San Diego is the winter home of the migrating lesser scaup, one of the most common diving ducks in North America. Scaups swim under water to find food in the form of underwater invertebrates such as crayfish, insects, and clams. There are various theories as to why they are called “scaup”. One theory is that they are named for the food, or “scalp” that they eat. But, the most accepted theory is that they are named for the calls of the female. Lesser scaup are similar to the greater scaup and are often hard to distinguish in the field. In the San Diego area, greater scaup inhabit saltier water such as those in salt marshes or bays while lesser scaup are usually seen around fresher water, though both species may inhabit the same area at the same time.
Usually, lesser scaup arrive in the San Diego in November, but this year they have begun to arrive a couple weeks earlier than usual. At Lake Murray, five were spotted in mid-October. Since then, their numbers have increased. Most of the early arrivals seem to be males. As the fall and winter months continue, the number of lesser scaups will increase greatly. Places like Lake Murray will see more than one or two hundred in peak season.
Around April or May, lesser scaup will leave the San Diego area, but there are sometimes stragglers, mostly male, who may be seen in the summer. Lesser scaup breed mostly in the northern Great Plains and prairies of Canada. Their breeding habits and practices are similar to the more common mallard. They lay plentiful eggs and have downy young who leave the nest soon after hatching. When these young mature after about two months, they will begin their migration with the adults back to San Diego and other areas in the southern United States, Mexico and Central America.