Wild Secrets — OCWD’s Seabird Colony
OCWD manages and protects the Santa Ana River Watershed through removal of nonnative invasive species, habitat restoration and wildlife management. OCWD has dedicated more than 1,100 acres of land for environmental preservation and invested millions of dollars for conservation. The following article highlights some of the many creatures that call the watershed home.
Burris Basin is located between Ball and Lincoln Roads in the city of Anaheim, encompasses approximately 125 acres, and is about 14.5 miles from the Pacific Ocean. It is the terminal basin in the Orange County Water District’s (OCWD; the District) recharge system and important for transferring water back and forth between the river system and Santiago basins. It also accommodates nesting seabirds.
The big draw for coastal birds is the abundance of fish, like threadfin shad. We found birds nesting on a 1.6-acre sandbar during reconnaissance for the 2008 Reconfiguration Project. There were many other smaller sandbars, too, so OCWD built them a 2.4-acre island as part of the project.
To accommodate nesting birds while the project was built in 2009, we deployed a 3,500 square-foot dock, which was anchored below an old pump station and covered in beach sand. The target species for the floating island was the endangered California Least Tern (CLT), but they were ousted by the larger nesting shorebirds, mostly Forester’s Terns (FOTE) and Black Skimmers (BLSK). The CLT continued nesting on the rim of the basin during project construction. So, we fenced off the little spots they chose and watched giant earthmovers rattle right past unperturbed incubating terns!
The birds that nested in the sparsely vegetated bottom of Burris Basin, but mostly on the island, in 2009 – 2019 included: the California Least Tern; Forster’s Tern; Black Skimmer; American Avocet; Black-necked Stilt; Spotted Sandpiper; Killdeer; Mallard; Gadwall; Canada Goose; and Egyptian Goose. We monitor nesting activity weekly on the island in May through July each year. There have been as many as 212 FOTE and 91 BLSK nests in a single year, and 12 – 18 pairs of CLT.
The terns usually nest right on the coast, but suitable sites are rare; having found a great fishing hole at Burris, they lingered to raise young. Their presence on the sandbars was challenging. If the water level was dropped at just the wrong time, the terns took up residence and bred on tiny islets only exposed during low water. Then, when the water had to be raised, nests could be flooded. Careful coordination kept the worst from happening and the permanent island was built high enough to avoid submergence. Once again, OCWD struck that critical balance, maintaining excellence in water management and renowned stewardship of the associated natural resources.
This wildlife article was written by Richard Zembal, natural resources director for the Orange County Water District (OCWD), whose award-winning environmental programs benefit both nature and water supplies.