Each fall, hundreds of volunteers with the Golden Gate Raptor Observatory track hawk migration through the Bay Area. To celebrate fall migration, here’s the second installment in a two-part interview with GGRO Director Allen Fish. 

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Q: What trends have you seen in recent years in terms of numbers, species, timing, anything else?

A: With 19 species of annual raptors, and a quarter-century of data, I could spend days on this question, but to give a few examples:

• Peregrine Falcon numbers have increased steadily over the 25 years of the GGRO count.  In 1985, we tallied one Peregrine every 200 or so count-hours at GGRO; today we see a Peregrine just about every other hour.

• We have started to mine our data for phenological changes — that is, changes in peak dates of migration that might be attributed to climate change.  Sharp-shinned Hawks seem to show some slippage of their peak dates over time, but the statisticians are still working on their part of the analysis, so I better not say too much.

Q: How many volunteers do you have counting on weekdays? On weekends?

A: Weekday counters, about 80 volunteers.  Weekend, about 60.  A volunteer makes a commitment to one weekday or weekend day every other week from August through December.  An exceptionally experienced volunteer with five to 25 years’ experience is the leader for the day.  He or she tries to see and corroborate every raptor.

Q: How does the Quadrant System work? Does it keep you from counting the same hawk multiple times? How was it created?

A: We split the 360-degree view-shed on Hawk Hill into four impossibly huge slices of pie that we call quadrants.  Two to three volunteers focus on one of these quadrants for an hour at a time trying to see every new raptor, and to pass every previously spotted raptor.  If we’re not sure whether a hawk has been counted already, we count it.  One person records species, ages, and sexes for the whole team.

Nothing can keep a human being from counting the same hawk multiple times on Hawk Hill.  We have learned from band recoveries and radio-tracking studies that raptors may leave Marin and come back days or even months later.  So how do we account for “double-counts?”  First off, we assume they happen.  And that they happen at some regular rate that stays consistent from year to year. …

Each fall, hundreds of volunteers with the Golden Gate Raptor Observatory track hawk migration through the Bay Area. From the top of Hawk Hill in the Marin Headlands, they spot and count raptors that are following the coastline south and then swerving inland when they reach the Golden Gate. GGRO’s Hawkwatch program is one of the unique treasures of Bay Area birding. To celebrate fall migration, here’s the first installment in a two-part interview with GGRO Director Allen Fish. 

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Q:  When does hawk migration season “officially” start, peak and end??

A: Most years we start to see the early migrants – young Redtails and Osprey in particular – right around the first of August.  We long ago made a decision that we would start to count and band right around August 15^th and carry our daily studies through at least the first full week of December.  Although, on the back end, some raptors, Redtails and even accipiters are still moving through until the first week of January.  Probably because of the moderate winter climate here, some raptors have a great deal of behavioral flexibility about when they move.  Some of this movement may not be classical migration, but would be more described as dispersal, that is, an ecologically-stimulated movement.

In terms of numbers of hawk-sightings, the highest flight-days of the season have fallen in a date-slot from about September 15 to October 8. However. the peak day usually hits in a smaller range of September 25-30. This peak is usually driven by Sharp-shinned and Cooper’s hawks. The big migration period — which tends to stay above 120 raptors per hour  and may peak at ten times that — lasts through about November 10.

Broad-winged Hawks near the Golden Gate Bridge / Photo copyright by George Eade

Q: About how many raptors are sighted on a typical day at the peak of the season?

A: Our peak days have ranged from about 600 sightings per day (six hours of counting per day) all the way up to 2,800 sightings per day.  That was on September 21, 1984.

Q: Which species are most common?

Turkey Vultures, Red-tailed, Sharp-shinned and Cooper’s Hawks together make up 87 percent of the flight.  Fifteen other species of diurnal raptors are seen most years.  We’ve seen Mississippi Kite on three occasions since 1976, and a Eurasian kestrel was banded here in 2007.

Q: Where are they coming from and going to?…

By Ilana DeBare

Welcome back to the Lake Merritt Tufted Duck!

Once again, a Tufted Duck has arrived to winter among the scaup of Lake Merritt in Oakland. This is of note since Tufted Ducks aren’t native to California — they’re a Eurasian species that occasionally turns up here, presumably migrating south with other birds from Siberia.

Its arrival sparked an interesting dialogue earlier this week on the East Bay Birding email discussion group. People started trying to figure out how long there’s been a Tufted Duck wintering at Lake Merritt. We at GGBA were happy to spot it last January during our first-ever Kids’ Bird Count at Lake Merritt, but the record goes back much further.

Bob Power reported sighting the duck each year from 2006 through 2012; Glen Tepke said he had seen one in 2005. John Harris saw one in 1998. Dave Quady noted that the Oakland Christmas Bird Count turned up a Tufted Duck in 1994 and every year from 1997 through 2004 except for 2002.

Traveling even further back in time, John Sterling recounted seeing one in the 1970s — when he was too young to have a driver’s license, and had his mother drive him to the lake! And Joe Morlan weighed in with a string of sightings in 1976-8.

