Abstract: The foraging behavior of Parus major and P. palustris in the secondary deciduous wood during winter and summer was studied. All data were gathered from November to February of next year 1988-1991 in winter and from March to July 1989-1991 in summer. Observations were made in secondary deciduous wood of Zuojia Nature Protection region of Jilin Province. The Great tit and Marsh tit are common permanent residents of secondary deciduous wood in the region. The height, positions(Horizontal and vertical of canopy), substrates, trees species, niche breadth and niche overlap of foraging of two species are very different. The height of foraging has been expressed as the distance from 0-4m, 4.1-10m, 10.1-15m and over 15m. Great tit feeds average lower than in Marsh tit. At foraging position of canopy layer in horizontal Great tit feeds on middle layer and out layer in winter and summer, while March tit feeds on out and middle layers. At vertical position of tree canopy, Great tit feeds on up, middle and low layers in winter, and on low and middle layers in summer, while Marsh tit feeds on up and middle layers in winter and summer, concerning the trees utilized for foraging Great tit feeds on Mongotian Oak, River Birch and Pierrot Willow in winter, while Mach tit feeds on Pierrot Willow, River Birch and Manchurian Linden. The results showed that two species did not over lap significantly in the places where they gather their food in order to utilize the common food resource differently.

Key words: photosynthate, lag time, pulse labeling, soil respiration.