Hydrornis baudii (S.Müller & Schlegel, 1839)

Gulson-Castillo, Eric R., Pegan, Teresa M., Greig, Emma I., Hite, Justin M., Hruska, Jack P., Kapoor, Julian A., Orzechowski, Sophia C., Shipley, J. Ryan & Winkler, David W., 2019, Notes on nesting, territoriality and behaviour of broadbills (Eurylaimidae, Calyptomenidae) and pitas (Pitidae) in Tawau Hills Park, Sabah, Malaysian Borneo, Bulletin of the British Ornithologists’ Club 139 (1), pp. 8-27 : 24-25

BLUE-HEADED PITTA Hydrornis baudii

Shy, quiet and difficult to observe during both visits; however, they were more reliably found and regularly heard during 2012. One pair was observed regularly that year ( Fig. 11 , blue points). The birds seemed to favour a particular rattan Calamus sp. clump and were often seen together. They were seen nearly every evening on 19–28 July, at 16.30–17.30 h, atop a west to east-running ridge, but also frequented in a swampy area at its base. When moving together, they sometimes called every 15–30 seconds. More frequently, one of the pair would call once or twice, then disappear. This pair vocalised after playback only if they had been calling previously. On 28 July 2012, just before 17.00 h, one gave several of the ‘alarm note[s] of the female’ ( Lambert & Woodcock 1996), then an upslurred porrrwuh?, perhaps similar to what has been described as a possible alarm call (B. Gee in litt. in Erritzøe & Erritzøe 1998). Lambert & Woodcock (1996) and Bruce (2003) suggested that the firstmentioned call, the loud and nasal kwee-ouu, is a ‘female alarm call’ but we observed both sexes give a call matching this onomatopoeic description ( ML 479549).

Although we never found a nest, JMH discovered a young bird on 30 July 2012, within the same territory ( Fig. 12 ). It followed its female parent closely, generally standing silently next to her as she foraged, but occasionally begging emphatically as she ate or moved onward ( ML 479513); we never saw it being fed. The young was a male, identified by its bright white throat (similar to that of an adult male). Given that no pitta is known to be dependent for more than two months ( Erritzøe & Erritzøe 1998), and that the bird showed remnants of gape flanges and of the orange bill tip shown by many nestling pittas, we consider that this was a juvenile (younger than two months) in pre-formative moult to immature plumage. This plumage does not precisely match the description for juvenile or immature plumage given by Lambert & Woodcock (1996) and Erritzøe & Erritzøe (1998), as neither source mentions a bright white throat. However, it is difficult to believe this bird was old enough to be moulting to adult plumage (given its gape and begging behaviour), and we suggest that previous descriptions of immature male plumage, based on two specimens ( Erritzøe & Erritzøe 1998), may not represent the complete range of pre-adult variation.

See Bornean Banded Pitta account for description of a possible interaction between that species and a Blue-headed Pitta .

During the drier season in 2013, birds sang less and were observed less frequently. However, whenever they sang they did so in long series, repeated every few seconds as they moved through the understorey. We detected the birds across a larger area than in 2012, sometimes in different areas on the same day (e.g., 9 March, when we had three birds 442, 324 and 285 m away from each other, respectively) and across the Tawau River. This leads us to suspect that at least three territories were established, although there could have been more.

One pair, which may have been the same as that observed in 2012, spent several days around 7–20 April 2013 near one segment of the Tawau River, on the main trail. They were often flushed from the trail as they foraged in the strip of forest between the river, the trail and the nearby swamp, although we never saw them leave drier ground. The birds disappeared as suddenly as they arrived in the area, and we suspect that they departed (rather than became less detectable), because we regularly walked this trail throughout the season.

Figures

Figure 11. Map of the topography of our study area showing sightings of four species of pittas during the 2012 field work: Black-crowned Pitta Erythropitta ussheri (purple), Blue-headed Pitta Hydrornis baudii (blue), Bornean Banded Pitta H. schwaneri (yellow) and Blue-banded Pitta Erythropitta arquata (red). Each point represents a sighting. Variation in point size and shape is an artefact of 3D plotting. The map demonstrates that the areas occupied by each species overlapped considerably, especially on the ridge in the centre, where all four species occurred in close proximity. Black-crowned Pitta was seen more commonly in low swampy areas, whereas the other three species occurred mainly on this ridge and its slopes. A fifth species, Hooded Pitta Pitta sordida, was heard infrequently and seen just once, a juvenile, at the green point. Grey lines represent trails, the brown line a water pipeline, and the blue line the Tawau River. 3D map courtesy of JAXA (2015).

Figure 12. Two frames from a video of an immature male Blue-headed Pitta Hydrornis baudii (top) showing a white throat, patches of blue in the underparts, and reddish wing-coverts, with an adult female Blue-headed Pitta (bottom). Frames from video ML 479513 (Justin Hite)