Daylight Saving Time as a factor in deer collisions in Wisconsin

If Wisconsin is known for three things, it must be cheese, the Packers, and deer-vehicle collisions in the fall.

As newsroom developer at the Milwaukee Journal Sentinel, I maintained the most complete database of deer accidents in the state from data acquired through an annual open records request from the Department of Transportation.

While the newsroom had published summary statistics from this dataset each fall for the previous five years, fresh data analysis revealed a surprising new factor: Daylight Saving Time.

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By visualizing the data in its most disaggregated state, we were able to visualize the rise in deer crashes that coincides with the end of Daylight Savings Time each year. Previous research from the University of Washington verified this trend, although that analysis did not include data from Wisconsin.

The end of Daylight Saving Time corresponds with “the rut” in Wisconsin, the mating season that is the most active period for white-tailed deer. Rolling back the clocks by an hour near the beginning of November brings rush hour into the most active time of day for the animals as well.

Completed: November 2023
Published by: The Milwaukee Journal Sentinel
Technologies used: HTML, CSS, & JavaScript / Observable Notebooks / Python (Pandas) / QGIS