Capricorn yellow chat
Common name: Capricorn yellow chat, yellow chat (Dawson)
Species name: Epthianura crocea macgregori
There are three recognised subspecies of yellow chat (Epthianura crocea).
- Epthianura crocea crocea is found in south-west Queensland, Western Australia, Northern Territory and South Australia
- Epthianura crocea tunneyi is restricted to the Alligator River area in the Northern Territory
- Epthianura crocea macgregori, the Capricorn yellow chat, is endemic to the Capricorn Coast in central Queensland. The Capricorn yellow chat was first collected in the Rockhampton region in 1859. Following these initial collections, it was not located in the region for some time and the sub-species was considered either a rare vagrant or possibly extinct until a small population was discovered in 1991 on Curtis Island. Subsequently in 2003 the sub-species was rediscovered in the Broad Sound region (north of Rockhampton) and the Fitzroy River delta in 2004, with these three locations forming the only known populations.
The Capricorn yellow chat is listed as Endangered under Queensland Nature Conservation Act 1992, and as Critically Endangered under the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999.
The Capricorn yellow chat is a small bird weighing 10–11g, with a wing length of 56–60mm and a bill length of 10.7–11.6mm. Breeding males have a bright yellow crown, olive back, yellow rump and a 4–6mm wide black bar across their chest, while non-breeding males are duller with the breast bar being less defined. Breeding females have a yellow crown, grading to an olive back and golden rump and vent, although the yellow crown is not always observed in breeding females. Non-breeding females are generally paler, with a white throat and chin.
Habitat and distribution
The Capricorn yellow chat occupies marine plains that are seasonally inundated with freshwater during the wet season and are dominated by salt-tolerant grasses and sedges with patches of samphire. The Capricorn yellow chat is not generally found in unvegetated salt flats or mangroves. These marine plains are generally treeless with the exception of adjacent mangroves and generally receive significant freshwater flows during the wet season (December–February) before drying out. These wetlands used by the Capricorn yellow chat are generally less than 5m above mean sea level and either below or within 1.5m of the Highest Astronomical Tide.
The Capricorn yellow chat is generally associated with levy banks or check banks that prevent saltwater ingress. These banks generally increase the wetland area, extend the period of freshwater inundation and support salt-tolerant sedges the Capricorn yellow chat uses for breeding.
The Capricorn yellow chat is found at one location at Curtis Island National Park, with the remaining populations found on private land at eight locations in the Fitzroy River delta (approximately 40km to the west of Curtis Island), and at eight locations in the Broad Sound region 140 km north. There is little or no habitat connectivity between the populations at these three broad locations.
In 2018, the total population size of the Capricorn yellow chat was estimated to be between 220–280 individuals across the known populations, with approximately 75% of the population found in the Broad Sound, 22% in the Fitzroy River delta and 3% in Curtis Island National Park. However, due to seasonal weather conditions, populations of the Capricorn yellow chats can fluctuate significantly following breeding events. As these populations are small, disjunct and fluctuate in size, each population is vulnerable to local extinction.
Life history and behaviour
Like the other species of Australian chats (Family: Epthianuridae), the Capricorn yellow chat breeds opportunistically following significant rainfall events. While the Capricorn yellow chat predominantly breeds in spring and summer following rainfall and inundation of the marine plains, breeding has been observed in all months except July. Rainfall and the subsequent freshwater inundation of the marine plains triggers insect activity and abundance, which provides a breeding cue for the Capricorn yellow chat. Birds have been observed to return to the same areas to breed each year and they can breed more than once per year. Breeding success is influenced by wet season rainfall in the preceding year, with the timing and volume of rainfall events also influencing breeding success.
The Capricorn yellow chat builds nests in grasses, samphire, or sedges between 35–120cm off the ground with high levels of vegetative cover within 1m of the nest. Observed clutch size ranges from 2–3 eggs, but adults have been observed feeding up to four fledglings. Nest failure has been observed due to inundation for extended periods from extreme tidal events.
During the breeding season the Capricorn yellow chat has been observed foraging on muddy substrates around the edges of channels for prey at the base of sedges and samphire, including flies, caterpillars of moths and butterflies, spiders, grasshoppers, damsel flies, winged ants, cockroaches, and beetles.
