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Greater Glacier Grizzly Bear DNA Project 1997-2002

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Principal Investigator

Katherine C. Kendall, USGS Glacier Field Station, Glacier National Park, West Glacier, MT 59936-0128. kkendall@usgs.gov

Lisette Waits, Fish and Wildlife Resources, University of Idaho, Moscow, ID 83844-1136. lwaits@uidaho.edu

Objectives

  • Population Estimation: Obtain a minimum count and density estimates of grizzly bears in the Greater Glacier Area using non-invasive genetic methods.
  • Monitoring Protocol: Model the statistical power of various non-intrusive sampling strategies and develop a protocol for monitoring long-term grizzly bear population trends.
  • Genetic Library: Assess genetic diversity of the grizzly bear population.
  • DNA from Scat and Shed Hair: Evaluate the effects of age, diets, and sample storage techniques on fecal DNA extraction success. Evaluate the feasibility of using DNA from hair found on rub-trees to identify bears.

Background

North American range map for grizzly bears (Ursus arctos)Grizzly bears (Ursus arctos horribilis) once roamed most of the North American Continent. Habitat destruction and direct conflicts with humans have reduced their range by 99% in the lower 48 states (right, click on map for larger version). Today, it is estimated that fewer than 800 remain south of the Canadian border. In 1975 grizzly bears were listed as threatened under the Endangered Species Act. The Greater Glacier Ecosystem may provide one of the only opportunities for long-term survival of this species south of Canada. However, many questions remain on how best to ensure the survival of this magnificent species.

Although it is generally assumed that the grizzly bear and black bear population densities in Glacier National Park (GNP) are higher than in surrounding areas, possibly approaching carrying capacity, studies of grizzly bears in two adjacent areas found no evidence of subadult emigration from the Park or of higher bear density near the Park border. It is likely that few, if any, bears range exclusively within the confines of the park throughout their life, or even within each year. Although they are fairly secure within Glacier National Park, when bears move outside the park boundaries, they are exposed to a variety of mortality risks. Because grizzly bear populations to the south and east of Glacier National Park are declining while a population to the northwest is growing, population trends in the park can not be inferred from neighboring areas. Black bear population trends in this region have not been studied.

The success of bear conservation efforts cannot be evaluated without reliable information on population trends. Until now, statistically rigorous population studies in forested habitat could only be accomplished with radio telemetry where large numbers of bears are handled. This impacts individual bears and the presence of collared/marked bears and frequent overflights impinge on park and forest visitor’s wilderness and solitude experiences. However, until recently, these methods remained the best available means for acquiring reliable population data. Recent advances in genetic techniques have opened the door to less intrusive approaches.

It is now possible to identify species, individuals, and gender with bear DNA samples from hair and scats. With appropriate design, sign surveys can be used to obtain an unambiguous minimum count and population index. Bear population density and sex ratio can be estimated from hair collected systematically at hair snag sites. The amount of genetic variation within the population can be described with materials from both sampling designs.

Study Area

Greater Glacier Bear DNA Project Study Area MapThe study area spans 8000 km2 of land under multiple ownership within the Northern Continental Divide Ecosystem in Northwest Montana. Study design allows data from contiguous studies in Canada to be analyzed with data from the Greater Glacier Area study for a regional grizzly bear population estimate of an area covering more than 20,000 km2.

Field Methods

HAIR SNAGGING

grizzly bear rubbing in bear hair trap lure pileThe study area is divided into 126 - 642 km cells. One barbed wire hair snag is placed in each cell and baited with a non-rewarding liquid scent lure. Hair snags are revisited after 14 days and all hair is collected from barbs using tweezers, placed in paper collection envelopes, and stored in desiccation chambers. Snags are relocated to another site within each cell every two weeks for five snagging sessions. Remote cameras were placed at some hair snags to learn more about how bears behave at these sites (grizzly bears investigating scent lure at hair snags during 1998 field season). Population density will be estimated with mark-recapture models using DNA "fingerprints" of bears identified from hair snagging in conjunction with those identified from sign surveys.

RUB AND SCAT SURVEYS

Sign survey is comprised of two components: hair from trees, cabins, or sign posts that bears rub on and scat left by bears as they travel the trails. Surveys of all 1200 km (~730 miles) of maintained trails in Glacier National Park were conducted a minimum of three times per year in 1998 and every 14 days May-October, 1999 and 2000. Crews hiked the length of each trail segment looking for any bear sign deposited since the previous survey.

grizzly bear rubbing on a bear rub tree

Rub Tree Surveys: During preliminary surveys, objects such as cabins and trees where bears rub were identified and marked. These were entered into a Geographic Information System (GIS) for assisting field personnel in relocating upon subsequent surveys. Information such as tree species, diameter, and distance from trail were also recorded. Over 750 rub objects were monitored during the study. To ensure better hair samples, each designated object has short pieces of barbed wire attached to the rubbing surface. All hair found on each individual barb is considered a separate sample. Using tweezers, samples are placed in paper collection envelopes and stored in desiccation chambers.

bear scat on a trail

Scat Surveys: Three ml of each scat was collected and placed in 12 ml of 90% ethanol to minimize DNA degradation. Any remaining scat on the trail is removed to prevent collection of that scat during future surveys. Location, composition, and estimation of age are recorded for each sample.

