The limestone area located in southwestern Guangxi in the south of China is part of a global biodiversity hotspot. As an important habitat of this limestone region, karst wetlands provide birds with necessary water conditions for their survival and reproduction. From 2007 to 2012, bird surveys were conducted in natural wetlands(pools, streams, springs and seasonal flows) in 14 nature reserves and 18 reservoirs in the limestone area of southwestern Guangxi. A total of 365 bird species were recorded in field investigations, including 103 water-dependent birds mainly seen in wetlands. Among these 103 birds, 10 species are globally threatened and 5 species have been placed under national key protection. The birds were selective in their use of the various types of karst wetlands. The number of bird species was the highest in pools and springs, with 304 and 266 respectively, followed by streams with 131 species. Reservoirs are the main wintering habitat for the large Natatores and in the rainy season the importance of seasonal flows is paramount. Seasonal changes in the utilization of karst wetlands by birds were obvious; the number of bird species in the dry season was much higher than during the rainy season. Bird migration and seasonal flows are the main reasons for seasonal variation in the number of water-dependent birds. These natural karst wetlands ensure the drinking water supply for more than 80% of the water-independent birds in the dry season. These karst wetlands are the wintering ground and stopover area for 58 species of migrant birds. At present, threats to the birds in the karst wetlands consist of illegal hunting, habitat changes and eucalyptus plantations. Karst wetlands are important for protecting biodiversity. More attention ought to be directed to these wetlands and protection efforts enhanced.
Although forest gap ecology is an important field of study, research remains limited. By plot setting and point counted observation, the response of birds to forest gaps in winter as well as bird distribution patterns in forest gaps and intact canopies were studied in a north tropical monsoon forest of southwestern China from November 2011 to February 2012 in the Fangcheng Golden Camellia National Nature Reserve, Guangxi. The regression equation of bird species diversity to habitat factor was Y1=0.611＋0.002 X13＋0.043 X2＋0.002 X5-0.003 X8＋0.006 X10＋0.008 X1 and the regression equation of bird species dominance index to habitat factor was Y3=0.533＋0.001 X13＋0.019 X2＋0.002 3（3-0.017 X4＋0.002 X1. There were 45 bird species （2 orders and 13 families） recorded in the forest gap, accounting for 84.9% of all birds （n=45）, with an average of 9.6 species （range： 2-22）. Thirty-nine bird species （5 orders and 14 families） were recorded in non-gap areas, accounting for 73.6% of all birds （n=39）, with an average of 5.3 species （range： 1-12）. These results suggested that gap size, arbor average height （10 m from gap margin）, arbor quantity （10 m from gap margin）, shrub quantity （10 m from gap margin）, herbal average coverage （1 m from gap margin） and bare land ratio were the key forest gap factors that influenced bird diversities. On the whole, bird diversity in the forest gap was greater than in the intact canopy. Spatial distributions in the forest gaps were also observed in the bird community. Most birds foraged in the ＂middle＂ and ＂canopy＂ layers in the vertical stratification. In addition, ＂nearly from＂ and ＂close from＂ contained more birds in relation to horizontal stratification. Feeding niche differentiation was suggested as the main reason for these distribution patterns.
