Notes on the Occurrence of Birds During the Spring Periods of 1948-1950, in Northern Emmet County, Iowa

Bird students are usually only vaguely aware of the orderly sequence of arrival dates of migrants and summer-residents in a given area. They know merely that certain species may be expected to appear at certain times each year. If data are compiled and presented in either tabular or graphical form, it becomes possible to evaluate year-to-year differences within one species and to make comparison between species. During the winter-spring-summer periods of 1947-1948, 1948-1949 and 1949-1950, the author gathered data on the occurrence of birds in northern Emmet County, Iowa. Although data were gathered from February through July of 1948 and January through May of 1949 and 1950, this paper, for convenience, includes only the spring periods following March 1. For data gathered prior to March 1 and a description of the study area, see Weston (1952). One-hundred and thirty-one days were spent in the field during March to July period of 1948, 81 and 68 during 1949 and 1950 respectively