Blog Layout

The Future in “Bear hair”: Will Noninvasive DNA Sampling Advances Minimize the Need to Capture & Handle Bears for Management & Research?

Tyler Brasington • Oct 12, 2020

Dear colleagues,  I am honored to have Tyler Brasington bring his field experience and knowledge to this blog as he writes about non-invasive grizzly research.  Thank you, Tyler!” Dr. Mark

Grizzly bear rubbing on tree.

Capturing and chemically immobilizing bears is stressful for the animal. Therefore, it is imperative that researchers and managers justify all capture events, thoroughly evaluating potential alternatives to a hands-on approach.(Bookhout 1, Jonkel 8, Kendall 9) In some cases, the information required to meet management and research objectives can only be obtained through capture and handling (i.e., deployment of radio/GPS collars for monitoring). However, if research questions and objectives can be answered using alternative, noninvasive methods, researchers should think about using these approaches first.(Cattet 6) The goal of this summary is to highlight new and developing non-invasive technologies and techniques which may offer broader applicability, better efficiency and effectiveness, and address multiple research questions simultaneously,(MacKay 13) while reducing the need to capture and handle bears in the field.


Capture and handling methods (i.e., deployment of radio/GPS collars) allow researchers to address questions surrounding the overall health of a population by drawing blood for complete blood count (CBC) generally reflecting the bears health and condition at the time of capture, disease analysis, tick borne diseases, cub survival, and causes of mortality. Collaring bears also offers the opportunity to answer spatially driven questions surrounding habitat preference and movements. Unfortunately, genetic sampling furnishes no details on age, reproductive status, body condition, daily movement patterns, or habitat use.10 Hair and scat sampling are two of the most common methods for obtaining DNA. Hair snare sampling is conducted employing a hair collection device, or a series of devices which include but are not limited to barbed wire, glue, adhesives, brushes, corrals, cubbies, using two approaches, baited or passive methods.(Boulanger 2, Boulanger 3, Kendall 10, Proctor 15, Proctor 16) These devices are positioned in a sampling framework, or study grid. For hair sampling to be successful, the devices deployed in the field must promote use by the animal. Population estimates have historically relied on observations and counting bears on the landscape.(Knight 11) The downside to this method is that bears may be counted more than once, or maybe not at all. Genetic sampling can provide an accurate and precise estimates of population size, however, this is usually years after the hair has been collected due to processing time required to extract DNA from hair samples. Even then, these population estimates are only considered a snapshot in time. Despite the non-invasive nature of genetic sampling, some species may avoid hair corrals and cubbies due to human odors. While genetic analysis via means of hair collection is generally expensive, it is extremely reliable.(Kendall 9) Hair DNA also experiences less degradation than scat, inherently producing more consistent results at a lower cost.(Kendall 10)

Hair Snag Sampler

Greater Glacier Bear DNA Project, Montana (1997-2002):


One of the better-known projects using genetic analysis and DNA hair samples was the Greater Glacier Bear DNA Project (1997-2002) led by USGS research scientist Katherine Kendall. One of the project’s significant accomplishments was estimating the average number of grizzly bears in their particular study area, calculating density inside Glacier National Park (1998: n = 240.7, 95% CI= 202-303; 2000: n = 240.6, 95% CI= 205-304).9 They found that the average density was 30 bears/1000 km2. This study included two types of noninvasive genetic sampling techniques: hair snags (baited) and rub trees (passive); which increased their sample coverage and helped improve population estimates.


Grand Teton National Park, Wyoming (2014-2015):


Researchers from the USGS Interagency Grizzly Bear Study Team (IGBST), Grand Teton National Park, and Wyoming Game and Fish sought to better understand how grizzly bears respond to the elk harvest during the Elk Reduction Program (ERP). They used methods outlined by Kendall & McKelvey 2008 and Kendall et al. 2009 for active and passive sampling. During their study (2014-2015), they successfully identified 31 grizzly bears (6 females, 25 males) via genetic hair sampling. The data acquired during their study informed crucial management decisions by suggesting that the late timing of the elk hunt helps limit the use of elk remains/carcasses to a small number of resident grizzly bears.(Van Manen 17)


As advances in genetic techniques continue, more research projects have the option to utilize non-invasive genetic sampling techniques. Examples of recent advances include several studies analyzing reproductive hormone levels, and stress levels using grizzly bear hair collected via hair snags.( Bourbonnais 4, Bryan 5, Macbeth 12, Mayer 14)


One specific study in British Columbia (Bryan 5) found that if grizzly bears in the region do not obtain enough salmon, they may exhibit chronically elevated cortisol and testosterone levels through increased nutritional and social stress.


The general consensus amongst wildlife professionals is that before using physical capture and handling, there should be a thorough evaluation of potential alternatives to a hands-on approach, such as non-invasive sampling (i.e., scat & hair sampling).(Bookhout 1, Cattet 6, Johnson 7, Jonkel 8)  While non-invasive sampling provides an opportunity to limit handling and capture events, producing precise and accurate estimates of population, further research is needed to improve current techniques and methods, as they are time intensive, and genetic population estimates only represent only a snapshot in time.


[Works Cited]


Tyler Brasington, Graduate Student University of Wisconsin-Stevens Point

Tyler Brasington is a current graduate student at the University of Wisconsin-Stevens Point. His research and work has focused on the ecology, biology, management of grizzly bears, and attitudes and perceptions of bear management. Tyler has worked seasonally in Grand Teton National Park since 2017, and is currently a wildlife management ranger for the Bear Management Office. 


