Response Model of Egg-laying and Incubation Dates of Anser indicus at Dan Island in Qinghai Lake to Air Temperature and Normalized Differential Vegetation Index
Qinghai-Tibetan Plateau is the highest geographical unit on the Earth, and its unique geographic setting makes it very sensitive to climate change. The birds might also be greatly affected lived in Qinghai-Tibetan Plateau, for example, the breeding population of bar-headed goose (Anser indicus). In this study the egg-laying and incubation dates of bar-headed goose were recorded from 2007 to 2016, and the response of the dates to air temperature change was studied. The results showed that there were (4 976790) individuals of breeding bar-headed geese population recorded in Dan island of Qinghai Lake from 2007 to 2016, which accounted for nearly 10% of the global population of bar-headed goose. The date of first egg laying of bar-headed goose was significantly related to monthly mean minimum temperature in April, and monthly mean maximum temperature in March, as well as the accumulated temperature above 5 ℃ in April; the incubation date was significantly related to mean normalized differential vegetation index in April and monthly mean temperature in May, with an adjusted R~2 of 0.68 and 0.7 respectively. The higher the mean maximum temperature in March and the accumulated temperature above 5 ℃ in April, the lower the monthly mean minimum temperature in April, the earlier was the first egg laying date. The larger the mean normalized differential vegetation index in April, the higher the monthly mean temperature in May, the earlier was the first bar-headed goose incubation date.