Beavers are constantly grooming and oiling their fur to waterproof it. Typically when grooming, a beaver sits upright with its tail curled under its body and extended in front of it between its two hind legs. This allows the cloaca (an opening which contains ducts for everything from evacuation to reproduction, plus oil and castoreum glands) to be exposed. The beaver uses its front feet to retrieve creamy-yellow waterproofing oil from its inverted oil glands and then rubs it carefully over all of its body. Without constant waterproofing the beaver’s fur would soon become soaking wet and the beaver would not be able to tolerate the cold water.
On some of the hot days we’ve had recently, my thoughts have turned to Turkey Vultures and their ingenious way of staying cool. They defecate on their legs and the subsequent evaporation cools the birds while strong acids kill bacteria.
Many snakes, including this Common Gartersnake, use smell to track their prey. In the roof of a snake’s mouth are two openings, called the vomeronasal organ, also known as Jacobson’s organ. Snakes smell by sticking their forked tongue in the air, keeping it constantly moving while they collect particles (mostly pheromones) on it from the ground, air and water. Next they pull their tongue back into their mouth and insert it into their Jacobson’s organ (one fork in each opening). Then the particles are analyzed and the snake determines whether prey or a predator is in the vicinity.
Many plants practice “delayed greening” of their leaves, including this Red Maple (Acer rubrum). An initial lack of chlorophyll prevents the leaves from photosynthesizing and making food, which means they have little nutritive value, and thus, appeal, to an herbivore. Most plants that delay greening have reddish leaves due to the presence of anthocyanin, a pigment which appears reddish. A majority of herbivorous insects and invertebrates cannot detect colors in the red range of the color spectrum. Young leaves suffer the greatest predation from invertebrate herbivores. Red leaves would be perceived by these leaf eaters as somewhat dark and possibly dead – not a choice food material. It is possible that the red coloration of new leaves allows the plant to make them unappealing to the herbivores that would otherwise eat them.
American Bitterns have returned to New England from their southern wintering grounds, and are announcing their presence with a unique song that Sibley describes as a “deep, gulping, pounding BLOONK-Adoonk” that they repeat over and over. These secret, well-camouflaged marsh birds are almost invisible as they slowly walk through marsh grasses. When they stand still and point their bill skyward, they are easily mistaken for the reeds they inhabit.
Given the amount of time porcupines spend in trees, it’s not surprising to see that their feet are well adapted for climbing. Long, curved nails that grip the bark, as well as “pebbly” foot pads designed to prevent slipping allow this prickly rodent to climb just about anywhere it wants to. (Hind foot pictured.)
Hepatica, a member of the Buttercup family, is one of the first woodland wildflowers to appear in the spring, sometimes when there is still snow on the ground. It is currently flowering in northern New England, as much as a month earlier than usual. Hepatica’s stem and flower buds are covered with dense, glistening, silvery hairs. Some botanists theorize that these hairs may, in fact, help the plant retain heat during cold March and April days and nights. Others see them as a deterrent to crawling insects, such as ants, which steal their nectar, given the chance — flying insects, including early flies, bees and butterflies, are more efficient pollinators. (Even if Hepatica isn’t visited by insects, it can fertilize itself.) Named after the Greek word for liver (“hepar”),due to its three-lobed, evergreen leaves which resemble the shape of a human liver, Hepatica, also known as Liverwort, was thought to be effective in treating liver disease.
With the warm temperatures this week, mourning cloak butterflies have been seen gliding through the leafless woods. Like eastern commas, question marks and red admirals, mourning cloaks overwinter as adults. They resemble dead leaves so much that from a distance the entire insect seems to disappear. Up close you can see the velvety texture of the wing scales, said to resemble the clothing mourners used to wear; hence, their common name. Mourning cloaks live up to ten months — an impressive life span for a butterfly. As they age, the yellow border of their wings fades to an off-white.
Every fall ruffed grouse grow skin-like fringes called pectinations on either side of each toe. They serve as snowshoes, helping grouse stay on top of the snow when walking, and also help them cling to icy branches while eating the buds of poplars and other trees in the winter. In the spring grouse shed these adaptive fringes. The bird whose foot is in this photograph met its untimely death about a week ago (they frequently fly into windows, as this one did), and I was curious to see the stage of development of the pectinations at this time of year. They appear to be about half to two-thirds the size they will attain when fully developed.
We think of monarch larvae as being impervious to the ills of milkweed, but they are very vulnerable when it comes to the sticky latex in the sap of their host plant. The mandibles of young monarch caterpillars are often glued together by this latex, preventing them from eating. Research shows that about 30 percent of monarch larval loss results from miring in this glue-like substance. One strategy young larvae use is to chew a near circle in a milkweed leaf, blocking the flow of latex to the enclosed surface area, which they then eat. If a monarch survives the first few stages, or instars, of its larval life, it uses yet another strategy to circumvent the latex. Older, larger larvae often cut through the midvein of a leaf they wish to consume, which dams the latex flow to the entire leaf beyond the cut. Look for limp leaves as you peruse a milkweed patch. If you find one, you may be rewarded with the nearby presence of a monarch caterpillar.
In an effort to look even more like a stick, this wingless common walkingstick (Diapheromera femorata), the only species of walkingstick in the northeast, has stretched its front pair of legs out straight in front of it, to either side of its two long antennae. In addition to being very well camouflaged, some species of walking sticks will rock their bodies side to side, resembling a twig swaying in the breeze. Worldwide, walking sticks range in length from an inch to over a foot and are often green or brown. Those in New England are usually about three inches length. Walking sticks are herbivorous, consuming the leaves of trees (often oaks) and shrubs, but we rarely see them, due to their camouflage as well as their nocturnal habits.
Robber flies have been covered in a previous posting, but their beak, or proboscis, deserves its own post, in my opinion. These predators perch and scan the sky for prey. When they see it they anticipate the prey’s direction and speed of flight and fly out and intercept it mid-air. Their objective is to paralyze the prey and liquify its insides so that the fly can drink it. The tip of the robber fly’s beak is covered with microscopic stiff bristles, designed to secure it within the wound it creates. Once this is achieved, a dagger-like shaft hidden inside the beak is used to stab its victim in the head or thorax and inject the paralyzing neurotoxic and digestive enzymes. The resulting fluid is sucked up by the fly’s beak, or proboscis.
If there’s any species that knows how to survive a heat wave, it’s beavers! More at home in water than on land, the beaver can hold its breath for up to 15 minutes, and swim up to half a mile under water. Beavers also have valves in their nose and ears that automatically close when beavers are submerged, and transparent nictitating membranes that act as a third eyelid, covering and protecting their eyes under water.