Answer:

First of all, we can see that these birds on on the water. They don’t have the usual body shape of loons, grebes, coots, phalaropes, or gulls, which leave us to believe they are a type of waterfowl.

It is difficult to note if they are either ducks of geese because we can’t see their bills and necks but, based on the photo, they don’t look very large, their bodies aren’t as rounded, and the ends of their wings don’t extend very far, which suggests that they are ducks instead of geese. Also, their body coloration is not like that of any of our local geese or introduced Mute Swans.

Now that we know they are ducks, we can also observe and consider their behavior—dipping their heads in the water shows us that they are dabbling ducks. If they were diving ducks they would be swimming completely under the water.

The coloration of the ducks is bright and they have a lot of contrast, revealing they are males. Female ducks are mostly mottled brown. That eliminates the potential of their being Mexican, American Black, or Mottled Ducks, as the males of those species look almost just like the females. Even then, Mexican Ducks are rare in Los Angeles County, and American Black and Mottled Ducks are generally not in Southern California.

Male Northern Pintails are well known for their long central tail feathers, which these male ducks obviously lack. They also have pale gray sides and backs which rules out male Wood Ducks, which have tannish sides and glossy black backs; American Widgeons, which have brownish bodies; Cinnamon Teals, which are cinnamon-red all over; Blue-winged Teals, which have mottled brown sides and backs; and Northern Shovelers, which have reddish-brown sides and white breasts and flanks. The ducks lack the green speculums that Green-winged Teals are named for and their undertails are all black. We are able to see that they have reddish breasts which are a common characteristic of male Mallards. That eliminates our last, other possible male dabbling duck, which is the Gadwall. We also notice that the ducks have other notable characteristics such as white tails and curled up back feathers in front of them. If we look closely at the duck on the right, we can see the base of its orange leg which confirms that the ducks in the photo are male Mallards.

The photo here shows both male Mallards—the one if the front having its distinctive green head and yellow bill mostly out of the water.

Congratulations to Thomas, Jake, Sequoia, and Calvin for figuring out Mallard!