Park Week 6/16/23

Summer Solstice Wednesday

Next Wednesday is the saddest day in the Northern Hemisphere’s solar calendar. The Summer Solstice marks the end of the happy period when days let longer, and the start of the backslide, with daylight gradually slipping away until we’re in the dark at rush hour.

Nevertheless, we gather to celebrate. Meet on Wednesday June 21 at 7:15 at the Chavez/Huerta Solar Calendar in the park. Map. The gathering will be led by Vivian White of the Astronomical Society of the Pacific (photo left) and Tory Brady of the Exploratorium. The sun will set at 8:30.

First Osprey Video

Osprey (Pandion haliaetus)

You never know what you’re going to see in Chavez Park. Three or four gulls were making a squawk off the north side, and I was ready to ignore them. But one of the birds definitely did not belong in that crowd. It was bigger, flew more slowly, and, well, it was a completely different bird. I was very lucky: it hung around long enough for me to set up my camera and catch a few seconds of video.

The Osprey is a fish specialist. More than 99 percent of its diet is fish. Many smaller bird species nest in cavities in the Osprey’s big nest, knowing that Ospreys don’t eat birds. The Osprey’s eyes are specially adapted for seeing fish in the water and compensating for refraction. It will dive after a fish, talons first, and may submerge completely, catching fish a meter below the surface. It has specially oily feathers that shed water as soon as it resurfaces. Contrast that with a Brown Pelican’s plunge dive: the pelican dives beak first, and never submerges completely. But the pelican’s feet are made for paddling, not grasping. The Osprey has unique talons. One talon is reversible so that it can grab and hold a fish on both sides. Once clasped, a fish is history.

After a grave population drop due to DDT and shooting, Ospreys have recovered and there is now a growing population of Ospreys nesting in the San Francisco Bay Area. They readily use manufactured structures like cranes, utility poles, and purpose-built nesting platforms. Most Osprey that nest in North America migrate to the tropics in winter. Many of them return to the same nesting sites and the same wintering spots each year. That’s remarkable because the sites may be thousands of miles apart, and the birds fly different routes going north and south. During nesting, pairs are tight and cooperate closely, with males feeding the female and the chicks. That done, the sexes migrate separately from each other and from their offspring. They generally migrate over land by day, but long stretches over water always by night. Young birds that have never migrated before are capable of navigating accurately across water by night to wintering spots they have never seen before, compensating for crosswinds and bad weather. It is believed that they almost certainly use the earth’s magnetic field as a navigational aid.

We already have two excellent Osprey images here, one by Shiyang Wu and earlier by John Davis. This one is the first Osprey I’ve photographed up close in the park (not counting this one), and the first Osprey video on this site. This Osprey went empty-taloned while I watched it. It took off due west.

Scoter Flock

The solo male Surf Scoter that visited here a few weeks ago must have liked it and spread the word. This week we had a flock of about 16 scoters of both sexes, mixed in with a few scaup, most of them snoozing at 10 in the morning near the Open Circle Viewpoint. Also nearby, not shown, a quartet of female Bufflehead, and a handful of mixed big grebes, Clark’s and Western.

Dry Birds of Note

As if to signal approval of our work to clear the lower passage in the Native Plant Area (see “Third Passage” below), this pair of California Towhees landed on a bush not ten feet from my camera in that path and hopped around to make sure I got their best angles. California Towhees are a bit larger than other sparrows. They mostly forage on the ground but build their nests in trees and bushes. At least one pair almost certainly lives and breeds in the Native Plant Area. Males and females wear the same feathers but males are a bit bigger. They eat a lot of weed seeds, including barley (“foxtails”). When they have young, they hunt insects to give their chicks protein.

The House Finches are probably the most numerous birds in the park at this season. You can hear their twittering north, west, and south. The House Finches are almost exclusively vegetarian, and are able to raise their chicks on a vegetarian diet. I expect to see newly fledged finches forming sizeable flocks in a few weeks if not sooner.

