Tod's Blog

Adventures with family & friends and other things I'm passionate about…

Estimating Oregon’s Black Bear Population

Posted by todblog on July 1, 2009

June 30, 2009

Each spring Oregon Department of Fish & Wildlife employees set out across the state to mark black bears and the information is then used to estimate the population in the state. What is a mark and how do we go about marking bears? A mark could be an ear tag, tatoo, or some other means of identifying an animal that has been captured and released back into the population. In the case of Oregon’s black bears, they get their teeth marked with the aid of tetracycline. Here’s how it works…

In the Southwest Region, we kick things-off in May with an early morning get together and invite volunteers to a hearty breakfast meal. Once the tables are cleared, volunteers roll their sleeves up and slip on a pair of gloves. They dive into the mountain of sliced bacon and pile of tetracycline laid before them and begin rolling individual capsules in a slice of bacon. Several people walk around and collect the rolls and stuff nine of them into a plastic mesh bag (approximately one pound). The bag gets knotted and twist-tied with a piece of rebar tie wire and placed in a cooler. The bacon bait rolling usually takes a few hours to complete and each wildlife district takes their coolers and enough bacon baits for their respective area.


ODFW employees, Dave & Dave serving up breakfast to volunteers before rolling baits.


Rolling tetracycline capsules into bacon slices, stuffing them into mesh bags and tying them with rebar tie wire

Hanging bacon baits begins as early as June 1. Baits are placed no closer than five miles apart from each other. This is to avoid potentially marking an individual bear more than once. The baits are placed high off the ground in trees with smooth bark. This means the bear must climb the tree to get the bait and it leaves telltale claw marks in the bark when taking the bait. Each bait is drenched with a special mixture to lure bears to the bait. The baits are left out for three weeks before checking for results.


Putting out baits in the spring is a great time to be out in the woods, it’s gorgeous country and there’s no phones.


Gourmet bait hung in a tree and drenched with scent to lure bear to the tasty treat!


An alder tree is raked by bear claws as it climbed this tree to take the bait. Result is a marked bear.

premolar (ODFW)

Bears recovered from damage complaints, roadkills, or hunter harvest have a small pre-molar tooth extracted to look for a mark.

annuli (ODFW)

With the aid of a special light and microscope, a cross-sectioned tooth will fluoresce if the bear consumed a tetracycline bait. The rings indicate years of age and when the bear was exposed to tetracycline (could be multiple years).

The actual numbers of marked and unmarked bears that are recovered each year are used to calculate the bear population estimate. If you’re interested in reading the details on how this estimate is calculated, visit the ODFW website and read the report on The Effectiveness of Tetracycline as a Marker to Estimate Black Bear Numbers in Oregon.

However, from my perspective, I can tell you that there are a lot of bears in southwest Oregon. There are plenty of damage complaints from people who live in bear country and from those on the edge of town. Just driving around the back roads will find you seeing lots of sign. More often than not the bears don’t get marked by us, they leave their own marks…

Here’s a link to a video segment on marking bears with tetracycline


Bears have an entirely different idea of how a treated 4×4 sign post is to be treated


11 Responses to “Estimating Oregon’s Black Bear Population”

  1. Uncle Howard said

    You have a fun job. Janet and Cassidy just returned from staying with Randy in San Diego..spent two days at Disnyland


  2. wendell said

    gives a whole new meaning to “bear baiting” as we know it.


  3. ralph saitos said

    Glad you’re enjoying your job with the Oregon bears. Be sure the bears don’t leave marks on you! You really do have a great job. Oregon is a beautiful place, so much open country. My niece loves going to college at Lewis&Clark. Take care. Work hard. love to all. ralph and jean


  4. Terri said

    You know, I took tetracycline as a teenager for my acne. No wonder my teeth glow at night. Thank goodness you don’t have to pull teeth from live bears to see if they’ve been marked. You’d have to collect hazard pay for that. Our summer is rocking. Teenagers are such a blast! Hope life is good for you too!


  5. todblog said

    I had it from my dermatologist too and I’ve had it prescribed as an antibiotic too. I imagine all my teeth got glowing rings on em too.


  6. Donna said

    ewww. I hate bears. I know that I’m on their food chain. Ugh. I guess they are up there with snakes and puhis.


  7. Bob Hera said

    Hi Todd & all,
    What a racket!! Looks like fun. That guy with black bear issue in Alaska that had so much media coverage is a close friend of mine. Fencing up the property really broke his heart. My son and I hunted and fished with him years ago. Love and Aloha to the family. Bob..


  8. cousin Karen said

    Wow, that was interesting. I remember Dad giving me tetracycline for something. The photos were so beautiful. By the way, I’m seeing Art Lum for physical therapy (strained my own neck to hand). We talked about Aunty Kay and Uncle Red. Art said it is Aunty Kay who really loved singing. Art’s voice sounds like Uncle Chew Mung’s.

    Lan Lan and I went for shave ice at what used to be Chun Hoon Market. All that’s left is the stump of the big tree that used to be at the front door of the market.

    Chinese Kitchen sells rainbow shave ice for $1.65.

    I spent so many hours waiting at Chun Hoon’s for mom to pick me up.

    We’re you baggin groceries there?


  9. Bea Kikawa said

    I’m so happy to hear about how much you enjoy your job. I wish that for all my kids. Bea


  10. Hi Tod-so very glad to hear from you! You’ve got a great job! I’ve been to Oregon with friends and done a little birding there. Yes, I’m an avid birder and absolutely love being out in nature.

    I was very sad to leave Kaimuki for Jarrett, was not my choice, as there was a great reduction in force that happened at that time, and the junior teachers were the first to be relocated. I had the least seniority in the music department.

    I’m retired now, and I go traveling mostly to foreign countries to see the birds. We take photos and video, and after each trip I make a DVD documentary of the birds and mammals we see . . .and any others like butterflies, reptiles, whatever! We love them all!

    Your blogs are great! They really are so entertaining and informative.
    Thanks for inviting me in!

    Much aloha,
    Norma Parado


  11. Chris Jones said

    Bear steaks are yummy!! I enjoy them fried with corn and a baked potato.


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