Australian Field Ornithology 2020, 37, 42–43 http://dx.doi.org/10.20938/afo37042043

Snake predation by the Tawny Frogmouth Podargus strigoides

George Madani

P.O. Box 3113, Hill Top NSW 2575, Australia Email: [email protected]

Abstract. Tawny Frogmouths Podargus strigoides have a diverse diet predominantly comprised of invertebrates. In contrast, vertebrates are only occasionally reported as prey. Records of reptiles as prey are scarce and no reptilian prey has been identified to species level. This is the first documented observation of a Tawny Frogmouth taking a live snake.

Introduction Observation On 7 October 2019, at 2115 h, while spotlighting in the The diet of the Tawny Frogmouth Podargus strigoides is vicinity of Barbers Lagoon, Boggabri, New South Wales well documented (Higgins 1999). This species is known (–30.696716, 150.118210, GDA94), a Tawny Frogmouth to preferentially prey upon terrestrial invertebrates such was detected perched on a fence-post. The area is as moths (Lepidoptera), beetles (Coleoptera), spiders characterised by cleared grazing farmland with sparsely (Arachnida), orthopterans and myriapods (Coleman 1946; interconnected patches of grassy woodland dominated Barker & Vestjens 1989; Rose & Eldridge 1997; Kaplan by Poplar Box Eucalyptus populnea. The observation 2018). It is also known to take vertebrates but reports was made on the boundary between an open paddock of this are infrequent (Barker & Vestjens 1989; Rose & and the surrounding native woodland. At the time of the Eldridge 1997). observation, there was no wind or rain. The temperature Vertebrate prey items noted in the literature include was ~23° C and the moon was waxing gibbous at 58% full with no cloud cover. The Frogmouth, apparently House Mice Mus musculus, particularly during population unperturbed by the spotlight, stared intently at the grass irruptions (Lea & Gray 1935; Coleman 1946; Vestjens below it, turning its head abruptly from side to side. It then 1973; Rose & Eldridge 1997; Davey & Einoder 2001); frogs, glided down and grabbed a prey item with its bill, ~1 m from including Eastern Banjo Frog Limnodynastes dumerilii, its launch point, before flying back to perch in a nearby Spotted Marsh Frog Limnodynastes tasmaniensis, Green Poplar Box (~6 m high). Prey capture involved typical Tree Frog Litoria caerulea, Brown Tree Frogs Litoria sally-pouncing behaviour (Serventy 1936; Robinson & ewingii, and Leaf-green Tree Frog Litoria phyllochroa Remsen 1990), which is common in this species (Higgins (Schodde & Mason 1980; Green et al. 1988; Barker & 1999). Upon inspection with binoculars, the prey item Vestjens 1989; Rose & Eldridge 1997); birds, including was identified as a Red-naped Snake Furina diadema, the Brown Treecreeper Climacteris picumnus and House Sparrow Passer domesticus (Lea & Gray 1935; Wheeler 1943; Coleman 1946); and, rarely, reptiles. Records of reptilian prey are scarce, with one record of an unspecified lizard found in the stomach contents of a Tawny Frogmouth (Barker & Vestjens 1989) and unidentified snake scales in faecal material in an active nest (Rose & Eldridge 1997). The best-known foraging style of Tawny Frogmouths is to hunt from perches: watching for prey before swooping down from an elevated position (Serventy 1936). The short, broad, hooked bill is suited to plucking prey from the ground and is well adapted to cope with wriggling, hard- shelled, stinging and biting invertebrates (Kaplan 2018). As with kookaburras Dacelo spp., Tawny Frogmouths are well known to subdue and kill prey by exerting traumatic injuries against a solid substrate (Hollands 1991; Kaplan 2018), which is assumed to make prey more consumable for adults or dependent chicks (Fleay 1925; Hollands 1991). Consequently, a strong bill that can crush the hard exoskeletons of insects such as beetles is also suitable for Figure 1. A Tawny Frogmouth with a captured Red-naped Snake at Barbers Lagoon, Boggabri, New South Wales. incapacitating larger soft-bodied prey such as lizards and The photograph was digiscoped with an Iphone 7 and mice (Kaplan 2018) and, in this instance, a small snake. Swarovski EL 8 x 32 binoculars and has been enhanced Here I present an account of a Tawny Frogmouth taking a with Lightroom 6 to better highlight the detail of the snake as prey. snake. Photo: Lachlan Hall Snake predation by Tawny Frogmouth 43

~20 cm in length (Figure 1). The Frogmouth grabbed the species may be more frequent than reported to date. snake midway along the body, incapacitated it by repeated Naturalists and birdwatchers alike should remain mindful beating against the branch with its bill, and then finally and observant to further insights into the diet of this swallowed the dead snake whole. species.

