01 March 2008 - 13:28, Tinman said:
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Our ten volunteers and two staff took on the ehrharta population on the Ledge today. Here they’re ambitiously attending to the cracks and crevices in the CPS stone wall along the Ledge’s plateau:

Ehrharta erecta is one of the most invasive grasses around. It originates in South Africa and was brought to the US as a potential turf grass. Unfortunately, it was released from a lab in Berkeley about 20 years ago, and since then it has run rampant throughout the Bay Area. It is a perennial grass that produces seed year ‘round—unlike native perennial bunch grasses that seed only once during the year. It also loves to grow close up to other plants, and frequently can be found right inside a clump of native bunch grass.

Here is a closeup of what we’re up against. In this case, the ehrharta grass is growing throughout a very nice patch of yarrow (Achillea millefolium). Left alone, the ehrhart will shortly smother the yarrow in a dense, high turf:

It requires meticulous work to remove the ehrharta while leaving the yarrow, but it can be done:

This isn’t a one-time step, though, as the ehrharta seed bank in all the soils of the Bay Area is such that new shoots will be back up in a couple of months. Still, triumphs such as what we accomplished today keep us coming back!

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12 February 2008 - 08:15, Tinman said:
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We mentioned previously the amazing bird habitat that was going to be impacted — but will not be if we stay on top of this — by the SFPUC pipeline retrofit. Here is a grand description of why we must preserve this part of Mt D: the most recent sightings report by one of the experienced birders who patrols Mt D regularly. This report was initially posted Sunday 2/10 to the sfbirds Yahoo group.

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The highlights were:

• Band-tailed Pigeon (single bird seen flying north)
• Orange-crowned Warbler (foraging in the iris and broom patch approx. fifty feet after the end of the trail fence, very plain gray with hint of brown to upperparts, celata?)

Other birds of local interest:

• Lesser Goldfinches (m,f)
• American Kestrel (molting male, missing several rectrices on right side of tail, observed capturing and eating a dragonfly)
• White-crowned Sparrows (at least four males singing on territory in the grassland area)
• Winter Wrens (several singing males heard from path before the X in trail)
• Song Sparrows (singing)
• Bushtits (pairing off?, only three or four seen with lots of chasing)
• Northern Mockingbirds (at least two, one of which was doing very realistic impressions of a gnatcatcher’s “mew” call and House Wren scolds)
• Hermit Thrushes (at least two heard)
• House Finch (singing)
• Dark-eyed Juncos (m,f)
• Pygmy Nuthatches (at least two “packs” heard high up in eucs)
• Chestnut-backed Chickadees (several heard only)
• Anna’s Hummingbirds (three males seen)

Also appearing:

• Western Scrub Jay
• Common Raven
• Mourning Dove
• Ruby-crowned Kinglet

Also observed was a hummingbird chase that may have been an Anna’s chasing a Selasphorus sp. but they disappeared before I could get on the smaller one. I also found it strange to not hear a single Yellow-rumped Warbler in the 20 minutes I was there (departing early?).

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