Fall Migration of Waterfowl to Bolsa Chica
by Babs Levitan
It’s Fall at the Bolsa Chica Ecological Reserve (BCER) and migrating water fowl are arriving daily after flying as many as 2,900 miles from nesting grounds that are as far away as the Arctic. Some species of water fowl travel in large flocks and others arrive in smaller groups or singly. The most common species of waterfowl that migrate into the Bolsa Chica to stay for the winter months are geese like the Brant and the Canada Goose; dabbling ducks like the American Wigeon, Gadwall, Green-winged Teal, Northern Pintail and Northern Shoveler; and diving ducks like the Redhead, Ruddy Duck, Bufflehead, Lesser Scaup, Surf Scoter and Red-breasted Merganser to name just a few.
What is it about the BCER that attracts all these migratory water fowl to choose to spend the winter here? The short answer is the availability of water, food and shelter. We humans need these exact same life sustaining amenities when we set out on a trip. The birds are using the Pacific Flyway in the same way we use the Pacific Coast Highway. Many species are very adaptable to stopping anywhere on the flyway to drink, eat and rest, whether it is for a few days or the whole Winter. Others have more specific needs and that makes them more interesting.
Here is a story about how on January 14, 2013 I got interested in the Brant. Notice that I am calling this goose a “Brant” because that is its official name according to the American Ornithologist Union (AOU). Before then I had only seen an occasional Brant at Bolsa Chica during Fall or Spring migration. That day I was leading a group of very curious 3rd grade students as part of the Bolsa Chica Land Trust’s Miracles of the Marsh outdoor education program. We noticed a group of about 25 geese floating and dabbling around in the Tidal Basin, pulling long blades of eelgrass out of the water and eating them. The students told me that it looked like they were eating green spaghetti. These geese were smaller and more compact than a Canada Goose, had a black head and a wide, almost decorative looking, “necklace” and were only a little larger than Bolsa Chica’s non-migratory, resident duck species, the Mallard. This group of Brants appeared to be wintering at Bolsa Chica because January is not when they would typically be migrating. The children did get me to be curious enough to keep checking to see if they were still in the Tidal Basin and resting on the mud bars until the end of March when I realized they were gone.
It was reasonable to think that a group of approximately 25 Brants were probably from several families of geese that had migrated south together in 2013 and were spending the winter at the Bolsa Chica. They had found the right water, food and shelter because of the big 600 acre wetlands restoration that happened at BCER between October 2004 and August 2006. After its completion in August 2006 the California Department of Fish and Wildlife (CDFW) now had a newly created tidal basin under its direction that could support commercial and sport fishing along California’s south coast. The goal was for it to be a healthy fish nursery for ocean species. The August 2006 opening of the inlet established tidal flow at Bolsa Chica’s newly created tidal basin. To make it a healthy tidal basin eelgrass was introduced with the goal of it getting established and growing large beds of eelgrass for the ocean animals to come in to eat, hide in, and safely lay their eggs in. What I saw that day in January 2013 looked like a mission accomplished moment because that wintering group of Brant were eating eelgrass. I decided to try to remember to watch to see if they would return in November and stay until March again.
I did some research on the Brants and learned that there are four subspecies of the Brant that breed and nest on the ground in family colonies in the Arctic. Their preferred habitats are marshlands, islands, and tundra during the summer summer breeding and nesting months. Each subspecies will migrate south for the winter to coastal areas, three in North America and one in Western Europe. The subspecies are identifiable by where they migrate to in the spring, where they nest in the summer and where they spend the winter months. Their belly and flank color can help with identification. At BCER we have the “Black” Brant subspecies that breed and nest in the western Arctic and have blackish bellies and winter on the Pacific coast as far south as Baja California. The “Gray-bellied” Brant breeds and nests very far north on the islands of the central Canada Arctic Archipelago and winter in western Washington around the Puget Sound. An “Atlantic” Brant has a pale gray belly and breeds and nests in the eastern Arctic and winters on the Atlantic coast of North America. The “Dark-bellied” Brant or Brent Goose, as it is known in Europe, breeds and nests in the Arctic coastal region of Siberia’s northwest and then winters in eastern England. All subspecies of the Brant are coastal birds found in tidal estuaries where they feed on beds of eelgrass.
During the winter of 2013/2014 I forgot to look for them. But on December 14, 2014 a volunteer (P. Knapp) for California Fish and Wildlife reported counting 122 wintering Brants. This was more proof of how successful the 2006 opening of the full tidal restoration of the marshes and newly created tidal basin had become. Bird and fish counts began to show larger numbers and more bio diversity of species developed throughout the whole food web at BCER. Some survey counts of wintering Brants in the following years have been:
- 2015- 199
- 2016- 234
- 2017- 329
- 2018- 201
- 2019- 414
- 2020- 450
- 2021- 548 (first count of Brant recorded in November)
Healthy tidal basins along the Pacific coastline all share one important feature, eelgrass growing in them. Eelgrass grows underwater around the marshy edges of tidal saltwater bays and basin on the muddy, sandy bottom to form what looks like a grassy meadow. The long blades of Eelgrass can grow up to 3 feet long and the Brant geese can be seen floating around and tipping their heads down into the water to pull out and eat what the students called green spaghetti. Eelgrass creates a rich food web that supports invertebrates, isopods, amphipods, worms, stars and clams. Birds and even small sharks eat the fish and other aquatic animal life foraging and hiding in the eelgrass. Shorelines have more stability when highly nutritious eelgrass beds form moisture holding sponge-like edges of washed up eelgrasses that provide protection and food for small creatures during low tides. Even though many species of waterfowl had found the Bolsa Chica Wetlands to have the perfect combination of water, food and shelter, it actually lacked eelgrass until the Tidal Basin restoration.
