Egrets in Hong Kong & Relationship between Nests and Weather - PowerPoint PPT Presentation

Egrets in Hong Kong & Relationship between Nests and Weather Josephine Wong Egret Research Group The Hong Kong Bird Watching Society

Egret Research Group • Established since 2002 Acknowledgements: • 1 Convenor, 3 members and – AFCD, HKSARG (Funding) 1 advisor – Colleagues from HKBWS • Our aims are research and (Coordination & Admin) education • Carrie Ma, Yu Yat Tung, Geoff Carey, • Lo Wai Yan etc – Seniors Provide baseline info since 1989 Dr. Lew Young – Helpers Provide support in previous studies • Dickson Wong.. Etc

Ardeids in Hong Kong • 18 species have been recorded in Hong Kong • 13 of them have breeding record in Hong Kong • Some of them are visitors (spring, autumn or winter visitors) scarce in sometimes in a year; some of them are common to abundant all year

Ardeids’ Ecological Value • Ardeids are tertiary consumers as they feed on fish, shrimp, snail and insect in different kinds of wetlands such as farmland, river, fishponds, gei wai and intertidal areas. • They helped us to balancing of whole ecosystem. • They can be used as one of bio- indicators, as trace element and organic pollutants’ will dissolve in to the water and absorbed by the producer, primary consumer and secondary consumer.

ERG’s work • Research: – Egretry Count in Hong Kong every year collecting baseline information – Desktop survey and analyzing different data – South China Egretry Survey • Hainan on 2004, and Guizhou on 2006 • Education: – Publishing leaflet – Organize Egretry Count Training Workshop – Providing training workshop to Undergraduate students – Provide a presentation in this seminar!

Hong Kong Egretry Review 2005

Egrets Nests and Colonies Trend from 1989 to 2006

1989 2006 Trend (89-06) ↑ GE 0 135 ↓ LE 325 305 ↓ NH 118 80 ↑ CPH 188 376 ↑ CE 90 121 ↑ Total 721 1,017

Comparison of Temperature and Rainfall with no. of nests and colony Log El Nino is occurred in year 1991/92, 1993/94 & 1997/98, caused an increase in the sea temperature and rainfall in these years in Hong Kong.

Statistic Only Cattle Egrets showed a marginal significant relationship with the rainfall during breeding season (r = 0.52, P = <0.05, N = 14)

Key Points • El Nino yrs: Decline in egret nests was noted in 1991 & 1997 but not in 1994 (highest no. of nests) • 1991 – Wetland lost in Deep Bay • 1997 – Heavy rains and warmer water temperature recorded late June – Aug (late breeding season). • Studies in Australia showed the relationship of no. of nests of cattle egret and prey availability in Hong Kong. • Cattle Egret nest number were correlated with total rainfall during breeding season in Hong Kong. • Further studies are needed for more reliable conclusion.

Conclusion • Over 1000 nests were counted in 2005 and 2006. • GE, LE, CE and CPH are OK but BCNH is declining

Recommendations 1. To visit the egretry in the Shenzhen side of Deep Bay 2. To monitor ardeid breeding success in major egretries, e.g. MPV and A Chau 3. To conduct focusing studies on Black- crowned Night Herons 4. To monitor Deep Bay in an integrated manner (allow better exchange of information among different monitoring)

Thank you very much