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Image by Anthony Roberts

When the Woods Turn Wild

Fresh tracks, rubbed trees, and mysterious scrapes appear throughout the woods. Decode the signs of Michigan's deer rut and discover what these clues reveal about the hidden lives of whitetails.

The annual mating season for white-tailed deer occurs in the fall and is called the rut. As the days grow shorter and nights grow longer, changing day length influences the production of melatonin, a hormone produced by the pineal gland. Research on white-tailed deer has demonstrated that melatonin influences seasonal reproductive activity, including changes in reproductive hormones and the timing of rutting behavior. These hormonal changes involve luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone, which play important roles in male reproductive development and behavior.¹˒²

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In Michigan, the white-tailed deer rut takes place primarily during the October and November, although timing varies by location and individual deer.³ As the breeding season approaches, bucks begin sparring with one another to establish dominance. These encounters may become more intense as competition for mates increases. Two other characteristic behaviors during the rut are rubbing and making scrapes. A rub is created when a buck works his antlers and forehead against a shrub or small tree, removing bark and leaving scent from glands on his head. A scrape is made when a buck uses his front hooves to clear leaves and debris from a patch of ground, often exposing bare soil. He may then urinate on the scrape and rub or lick an overhanging branch, depositing scent from facial glands. These scent-marked locations serve as communication points that other deer can read and understand.⁴˒⁵​​

As the breeding season progresses, bucks travel in search of does approaching estrus, the period when a female is receptive to mating. Deer rely heavily on their sense of smell to gather information about one another, including reproductive status. Bucks may follow, pursue, or tend a doe for a day or longer as she approaches receptivity. During this time, a buck may remain close to her and defend access against competing males. The timing and intensity of these behaviors vary among deer and populations.⁴˒⁵

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​A doe is generally receptive during estrus for only  approximately 24 hours, although the duration can vary. If she does not conceive during her first estrous cycle, she may return to estrus about 28 days later and have another opportunity to breed. Although most breeding activity occurs during the fall, the breeding season can extend into early winter, depending on the population and local conditions. For that reason, it is more accurate to describe the rut as gradually winding down than to assume that nearly all does are pregnant by a specific date in early December.⁴​

  1. Bubenik, G. A., Morris, J. M., Schams, D., & Claus, A. (1982). Photoperiodicity and circannual levels of LH, FSH, and testosterone in normal and castrated male, white-tailed deer. Canadian Journal of Physiology and Pharmacology, 60(6), 788–793. https://doi.org/10.1139/y82-110

  2. Bubenik, G. A., Smith, P. S., & Schams, D. (1986). The effect of orally administered melatonin on the seasonality of deer pelage exchange, antler development, LH, FSH, prolactin, testosterone, T3, T4, cortisol, and alkaline phosphatase. Journal of Pineal Research, 3(4), 331–349. https://doi.org/10.1111/j.1600-079X.1986.tb00756.x

  3. Indiana Department of Natural Resources. (n.d.). White-tailed deer biology. https://secure.in.gov/dnr/fish-and-wildlife/wildlife-resources/animals/white-tailed-deer-biology/

  4. Pierce, R. A., II, Sumners, J., & Flinn, E. (2017). Ecology and management of white-tailed deer in Missouri (Publication G9479). University of Missouri Extension. https://extension.missouri.edu/publications/g9479

  5. Missouri Department of Conservation. (n.d.). White-tailed deer. https://mdc.mo.gov/discover-nature/field-guide/white-tailed-deer

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