Figure 4From: Zoning for management in wetland nature reserves: a case study using Wuliangsuhai Nature Reserve, ChinaDistribution of water bird population in summer (2009–2011). DI is the distribution area with a density of 3000 water birds per km2; DII is a density of 2000 per km2; DIII is a density of 1000 per km2; “Breeding sites” refer to the breeding sites of Cygnus.Back to article page