Winter Dens

Standing hollow trees are favorite denning spots, but few trees are allowed to reach the mature stage at which the center rots and becomes hollow.  Such trees can be found in portions of the Boundary Waters Canoe Area in northeastern Minnesota, especially where they were fire-scarred a half century or more ago.

Rock crevices and caves are also used as dens, and these can remain useable for centuries, but usually not by the same bear and usually not in successive years.  The den that researchers found being used the most during four decades of study was used three times, each time by a different bear, and each time after an interval of six years.

Dens are also dug into hillsides or under the root system of a tree.  These dens may be dug during the summer months, long before they are needed.  Dug dens often collapse after use and therefore are seldom reused.

Bears also may den under the crown of downed trees or in brush piles.

Some bears just rake up a bed on the ground near a windbreak.

Winter Dens: 

	A 2-year-old male dug this den deep into a hillside under the roots of trees.
	A 5-year-old female black bear dug this den into a hillside the second week of September, and raked bedding into it a week later.  She gave birth to 3 cubs here in January.
	The roots of this tree stump frame the opening and provide the strength for the roof of this den dug beneath it.  A 2-year-old female wintered in this den.
	A 5-year-old female dug into the side of a brush pile to den.  She birthed and cared for 3 cubs in this open den.
	A 2-year-old female quietly slipped away from this deep open den of leaf litter when researchers approached.
	A 16-year-old mother and her 2 year-old cubs denned in the hollow created by the roots of a fallen tree.
	A good rock den will be used again and again, but seldom by the same bear and generally not in consecutive years.