This week in the woods, turkey vultures have soared, trout lily leaves have started to poke up, song sparrows have been singing, and aspen and red maple have flowered. This caddisfly larva – scooped from the edge of a thawing pond for observation before getting returned to the water – has built its case with its own silk and vegetal materials gathered from the immediate environment. Caddisflies’ cases, which protect against predators and aid in navigation and staying put under water, vary in style between caddisfly species (more than 1,500 recorded in North America) but also between individuals. Cases have tubular, pyramidal, or domed shapes and materials as varied as twigs, leaves, sand grains, pebbles, snail shells, and even other caddisfly cases. After making it through the winter as active larvae, most caddisflies will pupate and emerge as adults later in spring. Found in a variety of aquatic environments from lakes and streams to vernal pools, caddisflies depend on fresh, clean, cold water for food and oxygen and can serve as indicators of water quality.
A red fox and eastern coyote both made appearances within days of one another on a field abutting a forest in Vershire, Vermont. The red fox exhibited “mousing” behavior – using its keen hearing to listen for rodent activity under the last of the subnivean zone’s melting snow before taking a flying leap toward the sound and trying to come down atop the vole or mouse. Coyotes also hunt in this fashion, and both species can jump as far as 15 feet. However, as Todd McLeish reported in the Winter 2014 issue of Northern Woodlands, only red foxes seem to use the Earth’s magnetic field as a kind of range finder.
An opportunist and relative newcomer, the eastern coyote has colonized much of the Northeast since the 1940s and become the region’s top predator in the void left by wolves and mountain lions. While we saw the two overlap in this clearing, coyote and fox populations often have inverse relationships, with high coyote density tending to limit both the distribution and overall numbers of foxes. In part because of the eastern coyote’s mix of dog and wolf DNA, the canine hybrid has grown larger than the western coyote. (This particular individual’s heft has to do in part with its winter coat but could also have to do with pregnancy; most females breed in years with ample food supply, give birth between March and May, and can expect an average of six pups per litter.)
We tend to see mourning cloaks – like this one photographed by Ann Little – earlier in the year than most other butterflies because they have overwintered as adults, reducing the water in their bodies and producing antifreeze agents to endure the cold. With the melt, they emerge from tree cavities and furrowed bark and bask in the sun, the darkness of their chocolate-brown wings helping absorb heat. With so few flowers blooming and less nectar available for food at this time of year, mourning cloaks feed on tree sap and last fall’s rotten, unclaimed fruit that has begun to thaw. One of our longest-lived butterflies, mourning cloaks can sometimes survive for an entire year.
What have you noticed in the woods this week? Submit a recent photo for possible inclusion in our monthly online Reader Photo Gallery.