Pacific Great Blue Herons – Cowichan Estuary Nature Centre

Introduction

Look to the sky and you’ll note the return of the equal parts majestic and prehistoric looking birds we know as Pacific Great Blue Heron (Ardea herodias fannini), indicating spring is truly on its way. They haven’t strayed far, only dispersed to their winter fishing territories in local watersheds, as this sub-species is non-migratory. Herons can be observed in all sorts of habitats in the Cowichan Valley: from salt and freshwater marshes, streams, lakes, to backyard ponds and open fields where fish, frogs and other small amphibians are available to eat. Their gathering for nesting season is truly a sight to behold. You’ll see more and more showing up at the estuary or flying overhead with sticks in the bills for spring nest repair. And the Cowichan Estuary Nature Centre’s Web Cam makes it easy for you to tune in to watch nesting in action, or come to Hecate Park for a picnic to observe them first hand. Low tide is an especially good time to observe them forage in the mud flats! To access the Heron Cam scroll down to the bottom of this page.

Read

Learn about the 30-year nesting history in Cowichan Bay, and the launch of the heron cam project Heron Camera Launch

Join the Coastal Waterbird Survey every month. Everyone is welcome! Coastal Waterbird Survey

Look

The Cowichan estuary is an internationally designated Important Bird Area (IBA). A globally significant number of Trumpeter Swans (left) overwinter here. You can also see non-migratory birds like the Pacific Great Blue Herons fannini subspecies (right) at the estuary. Join the Coastal Waterbird Survey every second Sunday of each month to count birds from the shoreline. Image Credit: Barry Hetschko

Pacific Great Blue Herons forage in estuaries, marshes, rivers and grasslands. They have a mostly piscivorous (fish-based) diet, but they sometimes eat small mammals like mice and voles, or even frogs, salamanders and snakes! Image Credit: Barry Hetschko

Pacific Great Blue Herons are the largest wading bird in North America. They are about 1 meter in height, and their wingspan can be up to 2 meters. Despite their large size, they have long, thin legs that they tuck behind in flight. Image Credit: Barry Hetschko

How many nests do you see in this picture? Pacific Great Blue Herons often nest in colonies called rookeries. Herons return to this rookery in Wessex Ravine by the Cowichan estuary every year between February and April. They collect sticks to create nests high up in deciduous trees. In 2021, there were over 100 nests in the Wessex rookery with more than 200 adults! Image Credit: Tomo Nishizawa

Look at this aerial image of the Wessex colony captured by a drone! Nest data is traditionally collected by people on the ground using binoculars or spotting scopes. This is a labour-intensive and possibly inaccurate process, as it can be hard to see through the canopy. This image was captured during a pilot study conducted by Environment and Climate Change in 2019 to find out if drones are an effective way to monitor Great Blue Herons. Image Credit: Todd Manning, Strategic Resource Solutions

Great Blue Herons are sensitive to noise and human presence. In 2004, construction on a new housing development in Cowichan Bay led the herons to abandon their rookery. Thankfully, they re-established their nests at the current site in Wessex Ravine. Read more about the 30-year nesting history in Cowichan Bay above. Image Credit: Tomo Nishizawa

Great Blue Herons are monogamous (have one partner at a time) and lay between two to five eggs per year. Bald eagles are common predators of heron eggs and juveniles so the nest needs to be guarded constantly by the parents. Human disturbance such as noise can cause herons to temporarily leave their nest, leaving chicks vulnerable to predation. Image Credit: Barry Hetschko

Meet a juvenile Great Blue Heron! Compared to adults, juveniles have a black crown and are darker grey in colour. The crest (head feathers) is sticking up, indicating that the heron has just finished preening (cleaning its feathers with its beak). Baby herons learn to fly in around 60 days, and they depart the nest shortly after. Image Credit: Barry Hetschko

Meet Hoppy, the baby heron, with summer student, Kylie Porter. Hoppy was found wandering around the parking lot by the Nature Centre in the summer of 2021. He was brought to the North Island Wildlife Recovery Centre in Errington, and was later released at the Cowichan estuary. Image Credit: Kylie Porter

Watch

Watch the herons live at their rookery! The colony returned on February 17^th this year at the Wessex Ravine in Cowichan Bay. The Nature Centre will be working with FLNRORD (Ministry of Forests, Lands, Natural Resource Operations and Rural Development Contacts) to survey nest count and the number of fledglings using the heron camera.

Click on the screen above to activate the camera. Maximize the view by clicking the square in the bottom right corner. Take control of the camera for 5 minutes by clicking the Control toggle on the bottom right corner of the screen. Enjoy!

Listen

Caption: Herons emit deep squawks. Listen to the Great Blue Heron flying into a creek in the Comox Valley. Belted Kingfishers and American Crows can also be heard in the background.

Audio Credit: Simon Elliott, XC597965. Accessible at www.xeno-canto.org/597965.

Caption: Great Blue Herons are most vocal during the breeding season. Listen to the begging calls of juvenile herons at a rookery. Baby herons hatch after 25 to 30 days of incubation, and begin to beg for food. Adult herons regurgitate (bring swallowed food back up) to feed their babies.

Audio Credit: Christopher McPherson, XC445084. Accessible at www.xeno-canto.org/445084.

Resources

Find more images, audio and video clips of Great Blue Herons from eBird.
Look at this Audubon map on how climate change will shift the range of herons.
Watch National Geographic’s short video on the heron’s secret weapon!
Teach your students about urban sound pollution using resources from the Noise Project.
Listen to a podcast on the Squamish creation story of herons from Seeking Office.
Read a government report on heron populations on Vancouver Island and the Gulf Islands.
Read a research article from the NRC Research Press on how herons consume thousands of juvenile salmon.
Use a Merlin Bird ID app to keep track of the birds that you see in your neighbourhood!
Try the Nature Centre’s word search on estuary birds.