Melissa Pitkin (PRBO Conservation Science)
In this first ever State of the Birds report for San Francisco Bay, we learn that most bird populations are stable. Some species are clearly benefiting from conservation action while others are struggling. In the following pages, the report highlights these trends, challenges, and the actions people can take to make a difference.
Most bird populations are stable.
When we evaluated groups of birds for each habitat, we found that most are now stabilizing. This includes birds dependent upon subtidal (submerged) habitats, tidal flats, marshes, and oak woodlands and the endangered Spotted Owl.
Riparian birds and two endangered species have increased.
Riparian birds – species that require stream-side habitat – and two of our threatened and endangered species, the Snowy Plover and Least Tern, have shown some increases. Recently, the Snowy Plover has been increasing from very low levels, and the Least Tern may be starting to stabilize after years of population growth.
Grassland and coastal scrub-chaparral birds are losing habitat.
Species in these habitat types continue to be impacted by loss and degradation of habitat from development, invasive species, and lack of natural disturbances such as fire. These trends are consistent with the declining trend found in the National State of the Birds Report, 2009.
California Clapper Rail still struggles.
Perhaps one of the Bay’s most iconic birds, this rail still struggles because of habitat loss, predator pressure, and invasive species. Sea level rise will make it even harder for rails to persist as they are pushed into marginal habitat with rising seas and strong storms. Tidal marsh restoration efforts and scientific monitoring must continue to ensure that this endangered bird can persist into the future, especially as the location and extent of marsh habitat change.
All habitat types harbor species at risk.
Declines can be early warnings of a decline in ecosystem function. Causes of declines need to be investigated and actions should be taken to stabilize bird populations. Species to watch include: California Clapper Rail, Western Sandpiper, Forster’s Tern, Caspian Tern, Black-crowned Night Heron, Snowy Egret, Canvasback, Northern Pintail, scaup and scoters.
Sea level rise is a critical threat.
Habitat restoration needs to take advantage of the best scientific modeling to predict the best places to restore marshes and guide restoration design to ensure marshes, and the benefits they provide wildlife and people, are maintained.
Extreme weather events are predicted.
Climate models predict more frequent extreme weather events, such as strong storms, heat waves as the climate changes. These unusually strong events can cause nest failure, facilitate predation, and cause individual bird death.
The amount of tidal flat habitat needed requires more study.
Keeping one million shorebirds in San Francisco Bay requires better understanding of how many acres of tidal flats are needed to maintain the Bay’s high shorebird numbers. Understanding how sea level rise will change the amount and location of tidal flats is a high research priority.
Restorationists can learn from one another.
The South Bay Salt Pond Restoration Project will provide valuable lessons for future marsh restorations within the Bay.
Predator and invasive species control must continue.
Both animal and plant, and native and non- native predators and invasive species, remain an ongoing threat. Funding is needed for predator control, invasive removal, and outreach to the public on their role in reducing predators (such as feral cats) and invasive species.
Human activities can be designed to reduce impacts to birds.
Disturbance from human recreation, maintenance, and transportation activities is something we can control and reduce to lessen pressures to birds during their sensitive nesting period.
Science must continue.
Continued monitoring of the Bay’s bird populations is necessary, to evaluate our success at maintaining healthy ecosystems. Birds are the proverbial "canary in the coal mine." Tracking their populations will help us solve problems before they become "emergency-room cases."
A mix of public and private funding is needed.
To ensure our ability to protect existing habitats, respond to new threats, and maintain and enhance the quality of Bay waters upon which birds and people depend, a mix of funding sources is necessary.