The discovery of migratory bird nests interrupted recent mowing at a former landfill at Hamilton Field in Novato.Robert Tong — Marin Independent Journal
By Mark Prado, Marin Independent Journal
A bird roosts on a fence near the former Hamilton Army Air Field's Landfill 26 Cap. (Robert Tong/Marin Independent Journal)
The discovery of migratory bird nests at Hamilton Field has halted the mowing of tall grasses on a former landfill.
Several species, including burrowing owls, tricolored blackbirds and red-winged blackbirds were found during recent mowing work at Hamilton’s Landfill 26. Once the birds were found, mowing was stopped, according to the U.S. Army Corps of Engineers.
The Army Corps’ Sacramento District manages maintenance of the former airfield’s landfill, which includes the annual mowing aimed at reducing potential fire hazards posed by dry grasses. Mechanical mowing of the landfill cap is usually done after the last rains of spring, typically around May to June each year, according to the Army Corps.
But this year there was a surprise.
“During the mowing we noticed some birds were being flushed from their nests,” said Shellie Sullo, the corps’ project manager at Hamilton, noting a biological survey was done before the work. “But we think the birds made it back to their nests. They apparently like the tall grasses.”
About 10 acres of the roughly 40-acre site still needs to be mowed once the birds move out. The Army Corps contemplated using goats to clear the balance, but the animals would likely eat nests along with the grasses. If the mechanical mowing can’t resume, the weeds could be pulled by hand, Sullo said. The unmowed area is away from Hamilton homes and doesn’t present an immediate fire threat. Neighbors will get fliers about the issue next week.
Nesting birds have been rare at the site, but they likely turned up this year because a culvert carrying water around the perimeter of the site was installed over the winter. That provided a water source for the birds.
Given the new conditions, the Army Corps will reassess its mowing schedule moving forward, Sullo said. The corps is working to adjust time frames of the annual mowing maintenance to accommodate the nesting seasons of the birds. Currently, the corps expects to complete removing the grasses one way or another by August or September, after the end of the nesting season.
“It’s good they stopped mowing,” said Barbara Salzman, president of Marin Audubon, who expressed concern that the birds were not detected earlier. “It’s a good lesson that we should wait on this type of work until after nesting season is over. But I’m glad these birds were saved.”
In April, the California Fish and Wildlife Commission voted to list the tricolored blackbird as a threatened species. The burrowing owl and red-winged blackbird are protected under the Migratory Bird Treaty Act.
See full story in the Marin IJ HERE