Scientists unravel composition of old birds’ nests to fight climate change

By Molly McCrea

From Grizzly Island in Solano County to Memorial Park on the Peninsula, over 180 bird species build a next to reproduce and raise their young in the Bay Area.

But not a single local bird has ever built a nest like the ones researchers found in Ukraine. These small nests glisten with fiber-optic cables.

“These nests are very unique. I’ve never seen nests like this before, and I’ve seen many, many, many bird nests,” said Auke-Florian Hiemstra, a biologist at Leiden University in the Netherlands.

Near the front line of the Ukraine war, researchers found several small birds’ nests, all woven in part with fiber-optic cable. The tiny plastic strands are the remnants of drone attacks. Experts believe the nests are showing how birds are finding ways to survive in places devastated by humans.

“It tells us that the birds will accommodate changes to their environment as far as they can,” explained biology professor and botanist Justen Whittall, who specializes in plant ecology, evolution, and conservation at Santa Clara University. 

Whittall showed us a song sparrow’s nest that was collected a quarter century ago in the San Francisco Bay Estuary. Many birds, like sparrows, build nests to reproduce.

“They get one try per year at this, and if it’s either damaged, or destroyed or discovered by a predator or fails for any reason, their reproduction fails that year,” Whittall said.

He co-authored a report on nests found near a different kind of front line, called the transitional habitat, critical in the fight against climate change.  These habitats provide refuge to endangered species. They also buffer communities from storm surges and allow wetlands to adapt to sea level rise.

Whittall explained that the goal is to restore these habitats so they’re more resilient as the planet continues to warm.  And that means a focus on native plants.

“We know that vegetation is one of the best ways to hold soil into place and prevent inundation or flooding,” Whittall said.

To identify the best kinds of native vegetation, Whittall and his team used DNA technology on tiny samples taken from ancient nests found in Bay Area transitional habitats. One nest was collected on Grizzly Island more than a century ago.

“It’s a bit of a botanical time capsule,” Whittall noted.

The results identified several native plants. Experts believe native plants are the best approach to stabilize soil and for the habitat to survive extreme weather events. More modern nests contain far fewer native plants.

“By knowing the native plants from 120 to 130 years ago, we can begin to restore that lost habitat,” added Whittall.

As for the birds in Ukraine, the fiber optic strands may strengthen the nests but also entangle the birds. There is no data available to quantify how many offspring can survive in nests made with synthetic materials.