Because the spring catkins are out.
|Male and female red alder catkins|
The long, red catkins are the males. Female catkins are tiny and rigid. They will develop into hard cones, about 1/2 inch long; these will stay on the tree until next spring.
|Roadside alders, March 2016. Near Keta Lake.|
|More catkins. The male flowers grow in drooping clusters of from 4 to 6 catkins at the ends of branches.|