A bold landform rises from the ocean’s edge just north of the Russian River mouth, in Sonoma County, and above it a highway of hawks forms in the fall. Southbound raptors ride a band of air that’s shaped in part by the weather, in part by the Jenner Headlands terrain.
On a warm September day, four or five sharp-shinned and Cooper’s hawks may be in view at once within this sweeping landscape. These slender brown birds of prey, distinguished by their small size and their flap-and-glide flight styles, belong to the genus Accipiter, known for eating songbirds, especially in woodlands. Larger, soaring buteos are here as well—numerous red-tails and occasional ferruginous hawks—joined by northern harriers, American kestrels, white-tailed kites, peregrine falcons, ospreys, and others. Sharing the sky with these raptors is the turkey vulture, another common migrant that travels by day, as well as restless swallows and resident ravens.
A small band of citizen scientists, stationed on a rocky knoll on the high slope of Jenner Headlands Preserve, is watching all this. These hawk enthusiasts are disciplined and also full of passion, both for birds and for this stunning geography. And it’s no wonder: standing here above a vast sprawl of coast and ocean feels a lot like soaring.
Beginning in fall 2018, the public can visit Jenner Headlands Preserve, accessed via a state-of-the-art parking area some 1.5 miles north of the tiny town of Jenner. Nearly nine years have gone into creating trails and generating a management plan for the grassland, riparian, and forest ecosystems here. Jenner Headlands represents a conservation triumph: Embracing 5,630 acres, it is one of Sonoma County’s largest protected areas. The Wildlands Conservancy owns and stewards the preserve and was one of many partners contributing to its acquisition, a long effort spearheaded by the nonprofit Sonoma Land Trust.
Learning about Jenner Headlands’ wildlife and patterns is still in the early stages. One strand of knowledge concerns the raptors’ flyway through the preserve during fall migration. From the time hawk-watchers discovered this phenomenon, in 2009-’10, they postulated that the birds they were counting later funneled over Marin Headlands, 60 miles to the south and the locus of Golden Gate Raptor Observatory’s long-term study. A signal of this connection appeared on September 23, 2015, when at both sites extraordinary numbers of raptors were recorded. For example, 125 sharp-shinned and Cooper’s hawks were seen at Jenner Headlands, and 614 of the two species were spotted at the Marin Headlands. “Because of these citizen scientists’ dedication, we’re accumulating knowledge that’s meaningful on a regional scale,” says Brook Edwards, resident manager of the Jenner preserve.
EXPLORE JENNER HEADLANDS
Access: Find the Jenner Headlands Gateway on Coast Highway One about 1.5 miles north of Jenner. A beautifully designed parking area, with native-plant landscaping and erosion-control berms, accommodates more than 30 vehicles and includes two ADA spaces. Picnic tables nestle within a curving rock-wall “river.” A restroom building with a living roof, set within a former quarry, nestles onto a hillside. You’ll find interpretive signs here and the start of hiking trails.
Hiking: A 14-mile trail system allows hikes of short or long duration. A 3.5-mile loop leads to a historic barn at the preserve headquarters and also to Jenner Hawk Overlook. The Sea to Sky Trail, a rigorous 7.5 miles each way, with 3,600 feet of total elevation gain, leads to the top of an adjacent preserve owned by Sonoma Land Trust, the towering Pole Mountain. Some trails, including an ADA trail to a Russian River overlook, opened in September 2018.
Sentinel Point: On a knoll about half a mile from the parking area, The Wildlands Conservancy has placed a telescope in a concrete floor with labels prompting visitors to inspect the forest, river, and ocean where you might spy migrating whales in the winter.
The year-round presence of hawks at Jenner Headlands attests to the landscape’s vigor and seasonal rhythms. In the late spring and summer months, American kestrels nest in the cavities of snags or trees, Cooper’s hawks in the wooded ravines, and red-tails in the ridgeline, eucalyptus, and watershed forests. Red-tailed hawks appear everywhere, chasing one another, yelling about life (in red-tail language), hovering to hunt, perching possessively on stony outcrops or twisted tree limbs.
After the breeding season, and toward the end of fall migration, some hawks make this their destination for all or part of the winter. Likely the most impressive of these is the ferruginous hawk. The largest buteo, it has a 4.5-foot wingspan, a strong V-shaped soaring profile, and stunning plumage, often white below with rusty-feathered legs. According to Larry Broderick, a raptor enthusiast and founder of the Jenner Headlands Hawk Watch, “In good years, on average we get six to eight ‘ferrug’ in a day in winter, and we’ve seen up to 18 in one day! ‘Good years’ are when the prey base is in full swing, which is 50 to 75 percent of the time.”
The prey base of note would be meadow voles and pocket gophers, whose burrows densely pock these grassy slopes—evidence of a great seed feast. One trophic level higher, the rodents represent a feast for some of the raptors, coyotes, bobcats, and badgers.
That’s why the preserve is working to maintain the integrity of what strikes some as a very large patch of weeds. A few early visitors, on guided hikes, wondered if this grassy landscape would be restored to woodlands. “They didn’t understand that the soils here are too shallow for trees, but also that grasslands themselves are essential and valuable,” Edwards says. “This is about as close as we have today to a unique ecosystem that’s been more than 90 percent lost—the coastal prairie.” Once widespread, though limited to the western edge of California and Oregon, coastal prairie began to change when cattle were brought to the region and fire suppression became routine, and the prairie began to drastically disappear as development mushroomed along the coast. Coastal grasslands today include nonnative plants as well as surviving native species, but these grasslands have great ecological value.
