Black bear scat and hair DNA study to estimate population size and dispersal patterns of black bears (Ursus americanus) in Sonoma County and contiguous habitats

Affiliation

North Bay Bear Collaborative (NBBC, www.beingwithbears.org), in collaboration with California Department of Fish and Wildlife, Sonoma Ecology Center, California State Parks, Sonoma County Regional Parks, Pepperwood, Sonoma Land Trust, Audubon Canyon Ranch, Kashia Band of Pomo Indians, Land Trust of Napa County, and Recology.

Principal Investigator

Megan Walla Murphy

Project Goal

SEC and CDFW, as members of the North Bay Bear Collaborative, are proposing to pilot an innovative black bear scat and hair DNA study to estimate population size and dispersal patterns of black bears (Ursus americanus) in Sonoma County and contiguous habitats. 

Between 30-40 thousand black bears are thought to live in California and this number is increasing.  The need for this project is timely, as bear sightings and human/bear incidents are more prevalent in Sonoma County. With better understanding of how many black bears are in Sonoma County and how they are dispersing, we will be more informed regarding bear and habitat management, able to mitigate negative bear/human encounters and proactively engage our communities. 

These are key areas we propose to research:

  1. Estimate current black bear population 
  2. Genetic relationships amongst North Bay black bears
    1. Source population* 
    2. Home range size*

*Note: This pilot project is not designed to answer 2a and 2b, but we hope in subsequent years to answer these questions through lessons learned in this pilot phase.

In order to estimate genetic relationships and achieve population estimates, trained staff and volunteers will be collecting scat and hair samples for DNA analysis across Sonoma County and contiguous habitats. DNA samples will then be analyzed by Dr. Ben Sacks at UC Davis to determine areas of inquiry. 

Objective(s)

  1. Determine whether a spatial capture-recapture method using DNA extraction from bear fecal samples is feasible for estimating black bear abundance and density in the North Bay counties
  2. Collect at least 300 black bear fecal DNA samples (determine if enough scat is present to perform analysis)
  3. Estimate initial black bear abundance and density to provide critical baseline data for local black bear conservation and management
  4. Analysis of bear dispersal, occurrence, genetic diversity relatedness between across our region
  5. Produce map(s) that include: scat collection points, camera captures, evidence of track and sign, and confirmed observations. This map will help to determine bear range, presence/absence, and possible dispersal patterns. We will also be able to garner information about habitat use and seasonality of bear presence from this map. 
  6. Community science training and engagement for DNA collection 
  7. Public engagement, participation, and education on bear awareness, how to keep bears wild, and best bear management practices based on information garnered from DNA study. 
  8. Based on the results of this pilot study, develop a broader long term study for Sonoma County and contiguous habitat including population, bear chronology (seasonality, food sources, seasonal migrations), and further public outreach and education to reduce bear-human conflicts.

Method(s)

Phase 1 Preparation of materials, study sites, and volunteers

The preparation phase includes the following:

  • Creation of DNA collection protocols including but not limited to statistical significance, sample numbers and site locations.
  • Creation of field DNA collection kits
  • Creation of training and education materials for field DNA collection and volunteer teams.

Phase 2 Data Collection and Community Engagement

DNA will be collected primarily through bear scat and secondarily from hair snagged in trees, fences, etc. by a team of field scientists from the NBBC and trained volunteers. To attain the best possible results we will be collecting at least 300 DNA samples. These samples will be collected from pre-established study grids as well as incidental collection from scat and hair outside of the study sites. This pilot study will test and refine data collection protocols. 

Between 10 and 16 sampling cells, approximately 4 square kilometers in size, will be established within three study areas (Sonoma Coast, Western Mayacamas and Eastern Mayacamas). Cells will be placed in pairs, touching at one corner. Cells will be surveyed for at least four consecutive days. The same team of volunteers will complete all four days within one cell and ideally will also collect scat at the adjacent study site. This will ensure consistency of collection. An experienced field staff member will lead each volunteer team to ensure quality control. 

Each grid cell will be split into quarters. One quarter will be sampled each day. The volunteer team will conduct a meandering transect across this quarter to ensure the most complete coverage. 

In addition to DNA sample collection, three camera traps will be placed equidistant within the sampling grids to monitor for black bear presence and attempt to identify individuals. Scat samples will be delivered to the UC Davis Mammalian Ecology and Conservation Unit lab for genetic analysis, adhering to protocols for safe storage and transport.

Community bear awareness activities, including online and in person meetings, will be organized by NBBC members to increase community awareness on reducing human-bear conflict, protecting resources, and managing personal property and waste. 

Phase 3 Data Analysis, Reporting, Refining Study Protocols, Community Outreach

The final phase of this pilot study will include:

  • Data analysis of DNA samples
  • Initial mapping of bear occurrences and dispersal
  • Refinement of methodology and protocols for project expansion, including best practices and lessons learned 
  • Community outreach sharing results and finding of the project
  • Continued collaboration with NBBC to discuss findings and develop an adaptive management plan based on study results

Project Duration

This project is an ongoing multi-year research project.