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. …

By Bob Lewis

This year will be the 113^th year of Christmas Bird Counts in North America.  Golden Gate Bird Alliance sponsors two counts in our region, centered in San Francisco and Oakland.  Although Christmas counts are great fun and an opportunity to meet other birders, see a variety of birds and get a good understanding of what birds are available in our area, they also have a more serious side.

The National Audubon Society has made the results of all counts available to everyone at www.audubon.org/bird/cbc/hr/index.html. This Citizen Science data is used by environmentalists and ornithologists to understand population changes, and consider actions that might help to minimize the loss of endangered species.

Recently I took a look at data from the Oakland Count to see what it might say.

For a variety of reasons, it was easy for me to look at the data from 1974 to 2011.  This is a 38-year period.  I divided it in half, and compared the years 1974-1993 with 1994-2011.  Over this period, the population of Alameda County increased over 40 percent.  Another development that potentially affected bird populations was the Oakland Hills fire in 1991, just before the beginning of the second period.

I averaged the count data over each period, and applied some statistical tests to the results.  Here’s what I found, for the top 20 increases and decreases:

Birds with increasing populations			Birds with decreasing populations
Species	% incr.	Avg(1)	Species	% decr.	Avg(2)
Common Raven	1258	146	White-winged Scoter	95	199
Red-shouldered Hawk	978	29	Bonaparte’s Gull	94	164
Pygmy Nuthatch	362	95	Northern Pintail	90	1599
American Crow	302	386	Red Knot	88	117
Common Merganser	276	87	Horned Lark	87	45
Hairy Woodpecker	222	23	Pine Siskin	84	891
Black Phoebe	177	186	Ruddy Turnstone	77	22
Townsend’s Warbler	171	125	California Quail	77	432
Greater Yellowlegs	158	60	Glaucous-winged Gull	76	1386
Black-necked Stilt	121	162	Loggerhead Shrike	75	26
Wood Duck	116	17	Brandt’s Cormorant	74	107
Cinnamon Teal	110	40	Red-throated Loon	72	44
Marsh Wren	99	10	American Pipit	68	196
Acorn Woodpecker	97	39	Canvasback	65	1356
Nuttall’s Woodpecker	85	88	European Starling	64	6154
Rock Pigeon	78	2124	Wilson’s Snipe	63	33
Gadwall	76	152	Wrentit	60	445
Bufflehead	65	2093	Brewer’s Blackbird	60	1805
Brown Creeper	55	74	Burrowing Owl	58	10
Turkey Vulture	37	183	Red-breasted Merganser	57	90

 

(1)   This is the average number of birds seen per year during the second period, 1994-2011.

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