Shorebird conservation challenges on the Los Angeles River

Background/Question/Methods

The Los Angeles River represents one of the largest shorebird stopover, wintering and breeding areas in coastal southern California, with tens of thousands of individuals representing nearly 40 species of shorebirds are present each day nearly year-round.  While most of the acreage and ecological aspects of the original wetlands in the area were lost by the mid-1900s, alkali flat habitat attractive to many species of shorebirds was replicated decades later with the introduction of a year-round flow of treated wastewater.   Since the late 1980s, releases from a water treatment plant created the “Los Angeles River shorebird area”, attracting increasing numbers of shorebirds for the past three decades.  Birds feed on fly larvae supported by a thin film of algae-rich water along a broad cement channel, in several stretches beginning roughly 5 kilometers from the river mouth, extending more than 45 kilometers upstream. Here we summarize historical trends and recent developments within this semi-novel ecosystem, and offer suggestions for future research and conservation actions that could benefit large numbers of shorebirds and other native species in one of the most intensively urbanized areas of the world.

Results/Conclusions

Since intensive surveys in 2000-01, the most common species here (1000+ individuals/day) remain the Black-necked Stilt (Himantopus mexicanus), Western Sandpiper (Calidris mauri), and Least Sandpiper (Calidris minutilla).  These species are irregularly abundant through winter, and both the Black-necked Stilt and America Avocet (Recurvirostra americana), as well as the Spotted Sandpiper (Actitis maculatus) nest locally.  Thus, the river channel remains one of the most productive, and consistent, shorebird stopover sites in southern California.  Potential threats include a reduction in water releases and resulting lowering of water levels (ironically, due to increased water conservation), as well as anthropogenic pollution (plastics, metals).  As regional water priorities shift from wastewater disposal to re-use, this type of shorebird habitat will be at risk. By establishing a minimum baseline of water releases from the upstream water treatment plant during the critical fall migration period and working to identify and eliminate sources of contamination along its length, it is likely that a significant amount of high quality shorebird habitat could be maintained here indefinitely.