While walking, biking, or even driving along Shoreline Drive in late summer and into autumn, you might have noticed a very loudly squawking, swirling flock of slender-winged, bright-white and silvery birds. A closer look, if you followed one as the flock settled close together at the water’s edge, would reveal a quite dramatic bird. Adults are mostly bright white and pale silver and have a long pointed orangey-yellow bill and sport a black, mullet-like spikey rear head crown that makes them a slightly unusual candidate for their common name, ELEGANT tern. But they are gorgeous, no doubt about it… and raucous too!
They’re one of four tern species that are regularly sighted here in Alameda, though the various species have different schedules for their Alameda itineraries. The smallest tern is the most endangered, commonly called unfairly (in my humble opinion) the California least tern (simply meaning the smallest). Least terns nest at a closed site on the former NAS Alameda and they are generally only here from about May – August for their breeding season. Our Alameda waters and shorelines also host Forster’s terns and Caspian terns but the late summer into autumn time frame is when stunning, dense flocks of a few hundred migratory elegant terns visit Alameda’s shores.
More than 95% of the world’s population of elegant terns nests on just one minuscule island to the East of the Baja Peninsula in Mexico. After breeding there, many elegant terns head north along the Pacific Coast, brilliantly taking advantage of a seasonal buffet…the bounty of schooling baby fish (such as anchovy, sardine, mackerel) which hatch in Pacific estuaries. Because the southernmost estuaries’ fish populations hatch first, as the elegant tern flocks continue northward, their arrival time coincides with the slightly later peak populations of the SF Bay Estuary’s baby fish booms. Elegant terns seem to relish the rich feeding opportunities in late summer and autumn here in Alameda where we can marvel at their fascinating behaviors. Once they depart, elegant tern flocks may continue to try their luck fishing, going as far north as the Canadian border, so we’ll have to wait until late next summer to see them in such impressive numbers again.
Being fish eaters, elegant terns forage over the water where they plunge dive to grab fish at or very close to the water’s surface. At high tide on shallow beaches, like Crown Beach and the Elsie Roemer Bird Sanctuary, elegant terns frenetically pluck out one small fish at a time with their sharp, slightly decurved bill, and may carry it onshore to eat it, providing a quick energy-packed snack for themselves, or perhaps to feed a begging hungry youngster who is migrating for the first time. When not foraging and feeding, elegant terns conserve their energy on the warm sand or mudflat, where we typically see them roosting (resting), bathing, and preening themselves on or close to shore. As terns and all other shorebirds can only feed, or rest, as the rhythms of each day’s tide cycle allow, the best way to help terns (and all shorebirds) thrive is to refrain from disturbing them but simply admire them from a respectful distance.
Alameda’s shores are part of the San Francisco Bay Estuary, which is designated as a site of “hemispheric significance” for migratory shorebirds. The special concentration of shorebirds in autumn here represents a functional nexus point for migration. In autumn, Alamedans may notice Arctic-nesting shorebirds and Arctic and boreal-nesting waterfowl arriving locally in significant numbers. While some of these migrants may not linger here too long, shorebirds need to optimize their time here to rest, forage, and recover as most are epic marathoners. In the fall, Alameda’s waters also hosts numerous neo-tropical migrants, including elegant terns and brown pelicans arriving from the south, including Central American breeding sites. In addition, late summer into autumn is when still more species of shorebirds, including inland-nesting species such as long-billed curlews and marbled godwits, arrive here from far to the northeast, some from breeding grounds way beyond the Sierras, to spend their over-wintering period at coastal and estuary sites, including Alameda’s shoreline.
So our Alameda’s beachfront hosts birds which arrive here after starting their journeys from virtually anywhere, i.e. from as far north as the Arctic, from as far south as the tip of Tiera Del Fuego, or from inland sites even beyond the Rocky Mountains, such as Montana or Sasketchewan! If only more Alamedans realized what a unique opportunity we have to glimpse such an awesome array of birds that spend part of their year here at our beach, reminding us how precious this place is…
Cindy Margulis is a former Executive Director/CEO of Golden Gate Audubon, now Golden Gate Birds Alliance, and an enthusiastic champion for wildlife conservation and the wild species that share our shorelines. Rick Lewis is a longtime member of the GGBA along with other environmental organizations. This is part of a series of articles about our local wildlife and habitats by Friends of the Alameda Wildlife Reserve, part of the Golden Gate Bird Alliance.