5th graders on Bainbridge Island, Washington, have been collecting data over a 2-week period during the month of May for 13 years. The important component is that is it always over a 2-week period and always in May.
Students collect data from home and from specific long-term monitoring sites. The number of students may change and the locations (e.g., their homes) will be different, but after 13 years, there are enough data to document what species are common on the island across multiple habitats.
Because there is a possibility the same bird may be reported by different students over the 2-week period, data are averaged. Population increase and decrease can not be calculated without more specific data collection protocols.
