Biologists are trying to lure herons that have been nesting in downtown Oakland to move to Lake Merritt instead. Will it work?

On a sunny day at Lake Merritt, biologist Steven Peterson is halfway up a tree, testing a speaker that’s broadcasting a recording of bird sounds.

This is not the pretty trill of a robin. It’s the raucous screeching and squawking of black-crowned night herons, a wading bird that lives in the Bay Area.

“It’s crazy but it’s fantastic,” he says, grinning down from his spot high up on the ladder. “I love these birds. If you’re ever been by the rookery over there in downtown Oakland, this is what it sounds like. ”

Peterson is using the recordings to try and lure birds who’ve been nesting in downtown Oakland for years to come nest at this spot at Lake Merritt instead.

More bird work is happening a little down the lake shore. One man climbs a tree with ropes, and another rises into the canopy on a cherry picker.

Biologist Kevin Cahill stands down below, surrounded by a pile of U-Haul boxes. He opens up a box to show me what’s inside. “This is the heron nest,” he says. “This is where they’re going to stick their egg right here.”

Cahill ties a rope onto the box and sends it up to the arborist in the tree, who ties the nest into place on a branch to “basically build a new nest for these guys and gals,” Cahill says, “Hopefully to attract them here.”

These are the actual nests built by herons in downtown Oakland.

Developers got permission to remove the nests to make way for two new apartment buildings. In exchange, they hired this team of biologists to try and relocate the bird rookery — nests and all — to Lake Merritt, and use the sound recordings to draw their attention to this spot.

They’re also luring the black-crowned night herons by using other black-crowned night herons — fake ones, to be exact.

Cahill unwraps a decoy bird from its packaging, a model replica of the real thing.

Herons are foot-tall grey-blue birds with long necks and long legs for wading in the water. This one has metal post for legs, and is painted to look like the real thing, complete with a red eye just like the real birds.

It even has plastic monofilament line coming out of the back of its head to simulate the herons’ long crown feathers.

Cahill and his team are installing these decoy birds in the trees at Lake Merritt, right next to the relocated nests. Herons are social, they want to nest with other herons. So if the real birds see these decoys in the tree, the hope is that they’ll come join them.



“Looks pretty good,” Cahill says. “If I was a heron, I’d probably want to come check it out if I was flying by.”

Doing right for people and for birds

I’ve been waiting for this moment for a long time. I used to work at Golden Gate Audubon Society, a local bird conservation organization which pushed the city to require the developers to attempt this relocation project when we learned that the trees were going to get cut down.

For years now, two species of birds — black-crowned night herons and snowy egrets — have taken to nesting in downtown Oakland.

These herons are sort of like the raccoons of the bird world. They don’t seem to mind living around people, and they especially like the large ficus trees all over downtown.

Over the last few years, the number of herons nesting in trees downtown has grown, until it seemed like almost every ficus tree in downtown Oakland had herons nesting in it.

The main concentration of the rookery was in Ficus trees that lined a large parking lot on 14th Street, right across from the downtown Oakland post office, where the post office parked its postal trucks.

A heron rookery does not go unnoticed.

“It was noisy,” said Cindy Margulis, Executive Director of Golden Gate Audubon Society and my former boss. “And there was a lot of poop underneath all of the trees.”

It was wild nature right in the city, with the largest black-crowned night heron rookery in the Bay Area.

But some people did not appreciate the wildness of it.

In the middle of the 2014 nesting season, the downtown post office branch hired a tree trimmer to cut one of the nesting trees that hung over the parking lot.

Margulis says the post office was tired of the herons pooping on their postal trucks, “which are white and so is the bird poop. So I’m not sure a lot of people noticed but the postal people did not like it!”

As the tree trimmer attempted to cut the tree’s branches, a few nestling birds fell out. Passers-by who were aware of the birds intervened and got the tree trimmer to stop.

The post office was actually violating a federal law which protects nesting birds.

Four young birds had to be taken to rehab and were eventually released back into the wild. But it was a public relations scandal for the post office and a wake-up call for us as Audubon staff.

We realized that some people found these herons to be a nuisance.



There’s the poop and the noise, but then there’s also the matter of dead baby birds. Young birds can fall out of nests or sometimes even get pushed out by their siblings who are competing for food.

It’s the harsh reality of nature.



But what’s not normally part of nature is the concrete and cars of downtown Oakland. In a more natural environment, soft duff or mud cushions baby birds’ falls and bushes act like step ladders for birds to get back into nests.