The management challenge in this habitat now is to limit the dominance both of aggressive nonnative grasses and of woody shrubs like coyote brush.
Fire would be effective, as native people knew, but is not a viable option on the scale of this terrain.
So the tool of choice at Jenner Headlands, as in other regions where rangeland is regaining ecological function, is rotational grazing. Seven fields at Jenner Headlands, from 50 to 300 acres in size, are bordered with electrified cord that the resident cattle recognize. Since 2014, a herd of 80 to 90 cows and calves has moved from place to place in the grassland on a calculated schedule. These cattle are a rather charming breed, the Belted Galloway, solid black fore and aft with a thick white sandwich around the midsection; hence the nickname “Oreo cookie cattle.”
The herd is owned by Markegard Family Grass-Fed, which produces grass-fed beef and cooperates in grassland stewardship with a number of land trusts and conservation groups. At Jenner, the Oreo cattle remain in one or two fields just long enough to keep the nonnative grasses in check, promoting plant diversity and preventing a stifling thatch from blanketing the ground. Among the results are reduced fuel for wildland fires, and an increase in perennial grassland species that can improve the soil’s capacity to hold moisture and to sequester carbon from decaying vegetation.
To assess how well this approach is working, the preserve has been building a baseline of ecological data. A contract botanist here, Shelly Benson, has been surveying plant diversity in varied soil types since 2013. Of particular interest are the limited areas of serpentine soils that support greater proportions of native grasses, such as the perennial Stipa pulchra and the annual Festuca microstachys, as well as brilliant wildflower displays in spring.
Songbird abundance and diversity are another strong indicator of ecosystem health, and avian monitoring helps guide the management approach at Jenner Headlands. When the land purchase was complete, birders affiliated with Sonoma Land Trust, Redwood Regional Ornithological Society, and Madrone Audubon began documenting birds in the preserve’s forest and grassland habitats. “We were especially interested in birds of special conservation status,” such as grasshopper sparrows and marbled-murrelets, says Larry Broderick.
One such species, at home in the Jenner grasslands, is the radically inconspicuous grasshopper sparrow. Colored a lot like earth and dry vegetation, these little birds usually stay low, concealed in tall grasses. They’re known by the mechanical trill, resembling an insect’s buzz, that constitutes their song. This sparrow is a grassland specialist and, due to habitat loss, a California species of conservation concern. Yet hikers along the three-mile coastal loop at Jenner Headlands Preserve, especially in spring or early summer, have a good chance of hearing a grasshopper sparrow sing, and even of spying one of these streaky tan birds in plain view, foraging for seeds.
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Ecologists from Point Blue Conservation Science in 2010 compared the songbirds and raptors present in grassy habitat at Jenner Headlands with those in Sonoma Coast State Park, just across the Russian River to the south. In the preserve they found a suite of grassland specialists, including savannah, lark, and grasshopper sparrows; horned lark; and western meadowlark. In the state park, there were plenty of savannah sparrows but no grasshopper sparrows.
One reason may be patch size, an ecological metric that can be a defining factor in a species’ choice of habitat. “Land in the state park hasn’t been grazed for over 20 years,” Edwards observes, “and there’s significantly more coastal scrub interspersed with grassland there. So maybe grasshopper sparrows prefer a larger patch size of up to 1,400 acres, like we have at Jenner Headlands.”
Cattle aren’t the only reason the preserve has such a large grassland patch, but the grazers’ light presence does support grasses’ and herbaceous plants’ success. Here, grazing is modified and applied for conservation goals.
Similarly, in the forest ecosystem at Jenner Headlands, logging is used to support recovery of coastal redwoods. Mixed forests occupy more than half the preserve’s area, or about 3,100 acres. Towering ridgelines that capture summer fog drip support redwood groves, though big ancestral trees are extremely scarce. One huge, lone survivor almost surely escaped the logger’s whipsaw because of its deformity and scar, perhaps caused by lightning. Descendants of such ancient redwoods now grow in clumps of second- and third-growth trees: 5 -10 maturing individuals can sprout near their parents’ cut bases. Because they compete for root space and sunlight, the growth of all is slowed. Removing the smaller trees in each set over the years can free resources for the remaining larger ones to grow more rapidly.
In the grove destined for restorative timber harvest, swashes of spray paint mark the trunks of many trees. Black paint covers up older blue marks that meant “Cut this,” placed by a timber consortium that previously owned this land. “They were planning on taking the big trees, but we are planning on leaving those,” Edwards says. Now blue paint marks smaller redwoods to be cut. Assessing the results will guide decisions on whether to repeat the process every 20 to 25 years over the course of 150 years.
When it comes to this way of stewarding biodiversity, Brook Edwards and Jenner Headlands Preserve are the definition of visionary. Standing in the forest, gazing upward as if into the future, Edwards says, “Way up in the canopy of mature redwoods, there can be whole new trees growing upward from a break high in the main trunk, special ferns and lichens growing, and even little ponds that support aquatic life—a unique ecosystem that most of us never see.”
He can see it, though. “Just imagine this place in a thousand years,” Edwards says.