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Wednesday, March 16, 2011

Bear Den Visits Continued...

For several years, FLCC has been a partner with Region 8 DEC in their black bear studies. In today's post, I will focus on the data collected on cubs. 

Bears have an interesting reproductive strategy called delayed implantation. In NY, bears mate in June and July, but the fertilized egg does not develop in the female right away. In the fall, if the female has sufficient fat reserves, a chemical triggers the fertilized egg to attach to the uterus and begin to grow. Cubs are born only a few months later and are relatively small because their development time is so short.

Black bear cub, Wayland NY (3/10)
When we go to a den with cubs, they are kept in fleece sacks to keep them warm. They are weighed and sexed. The weight, however, doesn't tell much about the cubs' health unless one knows their ages as well. A study done some years ago in Virginia showed that you can tell the age of a cub by measuring its ear and hair length and plugging that info into an equation. The hair is measured on the top of the skull and is pretty straight forward. However, measuring the ear is a little more difficult. You know that little nub of flesh that sticks out of your ear close to the opening? It is called a tragus and bears have it too. Imagine taking a squirming cub and carefully lining up the ruler from the tragus to the tip of his ear. Now read the ruler to the nearest millimeter. Easier said than done...
FLCC students measure a cub's ear length (Wayland, NY 3/10)

A final photo of the tragus is below. Note also that this cub has some real blonde hairs. Most likely, he will grow out of them, but they make an interesting pattern now!

Black bear cub tragus (Canisteo, NY 3/11)

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