Effects Of Climate Change On Bird Community Structure In Dalai Lake Area

The Dalai Lake National Nature Reserve in Inner Mongolia is located at the border between China, Mongolia and Russia. It is an important stopover site of the northeast Asia bird migration routes, which is the Ramsar wetland site of international importance. For the global warming, the area of the lake decreased with the increasing of local temperature, which could influence the waterfowl community structure. Due to the increasing of temperature, the development of insects could advance, while the initiation of bird reproduction induced by the light period could not advance, which has resulted in the phenology mismatch between the bird and insect. To verify the influence of global warming to the bird community of northwestern grassland wetland ecosystem, we studied the correlations between temperature changes and the area of the Dalai lake, the relationship between the variation of waterfowl community structure and the area of the lake, and the synchronism between the insect development and the reproduction rhythm of Asian Short-toed Lark (Calandrella cheleensis) in the Dalai reservation of Inner Mongolia. The main results are as follows:The average temperature of the Dalai lake has raised 1.84℃ since 50 years and the lake area has reduced 372.93 km2. The annual average temperature is negatively correlated with the area of the lake (r=-0.31, p<0.05) significantly.There are 107 waterfowl species recorded in Dalai nature reserve during 2004-2013, belonging to 17 families,46 genus, Anseriformes and Charadriiformes are dominant taxa. The area of the lake is negatively correlated with the diversity index, the richness index, and the evenness index.The area of the lake is negatively correlated with the diversity index of Anseriformes, and the Charadriiformes, while the lake area is positively correlated with the Ciconiiformes diversity index. The area of the lake is positively correlated with the individual number of the red-crowned crane (G. japonensis), the White-naped Crane (G. vipio), the Common Crane (G. grus), but the lake area is negatively correlated with the individual number of the relic gull (Larus relictus), the whooper swan (Cygnus cygnus), the Tundra Swan (C. clumbianus), the mute swan (C. olor), and the demoiselle crane (Anthropoides virgo).During 2004-2011, the species diversity of waterfowl in Dalai lake reserve did not decrease with the lake area recession, but increased for the formation of the marsh wetland during the water recession. Meanwhile long-term depletion could cause desertification, which will influence the live of the waterfowls. Therefore it is necessary to study the relationship between waterfowl community and lake variation in long term.In the study area,20 successfully incubated nets have been recorded, and the average clutch size is 3.05±0.51. The period of incubation is 10-12 days, the birth peak is on 28th of May. The earliest and latest birth date is 6th of May and 1st of June respectively. The average nestling number per nest is 2.55±0.83 (n=20), and the average birth rate is 83.33%±23.42%(n=20). The Asian Short-toed Larks mainly eat the larvae of the orthopteran (locusts), which is 87.06% of total food.The earliest date when orthopteran larvae were captured in the study area is on 24th of April, and the number of the captured larvae reached peak value on 22nd of May. The earliest date the larvae appear was earlier than the date the earliest hatching of nestlings 12 days. The date of larvae number peak was earlier than the nestling hatching peak 6 days. In all the nests with nestlings,10% hatched during the larvae number peak,20% hatched earlier than the larvae number peak and 70% hatched later than the larvae number peak. The survival rate of the nests hatched during larvae peak was 100%, while the survival rate was 75% and 88.64% respectively for the nests hatching earlier and later than the larvae peak. The weight and tarsus of the nestlings hatched during the larvae peak grow 1.60±0.32 g and 1.79±0.20 mm every day, were all faster than the nestling not hatching during the peak of larvae.The nestling hatching peak of Asian Short-toed Lark’s mismatched the food peak in the Dalai reservation of Inner Mongolia. Most of the nestlings were hatched later than the larva peak. Some individuals, however, match the food peak. Therefore the Asian Short-toed Lark has the potential of microevolution to adapt to the food peak variation induced by climate warming.