By Jack Dumbacher

By now, most of the birds that summer in the Bay Area have settled into their new territories and are well on their way to producing this year’s family of nestlings.  The warblers, orioles, tanagers, and vireos are singing and defending their territories – often the same territories where they nested last year or will nest next year.  Likewise, many of our winter migrants are long gone, and probably already settled in their summer homes.

These long-distance migratory movements have long fascinated ornithologists, with the primary question: How do the birds find their way?

Decades of research have shown that birds use a variety of information including visual landmarks such as coastlines, rivers, stars and sun-angle.  Even odors have been shown to be important for homing pigeons.  But one of the most peculiar and interesting of all migratory aids is magnetic orientation.

Birds appear to have a magnetic sense.

Range map of Dunlins, from The Sibley Guide to Birds of Western North America. The Dunlins that winter in the Bay Area (blue) migrate long distances to summer breeding sites (goldenrod) in Alaska.

Avian magnetic sense was first demonstrated in the 1960s by Friedrich Merkel, Wolfgang Wiltschko and colleagues in Germany using caged birds in altered magnetic fields.  Birds adjusted their orientation when the magnetic field was altered.  This was a stunning and unexpected result – so much so that many other researchers sought to test the effect using magnets strapped to the backs of birds, and even created bird backpacks that induced magnetic fields using coils of wire with electrical currents (called Helmholtz coils).

More and more researchers showed that birds respond to magnetic fields, often in predictable and useful ways.  It’s now clear that birds can use this sense to orient to the earth’s magnetic field during migration.

The earth’s magnetic field contains a great amount of geographic information.  For example, the direction of the field lines identifies the north-south azimuth, and the polarity of the magnetic field lines identifies which direction is north and which is south.  The inclination (whether the field is level, pointed down, or up) can provide information about latitude.  The strength of the magnetic field also provides information about latitude, as the field is stronger near the poles than at the equator.  Local variations in the field could even be used as local magnetic “landmarks” for navigation.

But these are weak and subtle forces – can birds really use all of this information?…

By Janet Byron

Northern Shovelers are common in the Bay Area in winter months. But breeding season is another matter – so it was exciting news when a female Northern Shoveler and babies were recently spotted in Alameda County.

Golden Gate Bird Alliance board member Bob Lewis photographed the Shoveler with two ducklings on May 20 at Coyote Hills Regional Park in Fremont.

“The recently issued Alameda County Breeding Bird Atlas states the only confirmed record for the county was Hayward Marsh,” Lewis noted. “Time has gone on, and there may be others now. These birds were on the north side of the large pond across from the last parking area at Coyote Hills.”

Another birder, Jerry Ting, reported seeing the female Northern Shoveler with seven babies at the same spot in Coyote Hills a week earlier. He guessed that a pair of Northern Harriers nesting nearby may have taken the other ducklings.

The Northern Shoveler is a spoon-billed dabbling duck that breeds in freshwater and brackish ponds. While they are abundant on San Francisco Bay in winter months, especially in Santa Clara County and the South Bay, few have historically remained to breed. The Northern Shoveler’s breeding grounds include Alaska, southeastern Canada and the United States from northeastern California to southern Minnesota.

The only confirmed record in Contra Costa County was at McNabney Marsh in 1995. One was confirmed breeding in Marin County at Las Gallinas sewer pond in 1985, and they are spotted breeding occasionally in Santa Clara County.

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On Thursday May 24, the San Francisco Planning Commission and Recreation and Parks Commission are scheduled to vote on plans to install artificial turf and powerful night lighting on the Beach Chalet soccer fields in western Golden Gate Park. Golden Gate Bird Alliance plans to be there and speak out in opposition. We asked Conservation Director Mike Lynes — who has spent hundreds of hours following this issue since 2009 — to explain why we are so concerned over the future of land that is “just a few soccer fields in a city park.”

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The Beach Chalet Athletic Fields renovation project is one of the most difficult projects that Golden Gate Bird Alliance has grappled with in recent years.  The renovation project would replace up to 11 acres of natural grass and trees in the western end of Golden Gate Park with artificial turf and ten 60-foot light towers that will broadcast 150,000 watts of light into the historically dark part of the park.

Aside from concerns about the toxic nature of artificial turf, Golden Gate Bird Alliance is involved because the project will reduce the quality of the area for wildlife and for people who appreciate nature. The western end of Golden Gate Park has always been designed and managed to be more natural, an urban woodland with open meadows. Every major planning document — including the City’s General Plan and the Golden Gate Park Master Plan — mandates that the historic natural character of the western end of the park be preserved. The loss of the area is another big gash in the “death by a thousand cuts” faced by local bird and wildlife populations in San Francisco.

