Erythropitta ussheri

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 : 19-22

BLACK-CROWNED PITTA Erythropitta ussheri

The most common representative of the Pittidae in our study area. Unlike other pittas, their singing behaviour did not change noticeably between the two visits, except when pairs were tending a nest, when they became silent (see Gulson-Castillo et al. 2017 for a detailed description of parental care at a nest in 2013). Our observations were biased towards times when birds were singing—a simple, prolonged, whistle. We heard the subtle ‘wing-clap’ sonation ( Pegan et al. 2013) often during both periods, although only ever from a recently singing bird departing a perch ( ML 181755, 4:03). After bouts of singing, pittas often moved through the understorey and across the forest floor, perching on logs and roots to sing occasionally as they flipped over leaves, foraging. Once, JMH observed a pitta climb 2 m up a buttress to inspect a clump of leaf litter against the trunk.

Because we followed individuals in our study area closely and colour-banded most of them in 2013, we were able to use our sightings to calculate 95th percentile kernel densities of home ranges for each pair. One bird was colour-banded in 2012 and occupied the same area in both 2012 and 2013. Fig. 9 shows the estimated home ranges for five pairs, as well as a few sightings for a sixth pair in an area that we visited infrequently. Two pairs’ home ranges either overlapped slightly or had abutting boundaries (red with purple, and grey with pale blue in Fig. 9 ). Neighbouring birds sang in response to each other’s presence or to playback in the boundary area, and birds in the northern two territories frequently counter-sang at opposite sides of a gully. The active nest we found belonged to birds in the southern set of adjoining home ranges, and is shown on the map as a yellow point. All territories were associated with a tangled swamp or stream, usually the former, and some also included a segment of drier slope on the neighbouring ridge.

The plotted density kernels are probably fairly representative of the home range occupied by each pair, although without radio-tracking data we cannot eliminate the possibility that these areas were merely those parts of their territories in which the birds were most detectable (i.e. where they sing most frequently, or where the topography was most accessible). Indeed, small points outside the main territories, displayed as part of the pale blue and purple home ranges on Fig. 9 , demonstrate that birds sometimes visited areas where we usually did not detect them. The calculated areas of the home ranges are as follows: 6.5 ha; 5.3 ha; 14.4 ha; 4.4 ha; and 4.3 ha. However, these areas are affected by the number of points used to calculate them, and should be taken as very approximate estimates—larger sample sizes led to smaller estimates of range size. Phillipps & Phillipps (2014) interpreted Fogden (1976) finding two individuals within 20 ha to signify that the species’ home range size is c.10 ha, which is consistent with our findings.

Figure 10. A presumed hybrid or backcrossed female Using radio telemetry, Lambert & Howes Black-crowned Erythropitta ussheri × Garnet Pitta E. (in prep. in Lambert &Woodcock 1996; F. granatina (right), showing brighter coloration than Lambert pers. comm.) estimated, based on other female Black-crowned Pittas and a streak of red the small area used by individuals in their on the head and nape; at left is her presumed mate (©

Katherine Lauck) study, as many as 21–22 pairs per km 2 in Danum Valley, which is much greater than the density we observed at Tawau Hills; within the 3 km 2 area of Fig. 9 we found six pairs. Danum Valley may possess more suitable habitat than the area we surveyed in Tawau Hills, which contains numerous steep, drier ridges. All home ranges except one appeared to harbour a pair (the other held a single individual). One member of each pair (probably the male) sang more frequently and tended to be more brightly coloured (similar to Rainbow Pittas Pitta iris ; Zimmermann & Noske 2003). The putative females sang much less often—we would generally hear them once or twice during a prolonged visit to a territory. They occupied the same area as putative males and their songs did not elicit an aggressive response from the latter. Their songs were distinctly higher pitched than putative male songs. We subsequently used blood samples to determine the sex of captured individuals, which confirmed this ( Gulson-Castillo et al. 2017). We trapped a bird that appeared to be a hybrid or backcross with Garnet Pitta Erythropitta granatina . We took photographs, blood, audio and feather samples from this individual. This bird shared a territory with a male Black-crowned Pitta and sang less often than the latter, but more frequently than a typical female. We used the blood sample to confirm that the bird was female; it was the only female we caught that appeared to be just as brightly coloured as its mate (Fig. 10). The dark purplish feathers in the upper mantle of all Black-crowned Pittas (including the unusual bird’s mate) have a slight reddish tint at the fringes. In the presumed hybrid, a bright red streak emanated from these red-tinted feathers in the upper mantle and ended on the central crown (Fig. 10). This streak was not as broad or long as the red crown of a Garnet Pitta and although each so-marked feather was mostly red, their tips were still black (Fig. 10). This is probably the second or third report of a possible hybrid Black-crowned × Garnet Pitta ( Erritzøe & Erritzøe 1998) , matching the description of one collected in 1935 by V. von Plessen at Peleben on the Kayan River, North Kalimantan ( Erritzøe & Erritzøe 1998). Another potential hybrid was collected by Lumholtz at Kaburau, also on the Kayan River—it has much more extensive red than the other birds, resembling Garnet Pitta with limited black tips to some crown feathers, and not all authors accept this as a record of hybridisation ( Voous 1961, Lambert & Woodcock 1996). These other hybrids were collected c. 150–250 km from Tawau Hills Park. We found no other evidence of Garnet Pitta at Tawau Hills and observed no evidence of hybridisation in the other individuals we trapped.

Nine individuals were trapped, of which two were subsequently recaptured. The only bird caught in 2012 was radio-tagged with a c. 0.4 g beeper radio-tag. The night after its capture, we tracked the bird to its roost site, c. 2 m above ground on a branch with its plumage fluffed extensively, as in previous reports (L. Emmons in Lambert & Woodcock 1996). The following night, the tag was found in low shrubbery, evidently removed by the pitta.

Figures

Figure 9. Map of the topography of our study area showing home ranges of five pairs of colour-banded Black-crowned Pittas Erythropitta ussheri observed in 2013. Coloured shapes represent the 95th percentile of a kernel density of sightings of each pair. Colours represent different pairs’ territories. The location of a nest is marked by a yellow point. The map demonstrates the approximate number and size of Black-crowned Pitta home ranges, including apparent overlap between two pairs’ home ranges. Kernel densities were calculated in R using the function kde2d with default bandwidth. We had only four sightings at one territory (maroon points near the upper left corner) and display points rather than kernel density. Grey lines represent trails, the brown line a pipeline, and the blue line the Tawau River. 3D map courtesy of JAXA (2015).