Mixing with the Birds on the Olema Trail, Point Reyes

by on March 05, 2012

 

Originating in Dogtown, the Olema Valley Trail parallels a sag pond marsh along the San Andreas fault (see the previous "Rift Zone Trail" posting) that drains into Pine Gulch Creek and flows into Bolinas Lagoon. The dense stand of cattails (Typha) indicates standing fresh water with soil saturated year-round. Notice the cotton-like seeds fluffing from the flower spikes--perfect lining for the nests of hummingbirds, yellowthroats, and marsh wrens, species that are already building nests in this habitat.

Photograph by Jules Evens.

 

 

Olema Valley Trail (0.5 mi); Teixeira Trail to Ridge Trail (1.9 mi) and return with a side trip to Pablo Point (1.0 mi). Round Trip = 6.8 miles.

Conditions: Clear, cold, and very windy at the onset.

Google doesn’t seem to know from these trails, but you can see them on the alternative Open Street Map. Check out other hikes Jules has taken on this Google map.

Where the Olema Valley Trail intersects the Teixeira Trail, it crosses the marshy plain and one must ford Pine Gulch Creek before heading upslope (see cautionary trail notes, below). On the Teixeira Trail, as I climb the switchbacks that lead from the valley to the ridge, the morning wind whips through the forest fiercely, loud thrashing of foliage and creaking fir branches dominate the soundscape. Add to this the background noise of a heart pounding from the strenuous climb and the likelihood of hearing birdcalls or chipmunk chatter is almost nil. So, the hike up the hill becomes just an exercise in exercise.

At the ridge top, the trail forks, and I go left to Pablo Point, a one-way spur I haven’t taken since the 1970s. After a brief incline, the trail begins a gentle descent, providing a welcome respite from the relentless wind. Relying on my memory, I expect to arrive at an open knoll with a broad view of the lower reaches of Pine Gulch Creek, Bolinas Lagoon, and the Pacific beyond. The forest here must have been heavily logged in the 1960s because the trees are mostly second growth–rather small, crowded, of uniform age. Small stands of manazanita, now dead and lichen covered, attest to an earlier time when this southern knob of Inverness Ridge was more exposed to the sun. In a dark, dense copse near the end of the spur, large numbers of small pellets–dark bundles of hair and bone–are scattered along the trail. I collect a dozen or so for later inspection. Their small size and shape look like the castings of White-tailed Kites, a bird of prey that sometimes roosts in flocks. I suspect that’s what they are, but will examine them further when I return home.

The narrow footpath almost disappears amidst the dense firs. Although walking solo, inside my head my wife’s voice asks, “Are you sure you know where you’re going?” “Of course,” I answer, though I’m beginning to wonder if I’m lost, of course. The trail has all but disappeared when I find a sign for “Pablo Point” with the enigmatic designation “900 feet.” Does that mean ahead or elevation? Just beyond the sign is the grassy knoll I remember from 30 plus years ago, but the expected panorama is entirely obscured by Douglas firs that now stand at 30 or 40 feet. (“Just the right height,” as Mitt Romney would say.) So, the landscaped has changed over the decades, fir forest encroaching onto grassland, the natural succession of land left alone for half a century following a history of fire, grazing, and logging.

Fremont star lily

Star lily (Zigadene fremontii), also called “deathcamas” because of its poisonous properties. “The Fremont zigadene is one of the earliest plants to bloom in the spring, and its creamy-white, star-like flowers are always beautiful whether they are found on an open summit or in a brushy draw” (Marin Flora). This showy flower, on a stalk a foot or more tall, is often abundant after a fire in shrublands or chaparral. Like many other western plants and places, this zigadene is named after John Fremont (1813-1890), mapmaker and surveyor, who collected plants on several exploratory trips through the western states. Later in life he became a California senator and then the Republican candidate for president, losing to Democrat James Buchanan. Photograph by Jules Evens.

After lunch, I retrace my steps to the Teixiera Trail and continue on to its junction with the Ridge Trail (0.7 miles). I try to avoid backtracking when hiking, but out of the necessity of so doing this morning I realize that the return journey may reveal things missed the first time through . . . like a blooming star lily I must have walked right past on the way out to the point. Although growing amidst the forest, this must be a relict from several decades ago when this was a grassy knoll.

The wind has mostly died and sounds of the forest creatures have come alive.

In dense fir forest like this in winter, many of the smaller birds occur in mixed species flocks, foraging together through the foliage, seeking out miniscule spider eggs, leaf hoppers, and insect larvae. Chickadees seem to be the leaders of the pack, or at least the most vocal members, but they are often joined by other leaf- and bark-gleaners–Townsend’s warblers, brown creepers, red-breasted nuthatches, ruby-crowned and golden-crowned kinglets. I spend a good half-hour standing still, just watching and listening, enthralled by this mixed species flock. The vocalizations of some of these cohorts are very similar in quality, but different enough that each species is readily distinguishable to the practiced ear.

