Fri, 16 May 2008, 1:45pm, Tinman said:
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The eastern flank of Mt Davidson reveals a glimpse of what all of San Francisco’s hills once looked like, back when Mt D was known as “Blue Mountain” because of its prolific grassland wildflowers each spring. Thanks to Leland Stanford’s decision not to plant his part of the hill with eucalyptus, Monterey cypress and Monterey pine the way his neighbor Adolph Sutro did, we can explore this remnant of Mt D’s complex grassland and scrub communities.

What we see today has been significantly altered, however—just not as profoundly as Sutro’s tree farm next door. For one thing, there is considerably more scrub now than when grazing cows kept the coyote bush, huckleberry, and poison oak nibbled down. More importantly, Mt D’s grasslands now are inundated by introduced weedy annual European grasses that have nearly choked out our indigenous species.

The most robust of the native grass populations on Mt D are the large stands of Pacific reed grass (Calamagrostis nutkaensis) and California fescue (Festuca californica). Both are now flowering spectacularly along the northwest margin of the grasslands, with the California fescue particularly noticeable paired with the reddish-leaved huckleberry all along the northern flank of the grasslands. This part of Mt D is the best preserved location on the hill, and in fact is one of the most pristine of the Significant Natural Resource Areas anywhere in San Francisco.

Calamagrostis nutkaensis

Festuca californica

The eastern and southern portions of Mt D’s grasslands are significantly more challenged. Small pockets of our official state grasspurple needle grass (Nasella pulchra), red fescue (Festuca rubra), blue wild rye (Elymus glaucus), June grass (Koeleria macrantha), onion grass (Melica californica and M. torreyana), California oatgrass (Danthonia califonica) and bluegrass (Poa secunda) are apparent to the discerning eye.

Much more obvious, though, are the dense swaths of weed grasses: ripgut brome (Bromus diandrus), Italian ryegrass (Lolium multiflorum), rattlesnake grass (Briza major), rattail fescue (Vulpia myuros), and wild oat (Avena barbata). These annual weeds grow extremely rapidly, dump tons of seed, and then die. Unlike the native bunch grasses that put down roots 6-10 feet into the soil and live for decades to hundreds of years, these annual weeds provide no slope stabilization nor sustenance for the local food chain.

Unfortunately, measures that control these annual weedy grasses — periodic fire and grazing — are not possible on Mt D. Native grasslands evolved with and require both for optimal health, and Mt D demonstrates what happens when human intervention interrupts these natural forces: weeds predominate. The closest approximation possible is strategically-timed mowing right when the weed grasses have flowered but before they set seed — but this is not an option since the Natural Areas Program division of the Rec&Park Department is so poorly staffed and funded that they simply cannot perform this crucial task.

Nevertheless, when you next walk through Mt D’s grasslands, take time to locate the patches of native bunch grasses and note how many more insects and birds you see where the indigenous communities are relatively intact compared to where there is merely a weedy lawn. And then write Supervisor Elsbernd, the Mayor, the Rec&Park Dept General Manager, and the Rec&Park Commission and demand that the Natural Areas Program get the funding it needs to preserve Mt D’s grasslands, our most-threatened biological communities in the City.

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Fri, 16 May 2008, 7:17am, Tinman said:
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From one of the most adroit of the Mt D birders:

There will undoubtedly be more reports, as there were a throng of birders up on Mt. D. this morning when I left and folks mentioned some different species. Brian F. and Andy K. were there from sunrise on, followed by Josiah C. and me, David A., and 4 or 5 other folks.

Warm morning, variable wind gusts from the NE/E/SE. Migrants were moving through in small flocks (esp. Cedar Waxwings, warblers, W. Tanagers, Lazuli Buntings), many not setting down on the hill at all, but instead flying from low level to tree top level over the hill.

Species I observed with others between 6:50-8:40 AM included (conservative estimates of individuals):

• Band-tailed Pigeon 6
• Hairy Woodpecker 1
• W. Kingbird 3 fly-overs
• Olive-sided Flycatcher 1
• W. Wood-Pewee 2-3
• Pac.-slope Flycatcher 3+
• HAMMOND’S FLYCATCHER 2 (lower Ravine)
• DUSKY FLYCATCHER 2 (Ravine, East Bramble)
• GRAY FLYCATCHER 1 (East Bramble)
• Cassin’s Vireo 1 (lower Ravine)
• Warbling Vireo 10+
• Swainson’s Thrush 3
• Warblers:
  • Orange-crowned 2
  • Yellow 5+
  • Townsend’s 20+
  • Hermit 1
  • Wilson’s 20+
• W. Tanager 20+
• Bl.-headed Grosbeak 2
• Lazuli Bunting 20+
• Pine Siskin 1
• Purple Finch 1

Dragonflies: California & Blue-eyed Darners

Butterflies: W. Tiger Swallowtails

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