Abstract
1. A density of birds is calculated simply as follows in my method;
Ni=Zi/Ei (1)
where, Ni is territory numbers of i species in an area censused, Zi is individual numbers recorded in census, Ei is the census effectivity of i species which derived empirically from the study area survey (Ei=Zi/Ni).
Then, if there is a correlation originally between Ei and density itself, the equation (1) will become complicated. This paper dealt with this problem based on 9 years data taken at Takizawa and others.
2. The correlation coefficient (r) between the census effectivity and territory density in 9 years data of Takizawa area showed no significant level for every species (Table 1). Likely, the correlation coefficient between the census effectivity and territory density of several study areas, and between the song effectivity and territory density in Takizawa showed no significant levels (Table 2 and 3).
3. By these results, my simple method can be considered to be useful for the bird density estimation.
