Research | Spring Bird Count

Research

The Illinois Natural History Survey provides the ability to view, query, graph, and download the data generated by the Spring Bird Count. As you search through the data, please let us know of any errors (there could be some!).

The data generated from the Spring Bird Count can be used to estimate changes in populations of species throughout the state. Below is a graph of the number of crows detected per party hour throughout Illinois and in Cook County (i.e., Chicago). The graph shows a large decline in their population after the arrival of the West Nile virus in Illinois.

Graph shows sharp declines in crows in Illinois starting in 2004. — Spring Bird Count Crow Data

The next series of graphs shows the changes in selected species. Henslow’s sparrows, double-crested cormorants, and wild turkeys have shown large increases, loggerheaded shrikes and Upland sandpipers show large declines, and Swainson’s thrushes exhibit very large fluctuations from year to year, which is probably correlated with regional weather patterns affecting migration.

Wild turkey numbers have increased 500% from 1995 to 2005. — Spring Bird Count Wild Turkey Data

Double-crested cormorants increased sharply in early 90s and have continued to grow since. — Spring Bird Count Double-Crested Cormorant Data

Loggerheaded shrikes have alternated but overall are down over 300%. — Spring Bird Count Loggerheaded Shrike

Upland sandpipers have dropped to a third of 1980 levels, going up and down in the timespan. — Spring Bird Count Upland Sandpiper Data

Henslow's sparrows have increased sixfold between 2000 and 2005. — Spring Bird Count Henslow’s Sparrow Data

Swainson's thrushes have fluctuated widely from 1975 to 2005. — Spring Bird Count Swainson’s Thrush Data

Please note that, due to the nature of the data, declines or increases in certain species’ population trends may not accurately reflect true changes in overall populations. Therefore, statistical tests should be performed to determine if observed trends differ from a stable (no change) trend. Please contact Tara Beveroth or Michael Ward with questions about the data or if you suspect errors.