Tyler received his B.S. in Environmental Science from the University of Wisconsin – Whitewater. 


Tyler maintains the awesome website: www.yellowstonegrizzlyproject.org.

This and other practical and field-based tools are covered in more detail in my live and online chemical capture courses.


Share with your Connections

More articles for you....

By Mark R. Johnson DVM 01 Apr, 2024
As field questions arise, I'll be posting them on this Wildlife Capture and Care Blog. Follow us as field topics come up for discussion.  --- -- --- COVID Exposure to Bait Used for Capturing Lynx
Visual Guide to Wolf Dentition and Age Determination.
By Tyler Brasington 03 Feb, 2024
The Visual Guide to Wolf Dentition and Age Determination is the most comprehensive guide to date, focusing on wolf dentition, and the approximation of age based on visual wear patterns.
In the course of our work on the African continent, we are fortunate to work with a number of charis
By Dr. Joel Alves 23 Jul, 2022
In the course of our work on the African continent, we are fortunate to work with a number of charismatic species and none-more-so than the ones with sharp claws and teeth.
By Dr. Mark 17 May, 2022
Here is a great question sent to me from a wildlife biologist taking my online course, “The Foundations of Wildlife Chemical Capture”. Dr. Mark Colleen asks: Dr. Mark, I just finished Chapter 2 where you discussed the importance of accurate weight estimates to determine safe and effective immobilizing drug doses. I see you mentioned observing the ear size in relation to the body, but what are your other go-to observations for estimating body weight for bears? Dr. Mark’s reply: Great question. I have three predominant aspects that I consider when estimating body weight for bears: Ears give me a sense of how old the bear is. As bears grow, their head grows but their ears do not. So a big-eared bear is a small younger bear. A bear with little ears (relative to head size) is an older larger bear. We’re often estimating bear weights when they are in a culvert trap so I first notice if it is a large or small culvert trap because traps vary in size. A small culvert trap will make me think it is a larger bear and can skew my estimate. A larger trap will make a bear look smaller. My strongest reference is writing down my weight estimates on the drugging field form every time we do a capture. We also document actual weight as well. That way we are learning from every animal. When I have a partner at the capture, I ask them to also write down their weight estimate. After we weigh the bear, we know that whoever is least accurate buys the next coffee. It is interesting to note that we have always strived for being accurate with animal weight estimates within 10%. That is the professional standard. I realized that we strive to be accurate within 10% because when we work with ketamine/xylazine and Telazol combinations (which I have done for decades), small variations in dose really makes a difference in the downtime and depth of immobilization. Many biologists are now immobilizing bears with BAM and BAM is more forgiving. We can be 25% off in our weight estimates and not notice a difference in the immobilization. One major reason for this with BAM is that we have reversals to wake up an animal when we’re done. With ketamine/xylazine and Telazol combinations the anesthetics are not reversible. With Telazol, we have to wait for them to wake up and we must wait for ketamine to wear off before we administer the reversal for xylazine. So we don’t want to give them any more than we need to, but we want to be confident that we gave enough! In all cases, we still strive to be accurate within 10% for safe and successful wildlife immobilizations. To recap: Look at the ears Look at the culvert size Write down both estimated weight and actual weight on the field form so we learn from each animal. Care to learn more? Register for the online course, “The Foundations of Wildlife Chemical Capture“ .
Dear colleagues, it is a pleasure to have guest author, Dr. Liesel Laubscher of Wildlife Pharmaceuti
By Dr. Liesel Laubscher 30 Apr, 2022
Dear colleagues, it is a pleasure to have guest author, Dr. Liesel Laubscher of Wildlife Pharmaceuticals South Africa present this article on potent opioids. Dr. Mark
The Foundations Course Reviewed by Journal of Wildlife Diseases
By Dr. Mark 31 Oct, 2021
It is an honor to have the Journal of Wildlife Diseases (JWD) review our online course, The Foundations of Wildlife Chemical Capture. This is likely the first time JWD has reviewed an online course.
Collaring a lynx in Alaska
By Dr. Mark 21 May, 2021
Dr. Mark describes creating new drug combinations for immobilizing lynx Note: This blog article is a bit technical but it covers the basics for how to choose an immobilizing drug combination for a wildlife research or management program.
Wildlife Health podcast - Untold stories from 35 years of wildlife handling.
By Dr. Mark 15 Mar, 2021
Dr. Michelle Kneeland of WildlifeHealth.org is presenting a podcast interview with me as I share my stories and adventures from 35 years as a wildlife veterinarian. Listen to me describe a mountain lion capture in a severe winter storm. Hear what it feels like capturing grizzly bears.
wildlife pharmaceuticals
By George Carballo 11 Mar, 2021
Wildlife Pharmaceuticals and its subsidiary, ZooPharm, the legacy of retired Bill Lance, DVM, MS, PhD, are now part of the largest veterinary-compounding pharmacy in the U.S., Wedgewood Pharmacy, a respected name known to 9 in 10 veterinarians in the U.S. The acquisition was completed this past summer.
 I am honored to have Michelle Kneeland DVM write this inspiring article.
By Michelle Kneeland 27 Jul, 2020
“Dear colleagues, I am honored to have Michelle Kneeland DVM write this inspiring article. This blog will have guest authors once a month. Thank you, Michelle!” Dr. Mark Many wildlife students are becoming dismayed by the current job market and difficulties they face...
More Posts
Share by: