Richardson Bay Audubon Center’s migratory bird tracker pings its first visitor
Updated: Jul 16
Editor’s note — This article won fifth place for best writing in the California News Publishers Association’s 2023 California Journalism Awards.
On April 24, Red Knot 458809 — a plump, red-breasted shore bird weighing just over 4 ounces — was captured and fitted with a digital radio tag in the Biosphere Reserve of the Upper Gulf of California and Colorado River Delta in Mexico.
The bird likely had journeyed there from the far south, perhaps as far as Tierra del Fuego, before reaching the warm shores of Baja California. On May 26, it flew north, resting for a few hours in the brackish waters of the Salton Sea. The next day, May 27, it flew up the Central Valley to a slough near Merced, turned west to the coast, passed through Santa Cruz and continued up to the Bay Area, where it rested for a few minutes at the San Francisco National Wildlife Refuge in Fremont. Then the bird was off again, flying north to Marin, where it landed for 2 minutes, 39 seconds at Richardson Bay before continuing north.
At Richardson Bay, a tag on the bird’s back sent a signal to a radio tower perched on a hill at the Richardson Bay Audubon Center and Sanctuary in Tiburon. Computers at the center pinged, registering the bird as it flew by and adding to the database that was tracking the bird’s flight in real time. It was a moment center staff had been awaiting for almost a year.
“We were so excited, and there was a big sigh of relief,” said Paige Fernandez, a biologist at the center. “Now we know for sure it’s working on a real bird.”
“It” is a Motus tower, or a tower fitted with a radio antenna that uses automated radio telemetry to track the migratory journeys of birds, bats and even insects.
The tower, erected by staff at the Audubon Center on Greenwood Beach Road last July, is part of the Motus Wildlife Tracking System, which was set up by Canadian conservationists and allows a community of researchers, educators, conservationist nonprofits and ordinary citizens around the world to share data on the migratory patterns of endangered species. According to the project’s website, there are 1,671 Motus receiver stations deployed in 34 countries.
“It’s a community of scientists all contributing to this bank of knowledge,” Fernandez said. “With this we can know where the birds are stopping and how long they are there. This will help define conservation practices.”
Building a dataset in real time helps conservationists know which stopping-over areas are vital to migrating species and need protection.
According to a 2022 report by the North American Bird Conservation Initiative, more than half of American bird species are in decline. Birds are threatened by coastal and wetland development that fragments their habitats and a loss of food sources like insects and marine invertebrates. Extreme weather events associated with climate change threaten migrating species.
A common way to track bird migrants is to band them, but the bird must be caught and banded and then caught a second time at the end of its journey, which often doesn’t happen. Even if it does, banding only tells scientists where the bird started and where it ended up, and nothing about the journey in between. Radio tracking fills in the gaps, said Audubon Richardson Bay Center Director Casey Arndt.
“We can see them in real time,” Arndt said. “We can watch them through a lifetime and life cycle, where they breed, where they winter and what obstacles they come up against. We’re getting the answers to the journey questions we’ve never gotten before.”
According to the Motus website, birds are fitted with a digital radio tracking tag weighing less than one gram. Some tags stay on the birds for a lifetime, powered by tiny solar cells.
Motus towers are few and far between in the Pacific Northwest, although the network is more developed on the East Coast, Fernandez said. Last summer Audubon California approved the $8,000 purchase of the local tower, which arrived in unmarked boxes with no assembly instructions, much to the dismay of center staff, Fernandez said.
Help arrived from wildlife enthusiast Howdy Goudy, David Lumpkin from Audubon Canyon Ranch, Levi Souza from the California Department of Fish and Wildlife and Gabriel Reyes from the U.S. Geological Survey.
“They were truly lifesavers,” Fernandez said.
The helpers hauled the components up to the highest point on the reserve, the small hill behind the center, where it took two days to assemble. The receiver was set up to ping on a centralized database as well as on the center’s computers when a tagged bird flew by. The staff waited, checking their computers day after day for months, but no ping came.
Suddenly, nine months later, on May 27, came the event they had been waiting for. Red Knot 458809 pinged the tower as it flew by.
“We think all birds are amazing but when it pinged, we wanted to know everything about this bird,” Arndt said. “You feel like it’s your red knot.”
And Red Knot 458809’s journey continued to amaze. Known as some of the longest distance flyers on earth, red knots migrate thousands of miles from South America up to the high Arctic Circle to breed. The birds can be found on every continent except Antarctica, but on the East Coast their numbers have plunged due to overharvesting of horseshoe crabs, their main food source.
After leaving Richardson Bay, Red Knot 458809 flew north to Westport, Wash., where a Motus tower at the Coastal Interpretive Center pinged its presence. There it rested and fed in a shoreline estuary for four days before setting off over the open Pacific. It flew over the British Columbia islands of Haida Gwaii before finally reaching the Alaska coast, 11 days after it left Mexico. A Motus tower on the tiny, rugged island of Little Egg in the Aleutian Islands recorded its presence from June 6 to June 8. After that, it flew north to the Arctic Circle where, at least for now, the bird has been lost to science.
Contributing writer Gretchen Lang of Belvedere covers the environment.