Instead, these baby birds were falling out of the trees and were either injured or just unable to fly back up into the trees, and they’d get hypothermic or go hungry on the sidewalk.

“It was pretty gruesome,” Margulis says. “You would see birds dying or already dead laying on the street.”

Golden Gate Audubon knew it had to get involved.

We started a docent program and it was my job to train volunteers to monitor the trees. The docents came out almost every day to walk the streets of downtown Oakland and look for baby birds that had fallen out.

“They were looking under wheel wells; they were looking at the bus stop,” Margulis says. “They were looking everywhere that a little bird could hide in plain sight on a city street. I'm sure our docents looked ridiculous with their heads underneath the wheel wells in the parking lot.”

Once they found a fallen bird, they’d call the Oakland Zoo to come out and rescue the birds. The birds do not go quietly.

“The bird’s going to scream and it actually has this scream that is very much like a dinosaur,” Margulis says. “And they open their beaks really wide. It looks like they could swallow a cow.”

Zookeepers transferred the birds to the International Bird Rescue Center where the birds stayed until they were able to fly. Then Audubon released them into much better habitat, the marshes around the Bay.

This went on for two years. Then Audubon staff learned the main heron-nesting spots were slated for development. The trees that the post office once trimmed were now going to get cut down.

Audubon’s Cindy Margulis felt torn.

“I was struggling with how do we protect these birds, but obviously [this] is not the best place for them to be,” Margulis says.

She also didn’t want to stand in the way of development, because she knew it was needed. “Housing is a shortage for people in downtown Oakland,” she says. “The question was how can we do right for people and right for birds all in one fell swoop.”

Margulis decided to try something she wasn’t sure would work. She asked the City of Oakland to require the developers who wanted to cut down the trees to try and relocate the nesting herons. To her surprise, they agreed.

I have to say, I’ve wondered whether this was all worth it. Heron populations are doing fine in the Bay Area, at least right now. What if we spend all this time and money and it doesn’t work?

“It is a science experiment,” Margulis acknowledges. “There's no doubt about that. But it's based on good science.” She adds, it’s also an experiment that is fully funded by the developers.

The developers hired the local environmental consulting group H.T. Harvey and Associates to plan and execute the relocation.

After the herons finished nesting last year, biologists from H.T. Harvey collected the nests from the old trees, boxed them up, and stored them over the winter.

Those trees got cut down and now the nests are being installed in trees around Lake Merritt.

You can’t control Mother Nature

In downtown Oakland today, the trees where the herons nested across from the post office are gone. The parking lot is now a construction site. Ground broke on the apartment building just a few months ago. In less than two years, there will be a seven-story apartment building here.

Ray Connell takes me on a tour of the site. He’s the development manager for this building. When his company, the Holland Partner Group, bought the building, they learned that the city would require them to pay for the relocation of the herons.

Connell immediately searched the internet to learn more about the birds.

“The first thing that popped up was the debacle that happened at the post office several years ago,” he says. “That was a red flag!” He says, he knew, “Whatever we did, we could not do that.”

Connell drove around the site, but it was winter, before nesting season, and he didn’t see any of the birds. Fast forward to about six weeks later, and he saw all the herons flying into nest on the trees right at his property.

I just wonder: why would you buy a building that came with so many strings — or birds — attached? Connell tells me the relocation is costing his company and the other developer more than $200,000.



“As a developer you'd say [it’s] because we build apartments and that's great for us,” but Connell says the relocation is about more than that. “It's actually a really great thing for the city and for the birds because now hopefully they'll go to a place where they can actually thrive and we won't have ... baby birds falling off trees and getting hit by cars.”

The trees on Connell’s property are gone, but there are still trees across the street and herons have already begun nesting there in the last few weeks. It’s not a great sign. The hope would be that the herons hear the bird recordings and see the bird decoys at Lake Merritt and relocate there instead.

What will happen if all the herons who lost their nests just spread out to other trees around downtown? How will Connell feel after his company has put in all this work and all this money?

“You know you can't control Mother Nature,” he says, but, “it'll be a little disheartening. Hopefully over time they’ll move back to the lake. That’s the goal.”

Too soon to say

Back at Lake Merritt, biologist Miriam Eckardt is scanning the trees for nesting herons, just a few weeks after the nests were relocated there.

She spots an adult night-heron roosting in a tree on one of the islands at Lake Merritt, and notes it in her survey.

Eckardt will be coming out here twice a week throughout the nesting season, surveying for herons to see if the relocation experiment works.

It’s too soon to say whether the herons are taking to the re-located nests, but Audubon staff and building developers will be rooting for the birds.



