A study of diurnal activity patterns by Eurasian Curlew(Numenius arquata)at Ta-Du Estuary, Taiwan

• Main Authors: Liu Chao-Kuo, 劉照國
• Other Authors: 陳炳煌
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/82596249220995777281

碩士 === 東海大學 === 環境科學系 === 90 === The Eurasian Curlew (Numenius arquata oreintalis) is one of the uncommon wintering shorebirds in Taiwan, and the biggest population is at the Da-Tu Estuary. Because of the construction of the Tai-Power Generator, this population moved southward from the Da-Tu River mouth, and were found along the coastline at the Changhua Coastal Industrial Park during the last five years. Meanwhile, the counting data show that this population growth is decreasing. Due to the increase of reclamation and human disturbance, the conservation issues for this population are necessary and urgent. This research presents the daytime activity pattern and its relation with the abiotic factors of the Eurasian Curlew. The census proceeded from 5 October, 2000, to 25 March, 2001, and 25 days were successfully measured. The scanning method was used to collect data on different behaviors, and tide height, wind speed and temperature were selected as the abiotic factors. The Eurasian Curlews stood near the tide edge and moved with the tide during the high tide period. But the birds did not move with the tide as a group during the low tide period, but each individual moved from the group to the tide edge three or four times. The average percentage of rest was over 80%, showing that rest was the predominant behavior of daytime activity. The pattern is obviously much more correlated with the tidal cycle than with the day-night cycle. Both preening and resting proportions of time showed significant variation (p<0.01) with the wind scale; wind speed showed strong correlation (Spearman’s rho) with preening (r = -0.53) and resting (r = 0.24). The spatial, maintenance and feeding behavior showed a significant difference (p<0.01) between high tide and low tide periods. The human disturbance was mainly due to aquaculture, tourism and fishing, and the birds appeared to gradually get used to the noise. Feeding behavior and temperature are positive correlation ( r=0.20, p<0.01). The proportion of feeding showed significant variation (p<0.01) with temperature between the early-, mid- and late-winter. The proportion of feeding at low tide was higher than at high and mid tide. According to the low proportion of feeding during daytime, we suggest that the Eurasian Curlew may have nocturnal feeding at the Da-Tu Estuary.