Climate Change Threatens More Than 120 Native Bird Species In San Diego
Part of the joy of winter for Chris Redfern is watching the long-billed curlew wade along San Diego’s coastal wetlands.
“Its wingspan is about 3 feet, so it’s a pretty big bird, it has a very large down-curved beak,” said Redfern, executive director of the San Diego Audubon Society.
By the half-century mark, the migratory shorebird could disappear from San Diego.
“It’s going to have to adapt, it’s going to have to find ways to survive,” Redfern said.
Survive rising sea levels that are expected to inundate its intertidal habitat, including at Mission Bay, where many of the 20,000 long-billed curlews migrate to each winter to feed on crabs and shrimp.
“Imagine another 18 inches on top of this,” said Redfern, motioning to water in the Kendall Frost Marsh at Mission Bay during high tide. “A lot of these spaces that these birds are using to stay out of the water ... will be disappearing more and more as climate change affects our sea level rise.”
Also at risk of disappearing: the curlew’s summer nesting habitat of short-grass prairies in the Intermountain West due to warming temperatures and drought.
It's a story of disturbance, Redfern said.
“We know that with climate change, habitats are changing, they are moving, they are shifting their geographic locations,” Redfern explained. “Sometimes that means those habitats will just move north, sometimes it means they’ll shrink.”
He said many of San Diego’s coastal habitats, which are crucial migration stops for the winter visitors, will have no room to shift to.
“In this particular place…Kendal Frost Marsh is completely constrained by development,” he said.
The long-billed curlew is not alone in its plight to survive. A recent seven-year National Audubon study warns the habitats and migratory routes of more than half of the nearly-600 birds in North America are threatened by climate change.
“It’s going to cause populations to decline,” Redfern said. “All sorts of interactions are going to be happening that we can’t even begin to understand until we start seeing them happen and unfold in nature."
In San Diego, more than 120 native species face grim prospects, including the brown pelican, Allen’s hummingbird, and western snowy plover. Several other species are already victims of habitat reduction.
“Like the loggerhead shrike, which 25 years ago was fairly common, is now barely hanging on,” said Philip Unitt, curator of birds and mammals at the San Diego Natural History Museum.
Unitt said drought, heat waves and wildfires have already begun taking a toll on San Diego’s birds, including the pygmy nuthatch — a tiny songbird that used to thrive in the Cuyamaca Mountains before the 2003 Cedar Fire.
“It’s a bird that makes its living by probing into clusters of pine needles for insects,” Unitt said. “Well, if the pine needles are all burnt, if the pine trees are dead, or if the few that are re-growing are still only knee-high for 20 years, then there’s no habitat for the pygmy nuthatch.”
Unit said the prolonged drought is also deeply concerning.
“We can see easily, if we have too many drought years in a row, birds not reproducing and undoubtedly surviving poorly,” said Unitt. “The populations could dwindle away.”
Historical bird records are found in the museum’s library of tens of thousands of catalogued bird specimens, accounting for 90 percent of the world’s birds. Each specimen represents a particular time and place in the environment, Unitt said.
“This specimen, collected by Frank Stevens in the San Bernadino Mountains, 1885,” Unitt read from a tag on a dipper songbird.
Predicting which species will adapt to a changing habitat is difficult, said Unitt. Some will learn to live and feed in urban environments.
“We’ve seen that in the case of nuthouse woodpecker and cooper’s hawk and western bluebird,” Unitt said. “The species that we might not have predicted as an urban adapter but turned out to be so.”
Others face extinction or could cease to exist in San Diego — outcomes seen just a few times in San Diego’s history, said Unitt. —Like the black rail, which used to be around San Diego Bay before the 1950s.
Redfern said birds have always been used as bellwethers for the health of our world. He said the outlook for the long billed curlew is troubling.
“For someone who loves wildlife and is about protecting wildlife, this is our big challenge in our lifetimes.”