Genetic Methods

SAMPLE PROCESSING

Hair Samples: Recent work has found that a single bear hair follicle yields sufficient DNA to identify species, individual, and gender. Prior to DNA extraction each hair sample is examined to identify and isolate intact follicles. Acceptable DNA extraction rates are achieved with hair samples with at least five follicles and are the standard for this project. The hair follicles (5-10) are inserted into a solution that will breakdown the protein coat that surrounds the DNA in the follicle. The samples are then repeatedly "washed" chemically to remove any cellular debris and then stored in a refrigerator until DNA analysis is conducted.

Scat Samples: Fecal samples include cells shed from the intestinal lining which contain DNA that can be extracted. Despite recent advances, however, scat has been used as a DNA source only in small scale or preliminary studies due to lingering technical problems. It is more difficult, and thus more expensive, to extract DNA from fecal samples than from hair follicles. This difference is due to the presence of smaller quantities of DNA, DNA degradation, and the presence of plant polysaccharides that inhibit the polymerase chain reaction (PCR) used to amplify the genetic material.

DNA ANALYSIS

The DNA is amplified using the optimized polymerase chain reaction (PCR) setup to yield a mtDNA (mitochondrial DNA) or nDNA (nuclear DNA) product. The mtDNA is analyzed to yield species identification, whereas nDNA (microsatellites) is analyzed to yield individual and gender identification.

Data Analysis Methods

The number of grizzly bears in the population will be estimated with mark-recapture models using DNA "fingerprints" of bears identified from hair snagging in conjunction with those identified from rub object surveys.

Results

Field Results:

     
    1998
    1999
    2000
    Hair Traps:
    Trap Dates
    May-Aug
    # 14 day sessions
    5
    NA
    5
    # Hair Traps
    626
    NA
    633
    # Hair Samples
    5,582
    NA
    5,234
    Sign Surveys:
    Survey Dates
    May-Oct
    km Trail Surveyed
    1,180
    1,180
    1,306
    # Hair Samples
    867
    4,222
    3,118
    # Scat Samples
    767
    1,877
    1,782

Genetic Results: Individual identification using nuclear DNA (7-locus microsatellite analysis) was conducted for the grizzly bear hair samples identifying 185 individual grizzly bears in 1998 and 222 in 2000. Some of the 1998 scat samples were analyzed but due to poor success analysis was not conducted on the remaining samples.

Data/Statistical Analysis: Data analysis and population modeling have been completed. The manuscript has been published.

Related Publications

Journal Articles

  • Kendall, K. C., J. B. Stetz, D. A. Roon, L. P. Waits, J. B. Boulanger, and D. Paetkau. 2008. Grizzly Bear Density in Glacier National Park, Montana. Journal of Wildlife Management 72(8):1693-1705. [abstract]
  • Boulanger, J., K. C. Kendall, J. B. Stetz, D. A. Roon, L. A. Waits, and D. Paetkau. 2008. Use of multiple data sources to improve DNA-based mark-recapture population estimates of grizzly bears. Ecological Applications. 18(3):577–589. [abstract]
  • Murphy, M. A., K. C. Kendall, A. Robinson, and L. P. Waits. 2007. The impact of time and field conditions on brown bear (Ursus arctos) faecal DNA amplification. Conservation Genetics 8:1219-1224. [abstract]
  • Roon, D. A., L. P. Waits, and K. C. Kendall. 2005. A simulation test of the effectiveness of several methods for error-checking non-invasive genetic data.
    Animal Conservation 8:203-215.[abstract]
  • Roon, D. A., M. E. Thomas, K. C. Kendall, and L. P. Waits. 2005. Evaluating mixed samples as a source of error in non-invasive genetic studies using
    microsatellites. Molecular Ecology 14:195-201.[abstract]
  • Roon, D. A., L. P. Waits, and K. C. Kendall. 2003. A quantitative evaluation of two methods for preserving hair samples. Molecular Ecology Notes 3:163-166. [abstract]
  • Murphy, M. A., L. P. Waits, and K. C. Kendall. 2003. The influence of diet on faecal DNA amplification and sex identification in brown bears (Ursus arctos). Molecular Ecology 12:2261-2265. [abstract]
  • Murphy, M. A., L. P. Waits, K. C. Kendall, S. K. Wasser, J. A. Higbee, and R. Bogden. 2002. An evaluation of long-term preservation methods for brown bear (Ursus arctos) faecal DNA samples. Conservation Genetics 3:435-440. [abstract]
  • Murphy, M. A., L. P. Waits, and K. C. Kendall. 2000. Quantitative evaluation of fecal drying methods for brown bear DNA analysis. Wildlife Society Bulletin 28:951-957.

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Acknowledgements

Related Projects

  • Greater Glacier Black Bear DNA Project: The Black Bear Project objective was to determine a baseline population estimate for black bears in the Greater Glacier Ecosystem. For more information on the Greater Glacier Black Bear DNA Project
  • Northern Divide Bear Project (2003-2008): project website
  • Use of Remote Camera Systems: Remote video and still cameras were used to: investigate how grizzly bears, black bears, and other wildlife species respond to baited, barbed wire hair traps; bear use of naturally-occurring bear rubs, bear marking behavior, and effects of putting barbed wire on bear rubs to facilitate hair collection; how hair traps may be modified to improve detection probabilities. Use of remote camera systems to investigate efficiency of DNA-based sampling methods