Up in the Air

Climate Change Compounds Threats to Birds

Red knots in Delaware Bay, New Jersey (Photo: NJ DEP)

Each spring the red knot, a shorebird with a rust-colored belly, transects the globe, flying from the southern tip of South America to the northern reaches of the Arctic. Midway through this flight, the birds lay over at the Delaware Bay, where they refuel by gorging on tens of thousands of horseshoe crab eggs.

In the 1990s, this age-old migration ran into trouble when red knot populations began crashing. Evidence pointed largely to shellfish overharvesting, but recent observations by birders and researchers have revealed an additional threat from climate change: Warmer temperatures are prompting the horseshoe crabs to lay their eggs earlier in the year, meaning less food for the migratory birds when they arrive at the bay.

These findings and other research about the impact of climate change on birds are the focus of the 2010 State of the Birds report, issued by scientists from the Cornell Lab of Ornithology, The Nature Conservancy, federal agencies and other organizations. The group’s 2009 report found that roughly one-third of bird species in the United States are endangered or are in serious decline.

The 2010 report examines the vulnerability of birds to future threats, says Ken Rosenberg, director of conservation science at the Cornell Lab of Ornithology.

The report finds that birds most imperiled by past changes such as habitat loss—particularly seabirds, shorebirds and island birds (especially those in Hawaii)—are also the species most vulnerable to the impacts of climate change. For example, the scientists warn that rising sea levels will destroy key habitat for many marine birds.

On a positive note, the report suggests that many forest and grassland birds have already begun to adapt to climate shifts by relocating, in direction or elevation, to habitats more to their liking.

David Mehlman, director of the Conservancy’s migratory bird program, says the report’s analyses will help identify emerging risks to birds so that proactive steps can be taken to curb threats. “We need not only to protect where biodiversity is now, but where we think it’s going in the future,” he says.

In coordination with the report, the U.S. Department of the Interior is launching a network to pool climate research and to promote conservation strategies for threatened birds. This collaboration, Rosenberg says, “takes bird conservation to a new level.”

— Joshua Zaffos

Oil Alert

Digital Tool Helps Oil-Spill Responders Protect Alaska’s Coast

A snapshot of Sitka Shore, via Alaska ShoreZone (Photo: NOAA Fisheries)

In January 2009, fierce winds in southeastern Alaska tore loose a 181-foot ferry from a pier. The ferry ran aground on a small island, and the Coast Guard and volunteers headed to the scene to limit damage from a possible fuel spill. Before they arrived, the responders knew which sensitive tidelands and critical fisheries habitats were threatened, thanks to a set of new high-tech digital maps that provide a bird’s-eye view of Alaska’s coast.

The mapping project, Alaska ShoreZone, currently covers 17,000 miles of the state’s roughly 47,000-mile coastline, including areas such as Bristol Bay and Prince William Sound—the site of the Exxon Valdez spill in 1989. More than 30 organizations, including The Nature Conservancy, National Oceanic and Atmospheric Administration (NOAA), and state and tribal agencies, have worked together on the program since 2001, sharing $5.5 million in funds and plenty of expertise.

To get the images for ShoreZone, a helicopter buzzes the coast during low tide. A biologist and geologist hang out the open door, shooting photos and video, and recording audio commentaries on the coastline features below. The high-definition images and the narratives are digitized and made publicly available online.

“It’s fantastic to see the whole coastline,” says John Harper, a geomorphologist who has worked on ShoreZone programs in Washington state, British Columbia and now Alaska. “It really provides a different perspective,” he says.

Scientists have used the digital maps to identify important fishery habitats, such as underwater kelp forests and eelgrass beds. ShoreZone has played a critical role in explaining some of the interactions between estuaries—where rivers meet the ocean—and upland areas, says Laura Baker, a marine project manager with the Conservancy in Alaska.

“Our primary goal is to have the first inventory of coastal habitats in southeastern Alaska,” Baker says. By using ShoreZone information, the Conservancy is identifying areas of key conservation significance and fine-tuning strategies for protecting salmon runs, tidelands and coastal forests.

Crews responding to oil spills can use the data to prioritize areas where they need to act quickly. If a Valdez-like spill occurred now, responders could use ShoreZone to develop containment plans to protect sensitive wildlife habitat. Additionally, the program is feeding computer models to help manage commercial fisheries and control invasive species.

Says Baker: “It’s a tool to help us pick which areas to focus on.”

— Joshua Zaffos

Bivalve Blues

Report Reveals Global Risks for Oyster Reefs

Exposed oyster reef in the Chesapeake Bay, Virginia (NOAA)

Baymen harvest an average of roughly 99,000 tons of oysters each year from the warm waters of the Gulf of Mexico. But that kind of bounty is now uncommon: Around the world, 85 percent of shellfish reefs have been lost to overfishing and habitat destruction, according to a new Nature Conservancy report, Shellfish Reefs at Risk.

“Shellfish reefs are the single most impacted marine habitat globally,” says Mike Beck, a Conservancy marine scientist and lead author of the report. Beck and his team of scientists compiled status reports from more than 144 estuaries and found that reefs were in significant decline worldwide.

While records show that even the ancient Romans exploited shellfish reefs, the pressure on oysters, mussels and clams today is unprecedented. Overharvesting has led to the functional extinction of many oyster reefs throughout Europe, North America and other continents. In fact, most of the oysters we eat now come from aquaculture.

Global condition of oyster reefs (via The Nature Conservancy report)

Other major threats include disease and parasite outbreaks; the introduction of non-native species; pollution from the filling and dredging of coastal areas; and runoff from urban development, industry and agriculture.

Most countries tend to manage oyster reefs as harvesting fields and not much more, Beck says. We underappreciate and undervalue the “ecosystem services” that shellfish reefs provide, he says, such as filtering and purifying water, controlling erosion and supporting scores of other marine species.

While providing a global assessment of the threats facing shellfish, the report also outlines steps to help protect and restore threatened reefs. The scientists recommend that governments protect some of the best remaining reefs in places like the Gulf of Mexico and Georges Bay in Australia.

Beck also calls for new and existing funding to focus on the long-term restoring of reefs, not just on oyster harvesting; many restoration projects now allow harvesting only a year or two after oysters have been replanted. “We should allow reefs to rebuild themselves. And then we should allow harvesting of just the interest, not the principal,” says Beck. “We need to see the reefs return, not just the oysters.”

-Joshua Zaffos