In the early 1960s, museum archaeologist Alan Harn began a whitetail deer observation program that has been carried out to the present. Nearly 6,800 hours were spent in the field recording behavioral patterns of 1,379 whitetail bucks during 50 breeding seasons. This unprecedented volume of data, registered as Illinois State Museum Landscape History Program Technical Report 2011-000-11, provides new insights into deer breeding patterns that are of interest to a diverse audience of biologists, conservationists, naturalists, and hunters alike. Entitled “Five Decades at the Scrape: Observations on Variation in Whitetail Deer Breeding Patterns in Illinois”, the study describes the breeding process that begins with removal of antler velvet in the summer and culminates with antler loss in mid-winter.
Harn presents evidence that onset of the deer reproduction cycle is triggered by decreasing sunlight entering the eye (photoperiodism), and occurs at the same time each year regardless of weather, moon phase, or other natural condition. Through a series of charts, the analysis effectively nullifies the popularly held misconceptions of a single November rut or a “pre-rut” and main rut cycle by graphically demonstrating that breeding actually begins by mid October and continues with four rut peaks at 28-day intervals into early January. The study also determined that bucks abruptly alter their rutting patterns during each breeding interval by curtailing reestablishment of territorial markers, called scrapes, in favor of perpetual travel to directly intercept the increased numbers of females coming into estrus. Analysis of 593 fresh scrapes also documents wide inter-rut variation in the timing and preparation of these scrapes and explains their function within the breeding cycle. Figures depicting primary aspects of rutting behavior are included.