Bioacoustics of Yoyetta bushi

Distribution, habitat and seasonality . Plate 2E–F ; Fig. 1 ). Currently, Y. bushi sp. nov. is found predominantly in pockets of dry Blackbutt ( Eucalyptus pilularis ) or in Sydney Blue Gum ( Eucalyptus saligna ) forests at elevations greater than 500m in Girard State Forest and in the region of Nymboi-Binderay National Park ( Fig. 1 ). In Kangaroo River State Forest ( 30°07'S 152°51'E ), specimens are found almost exclusively within dry Blackbutt forest. More extensive analysis of bushland habitat by TJB revealed additional sites with the dry Blackbutt habitat in Wild Cattle Creek State Forest ( 30°11'S 152°48'E ) around 7km SSW of Towallum and at Clouds Creek ( 30°08'S 152°36'E ) around 24km WNW of Towallum where Y. bushi sp. nov. was also found and the song recorded. The species has also been located and recorded in Sydney Blue Gum forests within Girard and Moonpar State Forests. The areas inhabited by this species consist of small plateaus and ridgetops with forest which is more open than the surrounding denser bush ( Plate 2E–F ). Adult males show a preference for the dense crown of juvenile trees in the understorey or in more established forests with few juvenile trees, males call from the upper branches of eucalypts. Females have been observed on Forest Oak ( Allocasuarina torulosa ) and amongst the foliage of Blackbutt saplings but have been located most often sitting on the bark of small to medium sized dead trees within the understorey. Specimens have been observed from mid-October until early January. Populations of Y. bushi sp. nov. co-locate with Y. timothyi Emery, Emery & Popple , which was heard calling in the canopy at Girard State Forest, Towallum and Clouds Creek. Within Girard State Forest, they also co-locate with Y. ignita and another undescribed Yoyetta where New England Blackbutt ( E. campanulata ) forest converges with Sydney Blue Gum forest.

Calling song ( Fig 3 ). The male calling song is a series of clicking that ends in a short or long buzz. An examination of the song structure (all statistics, n =9 recordings from Towallum and Wild Cattle Creek localities) as illustrated in Fig. 3 shows each ‘click’ is a syllable comprising of 4-6 pulses ( 0.006 –0.026 s). Amongst recordings, the number of clicks in a sequence varied considerably from 9 to 41. The ‘short buzz’ at the end of a clicking sequence is a single syllable immediately followed by a short macrosyllable ( 0.030 –0.071 s; Fig. 3C, E ). By comparison, the ‘long buzz’ is an echeme that decreases in amplitude throughout ( 0.116 –0.348 s; Fig. 3B, D ). The frequency plateau of the male calling song ranges from approximately 10.3 to 16.3 kHz, with a dominant frequency between 11.6 and 14.7 kHz ( n= 3, RS1; Fig. 3F ). It was noted in the field by TJB that the length of the buzz component of the song will be switched back and forth without any apparent stimulus, but the longer buzz frequently precedes the cessation of calling. Y. bushi sp. nov. predominantly calls at rest and observed instances of males calling in flight are an exceptionally rare phenomenon. Calling occurs in sunlight with cloud cover significantly reducing activity. Males commence calling between 0830h and 0900h (Australian Eastern Daylight Savings Time (AEDT) GMT +11 hours) frequently moving between perches. By 1130h (AEDT) much of the activity ceases, males move higher into the trees and become more sedentary but will continue to call sporadically until late in the afternoon. Finger snapping can sometimes elicit a response from calling males when timed correctly, but more often than not, this technique fails to attract their attention. The calling song of Yoyetta bushi sp. nov. closely resembles the high-frequency songs of Yoyetta fluviatilis Emery, Emery & Popple and Y. robertsonae Moulds, Popple & Emery. However , its structure differs: Y. fluviatilis produces a short buzz followed by a click, whereas Y. bushi sp. nov. emits a series of distinct clicks before a short buzz. Similarly, the calling song of Y. robertsonae is much lower frequency and features evenly spaced groups of three clicks but lacks the final short buzz present in Y. bushi sp. nov.