It's almost winter and Double-crested cormorants (Phalacrocorax auritus) have returned to Lake Ralphine. They can be seen swimming low in the water then suddenly diving out of sight, only to return, often with a fish caught in their beak, which they flip about and swallow. Once they're done fishing, they fly up into this California black oak (Quercus kelloggii) or a Western cottonwood (Populus fremontii) that's nearby and spread their wings to dry and just generally hang out. Although the oak looks dead it isn't, not yet, anyway. It may be that being chosen by these large birds could eventually be the death of the tree. During breeding season Cormorants nest in colonies and the large amounts of....uh...poop that falls from the nests and from the adult birds makes the soil too toxic for the tree that the birds are nesting in, eventually killing it, forcing the birds to choose a new nesting site.
The Cormorants that spend the winter at Lake Ralphine aren't nesting but they certainly are loitering and congregating in one place, this California black oak.
Fairfax County Public Schools
All About Birds
BirdWeb (Seattle Audubon Society)
United States Environmental Protection Agency
United States Fish & Wildlife Service