Egg-laying character: Change in egg size, clutch size, and date of first egg-laying of varied tit (Parus varius) with elevation in Mt Jiri of South Korea

Abstract : This study was conducted to clarify the differences in egg-laying characters of Varied tit(Parus varius) as elevation in the Jiri-Mountain in spring of 2006. We set up 144 artificial nest-boxes at three sites where each of them had different elevation(about ht. 300, 900, 1500m), and checked egg size, clutch size and first date of egg-laying. At a result, There was no difference in egg size as elevation. But clutch size at high elevation was lower than at low elevation. Also, first date of egg-laying at high elevation was later than at other sites. In this research, we think that difference of clutch size at three sites result from 'individual adjustment hypothesis' and difference of first date of egg-laying have relation to sprouting date of leaves and distribution of insects.

 Key words : elevation, egg size, clutch size, Varied Tit, Parus varius