Golden-crowned kinglet

Golden-crowned kinglet, male. Although seldom seen at eye-level, the distinctive vocalizations fall out of the loftiest branches of firs. As Leon Dawson, author of the Birds of California (1923), says “it is really surprising how very few people know this amiable monarch. To one who seeks the honor of his acquaintance, he proves a most delightful friend . . .” Photograph by Ian Tait.

Most similar in tone and frequency are the “location calls” of golden-crowned kinglet, brown creeper, and chestnut-backed chickadee. These whisper songs are so sibilant, high pitched (between 4500 and 8000Hz), to be barely audible to the human ear.

Listen to the similar qualities of these vocalizations:

Golden crowned Kinglet
Brown Creeper
Chestnut-backed Chickadee

The nature of these sounds must aid communication between individuals and species through complex foliage across extensive forest tracts. The survival of the members of these mixed flocks depends on foraging success. These are all small birds, weighing only about as much as a buffalo nickel (5 grams) and with high metabolisms, so finding food in winter months is a full time job, a challenge that requires a group effort among individuals and among species–coopertation. (Kinglets, in particular, range into high altitude and high latitude habitats where winter weather is extreme. A former professor of mine, Bernard Heinrich, has explored the adaptations for survival in “Winter World: the Ingenuity of Winter Survival.”) The vocalizations of this suite of birds–all insectivores foraging in the forest canopy–differ from the complex melodies of those birds who inhabit the dense tangles of the understory–Swainson’s Thrush, Winter Wren–but more on that in the spring when those species are in full-throated song.

Milkmaids

Milkmaids (Cardamine) are the most common blooming flower along this and many other trails early in the season. Here, a flower is being nectared by a margined white butterfly, a species that has been fairly common on my last several outings. Note also the syrphid fly hovering off to the left; I had not noticed this when taking the photograph. Photograph by Jules Evens.

 

Farther down the trail, in the lowlands nearly back to Pine Gulch Creek, live-oaks replace the firs and I run into another mixed flock of foraging birds. Again, chickadees are the most vocal, but there are no kinglets, creepers, or nuthatches mixed in. Because the habitat here has transitioned from fir to live-oak forest, the composition of the foraging flock has changed–a different cast up to the same game of survival through cooperation. A pair of downy woodpeckers calls back-and-forth, a vociferous Hutton’s vireo scolds me, and several brilliant black-and-yellow Townsend’s warblers flit through the lichen draped branches. Then I notice a dazzling, daffodil-colored hermit warbler moving with the flock, a relative rarity here; the sighting provides me with the jolt of adrenaline sorely needed after a long slog.

Pine Gulch Creek

The undercut bank of Pine Gulch Creek is potential habitat of the federally endangered California Freshwater Shrimp (Syncaris pacifica), tiny (1.2-1.5 inch) crustacean endemic only to Marin, Sonoma and Napa counties, known only from a half dozen perennial streams, including Olema Creek. Although no records exist for Pine Gulch Creek, this is a highly cryptic species and it may occur here as well. Photo by Jules Evens. Inset: Public domain photo by U.S. Fish and Wildlife Service. Learn more about the shrimp (PDF).

 

Returning home after another invigorating hike, I pull apart those hairball pellets found on the Pablo Point trail. They are too small for most raptors, except perhaps white-tailed kite, American kestrel or one of the smaller owls–saw-whet owl or western screech-owl. Given the forested habitat and the abundance of pellets, kestrel is not likely, but kites tend to roost in communally, so this seems a likely candidate. The pellets are made entirely of hair, bone and teeth. One would expect the castings of small owls to contain some insect remains– scales or elytra (hardened outer wings)–but no such contents are in these pellets. There are no easily identified skulls, only small fragments of teeth and bone, apparently all of the same species. The pattern on the molars eliminates shrew mole or bats, which leaves only small rodents. Later that evening I meet my friend and colleague, Seth Bunnell, for happy hour at Nick’s Cove in Marshall and pull out an envelope of tiny rodent molars. Over Lagunitas IPAs, we examine the teeth under a hand lens and agree that the patterns–series of wwws– match those of the California meadow vole (Microtus californicus), the exclusive prey item of the white-tailed kite . . . another mystery solved.

Every outing provides some found treasure; this hike offers up an unexpected star lily, the whisper songs of kinglets, a dazzling warbler, and a pocket full of dead rodent remains.

Kite pellets

Regurgitated white-tailed kite pellets found in abundance along the Pablo Point trail. Kites forage in open country, but retreat to convenient communal roosting sites in the evening. Photo by Jules Evens.

