Tracker & Images
Tracking the Movement Patterns of Free-Ranging Minnesota Black Bears
For decades, Minnesota’s DNR has utilize collars on black bears to better understand how far they travel during the summer months and also this aids them to locate the den sites for hibernation. Such collars have a GPS system that allows the bears to be tracked on daily bases, e.g., emitted collar signals are triangulated by satellites in order to calculate monitor movements and distances traveled. Here we provide some previous examples of bear tracker data during the both active spring-summer-fall months and where they hibernated.
In order to utilize the bear trackers, you need to download the KML file and open the file with Google Earth.
What is a bear den?
Bear dens are shelters used by bears, primarily in the winter for denning and hibernation. Bears will use hollow trees, space under the roots of large trees, within rock crevices, and excavated holes in the ground. They will even use man-made structures like decks, brush piles, or abandoned buildings in a pinch. Dens provide insulation from the cold and protect hibernating mothers and their newborn cubs. Den types are classified as a nest, an excavation, or a den.
Click the images below for additional information about our experiences with bear dens.
This is what the inside of most dens look like after you get past the snow.
Another den site, covered with snow. Den opening are typically hidden in snow and brush.
Another den site, covered with snow.
The cubs pictured were actually born while their mother was hibernating. They are all snuggled together in the den.
Researcher spotted a bear den hiding in the snow under a wood pile and brush.
Snow is piled up around the entrance of the den.
When a den is identified, some snow is cleared and the entrance is covered with a tarp to block sunlight from entering the space inside the den.
Close-up of the most common entrance to a bear den found in the snow.
Researchers will asses the bear den using cameras and other equipment before they will begin working directly with the bears.
Why take infrared images?
Infrared (IR) imaging is the technique of capturing invisible infrared images and converting them into visible images. Infrared radiation is produced by all warm-blooded animals and objects with temperatures above absolute zero. As temperature increases, atomic and molecular activity increases, more heat or thermal radiation is produced, thereby emitting more infrared radiation. Hot objects give out more infrared radiation than cool objects. Researchers utilize infrared imaging to observe the external temperature of various research subjects.
What is a yearling?
A yearling black bears are between one and two years old. Yearlings typically leaving their mother in the late spring or early summer. These bears are often described as "gangly" or "teenagers" because they are tall and slender with long legs.
Important Note: While yearlings may appear to be alone and inexperienced, they are healthy and should be left alone.
Yearling cuddling under its mother's fur.
Yearling having a check-up. Screen part of a system used to download biologger data at the den site.
Two yearlings cuddled up next to their mother.
Three yearling ready for their check-ups. Black bears can have brown or black fur as yearlings.
Yearling getting their check-ups.
Female bear and her 4 yearlings. These hibernating bears had their vitals taken and are ready to be put safely back into their den.
Dr. Andrew Tri and Spencer Rettler assessing the health status of yearlings.
