This week in the woods, wet ground and cold weather have set up good conditions for needle ice, and you can find it “sprouting” along muddy trails. As Rachel Sargent Mirus explains in this Outside Story essay, these ice formations occur through capillary action. As water near the soil’s surface freezes, more water moves up from deeper in the soil. This also freezes and attaches to the ice layer. Through this additive process, as water expands into ice, the top of the ice layer is pushed upward, through pores in the soil. Needle ice can also form on rocks, if they have the right porosity. Check out Mirus’ essay to learn about a fun project you can try in your own freezer.
Golden-crowned kinglets are difficult birds to photograph; they’re tiny (about half the size of a chickadee), are often high up in trees, and they are rarely still for more than a couple seconds. This frenetic movement reflects their high fuel demands; as Kenrick Vezina notes in this Outside Story essay, kinglet metabolisms run high, and in cold temperatures, especially, these birds need to eat constantly. We found a flock of them along some railroad tracks, no doubt gleaning insects or other arthropods from tree buds. A fun fact about these birds: they have “snow tires.” Their bumpy, furrowed foot pads give them extra traction as they hop among trees’ icy twigs and stems.
Finally, we’ve noticed that the wet snow seems to have caused many hop hornbeam trees, a.k.a. iron wood, to shed their dried fruits. These take the form of partially inflated sacs that, in a breeze, slide across the crust of snow, and thereby help to disperse seeds. There’s a post on Mary Holland’s excellent blog, Naturally Curious, that shows how the fruits appear when they’re still arrayed in clusters on the tree. As Holland notes, the ‘hop’ in hop hornbeam’s name refers to its fruits’ resemblances to those of hops, Humulus lupulus, used in beer brewing.
What have you noticed in the woods this week? Submit a recent photo for possible inclusion in our monthly online Reader Photo Gallery.