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The Watershed Project

population decline

What’s in Your Watershed? | The Fiesty Dungeness Crab

By Jeff Embleton

If you look closely into the depths of the estuaries around the Bay, you may spot a Dungeness Crab resting near the sea floor. Dungeness Crabs make temporary homes in our watershed. They use the blend of salt and fresh water to grow into the large and grumpy-looking water dwellers that many people know and love (to eat). Dungeness Crabs generate tens of millions of dollars for their value as food for humans, but they also play an important role in the marine food chain. The Latin name Cancer magister means “chief crab.”

Physical Appearance
These crabs’ claws make them easily identifiable. Dungeness Crabs have five pairs of legs; including two large claws used to defend against predators and to tear apart larger prey. The crabs are typically beige to light brown with blue trim, and often tinted with light orange. The crabs have short eye stalks with small orbits, and a wide shell that they periodically molt.

Range
Dungeness crab can be found in coastal waters from Southern California to the islands of Alaska. There is debate as to precisely how far they naturally range, but it is generally agreed that they can be found in and around all estuaries on the western coast.

Diet
Dungeness crabs have a hefty appetite. They feed on shrimp, mollusks, crustaceans, eelgrass and other aquatic vegetation.

Mating
Dungeness crabs spawn in offshore waters, such as the Gulf of the Farallones. The larvae hatch during the winter months and drift toward coastal waters, tidal flats and estuaries to mature. The crabs use tidal currents and jellyfish to hitch a ride from the deeper and cooler ocean waters to coastal locations. Juvenile crabs can spend over a year in estuaries before returning to the ocean in fall.

Conservation Status
The Dungeness crab is not currently considered an endangered species. The Seafood Watch has named it a “Best Choice” of seafood to eat. During the juvenile stage of development, the Dungeness crab utilizes the estuaries as habitat during its maturation period. Any change to the estuary, such as dredging, may impact the crab’s continued success. Population numbers have dwindled in recent years from over-fishing and changes in water temperature.

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What’s in Your Watershed? | The Lovely Long-billed Curlew

By Dan Grannan

The long-billed curlew is an epic bird. Not only is it the largest shorebird in North America, it also displays one the greatest aerial shows of any avian flier. During breeding season, the curlew flies in fast loops as part of a courtship dance. This ostentatious display attracts both feathered mates and human bird-watchers alike. Named for its long, slender bill and “cur-loo” call, curlews are also called “candlestick birds” and are the namesake for San Francisco’s Candlestick Point.

Physical Appearance
Adult curlews have an elongated bill that curves downwards, a long neck and a small head, while the chicks have a much smaller and less curved bill. The females have a much longer bill than the males. Curlews’ underbelly and neck are cinnamon-colored and their crown and back are speckled with various shades of brown.

Range and Habitat
The long-billed curlews breeding range is massive. It spans from southern Canada to northern California, and also includes Utah, northern New Mexico and Texas. The curlew loves the sun and winters in California, Texas, Louisiana, and South Carolina as well as Florida, Mexico, and Central America. This range used to be much larger with massive numbers being found along the Great Plains and eastern prairies. Increased agriculture and livestock grazing has shrunk the range of the curlew.

Diet
In the summertime, curlews sample grasshoppers, beetles and crickets from the grasslands. Throw in a small amphibian from time to time and you have the ideal summer diet. During the winter months when the bird is sunning on the beach, small crustaceans, mollusks, berries and seeds are its delicacies of choice.

Child Rearing
Mama curlew lays four eggs in a grass-lined nest and incubates them for about one month. Papa curlew assists by taking turns warming and guarding the little eggs. Mama and Papa curlew use their multi-colored feather coats to camouflage and protect the nest from predators. Skilled actors, the adult birds are known to feign injury to lure potential egg-snatchers away from the nest. They also can take a more direct approach if needed, using loud vocalization and dive bombing to deter predators. Once hatched, the chicks are almost fully independent. The adults teach them to hunt grasshoppers and watch over them for up to 45 days, and then they are on their own. The average curlew life span is eight to ten years.

Conservation Status
Under the U.S. Shorebird Conservation Plan curlews are currently slated as “critically imperiled.” Habitat destruction is a major concern for the curlew. As marshlands are shrinking and prairie lands are developed or converted to farmland, the curlew is losing its potential habitat breeding grounds. With a current population size of only 123,500, monitoring and protection efforts are critical to ensure this population does not suffer the same fate of many other extinct species. You can help protect this lovely bird next month by joining The Watershed Project on International Coastal Cleanup Day to ensure that curlew habitat is free of marine debris.

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What’s in Your Watershed? | The Mighty Red Knot

By Christopher Lim

What weighs less than half a pound and travels over 9,000 miles each year? The Mighty Red Knot, Calidris canutus, is a truly remarkable bird. It makes one of the longest yearly migrations of any bird, traveling over 15,000 km from its Arctic breeding grounds to Tierra del Fuego at the tip of South America, flashing its colorful body and wings the entire way.

Physical Appearance
One of the most colorful birds in North America, Red Knots change color depending on their motives. During breeding season, it has an attractive cinnamon colored face, chest and undersides and dark brown wings. In winter, the Red Knot dons a more modest color scheme, with a gray head, chest and upper parts and a white belly. It has a pointed black bill and long, greenish legs. Males and females look similar. The weight varies with subspecies, but is between 100 and 200 grams. An adult Red Knot is 23-26 cm long with a wingspan of 47-53 cm.

Range and Habitat
The Red Knot is a world traveler. It breeds in drier tundra areas in the Arctic regions of Canada. The Red Knot then makes an unbelievable trek down to South America via both the Pacific and Atlantic coasts, often making stopovers in the mud flats of the San Francisco Bay. The Red Knot is also found in Europe and Asia. Outside of breeding season, it is found primarily in intertidal, marine habitats, especially near coastal inlets, estuaries, and bays.

Diet
Red Knots like seafood. They eat mainly invertebrates, especially bivalves, small snails, and crustaceans. On the wintering grounds red knots also eat a variety of hard-shelled terrestrial invertebrates that are ingested whole and crushed by a muscular stomach.

Mating
Red Knots are flashy creatures. During courtship, the male Red Knot flies up into the air, starts singing, glides around a bit and then lands with his wings pointed up. The female Red Knot lays three to four eggs in a depression in the ground. Both parents incubate the eggs. In fact, the male may do most of the incubation. The chicks hatch in approximately three weeks and they fledge in another three weeks.

Conservation status
As fellow watershed dwellers, it is important for us to protect this fascinating bird’s habitat. The fact that Red Knots come together at traditional staging areas during migration makes large groups vulnerable to pollution and the loss of food sources. The numbers of Red Knots appear to be declining; the populations wintering in South America dropped over 50% from the mid-1980s to 2003.

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