The Upper Pajaro River (Bolsa de San Felipe area) lies just east of the Monterey Bay area, in a triangle formed by Highways 101, 152, and 156. Major features for wildlife include San Felipe Lake, a natural, formerly-seasonal freshwater pond rimmed by a freshwater marsh and willows just south of Highway 152 about 10 miles east of Gilroy. The lake is surrounded by pastureland and agricultural fields that extend to the west and south, which are intersected by riparian vegetation, notably along Llagas Creek and the upper Pajaro River. Just northeast of the Bolsa, along Pacheco Creek (visible from Highway 152) is one of the most extensive sycamore riparian woodlands on the entire Central Coast. The southwest portion of the Important Bird Area is a raised area known as the Flint Hills, which feature extensive grassland and scattered seasonal wetlands. Though it has been virtually unexplored by biologists (Sam Fitton), it likely contains many surprises, perhaps even vernal pools. Finally, a former gravel pit on the southeast side of the Important Bird Area in the vicinity of Hollister, known locally as the Southside Ponds, support good numbers of waterbirds and have excellent restoration potential (Sam Fitton)
Public access is virtually impossible throughout this Important Bird Area, and any ornithological investigation has been done from public roads. It is known that a large colony of Tricolored Blackbirds (localized in the region) regularly breeds here, along with a handful of American Bittern (also along nearby Llagas Creek) and several species of waders and ducks. The agricultural lands provide important winter foraging and roosting habitat for Long-billed Curlew and all the expected species of geese, which join the thousands of waterbirds that commute between here, the South San Francisco Bay, the Central Valley and the Monterey Bay lowlands. This Important Bird Area is the winter home of such communally roosting raptors as White-tailed Kite and Ferruginous Hawk, and a tiny, remnant population of Burrowing Owl. The riparian thickets support many of the nesting lowland riparian bird species that were once common north to the San Francisco Bay but that have now been widely extirpated, including Yellow Warbler and a large population of Yellow-breasted Chat. Least Bell's Vireo has even nested here recently (Mike Rodgers, personal communication). These riparian birds may also be found along Pacheco Creek, along with taxa more typical of foothill streams (e.g. Western Wood-Pewee).
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Each year, more houses, in particular large "ranchettes", continue to claim more open habitat here, and more surface water in the area is lost to agricultural diversions and is pumped for the area's burgeoning human population. Other direct effects include road-widening and sprawl from the growing communities of Hollister and Gilroy. Unless urgent conservation measures are taken (land easements, acquisitions), the unique resources of this nearly un-studied Important Bird Area will be lost.
The Nature Conservancy (TNC) is exploring land acquisitions and conservation easements with some property owners in the area and SCVAS is partnering with Audubon California and TNC to introduce our chapter members and other birders to the Bolsa.
Major features for wildlife include San Felipe Lake, a natural, formerly-seasonal freshwater pond rimmed by a freshwater marsh and willows. The lake is surrounded by pastureland and agricultural fields that extend to the west and south, which are intersected by riparian vegetation. Just northeast of the Bolsa, along Pacheco Creek is one of the most extensive sycamore riparian woodlands. The southwest portion of the IBA is a raised area known as the Flint Hills, which feature extensive grassland and scattered seasonal wetlands. Though it has been virtually unexplored by biologists (SF), it likely contains many surprises, perhaps even vernal pools.