We had a flock of European Starlings in the park in 2022 and earlier, breeding and raising young here (“Starlings Do It” Jun 9 2019). They usually travel in flocks. This week I saw just one, a solo exploring the wooden shield around one of the porta-potties that the City shamelessly offers to visitors from all over the world. Starlings have few friends on account of their aggressive takeover of other birds’ nesting territories. They are most admired when they appear in the distance in huge numbers forming patterns in the sky called murmurations. This one bird could be a stray, or it could be a scout. We’ll see.

The traditional Red-winged Blackbird breeding area in the fennel forest on the northwest quadrant has been almost dead silent, apart from the odd Song Sparrow and House Finch. But there is red-wing activity on the northwest hilltop where the Peace Symbol sits, and also further south on the western ridge. There are almost certainly some nests in those areas. Proof: Crows have been diving and lurking there, looking to steal eggs and new hatchlings, and the male blackbirds have mounted ferocious aerial attacks to drive them away. I saw one such combat where the crow, with the blackbird hot on its tail, croaked cries of anguish. The blackbirds are smaller but they’re very passionate and fearless, and their beaks are super sharp.

Very active now in the park — so active that it’s almost impossible to photograph them — are the Barn Swallows. They thrive despite an energy-costly foraging strategy: swooping at high speed close to the ground, catching flying insects in the air. They’ve been clocked at more than 35 mph and can change direction on a dime. They build nests out of mud on buildings and other structures, but their nest location in or around the park continues to elude me.

In winter they’ll migrate to Central and South America. They can average 270 miles a day over a month-long migration flight covering 7,500 miles.

New Arrivals

Now that the Northern Mockingbird is here, the theory that birdsong is therapy for mental health will be put to a severe test. Not that this bird doesn’t sign pretty. It sings beautifully. The problem is getting it to stop. How much therapy can a human brain absorb? Well, this individual probably just arrived and hasn’t unpacked yet. I saw it flitting from the Nature Area into the seasonal Burrowing Owl Sanctuary, where it perched for a few minutes — silently — atop a Coyote Bush. You can sample its repertory in past years here and here. If and when it settles in and starts performing I hope to capture more of it.

The White-crowned Sparrow is a regular visitor to the park. They’ve appeared in 36 posts on this site. There is a subspecies, the nuttalli, that is known to breed and reside in the San Francisco Bay Area, but their residence in the park remains to be established. This may be one of the Bay Area residents. Or it may be a long-distance migrant taking a short break on its way to northern Alaska where they nest in large numbers in the fleeting summer season. It’s a pity one can’t have a little chat with them to find out their plans.

Savannah Survivors

What does a bird do after mowing machines have destroyed its nest and everything in it? In some locations, Savannah Sparrows will build a second nest and lay a second clutch of eggs. Whether that will happen in our park is the big question. The parent birds seem to have survived the mower. You can hear their high-pitched trilling, and I’ve been able to photograph a few of them, probably males, judging by their song (females may give short calls but don’t sing). But whether the females are still present and whether the habitat is at all acceptable to them for nest building is doubtful. Luckily, the mower was messy, leaving a number of streaks where a thin remnant of the original vegetation still stands. Will this be enough?

Third Passage

Bob Huttar clearing the passage

The difference between a jungle and a park is passage. When the Native Plant Area was built in the early eighties, it featured three passages that traversed it from south to north: an upper, middle, and lower.

Decades of deferred maintenance followed. The middle passage narrowed, and the lower passage closed up. Vegetation on both sides created an impenetrable thicket, a local jungle that attracted illicit overnight campers, collected garbage, and scared off daytime visitors. Aerial maps documented the disappearance of the lower passage over time, turning the western third of the area into a closed block. See the “Native Plant Area” page.

Then, in response to Chavez Park Conservancy’s insistent urging, the Park sent a contractor crew into the area in November 2020. One of its achievements was reopening the lower passage. The jungle became a park again. Teachers and parents felt safe enough to bring their kids here.

But then came this past winter’s long rains, and the amazing growth of just about everything afterward. Tall, dense stands of Wild Mustard and thistles and spreading branches of Lemonadeberry and Saltbush closed the lower passage off again. You could not even see that a path had once existed there.