Tufted Duck at Lake Merritt / Photo by Mark Rauzon, from http://rauzon.zenfolio.com

Mark Rauzon, who started the whole discussion with a sighting of the duck last week, summed it up this way:

A Tufted Duck has been reported 22 out of the last 36 years at Lake Merritt, Oakland. Mostly a single male was seen each winter from 1976-79, 1987, 1991, 1994, 1997-2001, and 2003-12. The same individual was likely reported in 1976-79, and again from 2003-12. And while they can live to be 45 years, it is likely that more than one individual male has been involved, as well as a few females. Many of us got it as a “lifer.” We’re lucky to live in an area where this Eurasian species winters.

For me, it’s also moving to consider that this could be the same male returning for several years in a row. Except for occasional banded birds, we don’t often get to know individual birds or their histories.…

By Ilana DeBare

Golden Gate Bird Alliance has many wonderful volunteers — sharp-eyed field trip leaders, personable docents, folks who assist with the unglamorous but essential work of maintaining our office files and member database.

But every so often we get a volunteer who, well, stands out from the flock.

Like Kathleen Curry – who recently built THIRTY-FIVE nest boxes for us from scratch!

Kathleen had building skills from her career as a general contractor. She had a garage filled with tools. She had a lifelong love of birds.

So when Volunteer Coordinator Noreen Weeden put out a request for help building nest boxes to sell as a fundraiser for GGBA, Kathleen answered the call.

In spades!

Kathleen collected scrap wood and perused a variety of nest box building plans to ensure that the end-result would be usable and healthy for birds. (Nest boxes need to have ventilation, the holes need to be the right size for the desired species, etc.)

Barn Owl box / Photo by Ilana DeBare

Then — together with volunteers Ken Bernicker and Michael Noel — she culled out any rotten or splintered wood, cut boards, sanded them, tacked the pieces together with nontoxic waterproof glue and a nail gun, secured the boxes with weatherproof screws, and waterproofed the rooves. Each box required several hours of work.

The result was a truck-full of nest boxes of varying sizes — small ones for titmice and chickadees, midsize for Western Bluebirds and Tree Swallows, humongous ones for Barn Owls.

We sold a bunch of the boxes at the Kensington farmer’s market this weekend. But more are available in our office: Come by during a weekday afternoon or call us at (510) 843-2222 if you’d like to buy one.

Kathleen unloads some nest boxes / Photo by Ilana DeBare

This was Kathleen’s first serious effort at building nest boxes. She had made bird houses with her kids when they were little — but that was quite a while ago.

Since then, her kids grew up (she now has six grandchildren!) and she became a birder.

Kathleen plunged in by taking our Birds of the Bay Area class about five years ago. “I had always been interested in birds, but until then, I’d been working so hard that I never had time to learn about them,” she said.

A Berkeley resident, Kathleen purchased a nest box for her own yard about four years ago.…

We at Golden Gate Bird Alliance have spent a lot of time advocating for the endangered California Least Terns at Alameda Point. But there are about 180 other species of birds that call Alameda home too — including Brown Pelicans. We’d like to share some wonderful photos and information about the pelicans by Alameda resident Richard Bangert, reprinted from his Alameda Point Environmental Report blog.

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The successful recovery effort for the once endangered California Brown Pelican is evident every summer through fall on Breakwater Island, an area which forms the beginning of the Alameda Point Channel leading to the ship docks and Seaplane Lagoon.  The breakwater is a wall of boulders built up from the Bay floor to reduce wave action in the harbor.

L-shaped Breakwater Island, largest Brown Pelican roosting site in San Francisco Bay. The former Naval Air Station is to the right. / Photo by Richard Bangert

California Brown Pelicans were listed as an endangered species in 1970.  The pesticide DDT was identified as the cause of their decline.  It caused reproductive harm, and altered the birds’ calcium absorption, which led to thin eggshells that would break under the parents’ weight.  Use of DDT was banned in the United States in 1972.

A recovery effort was launched in the 1970s on Channel Islands National Park off the coast of Santa Barbara. The only breeding colonies of California Brown Pelicans in the western United States are within Channel Islands National Park on West Anacapa and Santa Barbara islands.

Brown Pelicans relaxing on Breakwater Island on a sunny fall day. Their mouth sack is the largest of any bird and is used to scoop fish when they plunge into the water. / Photo by Richard Bangert

In the summer and fall, the Brown Pelicans can range from nesting colonies in Mexico and the Channel Islands all the way up to British Columbia.  Alameda Point’s Breakwater Island is the largest roosting site in San Francisco Bay. A safe, secure roosting area is essential for pelicans to rest, preen, dry their feathers, maintain body temperature, and socialize.

When the Naval Air Station was still active, the Navy enforced restrictions against boats landing on the Island and posted signs that warn against disturbing the birds.  Since the base closed, there has been no one to enforce regulations against disturbing the pelicans.

The California Brown Pelican was removed from the Endangered Species List in 2009 after an almost 40-year recovery. …