Abstract: In order to clarify the effect of hourly variability on water birds counts, and provide basic information for the designing of reasonable methods for water birds monitoring, data on water birds species and population were collected using the quadrat method at two sites situated along the estuary of north Erhai Lake, from January 28 to March 15, 2011. Twenty three species belonging to eight families and six orders were recorded in this survey. The detection numbers of individuals showed a significant diurnal variability during the session of investigation, with least detection from 8:00 to 9:59 and most detection between 16:00 to 18:00. The lower detection of water birds from 8:00 to 9:59 is likely due to the higher activity frequency of fishing boats during these hours. Within the different groups, hourly variations in the detections of population size of swimming birds were significant, but no significant correlations were found for wading birds, migrant birds and resident birds. Among twelve common species, individual species differed in patterns of activities in a day, and hourly variations in the detection of population size of five species were significant. Our results suggested that monitoring the water bird community of Erhai Lake should be conducted after 16:00.

Key words: sand-fixation shrub plantation, soil microorganism, soil quality assessment., soil nutrient