Discussion Acknowledgements I thank Lachlan Hall and Sabrina Velasco for assistance in the field and Elliot Leach, Ross Crates and Eric Vanderduys for kindly Direct observations of Tawny Frogmouths taking vertebrate providing comments that helped improve the manuscript. I thank prey are rare, and vertebrate prey constitutes only a small Brad Law for encouraging me to publish this observation. proportion of items identified in dietary analysis of stomach contents (Rose & Eldridge 1997). Specifically, in an analysis of the stomach contents of 40 Tawny Frogmouths References Rose & Eldridge (1997) found vertebrates (mice and frogs) Barker, R.D. & Vestjens, W.J.M. (1989). The Food of Australian formed only 4% of all dietary items compared with insects Birds: 1 Non-Passerines. CSIRO, Division of Wildlife & Ecology, (78%) and spiders and myriapods (18%). Canberra. Coleman, E. (1946). Foods of the Tawny Frogmouth. Victorian Although vertebrates are taken as prey less frequently, Naturalist 63, 111–115. they constitute a greater biomass than single invertebrate Davey, C. & Einoder, L. (2001). Predation of House Mice by the prey items. Conceivably the taking of individual vertebrate Tawny Frogmouth Podargus strigoides. Australian Bird Watcher prey items would be more energetically efficient than 19, 103–104. the effort required to hunt for an equivalent biomass of Fleay, D.H. (1925). The Boobook Owl and Tawny Frogmouth. multiple smaller invertebrate prey (Rose & Eldridge 1997). Emu 25, 91–93. Green, R.H., Scarborough, T.J. & McQuillan, P.B. (1988). Food Maximising foraging success and energy turnover could and feeding of the Laughing Kookaburra and Tawny Frogmouth enhance survival as it has been suggested that Tawny in Tasmania. Tasmanian Naturalist 93, 5–8. Frogmouths appear to accumulate fat after the breeding Higgins, P.J. (Ed.) (1999). Handbook of Australian, New Zealand season in preparation for periods of food shortage in winter & Antarctic Birds, Volume 4: Parrots to Dollarbird. Oxford (Rose & Eldridge 1997). University Press, Melbourne. Hollands, D. (1991). Birds of the Night. Owls, Frogmouths and Some seasonality has been observed in the diet of Nightjars of Australia. Reed Books, Sydney. the Tawny Frogmouth that reflects seasonal resource Kaplan, G. (2018). Tawny Frogmouth. 2nd edn. CSIRO Publishing, availability and the influence of climate (Rose & Eldridge Melbourne. 1997; Hollands 1991). Rose & Eldridge (1997) found Lea, A.M. & Gray, J.T. (1935). The food of Australian birds. Emu that some prey (such as beetles) were taken year- 35, 63–98. round, whereas moths and spiders were more frequently Robinson, S.K. & Remsen, J.V. (1990). A classification scheme consumed in summer, but caterpillars and cockroaches for foraging behaviour of birds in terrestrial habitats. Studies in were taken more in winter; vertebrates were taken more Avian Biology 13, 144–160. in winter when invertebrates were less available. Tawny Rose, A.B. & Eldridge, R.H. (1997). Diet of the Tawny Frogmouth Podargus strigoides in eastern New South Wales. Australian Frogmouths are also opportunistic to intermittent weather Bird Watcher 17, 25–33. events, with reports of frogs featuring predominantly in Schodde, R. & Mason, I.J. (1980). Nocturnal Birds of Australia. their diet following significant rainfall (Green et al. 1988), Landsdowne, Melbourne. and House Mice constituting 100% of all stomach contents Serventy, D.L. (1936). Feeding methods of Podargus. Emu 36, during sporadic occurrences such as rodent plagues 74–90. (Vestjens 1973). Although mammalian prey species such Vestjens, W.J.M. (1973). Wildlife mortality on a road in New South as House Mice remain active year-round, reptiles such as Wales. Emu 73, 107–112. snakes and other potential nocturnal reptilian prey such Wheeler, W.R. (1943). Birds and their prey. Emu 43, 143. as geckos may be available only in the warmer months, at least in the southern portion of the range of the Tawny Frogmouth. Received 24 December 2019, accepted 26 February 2020, published online 1 May 2020 Given the continent-wide distribution of Tawny Frogmouths across various habitats sympatric with many nocturnal snakes (Higgins 1999), snake predation by this