How human-made nests are helping eagles in Vancouver

An eagle is perched in the fork of a large deciduous tree. He’s standing on the edge of his nest, while his mate is off somewhere, possibly on the hunt for food. I’m told two baby eagles, or eaglets, are inside it, invisible from the ground.

It’s not just any nest. It’s an artificial eagle nest built by the Hancock Wildlife Foundation at Spanish Banks, as part of the organization's work preserving eagle habitats across the Lower Mainland.

It’s a perfect early June day at Spanish Banks. The sun is out, the tide is low, and a light breeze blows cottonwood fluff gently through the air. I’m standing about 100 metres away from the nest with Mike and Diana Seear, former health-care workers who have become avid volunteers for the foundation. They’re taking me out on a tour of some of the eagle nests around the city.

Like many retirees, Mike and Diana spend much of their time with their kids and grandkids. But they also devote a lot of their spare time to eagles — like the one we are currently taking turns looking at with binoculars.  

“It's amazing how many people don't even know that they're there until we tell them. They say, ‘What are you looking at?’ ‘Eagles,’[we say.] Because it's in a park that a lot of people go to,” Diana told me.

Indeed, I marvelled that I’ve walked and run down the Spanish Banks path countless times — often spotting eagles soaring high in the sky — without knowing that I was mere metres away from their home.

Building artificial nests

The nest we’re looking at today was built about five years ago. Its current occupants had once nested in trees immediately across Marine Drive on a steep, unstable slope. The nests fell down three or four years in a row, killing their chicks. This prompted the foundation to build them a new one, and the eagles occupied it about two years ago, once their own nest had completely fallen apart.

Not only did Mike help build the nest, but he also rescued the female after she got in a series of fights with another eagle.

“Other females will come and attack the nest and try to take over. So they have a harsh life,” he said.

Within two days, he had to disentangle the birds four times — a challenging job “because the claws really lock.” By the fourth time, “she had been pretty well beaten up,” Mike said, and the Seears took her to the Orphaned Wildlife Rehabilitation Society (OWL) for three months of rehabilitation. She was then released with a tracker on her back.

With the tracker, they saw that she spent about a year around the nearby UBC golf course. This year, she “mounted a return fight,” Mike said, kicking out the original aggressor, and returning to her old Spanish Banks territory — but now living in the new artificial nest.

“When you just look at an eagle's nest, you think, ‘Oh, there are two eagles. Fine.’ But when you have a tracker and you follow them all the time, it's like a soap opera,” Mike said.

This nest at Spanish Banks is one of several artificial ones built in Vancouver, with more throughout the Lower Mainland built by the Hancock Wildlife Foundation.

The organization, founded by revered eagle expert David Hancock, builds them to create additional habitat for the birds, as the “old veteran trees” they need to build nests fall over time or are removed for development, said Myles Lamont, the director of research programs for the organization. 

The nest building started after Hancock advocated that developers should replace nests when they tear them down, “and so we started to work towards this three-to-one mitigation ratio,” Lamont said. If developers took down trees with nests in them, they would have to create three new nests (so the birds had options to choose from). 

In B.C., removing eagle nests is illegal regardless of whether the nest is occupied at the time. However, a tree with an eagle’s nest can be removed with a permit from the province, which is granted in “rare circumstances,” like when a tree is considered hazardous, according to the province.

While eagle nests are protected under the B.C. Wildlife Act, Mike said, “it's in a slightly strange position that it’s accepted” for them to be torn down and replaced.

The foundation also builds nests if eagles are in “a persistent or problematic nest,” as is the case at Spanish Banks. 

Lamont said the City of Vancouver relies on them to build the nests because they don’t have the resources to do it itself.

“Nobody else does this kind of thing,” said Lamont. “We kind of fell into this by happenstance, mostly because David is really the only bald eagle biologist in Western Canada.”

How is the eagle population doing?

In Vancouver, the eagle population has been stable, with its main pressure being loss of habitat as the city densifies, said Francisca Olaya Nieto, a biologist with the Vancouver Park Board.

Nieto notes that eagles are “very particular” when it comes to the types of trees they use for nesting sites.

“They tend to come back to the same areas, to the same tree,” she said. “So it's just trying to provide that additional habitat where they're going to feel comfortable adopting a new tree or adopting an artificial nest.”

As eagles are on top of the food chain, a healthy eagle population is reflective of a healthy ecosystem. This was evident in the 20th century, when DDT, an insecticide that became infamous for its ecological impacts, decimated eagle populations in North America.

More recently, the 2021 heat dome was very bad for Vancouver’s eagles. The heat decimated the intertidal zone, where many eagles find their food. The metabolic water in the fish and other animals is also how eaglets stay hydrated, and they don’t last long without it, Mike said.

There were 24 active breeding eagle nests before the heat dome, and just 11 after it. 

Mike and Diana are also worried about avian influenza killing eagles. Since crows and waterfowl, which eagles eat, are highly susceptible to the disease, eagles are also at risk of catching it. It is something they keep an eye on as they monitor the birds around the city.

But overall, the raptors have been excellent at adapting to urban landscapes. Since 2021, the number of breeding nests has rebounded to 22, just slightly below where they were at before the heat dome. 

Mike says part of that resiliency is because eagles are tough and will eat anything. “You take away the fish, they’ll eat birds. You take away the birds, they’ll go to the dump,” he said.

There is still habitat conservation needed, but if eagles are returning, producing eggs, and successfully raising eaglets, “it’s an indication that the system is working and is somehow in balance,” Nieto said, with a healthy ecosystem in the area. 

Eagles in the heart of the city

Mike and Diana show me a number of other eagle nests (both eagle- and human-built) around Spanish Banks, UBC, and Camosun Park, before ending the tour at an artificial eagle nest at Vanier Park. The foundation built this one three years ago, and the eagles adopted it a year later. 

The Seears live close by, and while Diana credits much of what they learned to David Hancock, she says they also learned a lot by simply observing this pair of birds.

The nests are located right in the bustle of the city, with the sound of Sen̓áḵw tower construction nearby, visible Bard on the Beach tents, and people out on the seawall enjoying the sunshine. 

But as Diana led me to this artificial eagle nest in a swath of cottonwood trees behind the Museum of Vancouver, it somehow felt protected from it all. The nest was in a metal basket on what looked like an old hydro pole. In it, we saw one of the new eaglets. It flapped its wings awkwardly and peered down at us over the rim of the nest.

“Everyone's very lucky around Vancouver and the Lower Mainland,” Nieto said. “You look up in the sky and it [is] relatively easy to spot a couple of bald eagles. So I would say that is successful.”