyto longimembris (see Olsen et al. 2002, 2009; Olsen 2011). On Rote, of the south-western tip of Timor, there is one other owl, the Rote Boobook Ninox rotiensis (Verbelen 2010; Gwee et al. 2017). Some vertebrate prey of Barn Owls Tyto alba sumbaensis on Sumba and Rote, Indonesia Jerry Olsen 1 *, Stephen Debus 2 , Susan Trost 3 , Leah Tsang 4 and Harry Parnaby 4 1 Institute for Applied Ecology, University of Canberra, Canberra ACT 2601, Australia 2 Zoology, University of New England, Armidale NSW 2351, Australia 3 44 Wybalena Grove, Cook ACT 2614, Australia 4 Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney NSW 2010, Australia *Corresponding author: Jerry.Olsen@canberra.edu.au 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 clif setting near Nembrala (Nemberala) on the small island of Rote (Roti), of Timor, were collected in July 2001 and July 2002, respectively. The Sumba sample contained the remains of rodents (three Black Rats Rattus rattus, four Pacifc Rats R. 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-bats (24 Geofroy’s Rousettes Rousettus amplexicaudatus and six that were probably also this species). Figure 1. Location of Sumba and Rote, Indonesia. Is = Islands.