Most biological events (blooming of lilacs, Migration of geese) move ahead or behind together and does not fit onto an enviromental calandar better than the wall calander. The determining factors are in part phyical, changing lenghts of day and night, daily temperatures increments, fluctualion in rain fallfall, and in part biological, inherent in age of the plant or animal and the choriography of harmones. Sometimes associates force dependent creatures to adjust fall into step with theirs
Study of the biological calendar is phenology. It enables one to predict one biological event from the timing of another ie. The blooming of maples arrival of woodcocks, It foretells progression. The savanah sparrow that finds the first Pasque flower in Iowa will be in Minnesota a week later to find the first pasque flower there. This event interface striches across most of the county, an irregular line that twists ahead or behind far hills and lakes, and moves north in the sping and south in the fall.
The timimg of most events in this Almanac are based on 10 to 100 years of observations in the vicinity of latitude 42.5. Readers that live south at latitude 40 or north ar 45 can often subtract or add a week. In late spring the dates for latitiude 42.5 will be correct for latitiude 40 and in a early spring they will be correct for latitude 45.
As we travel north or south, a Variety becomes one Earth Day latter or earlier for each ten miles.