olive. Behaviour Breeding The yellow thornbill likely breed in solitary pairs, but in some areas, evidence of co-operative breeding has been found. Yellow thornbill nests are rounded and domed, with a small entrance near the top. Nests are usually made of bark-fibre and grasses matted together with spider-web, located in the upper foliage of shrubs and small trees. Clutches of two to four eggs are laid soon after the nest has been completed, and are incubated for 16–17 days. Vocalisation The yellow thornbill has a loud, two-note tzid-id call, notably different from calls of the closely related striated thornbill by its harsher, less insect-like sound. The call is repeated at various intervals throughout the day and is associated with contact between birds while foraging, as defence, or as a territorial advertisement. Feeding and diet Occasionally, yellow thornbills have been observed in feeding flocks of up to 35 individuals, as well as mixed-species feeding flocks. More commonly, however, they are found in smaller groups or pairs. They prefer the upper and middle levels of forest canopy, and can be found moving rapidly through the outer foliage searching for food, or looking under bark. Their diet consists mostly of insects, but they will sometimes eat seeds. They will also catch insects mid-flight. Habitat and distribution Yellow thornbills are found mainly within temperate and semi-arid areas, with their range just extending into the subtropical zone. Within these zones, yellow thornbills are found in a variety of habitats including shrublands, forests and thickets, preferring vegetation dominated by casuarinas or eucalypts, particularly in areas with a drier climate. Their range extends from northern and central west Queensland, south along the eastern coast of Australia through much of New South Wales, throughout Victoria and the Australian Capital Territory, and into the southeastern corner of South Australia. Conservation Their current status according to the IUCN Red List is Least Concern, but with a decreasing population. In developed areas such as towns or industrial sectors, the yellow thornbill has only been recorded in older development areas and not at all in more recently developed areas. This correlates with observations of general bird populations in residential zones, with native birds decreasing when the native vegetation is removed. Fire also affects population numbers, with only the oldest age-class present after fires. In farmland which undergoes regular harvesting, yellow thornbills have not been recorded. Fire, land development, agricultural insecticides and climate