San José, California, USA
Dan Wenny, San Francisco Bay Bird Observatory
Yiwei Wang, San Francisco Bay Bird Observatory
Only ten years ago, the outskirts of San José still hosted fields. In the meantime, warehouses and office buildings have sprung up. However, even in this urban sprawl, there are still a few patches of nature along the banks of Coyote Creek. They form a habitat for over forty resident and more than sixty migratory bird species. Here, Dan Wenny of San Francisco Bay Bird Observatory (SFBBO) set up a camera trap for Triggered by Motion.
The land around Coyote Creek Field Station, where the camera trap is located, belongs to the Santa Clara Valley Water District. The field station itself was established during the 1980s. At the time, the Water District built a flood control channel system along the banks of Coyote Creek. Because some of the riparian vegetation along the riverbank had to be removed during construction, Santa Clara Valley Water District established a restoration site at Coyote Creek, which today is Coyote Creek Field Station.
Work at Coyote Creek Field Station started in 1983. Here, resident and migratory birds are banded. This allows the SFBBO to monitor them over long periods to better understand migratory routes, stopover time during migration, and connectivity between breeding and non-breeding areas. The camera at the site is used to monitor potential predators of the birds near the banding station.
Predatory feral cats are relatively common, yet they were not often captured on camera, probably because it was directed towards the creek and not the inland. Instead of cats, the camera mostly recorded Mallards (Anas platyrhynchos), Red-tailed hawks (Buteo jamaicensis), and Raccoons (Procyon lotor). Great blue herons (Ardea herodias), White-tailed deer (Odocoileus virginianus), and Coyotes (Canis latrans) were recorded a little less often, and rarely, a Barn owl (Tyto alba) appears in the footage.
Conservation of vulnerable migratory species requires knowledge of all stages of the annual cycle. San Francisco Bay Area has much higher diversity in the winter than in the summer because of the lack of rainfall in the summer. Mild winter conditions make this area a magnet for migratory birds.
At Coyote Creek Field Station some species are just spring (April–May) or autumn (September–October) migrants and they use the area for only a few weeks while other species nest here (April–July) or spend the non-breeding season (October-March) here. Few species are present year-round. Thus, the field station provides important habitat for different stages of the annual cycle for different species.
The region around Coyote Creek is a major urban area of over 7 million people. Much of it was previously oak woodland that is now mostly urban and residential development. San Francisco Bay itself had tidal marsh and transitional uplands most of which have been replaced with salt ponds. A major tidal marsh restoration project is underway – still, the small patches of land that are left for wildlife must not be underestimated. Research has shown that not only large nature reserves but also smaller tracts of land like the riparian woodland around the field station are important for the many migratory birds in Silicon Valley.
This is one of the central findings that emerged from SFBBO’s work in San Francisco Bay: Although most conservation efforts are directed towards large high-quality habitats, small or degraded habitats should not be ignored.