Beach Chalet now, with natural grass fields What Beach Chalet would look like with lights

Proponents of the project have characterized the controversy as a being about “birds vs kids.” But simplifying the conflict and demonizing your opponents doesn’t do anyone any good. In truth, Golden Gate Bird Alliance and other project opponents are only asking the City to develop an alternative that meets the needs of soccer players while also respecting the history, character and ecology of the park. So far, the City has refused to do so. Fields can be developed elsewhere, but there is no other place like the western end of the Golden Gate Park.

There is no doubt that local athletes need more fields and playing time, and that the Beach Chalet is sorely in need of renovation. …

By Bob Lewis

Eddie Bartley and I have been teaching a new class for Golden Gate Bird Alliance this month called Romance in the Air. It focuses on territories, courtship, song, raising families – as those relate to birds, of course!  Springtime is the perfect time to give this class, and our first field trip was spectacular.

We went to Hayward Shoreline, and since the class is sponsored by GGBA, gained permission to enter the normally closed East Bay Regional Park District lands inside the gates.  After passing numerous singing Savannah and Song Sparrows, we came to a channel choked with reeds where Marsh Wrens were building nests.

All this, of course, relates to our class subject matter – the song of the sparrows was aimed at defining and defending their territory and attracting mates, while the polygynous male wrens were busily building multiple nests.  These nests define a courtship area, and an interested female will inspect the male’s handiwork, and perhaps then mate and lay eggs in the nest of her choice.  More likely, though, she’ll select a new nest site and initiate nest building there.

Savannah Sparrow / Photo by Bob Lewis

Most exciting to me, though, was a flock of about 350 Red-necked Phalaropes, coming from their wintering grounds off the South American west coast.  All in breeding plumage, they were an elegant group to behold.  Phalaropes are polyandrous, with the female being more brightly plumaged.  She may mate with several males once they arrive at their northern Canadian or Alaskan breeding grounds, laying four eggs in each nest.  The male will then incubate the eggs and raise the young on his own.  The birds we watched were feeding rapidly, fueling their long flight north.  They wouldn’t stay long, and we were lucky to see them.

Female Red-necked Phalarope / Photo by Bob Lewis Male Red-necked Phalarope / Photo by Bob Lewis

 

Adding to the excitement were hundreds of raucous Forster’s Terns bringing courtship offerings of fish, a few endangered Least Terns with the same plan in mind, and four Black Skimmers occasionally coursing over the marsh.  On our Sunday walk to the same site (we do two walks to each field trip site – one on Saturday, one on Sunday) Eddie spotted over 20 Black Terns, a very delightful bird to see.

Romance is in the air!

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Note: Although Bob and Eddie’s Romance in the Air class is underway and full, there are still spaces available in the class he will be co-leading with Rusty Scalf in June on Birds of the Sierra.…

By Ilana DeBare

High drama is happening amidst San Francisco’s high rises as four Peregrine Falcon fledglings learn to fly – and as intrepid human volunteers help them recover from potentially-deadly missteps.

The four chicks – two male, two female — hatched at the end of March in a nest on the 33^rd floor of the downtown PG&E building. By the beginning of May, they had gained their flight feathers and were ready to take wing.

But first flights – never easy anywhere – are particularly dangerous in a downtown of concrete canyons and glass walls.

“San Francisco is an incredibly difficult place for babies to fledge,” said Mary Malec, one of about 20 volunteers who are monitoring the falcons from street level and from a donated suite in a nearby office building with a view of the nest.  “There are so many buildings to run into. Some are glass, which birds can’t see. It’s easy for them to end up on the ground, where they can run into trucks and buses and all sorts of hazards.”

Amelia, one of the female falcons, who will be the last to fledge. Photo by Jim Dikel.

Within the past week, both of the young male falcons have had close calls:

Sutro’s Tower

Sutro, one of the males, flew to a nearby building last Thursday. When he tried to return to the nest site, he missed and tried to land on another building. But it had a smooth façade and his talons couldn’t find a grip: He dropped off and fell, flew, tried to land again, and ended up on an architectural pillar only 15 feet above the street.

“Baby Peregrines fly well – it’s landing that they don’t know how to do yet,” Malec commented.

Sutro would have had a tough time regaining the 33^rd floor  or comparable heights – where the parent falcons continue feeding the young ones — from such a low launch spot. So the fledge watch crew called Glenn Stewart, director of the Santa Cruz Predatory Bird Research Group and a kind of fairy godfather to young Bay Area raptors. At 9:30 p.m., the volunteers managed to find a ladder and Glenn climbed the pillar, trapped Sutro in a rescue box, took him to a vet for an overnight check, and returned him to the PG&E nest ledge.

The Perils of Perry

Perry, the other male eyas (young falcon), had flown successfully a couple of times last week.…