Saturday, March 17, 2018

Ruddy Ducks at Merced NWR

One of my favorites, the cute little Ruddy Duck (Oxyura jamaicensis) is a species of diving duck found across wetlands of the Great Central Valley during the winter and early spring.  They are a small, compact duck, often associated with other diving ducks, such as Buffleheads.  Of the six "stiff tailed" ducks in the genus Oxyura, the Ruddy Duck is the only species found in North America.
While the massive flocks of geese and Sandhill Cranes have nearly all left the Merced National Wildlife Refuge, the wetlands are still teeming with ducks!  Yesterday, I saw nearly a dozen different species of duck, which is almost all that one would expect to find there at this time of year.  (If you're curious, there were Blue-winged, Cinnamon, and Green-winged Teal, Northern Shoveler, Gadwall, American Wigeon, Mallard, Northern Pintail, Ring-necked Duck and Bufflehead, in addition to around 100 Ruddy Ducks.  Species not present (or that I missed) were Canvasback, Redhead, Lesser Scaup and Common Goldeneye.) 
Side note: all of the swallows have returned from their southern wintering grounds - Tree, Violet-green, Cliff, Barn and Northern Rough-winged Swallows were seen by the hundreds flying over the wetlands yesterday!
Ruddy Ducks forage for prey by diving to the bottom of shallow ponds and straining mud through their bills to separate out food items.  Prey includes aquatic invertebrates, from zooplankton, insects and larvae to crustaceans, worms and snails.  During the winter and migration, plant material also comprises part of their diet.  Feeding takes place most often at night, and the ducks spend their days resting with their head tucked under a wing while floating in large rafts of perhaps one hundred or more individuals.  However, when they arrive at their breeding grounds, the ducks pair up and are quite aggressive toward other individuals.  While Ruddy Ducks spend the winter and early spring in Central Valley, they breed farther north, largely in the wetlands of the Prairie Potholes region of the northern Great Plains. 
While many ducks burst upwards into the air from the water to avoid danger, Ruddy Ducks are more likely to dive under the water to escape predators.  Ruddy Ducks are rarely seen on land, as the majority of their lives is spent on the water.
The Ruddy Ducks, who have been with us all winter, are putting on their breeding plumage now, and the males are developing their brilliant blue bills.  Even though the crowd-pleasing flocks of thousands of charismatic geese and cranes have left the Central Valley for their northerly breeding grounds, there is still much to see and experience at our local wildlife refuges! 

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