Herons in the Estuary

The Cowichan Estuary is the proud home to the largest heron colony on Vancouver Island! Overlooking the bay, the rookery hosts over 110 nests with over 200 herons in residence!

The Big Picture

Canada is front and centre of the major environmental challenges of our time: the biodiversity and climate crises.  A staggering 3 billion birds – close to one in three individuals – have been lost from Canada and the United States since just 1970. Within Canada, the five main threats to birds are: habitat loss, pesticides and contaminants, invasive species and cats, collisions and the climate crisis” (www.birdscanada.org). Within that bleak picture is a glimmer of hope in that the 2019 State of Canada’s Birds Report (www.stateofcanadasbirds.org) states that wetland and waterfowl bird populations are increasing from historic low levels; a success story for conservation partnerships!

West Coast Great Blue Herons are considered vulnerable to disturbance by Bald Eagles and humans. Urban and rural development results in the loss of suitable nesting areas and disturbance to birds during their breeding season. Especially during the early stages of nesting, unusual events and loud noises may cause the herons to abandon their nests. Our rookery is no stranger to these affects.

The Herons of Cowichan Bay

The heron colony in Cowichan Bay has been used as a spring nesting site for almost 30 years. It began as approximately 95 nests tucked into a grove of alders surrounded and protected by mixed wood forest of conifers and Maples in the Wessex Ravine.

In 2004 a nearby housing development saw the clear cutting of forested area to the south of the rookery to the boundary of the colony and caused the herons nests to be exposed to increased predation by eagles. The herons attempted to return to the area the following year but were forced to abandon the area and rebuild in a lower section of the rookery.

In 2008 local residents in Cowichan Bay came together to successfully advocate for the creation of CVRD Bylaw 3083 (now amended to CVRD Bylaw 3605). This Bylaw applies to development within a 100 m radius of all great blue heron nest trees, with the objectives to protect the ecological attributes and socio-economic values common to critical habitat.

In 2014, it was properly tested during the construction of a condominium complex located only 30m from the colony. Development of which continued into the nesting period of the herons. Since it is such an important colony and heron stewards keep close watch on the birds, this development generated much controversy. MFLNRO staff met with the construction company, environmental consultants and the Cowichan Valley Regional District to develop several recommendations. These include noise reduction guidelines, and a disturbance monitoring protocol and the ability for the Province to issue a “stop work order” if disturbance was noted. Fortunately, the herons nested successfully and were not significantly disturbed.

In 2017 biologists recommended to the Province of BC that a heron webcam be installed at Cowichan Bay heron colony which was sited as a well established colony and perfect location to educate the public about this species at risk. The Cowichan Estuary Nature got to work fundraising and drumming up support from the local community, businesses and government.

In 2020 our heron-cam was installed atop a 68-foot tower at Wessex Ravine Park (thank-you CVRD for permissions and support) and joined the global wildlife bird-camera movement and is a valuable component of nature education for over 5000 visitors to the Centre, plus 1000+ students, each year. In addition, critical data will be collected and provided to local biologists, government agencies and conservationists working to preserve the habitat of our Pacific Great Blue Herons, fannini subspecies, a Blue Listed Species of Special Concern under the federal Species At Risk Act (SARA).


Launching the web-cam was made possible through the dedication of many people, starting in 2018 with a family bequest gratefully received from heron enthusiast Ann McKinnon. We are incredibly grateful for the fundraising and support of Centre friends like Jim Wisnia, Pacific Industrial and Marine, an Area D Grant-in-Aid, and to RBS Managed IT Services Ltd for installation and hook-up of the camera. Thank-you to everyone involved for your support!

For more information and to view our seasonally run heron-cam please check out our Heron-Cam page!