Field Guide to March 2024

The March Hare

By Rachel McKimmy

Have you ever heard the term “March madness” or perhaps “mad as a March hare”? These phrases may call to mind college basketball or Lewis Carroll’s Alice in Wonderland character, the March Hare; but they actually originate in behaviors displayed during the European Hare’s (Lepus europaeus) breeding season. In March, female hares (does) stand upright and violently fend off male suitors (bucks) with their paws and race their suitors across the countryside during tests of endurance. These “mad” behaviors most likely inspired the Alice in Wonderland character.

Snowshoe Hares (Lepus americanus) in the northeastern U.S. also seem to “go mad” during their breeding season, which lasts from March to July. This March Madness causes violence, with bucks using their powerful back feet to fight—occasionally kicking each other to death—for access to does.

The gestation period for Snowshoe Hares lasts 36 to 37 days, and baby rabbits (known as kits or leverets) are typically born between May and August. Does can produce one to four litters of up to nine kits per year. Interestingly, the number of young that are born may correlate with winter temperatures and the amount of snowfall. As winters continue to warm with less snow accumulation due to climate change, we may see smaller litters being born.

If you happen across signs of Snowshoe Hares this month, please make sure to share your observations with the Vermont Atas of Life on iNaturalist.

Spring Sunbathers

By Kent McFarland

Whether or not it comes in like a lion, March sometimes heads out like a butterfly. On bright sunny days in late March, when the sun’s rays bring warmth to the forests, you may spot one of the season’s first butterflies on the wing. Unlike most spring butterflies, these aren’t freshly emerged from a chrysalis. Instead, these early spring butterflies have been tucked away in cracks and crevices where they pass the winter months in a state of torpor. Species like the Milbert’s Tortoiseshell, Mourning Cloak, and Eastern Comma utilize this strategy to survive the winter and are the first butterflies seen out and about once the sun has warmed their wings. With no nectar available this early in spring, these butterflies are instead on the hunt for mates. You can add all of your butterfly sightings to eButterfly.

On those fleetingly warm, sunny days in March, you may also encounter a Painted Turtle, newly emerged from its winter hideaway under lake or pond ice. These hardy turtles’ body temperature averages just 43 F all winter long. To be active, they must raise their internal body temperature to 63–73 F. They achieve this by basking on logs, rocks, and other exposed surfaces. Basking not only warms up turtles but also helps them capture Vitamin D from the sun to metabolize calcium needed to grow and solidify their shells. As temperatures are prone to shift rapidly in March, Painted Turtles often can’t maintain this temperature for long and may not eat until May brings steadier warmth. March is a dangerous time for turtles, and mortality is high during the early spring when they are living on the energetic edge of life. If you spot any early, shelled sunbathers this month, be sure to report them to the Vermont Reptile & Amphibian Atlas.

Bugs in Buckets

By Spencer Hardy

March in Vermont is a unique time, highlighted by some of the best skiing and worst roads. However, nothing says March in Vermont better than sugaring. With metal buckets lining dirt roads and sugar shacks billowing steam, it seems everyone is celebrating spring’s return and all the sweetness it brings. And people aren’t the only ones—many other animals take advantage of this short-lived sugar source. Chickadees are occasionally seen picking at icicles on broken maple branches, and towards the end of the season, sap buckets can become very effective bug traps. An informal survey found at least eight different arthropod families (plus an unfortunate deer mouse) in sap buckets, with Winter Fireflies (Ellychnia corrusca) and Cutworm Moths and Allies (Family Noctuidae) being the dominant groups.

Mining bees (genus Andrena) are another group that appears to be fond of tree sugar. This group is one of the first to emerge in the spring, sometimes while there is still patchy snow cover. As with many solitary bee species, male mining bees tend to emerge a few days before the females. Human sugaring practices provide these bees with easy access to tree sugar around the time they emerge. However, humans aren’t the only mammals that provide this service—check out this awesome iNat observation to learn more.

Keep an eye out for bees and other insects on freshly cut maples (and in sap buckets) in late March and early April. Let us know what you find by sharing your observations to the Sap Suckers iNaturalist project! We would love to know how widespread this phenomenon is and what species are involved.

Skunk Oil: A Little Goes a Long Way

By Kent McFarland

There is nothing like the fresh smell of a spring morning—unless a skunk skulked about your neighborhood overnight. The Striped Skunk is armed with just a teaspoon of odiferous oil in its two anal glands, but a little bit goes a long way. These smelly yet charming mammals have recently begun emerging from their winter burrows, increasing your chances of catching a whiff of one nearby.

Skunk oil research has been going on for over a century as scientists have tried to determine what makes the stuff so potent that it can drive a bear away. Way back in 1896, Thomas Aldridge at Johns Hopkins University showed that humans could detect the smell at just 10 parts per billion, the equivalent of detecting just one drop of it diluted into a medium-sized backyard swimming pool. More recently, William Wood, a chemist from Humboldt State University, pointed out that a number of chemicals have been incorrectly attributed to skunk oil over the years, and his work has now given us a fairly complete understanding of the chemical compounds and how to neutralize them.

The scent-gland secretion is a yellow oil composed primarily of volatile compounds known as thiols and their derivatives. (A thiol is a compound distinguished by its sulfur-hydrogen bond.) Most of us immediately recognize the smell of ethanethiol (also called ethyl mercaptan), a common thiol added to otherwise odorless propane gas so we can easily smell propane leaks. Another thiol creates the “skunky” smell of beer after exposure to ultraviolet light. The thiol derivatives in skunk oil are not particularly strong on their own; however, they are easily converted to far more potent thiols when they react with water.

Skunks are reluctant to use the oils, though. With only enough for a half dozen sprays at most and a 10-day period to manufacture more, skunks will only spray if they absolutely have to. In an attempt to avoid spraying, skunks often give warnings. First, they show their striped white back to warn you. This is followed by threat behaviors, like stomping with both front feet, sometimes charging forward, and then edging backward, dragging their feet, and hissing. If all this fails, watch out.

Each spray gland has a nipple, and skunks can aim and direct the spray using highly coordinated muscles. A skunk can spray up to 25 feet and hit something fairly accurately up to seven feet away. When there is a target, they can direct a fine stream right at the victim’s face. When being chased, a skunk will instead emit a foul cloud for the predator to run into.

One predator remains undeterred by the pungent oil: the Great-horned Owl. The small size of the olfactory lobes in their brains suggests that they have a very poor sense of smell. Some individual owls can downright stink of skunk, a common complaint among wildlife rehabilitation workers. Their nests can even smell of their musky meals. But larger-lobed mammals quickly learn to avoid the white stripe in the night.