Breeding ecology of a marine plain dependent passerine, the Capricorn Yellow Chat 'Epthianura crocea macgregori',in north-eastern Australia

• Published in: Australian field ornithology Vol. 37; pp. 15 - 25
• Main Authors: Wayne A Houston, Robert L Black, Rod J Elder, Damon Shearer
• Format: Journal Article
• Published: 01.01.2020
• Subjects: Biodiversity conservation; Birds; Breeding; Ecological zones; Endangered species; Environmental aspects; Habitat; Rainfall reliability; Australia
• ISSN: 1448-0107

The habitat and timing of breeding of the Critically Endangered Capricorn Yellow Chat Epthianura crocea macgregori were studied over 12 years on the central Queensland coast. The labile breeding season, although summer-autumn dominant, corresponded to the wetter months and inundation of breeding habitat, allowing this bird to breed in any season or month following substantial rainfall, and more than once in a year in response to atypical rainfall events in the drier months. Formation of flocks showed a seasonal pattern, with flock size significantly greater during the post-wet period than during the wet or dry season. Breeding birds were in pairs or family groups, and dry-season flocks were small as the birds dispersed widely across the available dry habitat. The relatively large flocks (20-80) at some sites in the post-wet period (typically 4-5 months after breeding commenced) are postulated to coincide with maturation of young birds. Breeding was observed in grass-sedge swamps on marine plains and supratidal saltmarshes with vegetation taller than 40 cm. Nests were placed low (27 cm +- standard error 7 cm above the ground) in clumps of vegetation that averaged 69 +- 8 cm high, and the height of vegetation supporting dependent young averaged 108 +- 7 cm. Nestlings numbered between two and four (average 2.8 +- 0.2). Capricorn Yellow Chats nested in the same habitat and sites from year to year. In the southern part of their range, their requirement for tall (>40 cm) supratidal vegetation and site-faithfulness suggest that conservation prospects could be enhanced by protection of relatively small patches of breeding habitat. In the northern part of their range, co-existence with livestock grazing suggests that appropriate habitat-tall grass and sedge cover-can be maintained providing stocking rates remain conservative. In general, recognition and improved government protection of tall supratidal saltmarsh, as a distinct entity from shorter saltmarsh with regular tidal influence, would enhance conservation outcomes for endangered fauna.