Paving The Path Forward

The leaders of Mowbrays’ believe in nurturing and promoting the future leaders of MTS. By promoting our best and brightest, we feel the future of our company is in good hands.

Our team is passionate about our safety practices and the work that we perform. Together, our team is helping keep the community safe. Interested in learning more about our services? Contact us today to find out how we can meet your needs.

Robin Mowbray

Mowbray’s Tree Service Owner

With the passing of Gloria Mowbray in 2021, Robin Mowbray, the youngest daughter of John and Gloria Mowbray, is now the leader of Mowbray’s Tree Service. Robin started her career with MTS in 1993 working as an administrator, then transitioned into Payroll, and finally Human Resources. During that time she also worked with insurance companies, employee unions, and compliance. During her tenure MTS has grown from approximately 100 employees, to over 1,500 full time employees. Robin’s strength is her ability to listen to and have compassion for her Mowbray’s Tree Service family or, as other owners may label them, her employees.


  • Provide support for all MTS Departments
  • Provide strategic counsel and maintain focus on MTS as a woman owned business – WBE
  • Support her family as they continue to guide MTS into a bright future in the Vegetation Management Industry.


  • 20+ years of applied multi-utility tree service administration.
  • 10+ years as corporate executive.

Richard John Mowbray

Mowbray’s Tree Service President/CEO

Richard Mowbray, grandson to John and Gloria Mowbray, is the third generation of the Mowbray family to lead Mowbray’s Tree Service. Richard started his career in the Utility Vegetation Management (UVM) industry in 2005 as a groundman, and worked his way up to CEO. He has worked just about every position within Mowbray’s including crew foreman, hazardous tree removal specialist, crane operator and, in 2019, Corporate Safety director. 

During this time Richard has worked with utility companies in California and Arizona performing vegetation management and also the various wildfire projects throughout California. These utilities include the following:

  • Southern California Edison (SCE)
  • Pacific Gas and Electric (PG&E)
  • Sacramento Municipal Utility District (SMUD)
  • Arizona Public Service (APS)
  • Pacific Power and Light (PPL)
  • Add Bear Valley Electric Service (BVES)


  • Provide support for client and regulatory interface.
  • Ensure the operating units within MTS have the required support and guidance to continue to drive MTS to “Best in Class”.


  •  ISA Certified Arborist
  • ISA Qualified Tree Risk Assessor
  • TCIA Certified Tree Safety Professional
  • CA Contractors License C61/D49
  • NCCCO Certified Crane Operator
  • Licensed Timber Operator

Mike Bartelli

Mowbray’s Tree Service Sr. Vice President of Operations

Michael Bartelli is a seasoned industry professional and Certified Arborist with over 25 years of experience in Utility Vegetation Management. He joined the Mowbray team in 1991 and has been actively involved in the operations of Utility Vegetation Management as a General Foreman, General Manager, Project Manager, Area Manager, and most recently as the Sr. Vice President of Operations. During his tenure at Mowbray’s, Michael Bartelli has conducted and supervised vegetation management for utility companies to include:

  • Southern California Edison (SCE)
  • Pacific Gas and Electric (PG&E)
  • Arizona Public Services (APS)
  • Duke Energy
  • PacifiCorp


As the Sr. VP of Operations, Michael Bartelli oversees the day-to-day operations of the company, defines and implements operation strategies, structures, and processes. He is also responsible for managing the quarterly and annual budget process, and monitor performance to proactively identify efficiency issues and propose solutions.

Sergio Guerrero

Southern California Director of Operations

Sergio joined Mowbray’s Tree Service in 2010. During his 9-years in operations, where he started as a groundman, he held multiple positions with each one increasing his knowledge and passion for arboriculture. In 2019, Sergio became an MTS liaison for Southern California Edison working as a temporary Senior Specialist Inspector. Upon completing this assignment, Sergio returned to Mowbray’s where he was promoted to SCE Field Operations Manager. This position earned him 2020 Supervisor of the Year. In October of 2021, due to his experience, knowledge, and leadership skills, Sergio was elevated to the position of Director of Operations for Mowbray’s SCE Division.

As Director of Operations, Sergio implemented the ISA Tree Worker Certification Training Program which, within the program’s first 6 months, helped over 25 Foremen become ISA Certified. He is also part of the Heavy Tree Project, an annual compliance program that monitors and mitigates hazardous trees around electrical conductors.

In his spare time, Sergio Guerrero coaches children’s soccer for ages 6-7 and manages the Mowbray’s Indoor Soccer Team.


Oversees state-wide operations for Mowbray’s SCE Division which includes routine work, storm work, emergency work, the Hazard Tree Mitigation Project, and Mechanized Vegetation Management operations.


  • ISA Certified Arborist
  • ISA Certified Tree Worker
  • TCIA Certified Tree Safety Professional
  • Multiple OSHA certifications

    Axel Avila

    Mowbray’s Tree Service Health & Safety Director

    After working in Adventure Tourism for 8 years, Axel Avila began his arborist career in 2006 when he moved to Puerto Rico. During the following 12 years his passion and knowledge for the industry grew as he conducted tree care and maintenance across Puerto Rico, Mexico, and the United States.

