Cheshire and Wirral’s first breeding bird atlas took seven years of fieldwork. Why is this one only lasting for three years?
The main reason to try to keep the survey as short as realistically possible is that birds can change from year to year, in distribution and population. With some tetrads being covered in different years this could lead to misleading maps. The last breeding bird atlas took far too long, especially because 1978-84 was a time of big change for many birds, with some species declining by a factor of two or more during that time (e.g. Grey Partridge and Tree Sparrow). Of course we didn’t know at the time but it was bad luck that that period of major decline happened to coincide with the first Atlas. Whole areas in southern Cheshire were only visited in the last year and absences of some species could well be because of the population decline rather than a true difference in distribution.
