Population trend and conservation status of the Capricorn Yellow Chat Epthianura crocea macgregori

• Published in: Bird conservation international Vol. 28; no. 1; pp. 100 - 115
• Main Authors: HOUSTON, WAYNE A., ELDER, ROD, BLACK, ROBERT
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.03.2018
• Subjects: Annual rainfall; Annual variations; Birds; Climate change; Conservation; Conservation status; Drought; Dry season; Endangered & extinct species; Epthianura; Epthianura albifrons; Epthianura crocea; Epthianura crocea macgregori; Evaporation; Evaporation rate; Habitat utilization; Habitats; High temperature; Polls & surveys; Population decline; Population number; Population statistics; Rainfall; Rivers; Seasonal variations; Queensland Australia; Australia
• ISSN: 0959-2709; 1474-0001
• DOI: 10.1017/S0959270916000526

The average population size of Capricorn Yellow Chat Epthianura crocea macgregori was estimated at 251 +/-31 (SE) by repeated surveys over seven years (2004–2010) using consistent search effort at known occupied sites. Because the survey period coincided with a mixture of dry and wet years (drought from 2004 to 2007 followed by flood rainfall in early 2008 and 2010), it is particularly valuable as a preliminary benchmark upon which to base management decisions. Most of the population (74.5%) was in the Broad Sound area in the north, with lower numbers in the Fitzroy River delta area in the south (22%) and at Curtis Island (3.5%). Sites on Torilla Plain in Broad Sound accounted for two-thirds of the estimated population, making it a priority for conservation efforts. Depending on habitat configuration, some Capricorn Yellow Chats showed a seasonal pattern of habitat use, moving from flooded breeding habitats as they dried to refuge sites such as salt fields or upper marine plains in the dry season; distances moved being < 10 km. Standard surveys from Torilla Plain showed that the chat count during a sequence of above-average rainfall years was almost double that of the average for drought years: 162 +/-28 (2008–2015) compared with 85 +/-15 (2004–2007) respectively. Low population size, large annual fluctuations in population with prior rainfall, rapid declines in low rainfall years, a fragmented distribution and almost half the population concentrated at one site point to a subspecies vulnerable to chance events. Increased climatic extremes predicted by climate change such as higher temperatures, evaporation rates, extended droughts and more intense rainfall events add to its vulnerability.