Northern Double Dummer Thopha sessiliba

Northern Double Drummer Thopha sessiliba Distant, 1892

Male T. s. sessiliba

Female T. s. sessiliba

Subspecies: Thopha sessiliba sessiliba Distant, 1892 Thopha sessiliba clamoris Moulds and Hill, 2015 Species number (TNS): 004. Fore wing length: 50–63 mm. Distribution and seasonality: T. s. sessiliba is widespread through tropical Australia from north-west Western Australia into the Northern Territory as far south as Alice Springs and across most of Queensland, but becoming patchier in the south. Its distribution extends into New South Wales in the Narrabri district and at Lightning Ridge. In south-eastern Queensland, it has been found around Tinnanbar on the coast and inland around Goondiwindi. T. s. clamoris is restricted to the eastern margins of the Pilbara and Gascoyne regions of Western Australia. Across much of this species’ distribution, adults may be present from September until about April, but in southern Northern Territory, southern Queensland and northern New South Wales it is present sporadically between November and early March. Notable localities: Humpty Doo via Darwin, Boulia, Torrens Creek, Mareeba, Curtis Island. Habitat: Dry to subhumid coastal and inland eucalypt forests and woodlands. Populations are generally restricted to watercourses in more arid areas. Calling song and behaviour: A loud, piercing, electric whine, fluctuating in pitch; continuous, but often with a broken rhythm. The call can be quite difficult to distinguish from Thopha saccata. Singing occurs at intervals throughout the day when the weather is warm and sunny, and also at dusk. Like T. saccata, adults, including calling males tend to sit high on the trunks of eucalypts. Population sizes vary within each locality from season to season and sometimes populations can be for many years in any given local area. Colour variation: Dark specimens of T. sessiliba are known from the Mackay region and Cape York in Queensland, and from the Pilbara region of Western Australia (Moulds, 2008). Similar species: Eastern Double Drummer, Pilbara Double Drummer.