Climate change—With most areas of Capricorn yellow chat habitat just above or below highest sea levels, its habitat is particularly vulnerable to sea level rise which results in increased salinity making the wetlands uninhabitable for the bird. Sea level rise has been observed severely impacting Capricorn yellow chat habitat in Curtis Island National Park. Climate change also influences rainfall and associated hydrological regimes, and increases risk from drought, heat waves and fire, all of which have the potential to contribute to unsuitable environmental conditions for the species.
Hydrological regimes—The Capricorn yellow chat is dependent on periodical freshwater flows to maintain suitable habitat and stimulate breeding. Any structures that impede freshwater flows for industrial, agricultural or infrastructure purposes have the potential to impact Capricorn yellow chat habitat.
Inappropriate grazing—Throughout the species distribution ponded pastures, particularly para grass (Urochloa mutica), have been established for pastoralism. Without appropriate grazing, para grass will smother Capricorn yellow chat habitat and displace the birds, while high intensity grazing will result in trampling of essential habitat. Landowners/managers in these locations have been effective in managing grazing intensity that has allowed suitable habitat for the Capricorn yellow chat to be maintained.
Feral pigs—Feral pigs cause damage to Capricorn yellow chat habitat by uprooting sedges and grasslands that the birds use for foraging and breeding. They are also likely to disturb nests and take eggs. Feral pig numbers and impacts are influenced by seasonal rainfall patterns and their impacts are variable across the bird’s distribution.
Weed species—Multiple species of pasture grasses have the potential to smother Capricorn yellow chat habitat. Para grass is an ongoing issue that can be managed by appropriate grazing. Other potential pasture grasses of concern include aleman grass (Echinochloa polystachya) and olive hymenachne (Hymenachne amplexicaulis). The potential impact of aleman grass is unknown, while olive hymenachne is unlikely to be a problem due to its low salt tolerance. Harrisia cactus (Harrisia martinii) and prickly pear (Opuntia spp.) don’t directly impact Capricorn yellow chat habitat but have the potential to form thickets and prevent access for land managers accessing areas to undertake management works. Prickly acacia (Vachellia nilotica) is a problem at one location where it provides perching habitat for birds of prey to launch attacks on the Capricorn yellow chats, reducing their population.
Habitat loss—Historical loss of Capricorn yellow chat habitat for the use of the marine plains for industrial use (e.g. salt fields, port development) is likely to have occurred but its impact is unquantified. Capricorn yellow chat habitat can be found within existing salt fields. This threat is not considered active and the land manager is actively involved in Capricorn yellow chat management and conservation.
Low genetic diversity—Genetic diversity within and between populations is extremely low indicating that the populations could be at risk of inbreeding. Little or no connectivity between the populations increases the risk from this threat but requires further investigation before management intervention occurs.
Other potential threatening processes include feral predators (i.e. feral cats and foxes), increased soil salinity and unpermitted access but the impact of these threats remains unknown and they require further research.
A Yellow chat (Capricorn subspecies) (Epthianura crocea macgregori) Recovery Plan (awe.gov.au) (PDF, 1.11MB) was produced in 2008 but expired in 2013. Since its development in 2008, significant research into the ecology of the Capricorn yellow chat has been undertaken Central Queensland University. The Department of Environment and Science, in consultation with multiple stakeholders, developed the Capricorn yellow chat species summary and future directions report . It provides updated management actions based on contemporary knowledge to facilitate the recovery of the Capricorn yellow chat.
One of the key actions identified in the report was the establishment of a Capricorn yellow chat Working Group. This group was formally established in March 2021 with the aim of coordinating key stakeholders involved in the research, recovery and management of the species. Recovery actions currently underway by various stakeholders, include:
- Population monitoring—It is essential to monitor population changes through time to determine if management actions are effective or if urgent intervention is required. Population monitoring is currently being undertaken in a three-year program run by central Queensland Natural Resource Management organisation, Fitzroy Basin Association. The program is funded by the Australian Government’s Reef Trust with support from Birdlife Capricornia and researchers from Central Queensland University.