    In 2011 Axel Avila founded Senda Vertical, a company focused on propagating safe practices and best methods to the growing tree industry in Mexico. In 2014 Axel returned to the United States and began his training as a Safety Instructor in the State of Colorado.

    Axel Avila joined the Mowbray’s team in 2019 as a Trainer and has worked diligently to support Mowbrays Safety Program. In 2020 Axel became the Safety Director for Mowbray Tree Service where he continues to work towards the advancement of the safety culture. 


    Responsible for overseeing Mowbrays Tree Service’s Safety Program. Manages all safety communication to safety and training personnel. Develops, reviews, and implements safety policies to coordinate and evaluate safety efforts. Generates and manages the corporate Safety and Training budget. 


    Some of Axel Avila’s achievements include: 

    • ISA Certified Arborist
    • ISA Certified Utility Specialist
    • ISA and Mexican Association of Arboriculture (AMA) guest speaker.
    • TCIA Crane Operations Specialist
    • TCIA SRT Climber
    • TCC winner of the Rocky Mountain Chapter. July 2016

    Leticia Aguayo

    Mowbray’s Tree Service Contracts Manager

    Leticia Aguayo joined Mowbray’s Tree Service in 2008 as an Administrative Assistant and Purchasing Associate in support of Mowbray’s Fleet and Safety Departments. In 2012 Leticia stepped away from her position at Mowbray’s but returned in June of 2016 as an Administrative Analyst for Mowbray’s SCE Division where she worked on the Bark Beetle and DRI projects. Leticia’s success as the analyst on these projects led to her promotion in January of 2020 as Mowbray’s DRI Office Manager.

    Due to her work ethic, leadership skills, and ability to effectively communicate with Mowbray’s employees, subcontractors, and clients, Leticia was promoted to Contracts Administrator in late 2020 where she assisted Mowbray’s Contracts Manager in the review of contracts and analytics regarding bids for prospective clients. In November 2021, Leticia was promoted to Mowbray’s Tree Service Contracts Manager.


    • Review, prepare, and approve all contracts for clients working for or with Mowbray’s Tree Service
    • Review, prepare, and submit all contract bids from prospective clients
    • Review all MTS project data and analytics for submittal to MTS Management for future contract opportunities.
    • Onboard all subcontractors working for or with Mowbray’s Tree Service
    • Review all Mowbray’s Tree Service equipment lease agreements.


    • TCIA Certified Tree Safety Professional
    • CA Contractors License (C-61/D49)

      Holly Palmer

      Mowbray’s Tree Service Billing Director

      Holly joined the Mowbray’s team in 2017 as an invoicing associate. Her attention to detail, exceptional organizational skills, and ability to communicate and coordinate with Utility Representatives and other members of the billing department led her to a management position within her first year at Mowbray’s.  In her new management role, Holly successfully re-structured the billing operations for Mowbray’s SCE Division making it more efficient and manageable. The systems she implemented in the SCE Division’s Billing Department were so successful that it became clear other departments needed to adopt some of her ideas and processes. In 2020, Holly was appointed Billing Director for all Utility Contracts to include:

      • Southern California Edison (SCE)
      • Pacific Gas and Electric (PG&E)
      • Sacramento Municipal Utility District (SMUD)
      • Bear Valley Electric Service (BVES)
      • Liberty Utilities


      • Oversees company invoicing operations to achieve compliance and weekly invoicing goals.
      • Coordinates invoicing operations with Department Managers and District Coordinators.
      • Monitors work release, tracking and completion of work points.

      Karen Jimenez

      Mowbray’s Tree Service Payroll Administrator

      Karen Jimenez joined Mowbray’s Tree Service in 2015 as a payroll associate with over 10 years of experience in Administrative and Customer Service functions. Karen’s ability to manage the payroll for Mowbray’s ever-growing workforce, implement new payroll laws, and her exceptional coordination efforts with Human Resources earned her the position of Payroll Administrator in 2019. In this new roll, Karen has been instrumental in transitioning Mowbray’s payroll department into the digital era by implementing digital time records and ADP payroll systems. Karen and her team ensure that Mowbrays payroll department complies with all Union contracts, and all inquiries are resolved.


      Ensure Mowbray’s Payroll complies will all local, State, and federal Labor Laws. Oversee the payroll department to ensure timeliness and accuracy. Coordinate with Human Resources to update the system for employee changes. Verify Mowbray’s Payroll compliance with Union Contracts.


      • Associate degree in Biology – San Bernardino Valley College.
      • Associate degree in Physical Sciences – San Bernardino Valley College.
      • Certified by The American Payroll Association in their Fundamental Payroll Certification.

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      686 E Mill St.
      San Bernardino, CA 92408

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