Illinois Birds A Century of Change

About this book

A project that began with two young men walking across rural Illinois toting shotguns and field glasses evolved into the first systematic bird survey in North America (Hickey 1981). When Stephen A. Forbes, Director of the Illinois Natural History Survey from its creation until 1930, directed Alfred Gross and Howard Ray to travel the state in 1906, no one in the country had yet attempted to count all the species of birds they observed across habitats, with a specific and repeatable method. Through 1909, Gross and Ray crisscrossed the state in all seasons, by foot, horseback, train, and steamboat, while counting and collecting the birds they saw.

In the mid-1950s, Richard and Jean Graber were newly hired ornithologists at the Illinois Natural History Survey. Among the first projects they undertook was to repeat the 50-year-old surveys during the summer and winter months of 1956-1958. The Grabers' 1963 publication, "A Comparative Study of the Bird Populations of Illinois, 1906-1909 and 1956-1958," remains the standard for assessing changes in bird populations of the state for the first half of the 20th century. With the exception of two obscure summer bird censuses by the U. S. Biological Survey (Cooke 1915, 1916), data on bird populations are scarce for most of North America until the Breeding Bird Survey began in the mid-1960s (Peterjohn et al. 1995).

From 2007-2009 we collected additional data that provide a bookend to what is now a 100-year bird survey. We present a summary of the changes to the summer bird populations and habitats across the state over the past century. Whereas our use of air-conditioned vehicles on interstate highways, use of Global Positioning System satellites to record our movements, and analysis of data on laptop computers would have been pure fantasy to our predecessors, their methods for counting birds in the field have been essentially retained.

This study provides three snapshots spanning a century. Important changes in the avifauna undoubtedly occurred within these windows, such as those documented by Charles Kendeigh at Trelease Woods near Urbana from 1922 to 1976. Kendeigh (1982) reported a spike in the abundance of arthropods and the forest birds that feed on them in the 1950s, when Dutch elm disease eliminated a common canopy tree and there was a surge of plant growth from the understory. The unique span of time and geographic scale are this study's strengths. In Illinois, where land cover and land use have changed dramatically owing to agricultural practices and development, insights into the dynamics of bird communities and populations over a diverse suite of habitats are crucial to understanding the past, present, and future sustainability of the avifauna across Illinois and the Midwest. Our goal for Illinois Birds is to summarize the results of surveys conducted across all three time periods. We direct our findings to a broad audience under four major headings: The Changing Illinois Landscape, Bird Communities Through Time, Species Accounts and Looking Back, Moving Forward.

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