On Saturday June 10, I joined Chavez Park Conservancy Volunteer Coordinator Bob Huttar on a mission to open that passage up again. With the help of a battery-powered hedge trimmer and a manual lopper, in about an hour and a half we restored the passage. It’s not a broad trail, and it isn’t meant to be, but it’s a path that you can see and walk through without a machete. Mission accomplished, for now.

How Tall the Grasses

Young Monterey Cypress in Native Plant Area

This young Monterey Cypress tree could play basketball. It’s 6 foot 8. But the grasses around it overtower it. They could be eight feet tall. Luckily, the tree has friends. Chavez Park Conservancy volunteers have cleared space around it, laid down mulch around its foot, and provided it with regular drinks of five gallons of water. (Bob Huttar watered all of them last Saturday after clearing the lower passage, see item above). Thanks to all this help and protection, the young tree is thriving. It’s a solid saturated green without any dry or brown branches. It has a great start and, with continuing care, will provide shade for park visitors and habitat for wildlife for decades. Chavez Park Conservancy volunteers planted two dozen similar trees (Monterey Cypress, Torrey Pine, California Live Oak, California Buckeye) in the Native Plant Area. The City provided most of the starters, but our volunteer labor keeps them alive. After the next rainy season they’ll be more or less established and need less care, like children that grew up.

I’ve read about the historic tallgrass prairie in the US Midwest, where the grasses rose so high that a human needed to get on horseback to see over them. I didn’t really believe it until this year. Several of these grasses are stunningly beautiful. Waving in the wind against the sky they seem like the beating pulse of the earth. Their flowery tops, some of them, look like upside down chandeliers. Others seem like tiny balloons. Great meadows of them provide the human soul with the balm of being immersed in nature.

It is a misguided sensibility that massacres them and substitutes a militaristic wasteland in their place. Granted, in some areas human activity must prevail, such as for flying kites, unleashing dogs, or having picnics. But there are dozens of acres in the park where nature should prevail. Where grasses should prevail. Because grasses are habitat for wildlife and balm for the human soul.

Short On Gas

Attentive visitors crossing from the perimeter trail on the east side to the Off Leash Dog Area may have noticed a run of heavy black plastic pipe on the surface. The same may be found elsewhere as well. Informed sources say these are jumper pipes replacing the original buried plastic pipes that carry landfill gases from the buried extraction wells to the Flare Station. The original buried pipes, it seems, are partially or wholly blocked by moisture from the recent heavy rains. As a result, the Flare Station is not getting enough gas for full-blast operation and has been running intermittently part of the time. The buried garbage is very old and there is little gas left to pull out. Field technicians from SCS Engineering, the firm that has the contract to maintain the gas extraction system, face a challenge tuning the valves on the wells to extract what gas is left. There are plans to lay additional surface pipe in the coming weeks.

Although the jumper pipes aren’t pretty, they block the mowing machines and keep the natural grasses and weeds alive in their vicinity. That may be a boon for ground-nesting birds such as the Savannah Sparrows. But it’s an open question whether these strips of surviving vegetation are enough for nest building and egg laying.

Black plastic pipe on surface to carry landfill gases to Flare Station

Squirrel of the Week

What happened to its ear?

It’s a rough neighborhood sometimes out on the rocks on the west shore of the park. The Red-tailed Hawk, when it’s here, can take off much more than an ear. It’s the only raptor that’s been photographed taking a Ground Squirrel here. Barn Owls can do it theoretically, but they haven’t been around much, and if they’ve taken a squirrel, there’s been no sign of it. The other local raptors, such as the White-tailed Kite, look for smaller prey, such as voles.

Then there’s the canines. A dog on leash is no danger. But some owners let them off leash, or let the dogs run loose with leash attached, such as the pair in the photo at the right. When dogs are loose, they can turn from family pets into wilderness predators. This pair tried to dig into a squirrel burrow next to the rocks. A bit later, one of them scrambled on the rocks sniffing for prey. They’re sure-footed and quick, and they have big teeth.

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