Aging a bear by its skull

by Mar 21, 2016Maine Black Bear

Aging a bear by its skull

When you kill a bear in Maine, you are legally required to submit a tooth to IF&W so that the bear can be aged and logged into the records.  Each tooth is cut, like a tree, and the rings are counted. Biologists can learn about the health of the bear and it’s age. Assuming that the tooth gets to where it needs to be.

Typically, it takes a year for the data to be published.  The link to the information is usually posted all over social media and eager hunters share how old their bear was.  I couldn’t wait to find out how old this guy was. The popular vote was about 8 years old.

When the data was posted, I searched.  I looked up my name.  I looked up my guide’s name. I looked up the tagging station and the date.  I knew a few numbers in my tag and couldn’t even find that. My bear was not listed!

I sit on the Black Bear subcommittee for the Big Game Species planning process and see Jen Vashon and Randy Cross almost monthly.  So, I asked Jen about my bear’s missing tooth. I gave her my tag number, where I shot the bear and where I had tagged it.  She started diving into computer records to see what she could find.  Meanwhile, Randy asked about the skull.  After handling more than 4,000 bears in his 32+ year career, he was pretty good at aging a bear by its skull and teeth.

I quickly pulled up these pictures and asked him what he thought.  I explained that most people who looked at the bear thought that he was 8.   He laughed, “It was more than 400 pounds… no way is that bear eight years old.”

Randy started talking about the characteristics that stand out on a skull.  First: the teeth.  Since my skull had been cut several times, in order for the skull to be put back together, it had to be glued and is now one piece and not two.  Randy could guess by looking at the picture of the teeth but it wasn’t totally clear and no pictures showed the inside ware of the bottom teeth.

The top of the skull though was a different story: The crest was big, height-wise and length-wise. It ran along the entire top of the skull.  Randy explained that you only see that in old bears and you can age them based on how big that ridge is.

You can tell the age of a bear based on the crest on top of their skull

Another telling characteristic is how smooth the bone is.  In the second picture, you can see that my bear’s skull is not smooth but bumpy and porous looking. That is another sign of an old bear.  As bears age, so do their bones and they begin to break down.  Young bears have very smooth skulls but the older ones… you can see where the bones are starting to separate. 

The porous-looking skull indicates that the bear is old and its bones are beginning to break down

From the photos that I showed Randy and his decades of knowledge (he has more years of experience than ANY bear biologist in North America) he estimated that at the very least, my bear was 12-15 years old. At least. 

Jen returned with a piece of paper in her hand.  There were 7 bears tagged at the station that I tagged my bear in. Only two of them were aged (via teeth) but I was listed in the kill log, so my info and tag were in the system. There was a chance that since I shot my bear late in the season, it was sent in late or sent in with the 2015 bears and could turn up at some point.  

Or, the dope who registered my bear didn’t send in the tooth. 

I was fortunate enough to have Randy and Jen help me figure out the age of this bear. The lost tooth just adds to the incredible story and issues that I have had with this bear since that second when I squeezed the trigger. 


  1. Randy knows his stuff for sure. Explain to me why the skull was cut several times in order to be put back together.???

    • The skull was cut because the butcher didn't know what he was doing. He cut it in half and almost cut one of those pieces in half. Luckily, my guide stopped him from ruining it any further and my taxidermists knew what they were doing to glue all of the pieces back together = minus the cheek bone that was destroyed.

    • Bizarre I don't think I would use that butcher again.

    • Never ever! I had a record book bear until he got to it.

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Erin Merrill, author of And a Strong Cup of Coffee, is president of Women of the Maine Outdoors, a senior writer for Drury Outdoors, a contributor to the Northwoods Sporting Journal and passionate all things Maine, Hunting, and the Outdoors.