Timothy G. O'Brien

The Potential Of Christmas Bird Counts For Monitoring Presence Of Exotic Bird Species

The 1975 Christmas Bird Count was divided into 10 blocks, each comprising 100 observation units, encompassing the continental United States and Alaska. A random sample of 10 observation units was drawn from each block, assuring an even distribution over the continental United States and Alaska. Nine major metropolitan areas which were not drawn in the random sample were also studied. Each unit in the sample was examined for each of the years 1956, 1966, 1973, 1974 and 1975. The occurrence and number of each was recorded for all sample units for all years. Results indicated that a total of...

Year
1977