Caribou, Deer, Elk & Moose - Sounds Wild
What Triggers Rut in Deer?

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Transcript

On a crisp November day, a Sitka black-tailed deer hunter blows a deer call, hoping to entice a buck to come in. It’s mating season, a time known as the rut, and the call imitates a doe in estrus, one receptive to mating. A hormone-charged buck just might be attracted.

The rut is triggered by the change in daylight – the photoperiod. Daylight regulates hormonal activity for many animals. Does going into estrus is tied to photoperiod. Photoperiod triggers changes that occur in bucks before the rut -  antlers harden for the year, they rub them and the velvet strips and sheds, their necks swell and they begin sparring with each other. It all peaks as the does go into estrus. In Alaska, rut peaks in mid to late November. Deer in more moderate climates tend to have a wider rut window.

Rut is about mating, but the timing is all about pregnancy and dropping newborn fawns in late spring. Fawns drop when the weather is the best and when food is becoming most abundant. They have the maximum time to grow over the summer, and does have time to rebuild fat reserves for the winter. Also, fawns dropping at the same time saturates the landscape with fawns, which overwhelms predators.