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        Discussion Area °Q½×°Ï >> General ¤@¯ë°ÝÃD >>  Two egret papers - ¤G¥÷ÆO³¾¤åÄm
        
(Message started by: Captain on Jun 12^th, 2006, 11:57am)

Title: Two egret papers - ¤G¥÷ÆO³¾¤åÄm
Post by Captain on Jun 12^th, 2006, 11:57am

»´äÆ[³¾·|¥Xª©¤F¤G¥÷Ãö©ó»´ä¤Î®ü«nÆO³¾ªº¤åÄm¡C¤åÄmªº¦WºÙ¤Î¼¼n (¥u¦³^¤å)¥i©ó¤U±¬Ý¨ì¡CY·Q¬Ý¨ì¾ã¥÷¤åÄm¡A½Ð¹q¶lP¶ÀÛ©÷ (wongca ptain@ya hoo.com) ©ÎÆ[³¾·| (hk bws@hkb ws.org.hk)¡C

HKBWS has published two papers about egrets in Hong Kong and Hainan. The titles and abstracts are shown below (Eng only). Should you would like to receive a full paper, pls email to Captain Wong at wongca ptain@yah oo.com, or HKBWS at hkb ws@hkb ws.org.hk.

These two papers are

Nest Numbers of Five Ardeids in Hong Kong, South China,1989-2004: Does Weather Affect The Trend?
L. C. WONG AND L LEWELLYN YOUNG  
Waterbirds 29(1): 61-68, 2006

Abstract.
¡XThis study reports on the number of nests and colonies of Great Egret (Ardea alba), Little Egret (
Egretta garzetta), Cattle Egret (Bubulcus ibis), Chinese Pond Heron (Ardeola bacchus) and Black-crowned Night Heron (Nycticorax nycticorax) in Hong Kong between 1989 and 2004. Little Egret, Chinese Pond Heron and Black-crowned Night Heron were the dominant local breeding ardeids. Regression analysis of the number of nests and colonies with year revealed that the number of nests of Great Egret, and the number of colonies of all ardeids, except the Black-crowned Night Heron, showed a significant increase. The number of nests of Great Egret increased from no nests in 1989 to 85 in 2004. The other species fluctuated from 100 to 300 nests each, except for Cattle Egret which stayed steady at about 100 nests. Regression analysis of the relationship between climate variables and residuals, after removing the effect of any long-term trend, shows that there was a significant positive association of the number of nests of Cattle Egret with total rainfall during breeding. The increase in numbers of colonies, but not the number of nests, indicated that previously large colonies had split into smaller ones, presumably due to loss of feeding and nesting habitats. The El Niño events in 1991 and 1997, but not in 1994, coincided with declines in nests. The magnitude of El Niño may be related to the impact on nesting ardeids, but other local confounding variables, in particular feeding habitat availability, should also be considered. The number of Great Egret nests in Hong Kong is of regional importance, as it is about half the known nests in southern China. It is recommended that monitoring of breeding success should be initiated in major colonies, as well as an integrated wetland monitoring for Deep Bay and Starling Inlet.

Ardeid Nesting Colony Survey in Hainan, China
W. LIANG, L. C. WONG AND J. Y. P. WONG
Waterbirds 29(1): 69-75, 2006

Abstract.¡X
A survey of ardeid nesting colonies in Hainan Province, China, was made between May and August 2004 and recorded 5,287 nests of four species (Little Egret (Egretta garzetta), Cattle Egret (Bubulcus ibis), Chinese Pond Heron Ardeola bacchus and Black-crowned Night Heron (Nycticorax nycticorax), in 18 colonies in the northern area. Chinese Pond Heron was the dominant nesting species (62% of the total nests), while the Black-crowned Night Heron was the least abundant (4%). Numbers of the Chinese Pond Heron in Hainan is probably related to the presence of extensive ricefields in this area. Fewer numbers of nests of all species in the field were recorded compared with expected obtained from nest densities over a ricefield-dominated landscape in a previous study of ardeid nest abundance in central China. This suggests that nest density in central China could not be applied in Hainan and the assumption of 5 million nests in China requires further study. Based on available information for south China, numbers of nesting Cattle Egret and Chinese Pond Heron in Hainan (75% of total nests of each species), Black-crowned Night Heron in Guangdong and Guangxi, and Great Egret in Hong Kong (80%) are of regional importance. Using media to invite readers to report nesting colonies is recommended for similar surveys in a large area as it provides a cost effective approach to minimize sampling effort.