Abstract:Vegetation coverage is an important factor influencing the nesting habitat selection for Saunders′s gull (Larus saundersi). It is endemic to the Common Seepweed (Suaeda glauca) habitats for breeding in Yancheng National Nature Reserve (YNNR), which have been lost and degraded because of human land use and expansion of Smooth Cord-grass (Spartina alterniflora). We used satellite images in 1992, 2002 and 2007 to quantify the coverage change of Common Seepweed through the non-dense dimidiate pixel model from normalized difference vegetation index (NDVI) for the core area of YNNR. The Common Seepweed habitats on which this species depends in the study area decreased in area from 4772.3 hm2 in 1992 to 4062.2 hm2 in 2007 with annual rate of 47.34 hm2/a during the past 15 years. The mean coverage of Common Seepweed habitats increased form (27.6±3.8)% in 1992 to (35.4±2.0)% in 2002, and then to (53.1±4.5)% in 2007. Meanwhile, we used 184 nesting locations in 2002 and 109 nesting locations in 2007 to qualify the mean coverage of Common Seepweed habitats for Saunders′s Gull, which were (35.08±4.8)% and (37.58±7.6)% respectively and showed no significant difference in 2002 and 2007 (P=0.066). Combined with the grids of water source distance and human disturbance distance, the suitable nesting habitats for Saunders′s gull in the study area were also explored, which increased in area by 94.4 hm2 from 1992 to 2002, and then decreased 434.8 hm2 form 2002 to 2007 with annual decrease rate of 86.97 hm2/a. Based on this decreasing rate, we predicted that the suitable nesting habitats for Saunders′s gull will be disappeared within 19.8 years in study area. This paper also discussed the implication of our results for the conservation of Saunders′s Gull and its habitats, and the use of remote sensing methods in conservation.