Monday, March 30, 2009

come to the park!

butterflies are migrating!

ps-they are painted ladies

Friday, March 6, 2009

fort funston

It's low tide time again this weekend. My love affair with low tides started when I was a tiny person and got to spend hours on the rocky beaches in Seattle, peering under rocks for all the amazingness that lurked underneath (thanks Mom!). To this day one of my favorite places in the entire world is on the beach at a low tide.

So one of the things that has always bummed me out about San Francisco was its lack of rocky shores for exploring. There are truly amazing beaches just north and south of the city but they are, sadly, rather difficult to reach by public transport. (I will say in San Francisco's defense that the only octopus that I have ever seen at a low tide anywhere was in the rock wall off Marina Green. That was great.)

The ocean was calling my name last month at low tide, so I headed out to Fort Funston by way of a long walk down Ocean Beach. And honestly, it was lovely. The sandstone cliffs are beautiful, composed of soft soft rocks from the Merced and Colma Formations. The Merced Formation makes up most of the cliff face and the Colma Formation is the thin sandy layer at the top. The Merced was deposited from about 2 or 3 million years ago to about half a million years ago and the Colma, about 125,000 to 55,000 years ago. In some sections of the cliff face you can see a thick, chalky substance-veins of volcanic ash thrown from Mount Lassen thousands of years ago!

At the base of the cliffs is this thick black sand. I thought this was the sad remnants of the Cosco Busan spill but it turns out that it's a kind of iron ore called magnetite. The magnetite is a part of the cliff walls, and as the sandstone erodes, it leaves the heavier iron-based magnetite on the beach.

So I was relieved that the black stuff wasn't oil. But oh man, was there a lot of other garbage at the high tide line. From a distance I thought this junk was was sad to get up close and realize it was all plastic and styrofoam.

Ah....but there were shells lower on the beach.

Western Sand Dollar
(Dendraster excentricus)

These lovely critters form dense beds in the low intertidal and subtidal zone in the sand just beyond the break zone of coastal areas. Their living body consists of a rigid test (a hard external covering) covered with movable spines, usually a pale gray-lavender to a dark purplish black. The lovely flower-like pattern on the aboral side of the body is composed of pore pairs whose specialized tube feet are used for gas exchange. At the center is the madreporite - a perforated structure that forms the intake for their water-vascular system-a system of water-filled canals that connect with tube feet, which the animal use for locomotion, feeding and breathing. It's fun to stare at the ocean and imagine all the life out there just underneath the surface.

Wednesday, March 4, 2009

San Bruno Mountain

You know how you can live near a restaurant and walk by it every day and then one day, after years of walking by, realize they serve the kind of food that you absolutely LOVE......and you go and it's great, leaving you wondering why on earth you never went there before?

Last weekend B and I went to San Bruno mountain. For the first time. Which is totally ridiculous because it's truly lovely there. We saw....

Moss and Lichen (loving the rain)

A huge ant colony. I read later that there are 27 native ant species on San Bruno Mountain. What kind of ants are these?

Fritillaria affinis (aka Mission Bells or Chocolate Lily)

My number one terrestrial mollusc!

Ariolimax columbianus (aka the mighty Banana Slug )

Sunday, March 1, 2009

up in the sky!

Where would you go if you wanted to see one of the fastest predators on earth?
Would you believe me if I told you that right now you have a good chance of finding one at Main and Beale in downtown San Francisco?

No, cheetahs aren't hanging in the Financial District, but a couple of Perigrine falcons (Falco peregrinus) are. How do you know if you're looking at a peregrine? They are crow-sized falcon, with a blue-gray back, barred white underparts, and a black head and "moustache". These birds can be found all over the world, hence the name, which means "wandering falcon" (a fancy word for wandering around on foot is "peregrination").

The Peregrine Falcon became an endangered species due to the use of pesticides, especially DDT. Since the ban on DDT in the 1970s, the many populations have recovered, supported protection of nesting places and releases to the wild. Interestingly, lots peregrines have settled in cities, with tall buildings that stand in for cliff faces and a plentiful supply of food (especially pigeons). They search for prey either from a high perch or from the air. Once prey is spotted, it begins its stoop, a dive in which they can reach speeds of 200 mph. Peregrines strike their prey with a clenched foot, which stuns or kills it, then turn to catch it mid-air. I saw a peregrine catch a pigeon on Mission and 3rd-it's a truly impressive display.

The fine folks at the Santa Cruz Predatory Bird Group have been instrumental in the recovery of peregrines in California. As part of their education and outreach they have installed cameras in San Francisco and San Jose to allow the public to peer into the lives of these amazing birds. There has been much drama with the San Francisco birds with the much loved Gracie and George abandoning downtown for the Bay Bridge and then vanishing altogether from the city. This year there are two new birds on the nest cam.-now is a great time to start watching. Peregrines mate for life and go through some really charming courting in the lead up to mating. Sadly (or luckily for my productivity) I can't stream video at work, but if you can, you should check it out.

If you want to see some truly remarkable images of these (and other) birds, check out the website of Glenn Nevill. Or, if you want to try to catch one in person, try some of the spots on this map.

Happy perigrinations!