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It's About Time - February 2013

Antler lichen, Evernia prunastri

Why do mosses and lichens fall out of the trees in winter? Close to the end of every year, clumps of moss and lichen appear around almost every oak and maple tree in town. These are the branch species, different from terrestrial mosses and lichens. It is most prominent in parks where the lawn hasn’t been mowed since late fall. For years I attributed the lichen rain to wind storms, but that never struck me as the whole story. A comment in the Mount Pisgah Arboretum newsletter by its caretaker made a light go on in my head. Tom had noticed Steller’s jays tearing moss clumps out of oaks, foraging for critters that hide in the moss. In our neighborhood I figure it is mostly crows and scrub jays. I have also seen crows tearing up clumps of moss on a roadside, obviously insect hunting. I asked Tom about the lichens. Not birds but the fox squirrels pulled them off. We have plenty of squirrels in town, so I’ll blame the lichen fall on them.

Waiting for the days to get longer, and warmer, gave me the thought that ancient people from northern latitudes paid more attention to the sun and the solstices. Druids and Celts built monuments like Stonehenge to mark the sun’s movements. They celebrated the equinoxes and cross quarter moments. Only where the nights are clear and temperate did stargazers focus more on the moon’s position in the zodiac. No wonder astrology had its roots in Babylon.