Fort Funston Bank Swallows June 24, 2012
Posted by Dan Murphy in Birding, Conservation
Photo by Dan MurphyBy Dan Murphy
A unique San Francisco treasure is the Bank Swallow colony at Fort Funston. And just as unique is its current nesting site — a band of rip-rap placed there illegally (oops!) by the San Francisco Department of Public Works.
Let’s start with the basics. This year there are at least 110 nest burrows between the rock revetment (rip-rap) placed on the beach by the Department of Public Works and the crumbling roadbed above. If you want cute and super hyperactivity, you’ve got to love Bank Swallows. These brown and white swallows with the distinctive black breast band are our smallest members of the swallow clan and among the longest-range migrants.
On my most recent visit in mid-June, there were at least a half-dozen swallow families of four to six birds swarming around the colony. The young had probably fledged in the early morning and were bidding farewell to the colony before heading all the way to Ecuador or Columbia for the rest of the year.
Can you believe our tiniest swallow migrates all that way? The first birds arrive on April 1 — yes, it’s predictable — and the last depart by August 1. Mid-May to mid-June sees the height of activity at the colony. It’s just non-stop activity. There must have been insects on the beach because there were often a dozen or more adult birds pecking away there. They use the beach to get bits of wrack for nesting material early in the season, but this is the first time in over 30 years of observations I’ve seen them apparently feeding on the sand. The fun never ends with these guys.
Two juvenile Bank Swallows in their burrow at Fort Funston / Photo by Dan Murphy
Bank Swallows have been recorded at Lake Merced since at least the early 1900s. There was also a colony near Skyline and Sloat that was destroyed when Skyline Blvd. was built. We don’t have records of when they started nesting at Fort Funston, but it’s safe to say they’ve been there since the 1960s. In better times they used the bluffs at Fort Funston between their north end and Panama Point, the point you can see to the south from the parking lot.
About four or five years ago, the compacted sand that forms the cliffs at Fort Funston started to slump into loose dune-like sand instead of the old sand cliffs that made for good swallow burrows. It was then Ravens finally discovered how to access all that juicy protein. Three years ago I was surprised to see huge, oblong excavations at over a dozen Bank Swallow burrows, a clear sign the Ravens had dug out the nests.
That was the end of any effort to nest in the natural bluffs. It could easily have been the end of this swallow colony.
But wait — they were saved by the Department of Public Works.
Can you believe an illegal rock revetment — rip-rap to most of us — would save the day? Well, it did. Public Works did an excellent job of installing huge rocks at the base of the cliffs to curtail erosion. Too bad they didn’t go to the state Coastal Commission for a permit!
You know how it’s supposed to be easier to ask forgiveness instead of permission? Not this time. The City was ordered to remove the rocks, eventually. Meanwhile, the swallows discovered a substitute for the natural cliffs — a compacted 20-foot-high sand cliff that appeared between the rip-rap and the road bed. Protected from above and below by a hardscape, the sheer cliff was ideal for Bank Swallows. The colony is about one third smaller than in the past, but it’s there. They love it.
The swallows have built burrows in the sand cliff sheltered between this rip-rap and the road above / Photo by Dan Murphy
Now the problem is what to do. We’re not talking about an endangered species here. Bank Swallows — known as Sand Martins elsewhere in the English-speaking world — are numerous around the northern hemisphere. The only thing unique about our colony is that it’s the only one in San Francisco, and one of just four remaining on the entire California coast.
In the Central Valley, a significant restoration program is removing rip-rap from rivers in an effort to restore nesting habitat. But here in San Francisco, it looks like the rip-rap is the only thing saving this incredible colony from extirpation.
So there’s our problem. What can we do to save the Bank Swallows? Okay, a t-shirt would be really cool and I’d be the first in line to buy one. But really, what should we do? What can we do? We’ve made all the stakeholding agencies aware of the problem. Now you know about it. What would you do? Should we let nature take its course and say good-bye to the colony?
There’s lots of time to think about answers, so this is a rare environmental problem for which we have time to think and plan.
One note: If you visit, be sure to do so at a very low tide because access is difficult from the parking lots to the north. If you don’t mind wading through the dogs at Fort Funston, access may be easier from the south. I mind, so I haven’t tried that route.
Tags: Bank Swallows, Fort Funston, San Francisco birding.
Maybe DPW, as mitigation for their error, can erect a fake nesting wall, mimicking the preferred habitat, stabilize it near the cliff and make it of materials that will deflect the ravens (of which we have waaaaaaaay too many).
The bank swallows have been moving back and forth (north and south along the cliffs at Fort Funston since the mid 1990′s. (Certainly longer, but that’s as long as I have been watching them regularly.) The only real constant is that they select some new nesting area each year, while re-using some as well. They choose their locations for their own reasons; I doubt that anyone can say why a particular location is chosen in a particular year.
Constructing nesting areas, complete with bored burrows, has been tried along the Sacramento River. It didn’t work; the swallows chose their own areas for their own private reasons.
Here’s my idea. Leave the swallows alone. They clearly adapt to what nature has thrown at them and they clearly adapt to rock embankments. They are optimistic and clever (swallows, not the city) and they will endure. Ted.
Dan,
Thank you for this article. I have been out of town for a month, so it reminded me about the sightings. Gotta check the tide charts and then see for myself. Nice pics, too.