- Climate change—The effects from climate change on the Capricorn yellow chat are extremely difficult to mitigate. Many populations are associated with levy and check banks that protect their habitat from sea level rise. While these existing banks are able to be maintained, legislative requirements to protect other species (i.e. fisheries) prevent the construction of new banks to create or protect other areas of Capricorn yellow chat habitat. Greening Australia has produced a detailed report on the feasibility of maintaining habitat for Capricorn yellow chat and to mitigate the impacts of climate change, specifically looking at sea level rise.
- Feral pig control—The Fitzroy Basin Association is supporting landowners to undertake feral pig control, while Queensland Parks and Wildlife Service (QPWS) actively controls feral pigs and other exotic herbivores located in Curtis Island National Park.
- Grazing intensity—The majority of sites where Capricorn yellow chats are found are located on pastoral properties where landowners/managers manage stock grazing at an appropriate intensity to maintain suitable habitat for the birds. Support for landowners/managers to improve grazing intensity has been provided through the development of a Capricorn yellow chat habitat guide produced by Greening Australia.
- Hydrological regimes—Any proposed development on the marine plains (e.g. industry, infrastructure, agricultural) requires appropriate assessment against local, state and/or federal government assessment guidelines. This assessment process considers whether a proposed development will have a significant impact on the species’ habitat, and whether these impacts can be avoided or mitigated.
- Weed control—Weeds are actively controlled throughout the Capricorn yellow chats distribution. Pasture grasses are actively managed by landowners by using appropriate grazing regimes to reduce the abundance of para grass while minimising impacts to Capricorn yellow chat habitat. Greening Australia has also been supporting landowners with weed management works on private properties, while QPWS actively manages weeds in and around Capricorn yellow chat habitat in Curtis Island National Park.
- Habitat loss—Ongoing engagement with stakeholders that are involved in existing and emerging industries that use the marine plains is required to minimise the impact to Capricorn yellow chat habitat. Existing industries are engaged in the program to protect Capricorn yellow chat habitat.
Further research into the Capricorn yellow chat is required, specifically genetic diversity within and between subpopulations to identify management actions required and the interaction between Capricorn yellow chat and para grass to improve grazing practices.
As these management actions are delivered and results from the population monitoring program and research programs are identified, this information will be updated.
Black, R. Study of the potential actions to mitigate effects on Capricorn yellow chat habitat due to climate change impacts of changing rainfall and rising sea levels Report prepared by Birdlife Capricornia for Greening Australia, Rockhampton, Queensland
DES 2020 Capricorn yellow chat species summary and future directions report. Brisbane, Department for Environment and Science, Queensland .
Houston, W & Melzer, A 2008, Yellow chat (Capricorn subspecies) (Epthianura crocea macgregori) recovery plan, accessed from http://www.environment.gov.au/system/files/resources/ecd1aa78-2135-49d0-8b0b- dce3325b3f98/files/e-c-macgregori.pdf (PDF, 1.1MB)
Houston, W, Black, R, Elder, R & Shearer, D 2020a, ‘Breeding ecology of a marine plain dependent passerine, the Capricorn Yellow Chat Epthianura crocea macgregori, in north-eastern Australia’, Australian Field Ornithology, vol. 37, pp. 15–25.
Houston, WA 2013, ‘Breeding cues in a wetland-dependent Australian passerine of the seasonally wet-dry tropics’, Austral Ecology, vol. 38, no. 6, pp. 617–626.
Houston, WA, Aspden, WJ, Elder, R, Black, RL, Neaves, LE, King, AG & Major, RE 2018b, ‘Restricted gene flow in the endangered Capricorn Yellow Chat Epthianura crocea macgregori: Consequences for conservation management’, Bird Conservation International, vol. 28, no. 1, pp. 116–125.
Houston, WA, Elder, R & Black, R 2018a, ‘Population trend and conservation status of the Capricorn Yellow Chat Epthianura crocea macgregori’, Bird Conservation International, vol. 28, no. 1, pp. 100–115.
Houston, WA, Elder, R, Black, RL, Shearer, D, Harte, M & Hammond, A 2020b, ‘Climate change, mean sea levels, wetland decline and the survival of the critically endangered Capricorn Yellow Chat’, Austral Ecology, pp. 1–17.