Over the weekend we experienced not only record-breaking warmth (64 F. in Seattle), but also a steady stream of pine siskins in flocks of 20-60 birds! The top photo shows a segment of our Katsura tree, which was decorated with this many birds throughout. They arrived each morning to crunch seeds for about 20 minutes, then move on to another tree. Wild seed party!
We usually see one or two pine siskins throughout the winter, flying in a mixed flock with the junkos and chickadees. They are fond of suet, and a tell-tale ID is that the pine siskin won't land on the suet, but instead flutters in front of it and pecks. Pine Siskins look a lot like the female finches that they fly with and they also look deceptively like a song sparrow-from the front. The best way to ID a pine siskin is to note the yellow patches on the tail and the wings. They also have a really pointy bill (compared to the finch wives).
What is causing the irruption of pine siskins? Audubon states that the irruption is a 2-year cycle, and is most likely driven by a shortages of seeds in spruces, pines, birch, and alder in the Canada and western US states.