The bird survey data has been collected since 1987. It is divided into periods of 5 years, and each year is divided into 48 quarter months.
We provide two ways of plotting all or part of the data onto the grid below. in both plots the horizontal axis is the time of year in quarter months and the vertical axis is the specis count. The vertical grid lines denote monthly boundaries.
Line Graph.
The first type of plot is a line graph where the number of species in each completed survey
period is plotted versus time of year (quarter month). The data for each period is
connected by colored line segments where the colors form a red-yellow-green-blue
spectrum according to the years in which the surevey occurred; red for the earliest
period and blue for the most recent. The black line shows species versus time of
year for the combination of all the survey preiods.
Period Differences.
The second type of plot examines the differences between the survey periods. It displays the
band that encloses the amounts by which the number of species in each 5 year period excedes or trails the average
in each quarter month. For each quarter month we also calculate the correlation
between the counts and the period in which they occured. This correlation
coefficient is used to assign a color chosen from spectrum shown in the legend.
Thus red colored weeks have experienced a reduction in number of species over the years.
Whereas, blue weeks have experienced an increase.
Categories to be included in the plot:
| Time categories | Habitat categories |
|---|---|
| Year round resident or visitor. | Lakes and ponds. |
| Summer resident or visitor. | Marshes, shorelines and mudflats. |
| Winter resident or visitor. | Grasslands and praires. |
| Migrant. | Woodlands, savannahs and conifers. |
| Vagrant. | Shrubby areas. |
| Agriculture fields and lawns |