The rut is the annual breeding season for white-tailed deer. This period involves biological changes and behaviors that culminate in reproduction.
What is the Deer Rut?
The deer rut is the mating season, driven by environmental cues. The primary trigger is photoperiod, the changing amount of daylight hours. As days shorten in late summer and fall, decreasing light signals hormonal shifts in bucks and does. This prepares deer for breeding, ensuring fawns are born in spring.
Michigan’s Rutting Calendar
The rut in Michigan follows a predictable annual pattern, divided into distinct phases. The pre-rut typically begins around the third to fourth week of October. During this phase, bucks become more active, sparring and creating rubs and scrapes. Does may also show early signs of approaching estrus.
The peak rut, or breeding rut, generally occurs from the first through the third week of November. During this period, most does enter estrus, and breeding activity is highest. The peak of breeding is estimated around November 17th. Bucks become less cautious, focusing on finding receptive does, leading to increased daytime movement.
Following the peak, the post-rut phase starts around Thanksgiving and extends through mid-December. Activity decreases as many does have been bred. However, some does that were not bred during the primary rut may cycle into estrus again about 28 days later, leading to a “second rut.” Doe fawns reaching sufficient body weight can also become sexually active.
Understanding Deer Behavior During the Rut
During the rut, bucks exhibit increased aggression due to rising testosterone. They engage in sparring, a low-intensity pushing and shoving with antlers, to establish dominance. Bucks also create “rubs” on trees and “scrapes” on the ground. These markings serve as visual signals, depositing scent from glands to communicate their presence.
Once does become receptive, bucks intensify their search, often abandoning caution. They actively seek out does, sometimes chasing them for hours or days before breeding. Does enter estrus for a short window, typically 24-72 hours, when they are willing to mate. If a doe is not bred, she may re-enter estrus about 28-30 days later.
Significance of the Rut for Wildlife
The rut significantly impacts deer movement. Bucks, driven by breeding instincts, expand their home ranges and travel greater distances, often moving more during daylight. This increased activity, coupled with reduced focus, contributes to a higher risk of deer-vehicle collisions. Michigan experiences a high number of deer-involved crashes, with October and November as peak months.
Drivers should be vigilant during dawn and dusk, periods of increased deer activity when deer are less cautious. If one deer crosses the road, more may follow. For observers, the rut offers a chance to witness unique deer behaviors, providing insights into their reproductive cycles and social dynamics.