Brants do not start their southward fall migration directly from their summer nesting areas to their wintering coastal homes. Families of a monogamous pair of Brant with their hatch-year offspring stick together and move to staging sites in the Arctic to molt before starting south. These large migration flocks need sedge and grassy plains for foraging next to shorelines that provide escape possibilities for them while they complete their molt before migrating south. During a molt their flight feathers fall out and they are flightless until new flight feathers grow in to replace them. This takes about a month. Being in a large group probably provides them with a safety in numbers feeling during the molting process and during migration. Ducks also do a late summer molt to replace their flight feather with stronger, new ones before they migrate. Only the adults replace their flight feathers during this molt. Our year round resident Mallards can look pretty “messy” during their late summer molt too. All the other migratory duck species usually arrive from their nesting areas with new feathers in place. The drab coloration of eclipse their plumage is an adaptation that allows the normally colorful males to hide out in clumps of vegetation in wetlands while they wait for their fresh plumage and new flight feathers to grow in.
November to March is the right time to find the Brants at BCER as they float around the Tidal Basin grazing on eelgrass at low tide and many others can be observed standing or resting on the exposed mud bars. These are also the perfect times to look for banded birds. If you spot any, record the colors of the bands on each leg, noting any alpha numeric data on them, and remember to include the date and location of your bird sightings. Then you can report this information to USGS at www.reportband.gov and from that data they can report to you when and where each bird was banded and any other observations the people doing the banding noted. A Brant migration flock will be composed of many family units that travel together and each of these will probably include a monogamous male and female pair of parents traveling with their current hatch-year offspring. Geese are banded on their nesting grounds, so where they were banded will also give you clues about which subspecies any one bird is likely to be. Any data you submit to USGS on banded birds you see is then available to researchers studying the birds so we humans can try to help them survive.
On 12/07/2019, 9 Brant’s bands were tabulated and sent to USGS (www.reportband.gov). The results were posted by R. McNab to Orange County Birding Online Group 12/12/2019. Most (8 of the 9) were in a tight group and had light green bands with white alpha numeric codes (example: green/white 7+V). This might have been one or two family groups that had migrated together to the Bolsa Chica. 7 were all banded the same day, 07/26/2019 and included 2 adult females, 1 adult male, 1 hatch-year female, and 3 hatch-year males. The 8th green/white banded Brant with a green/white band was an adult male banded 07/31/2014 and the banding location for all 8 was Nuisquit, North Slope Borough, Alaska. The 9th banded Brant was an adult male that had a (yellow/black 3-7) band with a reported banding date of 07/12/2014 from different location near Chevak Census Area, Alaska.
All the saltwater wetland dependent species are facing threats. The migrating birds we enjoy seeing are very dependent on their ability to access life sustaining water, food and shelter. The health of the food web in their nesting and wintering areas are endangered on the Pacific coastline. As the percentage of saltwater wetlands continues to decline here in California we can each do our part to protect our remaining open space habitats. Also, if you see banded birds, report any information you can gather to USGS www.reportband.gov . This information is important to U.S. Fish and Wildlife Service’s monitoring of threats to the Brants and other species. They had estimated the total population of Brants to be about 315,200 in North America between 2002 to 2011. Waterfowl biologists are now concerned that their target levels show a decline. The most serious threat is probably the loss of wintering habitat due to climate change and sea level rise. Changes in the Arctic temperatures can result in rising ocean levels covering coastal grazing grounds during the summer nesting season. Brant are a game bird and USFW estimate that 30,000 are hunted each year. Also in the Arctic, native communities have historically collected Brant eggs and done drives of the flightless, molting birds as part of their life sustaining food source. The continued development of petroleum extraction on their nesting grounds likely does harm to populations of Brants in some parts of the Arctic.
Today in California only a little more than 5% of California’s original, coastal, saltwater wetlands have not been lost to development. Thinking about what impact our behavior has on the whole Animal Kingdom here on our planet is a way for we humans to realize we face the same issues as all the other living animals and plants here on Earth do. Can we share and protect our open space, work to make our water and air quality and better in our “habitat”? Can we find ways to control our CO2 emissions with renewable energy sources? We are all in this together so it is time for all of us to think about how all of can be stewards of the Earth.
photos: Steve Smith, Jay Spring, Debbie Quintero, Larry Kaufman, Mark Perenchio, Robin Hoyland, Kurt Bayless, John Hannan, Babs Levitan