September is a subtle month. Its changes creep up without being readily noticed. Daylength shortens most rapidly around the equinoctes. We come to realize that summer is over and fall is practically upon us. It is typically a sunny month, one of the best for hiking in the mountains. Nights can be quite chilly but the absence of mosquitoes makes watching the campfire a treat.

Crows hang around the walnut trees that droop over streets, waiting for passing cars to crack open fallen nuts. I’ve watched them compete with squirrels for these morsels. The squirrels are not as good as crows for this because the crows know how to drop nuts in the path of cars. Squirrels gnaw off the walnut’s bitter husk and bury hundreds.

Most of the native flowers have long since finished blooming but the leafy beggarticks (Bidens) reach peak bloom this month. It reflects their affinity for wet places that dry out at the end of the season. Its serrated leaflets are so similar to Cannabis it occasionally fools people into thinking they have found escaped marijuana.

An evening walk in an open woodland is not likely to be a quiet pastime this month. Insects like cicadas are calling out to find mates, sometimes almost deafening. Their abundance varies from year to year, with some species appearing only after intervals of many years. Some plants are sporadic in appearance, too. This is the first year since 2009 that the mosquito fern is turning ponds purple red.