Relationships between changing water levels and numbers of wintering tuber-eating birds in Poyang Lake National Nature Reserve

Abstract

以4种食块茎鸟类——白鹤(Grus leucogeranus)、白枕鹤(Grus vipio)、鸿雁(Anser cygnoides)、小天鹅(Cygnus columbianus)为研究对象,分析越冬候鸟种群数量与鄱阳湖保护区内湖泊水位变化的关系.2003 2007年越冬季节,采用直接计数法调查鸟类的种群数量,通过非参数回归分析鸟类种群数量与水位之间的关系.结果表明,虽然4种食块茎鸟类的种群数量最高值分布在不同水位,但峰值水位差异较小,且种群数量与水位关系的总体趋势呈现一致性.随着保护区内湖泊水位的下降,鸟类种群数量呈现先增长后减少的倒V字形趋势.在水位由16.0 m降至14.8 m(吴淞高程)的过程中,鸟类种群数量随着湖泊水位下降逐步增加达到最高峰;在水位由14.8 m降至13.5 m的过程中,鸟类种群数量随着水位下降而减少.当鄱阳湖水位处于14.5~15.5 m之间时,食块茎鸟类的种群数量较高,其种群数量最高点出现在水位14.8 m左右.2003 2005年3个年度鸟类种群数量与水位的关系相似,呈现出先增多后减少的单峰趋势,峰值水位均位于14.75~14.90 m之间,2006和2007年平均水位升高,鸟类种群数量分布的峰值水位也高于前3年,峰值水位出现在15.25 m附近.由于受到良好保护,大湖池和沙湖鸟类种群数量与水位的关系稳定,而梅西湖未呈现出有规律的变化趋势.研究表明在本研究区域中,水位在14.5~15.5 m之间4种食块茎鸟类的种群数量较高,该研究结果对鄱阳湖国家级自然保护区水位管控具有指导意义.;Population numbers of four tuber-eating bird species(Grus leucogeranus, Grus vipio, Anser cygnoides and Cygnus columbianus) were surveyed and water levels were recorded to analyze the relationships between changing water levels and bird population numbers in Poyang Lake National Nature Reserve. During the winters(from October to next March) of 2003-2007, the population numbers of the four tuber-eating birds were surveyed by direct counting method, and the relationship between water levels and population numbers was analyzed by using non-parametric regression method in SAS. The results showed that the changes of population numbers of the four species with the fallen of water levels appeared consistent. With sustainable fall of water level, the bird population first increased and then declined showing an inverted V-shape. When water level changed from 16.0 m to 14.8 m(Wusong Elevation), the population numbers increased with the fall of water level. However, the bird population decreased when water level fell from 14.8 m to 13.5 m. Higher population numbers occurred at water levels between 14.5 m and 15.5 m. The highest population number occurred at about 14.8 m. The changes of population numbers of 2003-2005 in the winter showed similar unimodal patterns, with highest numbers occurred at 14.75-14.90 m. In the winter of 2006 and 2007, with the rise of the average water levels, the water level of peak population numbers rose, occurred at about 15.25 m. The relationship of water levels and population numbers were relatively stable at Dahuchi and Shahu, for these two lakes were under well protected, while in Meixihu, there was no significant trend in the changes of population numbers and water levels. The result helps guiding the water level management for Poyang Lake National Nature Reserve.