 

Acknowledgements: Thanks to Seth Bunnell, Ken Davenport, Paul Opler, and Bob Stewart help identifying insects.

Trail notes

Olema Valley Trail (from The Point Reyes National Seashore website)

During the winter and spring, the Olema Valley Trail is often flooded and very muddy in a number of locations and hikers on this trail in the winter and spring may wish to wear or bring along knee-high waterproof boots. There is a ford just south of the Teixeira trail junction at which the water is frequently knee-deep and opaque with silt, the current strong, and the bottom uneven and covered with unstable, loose stones. This section of Olema Valley Trail is subject to seasonal (winter/spring) flooding.

Pablo Point Trail sign

Pablo Point Trail sign. 900 feet above the confluence of McCormick and Pine Gulch creeks. Photo by Jules Evens.

Teixeira Trail

The Teixeira Trail crosses Pine Gulch Creek immediately after leaving the marshy area described above. If the level is not too high, as this winter, one can skip across the stones in the river bed without getting too wet. From there on, the trail is well maintained though fairly steep (moderately strenuous), as it climbs the eastern slope of Inverness Ridge.

Pablo Point Trail

A narrow footpath, not well traveled or well maintained, that is easy to lose in sections. If you head south and take the least vegetated route, you will eventually find the Pabl Point Sign.

Wildlife Sightings

BUTTERFLIES
Margined White
Satyr Comma
Unid’d skipper

BIRDS
Allen’s Hummingbird
Anna’s Hummingbird
Band-tailed Pigeon
Bewick’s Wren
Black Phoebe
Brown Creeper
Bushtit
Chestnut-backed Chickadee
Common Raven
Common Yellowthroat
Dark-eyed Junco
Downy Woodpecker
Fox Sparrow
Golden-crowned Kinglet
Golden-crowned Sparrow
Hairy Woodpecker
Hermit Thrush
Hermit Warbler
Hutton’s Vireo
Lincoln’s Sparrow
Marsh Wren
Northern Flicker
Pacific Wren
Pileated Woodpecker
Pine Siskin
Pygmy Nuthatch
Red-breasted Nuthatch
Red-shouldered Hawk
Red-tailed Hawk
Red-winged Blackbird
Ruby-crowned Kinglet
Song Sparrow
Spotted Towhee
Steller’s Jay
Townsend’s Warbler
Turkey Vulture
Varied Thrush
Western Scrub-Jay
Wrentit

MAMMALS
Black-tailed Deer
Bobcat (scat)
California vole (in kite pellets)
Coyote (scat & tracks)
Gray Fox (scat)
Horse (scat)
Human being (2 on mountain bikes)
Raccoon (tracks)
Striped skunk (tracks)

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2 comments:

magwhls on April 4th, 2012 at 12:00 am

I have a question about this wonderful article, and enjoy reading new writing from Jules. His book about Pt. Reyes is one of my favorites! Anyway, I had thought, and this has been borne our by my experience as a WildCare & Hungry Owl Project volunteer cleaning hawk pellets out of cages…that only the owls have bones and teeth in their pellets. Hawk pellets have only fur in them. Not sure where Kites fit into that because I’ve never cleaned up Kite pellets! Do Kites have similar digestion as owls and thus do not process the bones and teeth? Owls don’t have crops to predigest food, so I imagine that is one part of the reason why their pellets contain bones, teeth and insect exoskeletons. I’ve always been fascinated by the fact that hawks do digest the bones and owls don’t – why? How do owls get their calcium? I’ve never found a definitive answer to these questions. I’ve decided that owls MUST be removing some calcium from the bones before ejecting the pellet, and that it borne up by the fact that misguided people who find baby owls and feed them hamburger, or other inappropriate foods, end up causing them to have metabolic bone disease if they don’t turn them over to a wildlife hospital in time. Thanks for any insights that can be provided!

Jules on April 5th, 2012 at 12:00 am

Intriguing question, Magwhls! Kite pellets do contain bone fragments, especially mandibles and teeth, but also vertebrae and occasionally skull fragments. According to my friend Hans Peeters (Owls of California and the West, U.C. Press. California Natural History Guide #93), kites are unique among the hawks in this regard. However, I believe I’ve found the exoskeletons of insects in pellets of the American Kestrel. Regarding the calcium question: Calcium is one of the most common minerals in the bodies of vertebrates (and invertebrates?)—nerve cells, tissue, blood all contain calcium—so I doubt that owls run a calcium deficit. That said, an article in the American Naturalist (vol. 144, No. 6, Dec. 1994) speculates that calcium is a limiting factor in reproduction of flying vertebrates, especially bats.

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